COMPARATIVE SEED ECOLOGY OF NATIVE AND ALIEN PLANTS OF OPEN UPLANDS

Christopher Sean Blaney

A thesis submitted in conformity with the requirements for the degree of Master of Science

Graduate Department of Botany University of Toronto

O Copyright by Christopher Sean Blaney 1999

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COMPARATNE SEED ECOLOGY OF NATIVE AND ALIEN PLANTS OF OPEN UPLANDS

Master of Science 1999

Chnstopher Sean Blaney

Department of Botany

University of Toronto

Plant invaders may gain an advantage over natives because only enemy-free species are likely

to invade (the predator filter hypothesis), or because invaders lose enemies while moving to a

new area (the predator escape hypothesis). Working at the Joker's Hill Field Station, near

Newmarket. Ontario, 1 bave combined site descriptions, surveys. and experiments to

investigate the role of predaton and pathogens in seed ecology, and to understand their role in

the establishment and spread of exotic species.

Results indicate that seeds of both natives and exotics suffered significant losses to above-

ground predators and below-ground pathogens. Losses vaned among species and habitats;

wrtlands had particularly high levels of fungal mortality. Aliens and natives did not

consistently differ in their susceptibility to predators and pathogens, even when analyzed using

methods that controlled for phylogenetic biases. These results suggest natural enemies of seeds

do not as a general rule determine invasive ability.

ACKNOWLEDGEMENTS Many people contributed to making my time as a Master's student enjoyable and rewarding, and

1 will do my best to recognize them al1 here. To those 1 have left out, my apologies, 1 am wnting

this just hours before I have to submit, but to everyone my deepest thanks.

First and foremost 1 should recognize the efforts of my supervisor Professor Peter Kotanen, who

was unceasingly attentive to my needs and generous with his tirne, advice and funding. 1 could

not have completed this project without his help. He has gone well above the effort required of a

supervisor and has taught me a great deal. 1 feel privileged to have worked with him as a student

and as a friend. 1 have also benefitted greatly from the guidance and suggestions of al1 of the

mernbers of n ~ y supervisory cornmittees, which have included Profesors David Wedin, Spencer

Barrett. Robert Jefferies and Gary Sprules. Aside from my committee, Professor Linda Kohn

provided advice on a nurnber of issues related to soi1 fungi, and Professor Peter Bal1 was always

ready to assist in the identification of tricky plant specimens. Interactions with many student

colleagues have helped shape and sharpen rny academic skills as well providing happy

diversions. Che Elkin. Marc Johnson, Luc Bussiere, Brendon Larson, Patrick Lorch, Andrea

Case and rny fellow seed bank afficionado Esther Chang deserve special mention in this regard.

Jutta Stein, Greenhouse Technician at the University of Toronto at Mississauga deserves

pürticular individual recognition. She went to great efforts to ensure my plants survived in the

greenhouse. She always made space for my odd assortment of rather weedy specirs, even when

they were spreading into ber pots. Her efforts not only allowed me to complete my thesis, but

also enabled me to confidently have a life on weekends, knowing the crucial plants were well

taken care of.

My work was aided substantially by the numerous field and laboratory assistants, paid and

unpaid, who spent time in the Kotanen lab - Michelle Tseng, Sonya Carl, Arthur Poon, Joel

Sotomayor, Sandra Benvenuto, Sheenagh Bell, Bill Kilburn, Carl Rothfels, Vijanti Ramlogan,

Reagan Szabo, Marc Johnson and Uyen Dias. Not only did they offer able assistance on many

difficult and repetitive tasks, they left me with many of my best, lasting memories of my time at

Erindale.

At the Joker's Hill field site, property manager William Fox was always available when needed

and was generous with the sites resources. The donors of the property, Murray and Marvelle

Koffler should also be recognized. They have given the University of Toronto a unique gift, the

value of which it is only just beginning to fully recognize. The Joker's Hill property is a rare

jewel in the southem Ontario landscape and was a joy to work at.

I would also like to recognize my parents, who first inspired my love for the natural world and

who have always been entirely supportive of my interests. Finally. to Becky Whittam, who has

been my most important source of encouragement, sympathy. sustenance (literal and spiritual)

and serene working conditions in the difficult tirnes leading to thesis completion. I thank you for

your love and patience.

TABLE OF CONTENTS

Contents

ABSTRACT ACKNOWLEDGEMENTS TABLE OF CONTENTS LIST OF TABLES LIST OF FIGURES CHAPTER 1 - General Introduction

Overall Introduction Biological Invasions Seeds and Their Enemies Predator Escape and Predator Filter Hypotheses The importance of phylogeny Old Fields Objectives

CHAPTER 2 - Vegetation of Joker's Hill Introduction

Site overview

Landfons and early human history of Joker's Hill

Native plant communities: The historie setting

Old fields: The study system

Survey Methods The local species pool: Overall vascular plant species

Species presence and abundance for main tkld sites

Seed bank estimation for main field sites

Results and Discussion Overall vascular plant species pool

Rare native plant species

Species presence and abundance at main field sites

Seed bank estimation for main field sites

Conclusions

Page

Contents - Pape CHAPTER 3 - Experimental Survey of Native and Alien Seed Mortality 36

Introduction 37 Methods 40

Study site 40

Experimental S pecies 4 1

Treatments 44

Soi1 srtrfnce seed predatinn experiment 44

Seed bank mortalin, experiment 45

Analysis 46

Resu l ts 47

Soi1 surface seed predation experiment 47

Seed bank mortality experirnent 53

Discussion 72

Soi1 surface seed predation 72 Predator iden tity 7 2

O v e r d seed rernovcrl 7 2

Patterns in trentmerrt efects 74

Seed bank mortality experiment 75

Fwzg i d e addition 75

I n vzrrebrate e.rclusion 76

Tenzporal pattern in seed recovery 77

Treatment efsecrs vs. seed size 78

Twonomic pattenz 78

Aliens vs. Natives 79

Contents Pape CHAPTER 4 - Comparative Experiments on Fungal and Habitat

Effects on Seed Bank Mortality Introduction Methods

Study site

Experimental Species

Treatments

Analysis

Results Overüll seed recovery

Overall effects of fungicide addition

Variation in seed recovery between species

Variation in recovery by origin

Discussion Does fungal mortality influence seed persistence in the soi1 seed bank?

Do seed recovery and fungal mortality vas, between wetland and

upland meadows?

Does fungal mortality V a r y betwren closely related natives and alirns?

CHAPTER 5 - General Conclusions Achievernent of thesis objectives

a) to provide background information on the site and biological

setting of the experiments

b) to determine whether seeds suffer significant losses to predators

before incorporation into the seed bank

C) to deterrnine whether seeds suffer significant losses to seed predators

and uathooens in the seed bank

Contents Page CHAPTER 5 (cont'd)

d) to discover whether seed losses to naturd enemies differ among species

e) to determine whether seed losses to natural enemies differ between habitats

f) to determine whether seeds of native and alien species differ in their susceptibility to natural enemies

g) to determine whether differences in seed losses between natives and aliens occur independent of their phylogenetic

relationship

Limitations of the work General Conclusions

LITERATURE CITED

APPENDIX 1 - Vascular Plants of Joker's Hill APPENDIX II - Rare Native Vascular Plants of Joker's Hill APPENDIX III - Birds of Joker's Hill APPENDIX IV - Mammals of Joker's Hill APPENDIX V - Reptiles and Amphibians of Joker's Hill

104

1 O4

105

105

1 O5

1 O6

1 O7

1

XX XXI 1

XXVI XXVII

vii

LIST OF TABLES

Table 2.1.

Table 2.2.

Table 2.3.

Table 2.4.

Table 2.5.

Table 2.6.

Table 3.1.

Table 3.2.

Table 3.3.

Table 3.3.

Species present at Dead Man's Curve and Wet Meadow field sites, within

the area of the Kotanen plots.

Abundance of species found in intensively sampled plots at Dead Man's

Curve field site.

Abundance of species found in intensively sampled plots at Wet Meadow

field site.

Geninable seed banks (mean seedslm2 2 SEM) from top and bottoni

halves of cores from Dead Man's Curve and Wet Meadow field sites,

fall 1997 and spring 1998 trials.

Garminable seed bank (mean seeds/m2 to IO cm depth t SEM) at the

Dead Man's Curve field site, fdl 1997 and spnng 1998.

Germinable seed bank (mean serdslrn2 to I O cm depth - SEM) at the

Wet Meadow field site, f d l 1997 and spring 1998.

Experimental species for seed bank mortrility and soi1 surface seed

predation experiments, indicating presence on Joker's Hill research

station property, and at the Dead Man's Curve research site.

Resuks of seed predation experiment: Mean proportional seed recovery

+. SEM.

Results of 3-factor randomized block factorial ANOVAs on overall,

nativeand alien data from seed predation experiment.

Seed predation experiment; vertebrate exclosure and invertebrrite

e~closure effects on seed recovery by species, with seed weights.

viii

Table 3.5.

Table 3.6.

Table 3.7.

Table 3.8.

Table 3.9.

Table 3.10.

Table 3.1 1.

Table 4.1.

Table 4.2.

Table 4.3.

Table 4.4.

Proportions of total seeds in each trial recovered as seedlings in the field

and by germination in the greenhouse in the seed bank experiment.

Results of 3-factor randomized block factorial ANOVAs on overall data

(native + alien), native data and alien data for 4 month trial of the seed

bank experiment.

Resul ts of 3-factor randomized block factorial ANOVAs on overall

data (native + alien), native data and alien data for the 1 i month trial

of the seed bank experiment.

Results of 3-factor randomized block factorial ANOVAs on overdl data

(native + alien), native data and alien data for the 14 month trial of the of

seed bank experiment.

Results of four month trial of seed bank expenment: Mean percentage

seed recovery corrected for soil losses, by treatment and species, A SEM.

Results of l 1 month trial of seed bank experiment: Meaii percentage seed

recovery corrected for soil losses, by treatment and species, I SEM.

Results of 16 month trial of seed bank expenment: Mean percentage seed

recovery corrected for soi1 losses, by treatment and species, I SEM.

Experimental species for the seed bank - habitat expriment, indicating

presence on Joker's Hill research station property.

Results of 2-factor randomized block factorial ANOVAs (fungicide

treatment x species) on recovery data for the upland and wetland trials

of the seed bank - habitat experiment.

Mean * SEM percentage seed recovery, by treatment and species: Seed

bank - habitat experiment, upland trial.

Mean t SEM percentage seed recovery, by treatment and species: Seed

bank - habitat experiment, wetfand trial.

Table 4.5. Results of 3-factor randomized block factorial ANOVA (fungicide

treatment x origin x genus) on the recovery data for the upland trial of the

seed bank - habitat expriment. 94

Tabk 4.6. Results of PIC ANOVAs (fungicide treatment x genus) on native vs. dien

contnst data for the upland and wetland trials of the seed bank - habitat

expriment.

LIST OF FIGUWS

Fipure Ti tle Pape

Figure 2.1

Figure 3.1.

Figure 3.2.

Figure 3.3.

Figure 3.4.

Figure 4.1.

Map of Joker's Hill property . 14

Ovenll results of the above-ground seed predation experiment: Proportion

of seed recovered in controls and predator exclusion treatments.

Results of the four month trial of the seed bank experirnent. by mcthod of

recovery (germination in field and germination in greenhouse). Proportion

of seeds recovered are corrected for physical losses. Results are given for

all species, for native species only and for aiien species only. 63

Results of the 1 1 month trial of the seed bank experiment, by inethod of

recovery (germination in field and germination in greenhouse). Proportion

of seeds recovered are corrected for physical losses. Results are given for

al1 species, for native species only and for alien species only. 64

Results of the 16 month trial of the seed bank experirnent, by method of

recovery (germination in field and germination in greenhouse). Proportion

of seeds recovered are corrected for physical losses. Results arc given for

al1 species, for native species only and for alien species only.

Results of seed bank - habitat experiment; proportion of seed recovered in

upland and weiland habitats, for native and alien species, under control

and fungicide addition treatrnents.

CHAPTER ONE

GENERAL INTRODUCTION

CHAPTER 1 : GENERAL INTRODUCTION

Overall introduction As the primary means of reproduction and dispersal for most plants, seeds are a fundamental pan

of most plants' life cycles. A vast literature exists covenng seed biology, both in ecology and in

a wide range of other disciplines. Nonetheless, some aspects of the field ecology of seeds are not

well understood. Most seeds are small and their fates are hard to follow once they leave the

parent plant. This is unfonunate since it can leave a vast proportion of a species' total mortality

as an unknown. With this gap in the understanding of plant population demography, questions

about the extent to which seed pathogens and predators structure plant communities and the

utility of seed ecology in providing useful predictors of plant invasion are difficult to answer

The general goal of this thesis is to investigate the role of natural predators and pathogens in sced

ecology, and in particular to understand their role in the establishment and spread of exotic

species. In the pages ahead, these themes will be more fully developed

Biological invasions Exotic, or alien species are those species which have arrived at an area outside their natural range

with deliberate or unintentiond human assistance (Elton 1958. Baker 1974, Groves and Burdon

1986, Mooney and Drake 1986, Drake et al. 1989, Py Sek et al. 1995, Mack 1996, Williamson

1996). Today few, if any, regions are free of alien species, and the frequency of biological

invasions continues to increase with human alteration of natural ecosysterns and the increasing

global interdependence of economies (Dicastri 1989, Viiousek et al. 1996). Vascular plant

invaders are especially numerous (Pyiek et al. 1995, Cronk and Fuller 1995). For examplc.

Heywood ( 1989) estimates the introduced vascular flora of Australia at 1500 - 2000 species.

Kent ( 1992) lists 1 189 established alien species in the British Isles and Scoggan ( 1978) lists 88 1

alien species in Canada. The first alien plants reached North America with the earliest European

settlement. Whitney (1994) cites early records showing that at Ieast 40 species of European

weeds were established around settlements in Massachusetts in 1672, with numbers rising to 140

species in the Boston area by 1840. Today, alien species generally make up 25 to 35% of local

floras in northeastern North Amerka (Whitney 1994), with higher percentages in heavily

urbanized areas. The proportion of aliens continues to increase as new invaders arrive. Additions

to the Ontario weed fiora are made every year (e.g., Blaney, Oldham and Reznicek 1997,

Oldham 1998, 1999) and the rate of invasion may be increasing, as has been suggested for

Illinois (Henry and Scott 198 1).

lnvading species can profoundly alter ecosystem processes, structure and composition, posing

CHAPTER 1 : GENERAL lNTRODUCTlON

serious concerns for the conservation of native species and often costing millions of dollars in

remediation and control efforts (e.g., Heyligers 1985, Vitousek 1986, Vitousek et al. 1987,

Braithwaite et al. 1989, Hughes et al. 1991, Mack and D'Antonio 1998). Although consequrnces

of some biological invasions can be ecologically devastating. most arriving plant invaders never

become established, or have no noticeable impact if they do (Williarnson and Fitter 1996a,

1996b). The potential for alien species to have major negative impacts and the substantial

variation in invasiveness between even closely related species has stimulated a grcat deal of

interest in the liteature. Many researchers since the 1950s have attempted to develop generül

rules to help predict which species will make successful invaders (e.g., Elton 19%. Baker 1974,

Groves and Burdon 1986, Mooney and Drrike 1986, Drake et al. 1989, Pimm 1989, Mack 1996,

Williamson and Fitter 1996a, 1996b) and which communities are susceptible to invasion (e.g.,

Crawley 1987, Mack 1989, Rejminek 1989, Groves and Dicastri 199 1). These efforts have

produced few, if any, rules with strong predictive value (Perrins et al. 1992. Lodge 1993, Mack

1996). One reason for this lack of success is the fact that aliens are extremrly diverse. Rules

demonstrated to apply to one group (Le. the genus Pinus, Rejminek 1995) may fail when applied

to other groups. Another reason for the difficulty in developing a predictive ecology of invasions

may be the methods used to derive the predictions. Early efforts tended to involve single-species

case studies or generalization based on analyses of successful invasions. without much

observation of unsuccessful invasions, or resistant communities (Burke and Grime 1996) or

studies of mutiple species. Some recent studies have used statistical analyses of large species

pools to correlate plant traits with invasion across taxa (e.g., Mazur 1989, Scott and Panetta

1993, Crawley, Harvey and Purvis 1996, Kotanen, Bergelson and Hazlett 1998) but there ;ire still

very few explicit, experimental tests of hypothesized rules about plant invaders. As Burke and

Grime (1996) state, "There is now an urgent need for the initiation of field experiments that test

some of the more important invasibility hypotheses that have been gencnted from the study of

past case histones."

Seeds and their enemies Many species suffer the majority of their mortality at the seed stage (Roberts and Feast 1972,

Harper 1977, Cook 1980, Cavers 1983). Seed predation has been studied extensively and is well

surnrnarized in several reviews (Thompson 1987. Louda 1989b, Crawley 1992; Chambers and

MacMahon 1994). Patterns of seed mortality may be important in deciding the distribution and

fate of plant populations (Janzen 1972, Grubb et al. 1982, Howe et al. 1985). and the results of

interactions between competing species can be decided by the relative mortality patterns of their

seeds (V.K. Brown et ai. 1987. Louda 1989a). Crawley ( 1992) suggests that pre-dispersal and

post-dispersal seed predation have a number of contrasting features. The predator taxa involved

overlap. but host-specific insects are often important in pre-dispersal predation, while post-

dispersa1 seed predators are mostly genenlists with respect to the seed species consumed.

Studies of post dispersal predation in North American and Old World deserts have shown that

their comrnunities of obligate granivore taxa, especially rodents and ants, produce intense

predation with very strong cornmunity level effects (Reichman 1979. Abramsky 1983. Parmenter

et al. 1984, Heske, Brown and Guo 1993). Tropical forests have also been well studied.

especially with reference to seed predation risk relative to dispersal distance. Seed beetles

(Bruchidae; Janzen 1972, 1975) and seed bugs (Lygaeidae; Howe et al. 1985) have been shown

to severely restrict seed survival near the parent tree in tropical forests. In old fields in

northea~em North America. post dispersal seed predation is generally less intense. The ants,

rodents and birds which eat seeds are mostly facultative granivores which may switch to other

food sources in the summer (Mittelbach and Gross 1984. and references therein). Post dispersal

seed predation may still exert an influence on species' distribution and abundance in old fields

(Reader 1993, Hulme 1994). In old fields vertebrates are generally more important predators

than anis (Mittelbach and Gross 1984, Hulme 1994), at least for the larger seeds (Thompson

1987). Factors such as predator identity, seed abundance and dispersion and nutritional value cm

al1 affect the cntical size below which seed predation by birds and mammals is reduced. Studies

by Kelrick et al. ( 1986), Mittelbach and Gross (1984) and Reader ( 1993), however, suggest that

seeds below 1 to 3 mg tend to escape predation by a wide range of vertebrates.

Those seeds not consumed by predators immediately after dispersal become part of the soi1 seed

bank. Seed banks Vary in size between habitats (Roberts 198 1, Thompson 1987, Leck et c d . 1989.

Baskin and Baskin 1998), with differences retlective of patterns of addition and loss from the

seed bank. Input to the seed bank is only through seed rain, but the magnitude of seed rain alone

does not necessarily retlect the size of the persistent seed bank in a comrnunity. Species

composition is an important determinant of a community's seed bank size because seed min and

the intrinsic capacity for long term persistence both vary widely across species (Crawley 1997,

Baskin and Bmkin 1998). The value of long terni seed banking for a plant species varies with its

life history and the regularity of opportunities for reproduction. Thus longer lived species with

relatively constant opponunity for recruitment are less likely to produce large, long term seed

banks than are short Iived plants in habitats which experience wide tluctuations in abiotic

conditions, though exceptions to these generalities are also numerous (Baskin and Baskin 1998).

In addition to the intrinsic seed longevity of a cornmunity's species, extrinsic factors will

influence seed bank composition and abundance. primarily by affecting the rate of seed loss from

the seed bank. tosses from the seed bank occur in one of two main ways. Seeds rnay be killed

CHAPTF.R 1 : GENERAI. WTRODUCTION

by predators, pathogens or chernical deterioration or they rnay germinate. These factors are in

tum controlled by predator and pathogen abundance and by abiotic conditions, such as rnoisture

and temperature regime (Cavers 1983, Chambers and MacMahon 1994). Seed distribution in the

soil column and germination are also strongly influenced by soil disturbance in many

communities (Leck et al. 1989). Thus seed banks in communities with similar species

composition c m still Vary substantially if germination or seed mortality differs, as with the

increased fungal mortality associated with moist microclimates in tropical forests (Augspurgrr

and Kelly 1984).

In addition to the intrinsic seed longevity of a community's species, extrinsic factors will

influence seed bank composition and abundance, p r i m d y by affecting the rate of seed loss from

the seed bank. Losses from the seed bank occur in one of two main ways. Seeds rnay be killed

by predators, pathogens or chernical deterioration or they rnay germinate. These factors are in

tum controlled by predator and pathogen abundance and by abiotic conditions, such as moisture

and temperature regime (Cavers 1983, Chambers and MacMahon 1994). Seed distribution in the

soil column and germination are also strongly influenced by soil disturbance in many

communities (Leck er al. 1989). Thus seed banks in cornmunities with similar species

composition can still Vary substantially if germination or seed mortality differs, as with the

increased fungül mortality associated with moist microclimates in tropical forests (Augspurger

and Kelly 1984).

For species with long term seed banks, this stage may actually be where most mortality occurs

(Cavers 1983, Chambers and MacMahon 1994). Despite the potential importance of seed bank

mortality (Cavers 1983, Cavers and Benoit 1989, Crawley 1992, Chambers and MacMahon

1994, Baskin and Baskin 1998) there is strikingly little experimental work examining its causes

in natural systems. Pathogens are often suggested to be important and there are a number of

reasons to believe that fungi may be an important source of mortality for seeds in soil seed banks

in natural habitats. Soi1 fungi are ubiquitous, abundant and include many important decomposers

with the ability to secrete extracellular cellulase and proteolytic enzymes (Crist and Friese 1993).

Many fungal plant pathogens, including some which can have significant community level

effects (Kliejunas and Ko 1976, von Broembsen and Kruger 1984. Augspurger and Kelly 1984)

are also soil borne (Garrett 1970). Additionally, the importance of fungicidal seed coatings in

agriculture (Taylor and Harman 1990), the fungal scarification of some seeds with hard seed

coats (Gogue and Emino 1979, van Leeuwen 1981, Guttridge et al. 1984) and the presence of

fungal-inhibiting compounds in seed coats (references for 8 species given in Baskin and Baskin

1998) d l suggest that fungi are likely to be an important source of seed mortaiity in soil. A few

CHAPTER 1 : GE- PJIXODUCTION

studies in the ecological literature do provide evidence of fungal degradation of seeds in soil.

Crist and Friese (1993) found that proportions of decomposed seeds among 5 shrub-steppe

species ranged from <5% to 93.5% over 10 rnonths. They implicated fungi as a causal agent by

isolating 7 fungal species from the retrieved seeds. Lonsdale (1993) specifically demonstrated

increased seed survival after experimentally reducing soil fungi in a natural cornmunity. finding

that fungicide addition resulted in a 10-16% increase in seed survival for Mimosa pigra in

northem Australia.

Although the ecological literature is rather deficient in its examination of fungus-induced seed

rnortality, the plant pathological literature, especially that which relates to agriculture. contains

an abundance of information on fungi isolated from particular seeds (e.g. Neergaard 1977, Ginns

1986) and on the effects of anti-fungal treatments on crop germination, survival and yield

(Torgeson 1969, Sharvelle 1979, Sinha et al. 1988).

Damping off diseases caused by fungi are known to be a major source of mortality at the seed

and early seedling stages in crops with some evidence that this may be a general phenornenon in

natural habitats as well. Damping off disease organisims are extremely common and widespread

in zones of moist tropical and temperate climate worldwide and have major agricultural and

ecological impacts in a range of habitats (Kliejunas and Ko 1976, von Broembsen and Kruger

1984. Augspurger and Kelly 1984, Manners 1993, Blakeman and Williamson 1994. Lucas

1994).

Broadly defined, dûrnping off disease can refer to both seed and stem rots of plants at al1 life

stages (Agrios 1978). The stricter definition in more common usage is, "...destruction of

seedlings near the soil line, resulting in the seedlings falling over on the ground" (Agrios 1978).

The relatively rapid deterioration and disappearance of seeds and seedlings affected by damping

off means that specific, focussed effort at disease detection may be required in studies on fungal

seed and seedling mortality. The fungal species involved in damping off are primarily

generalists with a very broad range of host plants recorded (Manners 1993, Blakeman and

Williamson 1994, Lucas 1998). Ginns (1986) reviews host records of plant pathogenic fungi in

Canada, listing damping off organisms associated with a number of the study species of Chapters

3 and 4.

The pathogens most commonly associated with seed rots and other damping off diseases are

summarized in Agrios (1978). He lists members of Oomycota (Pythium spp., Phytopthora spp.),

CHAPfER 1 : G E N E W INTRODUCTION

Basidiomycota (Rhizoctonia solani and other Rhizoctonia) and lmperfect members of the

Ascomycota (Botrytis spp.). Often, the same fungal genera or species associated with seed rots

are known to cause a diverse range of other plant pathologies of roots and above ground plant

parts (Agrios 1978, Manners 1993, Blakeman and Williamson 1994, Lucas 1998). Moisture

level in the soi1 is one of the major factors influencing which of the above pathogens are likely to

be prevalent. The Oomycota, now considered to be only distantly related to the t u e fungi, have

flagellated zoospores, making them more water dependent than tme fungi (Kendrick 1992).

They are likely to be the predominant seed pathogens in very moist soils (L. Kohn, pers. comm.).

Predator escape and predator filter hypotheses

The crucial role seeds play in reproduction and dispersal for most plants means that

understanding seed ecology is especially important in developing an understünding of the füctors

that control the success of invading species. Significant differences in seed weight and

persistence between invasive and non-invasive or native and non-native species suggest that seed

biology rnay be useful as a predictor of invasiveness, both within narrow taxonornic groups

(Rejminek 1995) and across entire floras (Mazur 1989, Crawley. Harvey and Purvis 1996).

Crawley, Harvey and Purvis (1996) found that British aliens were more likely than natives to

have long term seed banks and Rees and Long (1992) found that 75% of species undergoing

range expansion in Bntain (both native and alien, but skewed towards aliens) produced long tem

seed banks. Sirnilarly, almost al1 of the world's worst weeds listed in Holm et al. ( 1977) produce

substantial seed banks. The link between seed banking and invasions is a logical one. Seed banks

are known to be important in buffering against poor reproductive years and the stochastic events

which can wipe out small populations. Most invaders would repeatedly face these barriers during

establishment (Baker 1974, Grime 1979, Keddy and Reznicek 1982, Rees and Long 1992) and

spread (Barrett and Richardson 1986, Barrett and Husband 1990). The presence of a long term

seed bank is also suggested to be one of the most important factors limiting the effectiveness of

seed predators in biological weed control (Holloway 1964, Dahlsten 1986).

One frequently proposed hypothesis is that invaders succeed because they experience lower

levels of pathogen and predator attack than do natives. There are two distinct reasons that aliens

rnight enjoy lower rates of seed loss than natives. Both of these hypotheses argue that a low Pest

load is important to invasion. The distinction lies in the mechanism causing this low load. First,

invaders may lose their natural enernies when they are transponed to a new area (the predator

escape hypothesis: Elton 1958, Crawley 1986). Second, perhaps species with intrinsically low

rates of seed predation make better invaders because they are less likely to be eliminated by

natural enemies in their new habitat (the predator filter hypothesis). These two hypotheses are

CHAPTER 1 : GENERAI, INTRODUCTION

difficult to distinguish, but the escape hypothesis predicts that invaders should have lower Pest

loads in new habitats, while the filter hypothesis predicts that pest loads are equally low in both

original and new areas. As well, the escape hypothesis refen primarily to the loss of species-

specific enemies. while the filter hypothesis is more likely to apply to generalist enemies.

There is some supporting evidence for both hypotheses. The strong host specificity of many plant pathogens and predators (Harper 1977, Dinoor and Eshed 1984. Crawley 1992) suggests

the potentid importance of predator escape for plants arriving in new regions. Most alien plants.

excepting ornamental species. are probably introduced as seed, rneaning that that certain types of

predators and pathogens are unlikely to have arrived with them. It should be noted, however, that

fungal and other pathogens are often transported on seeds (Neergaard 1977. Agarwal and

Sinclair 1997), so invaders may be less likely to escape from specialist seed-borne pathogens.

The concept of predator escape is fundamental to biological control effons. which often attempt

to replace "lost" predators. Certain spectacularly successful biological control efforts. as with

Opiimia species in Australia (Mann 1970) and South Africa (Zimmermann et al. 1986), and

Hypericum perforarurn in California (Huffaker and Kennett 1959) strongly suggest it to be true

for some plant invaders. However, the fact that rnost biological control effons fail (Crawley

1986) suggests that these examples may not be typical. Further evidence links predator escape at

the seed stage to invasiveness. Some invaders have been shown to develop larger seed banks in

new regions than in their native habitats. Lonsdale and Segura (1987) found that seed banks of

~Minlosa pigra were approximately 100 times larger in Australia than in its native range in

Mexico. Research in coastal shrublands in Mediterranean climate zones of Australia and South

Africa (Weiss and Milton 1984) has shown that seed banks of the reciprocally invasive Acacia

longiJoliu (native to Australia) and Chrysanrhemoides rnonilifera (native to South Africa) were

increased 44 and 13 16 times in new regions.

There has been less investigation of the idea that species subjected to low Pest loads make better

invaders; however, the evidence that sorne cornrnunities resist invasion (e.g., Pimm 199 l), points

to the possibility that the predator filter hypothesis may apply in sorne cases. Additionally,

correlations between seed size and predation rates, and between seed size and invasiveness

(Crawley, Harvey and Pagel 1996) suggest that native and alien species may have intrinsically

different rates of generalist predation, as predicted by the filter hypothesis.

The importance of phylogeny Native and alien species within the floras of particular areas invariably have different taxonornic

distributions (Heywood 1989, Crawley, Harvey and Pumis 1996). This can lead to problems of

ÇHAPTELGENERAL INTRODUCTION

interpretation when considering differences between natives and aliens using correlation across

numerous species. Analyses of phylogenetically independent contrasts (PICs) can help to clarify

the results obtained by correlational methods. PICs can detect relatively subtle native-alien

differences which othenvise might be lost in the "noise" created by the inclusion of very different

species in the same dataset. Second. PICs can help detect whether or not a significant result is an

artefact produced by phylogenetic confounding. as in the following example.

Suppose we were trying to determine the importance of disease resistance for alien species and

we fi nd that the average alien species has signi ficantl y greater resistance than the average native.

This resu1t suggests that disease-resistant species are more frequent invaders. This is an

important conclusion, but this TIP approach (Le., no phylogenetic correction) cannot eliminate

the possibility t hat di fferences in disease resistance between natives and aliens are merel y characteristics of the phylogenetic groups to which they predominantly belong, and are unrelated

to the characters which actually lead to invasiveness. The effects of origin are confounded with

al1 other traits which are conservative with respect to phylogeny (Felsenstein 1985; Harvey and

Pagel 199 1 ; Gittleman and Luh 1992; Miles and Dunham 1993). The solution to these problems

is to adopt a PIC (phylogenetically independent contrast) approach (Felsenstein 1985; Harvey

and Pagel 1991; Gittleman and Luh 1992; Miles and Dunham 1993). PICs control for

phylogenetic correlation by contrasting native and alien clades which are more closely related to

each other than to any other clades in the species set. They describe what aliens do, relative to

othenvise similÿr relatives. In doing this. they reduce both irrelevent phylogenetic noise and the

risk that any effects detected are actually spurious correlations. If the PIC approach were used

and it was still found that aliens had greater disease resistance than natives, the result would be

unlikeiy to be a consequence of some confounding trait shared by related invaders but unrelated

to invasiveness. Sorne studies already have applied the PIC approach to cornparisons of native

and alien floras (Crawley, Harvey and Purvis 1996, Kotanen, Bergelson and Hazlett 1998).

Old fields

Southem Ontario, like most of eastem Nonh America, has been highly altered since seulement.

The forest dominated landscape has been greatly reduced and fragmented south of the Canadian

Shield to one of forest patches amid largely open active farmland, urban areas and old fields. Old

fields, the system in which this thesis was conducted, are open areas which have been cleared by

humans, usually for agriculture, and subsequently abandoned to natural successional processes.

These areas differ substantially in species composition from natural upland openings in that they

contain a mix of alien and native species. In southem Ontario, they also have become a much

CHAPTER 1 : GENERAL INTRODUCTION

more prominent feature of the landscape than were natural openings in pre-European times

(Riley and Mohr 1994).

The fact that old fields are not a natural feature of the landscape begs the questions "Whcre do

old field species corne from?". Some of the alien species, including many legumes and the

grasses such as Pua pratensis and Brornus iriemis which are often community dominants, were

introduced deliberately to NA as hay and forage species for livestock. Many other alien species

have spread from plants originally grown for medicinal or food use by early settlers (Whitney

1994). A great many alien plants were also introduced accidentally; in ship ballast, livestock

fodder, impure seed imponed from Europe and suaw used as packing material (references in

Whitney 1994). The presettlement origin of the native North Arnerican species of old fields is

sornewhat more questionable. Many species are known to have mignted eastward from the

prairie regions after forest clearance (many examples in Voss 1972, 1985, 1998). but the fact that

most old field natives currently have primarily eastem distributions rules this out as a general

hypothesis. Marks (1983) presents a good examination of the issue, suggesting that old field

natives include both true pioneer species which took advantage of temporary forest openings

caused by fire, wind or other disturbance as well as species which specialized in uncornmon but

persistently open habitats such as cliffs, rock outcrops, barrens and prairie outliers. Marks feels

that the latter of the two modes applies best to most native old field species. Cenainly the

presence of many typical old field natives in naturally open communities in Ontario today

(Catling and McKay-Kuja 1992, Catling and Catling 1993, Catling 1995, Catling and Brownell

1995) implies that these areas could have been important sources for native colonizers of newly cleared land.

Old fields and sirnilar open habitats are often used as a mode1 system in plant ecology in both

Europe and North America because they are usually readily available around any settled area and

because their successional nature means that studies can be more rapid and tractable than many

of those in longer lived communities such as mature forests. Old fields generally contain a mix

of native and alien species (Curtis 1959, Maycock and Guzikowa 1984), and therefore they offer

good opportunities to examine differences between the two.

CWAPTER 1 : GENERAL INTRODUCTION

OBJECTIVES The general goal of this thesis is to investigate the role of natural predators and pathogens in seed

ecology, and in particular, to understand their role in the establishment and spread of exotic

species. Using old fields as the study system, this thesis is intended:

a) to provide background information on the site and biological setting of these

experiments (Chapter 2)

b) to determine whether seeds suffer significant losses to predators before incorporation

into the seed bank (Chapter 3)

C) to determine whether seeds suffer significant losses to seed predators and pathogens in

the seed bank (Chapter 3,4)

d) to discover whether seed losses to natural enemies differ among species (Chapter 3.4)

e) to determine whether seed losses to natural enemies differ between habitats (Chapter 4)

f) to determine whether seeds of native and alien species differ in their susceptibility to

natural enernies (Chapter 3,4)

g) to determine wheti-ier differences in seed losses between natives and aliens occur

independent of their phylogenetic relationship (Chapter 4).

Chapters 3 and 4 represent two different approaches to the problem of whether aliens and

natives differ with respect to their natural enernies. Chapter 3 represents a "traditional"

comparative approach using a very broad range of potential colonists; this chapter

documents whether differences exist between locally occumng natives and exotics. Chapter

4 represents a more refined experiment using congenenc pairs of natives and exotics; this

chapter documents whether exotics differ from close relatives, which are expected to share

many seed characteristics. Results in both chapters may reflect both the escape and filter

hypotheses, but by asking whether exotics differ from the values othenvise expected for

close relatives. Chapter 4 provides a more direct test of the escape hypothesis.

CHAPTER TWO

VEGETATION OF JOKER'S HILL

CHAPTER 2. JOKER'S HTLI .; VEGETATiON

Introduction Southem Ontario, like most of eastem Nonh America, has been highly altered since European

settlement. Natural areas have been greatly reduced and fragmented and entirely new

communities made up of a mix of native and alien species have become a prominent feature of

the landscape (Riley and Mohr 1994). The range of communities with different histories of

human disturbance at Joker's Hill offers good opportunities to study the factors important in

plant community development. Portions of the forests on site are unusually mature and

undisturbed and bear a strong resemblance to the habitats present before settlement, while the old

field and early successionai forest sites are typicai of much of the altered southern Ontario

landscape. In this chüpter 1 present an overview of the major plant communities of Joker's Hill.

giving special reference to detailed examinations of the representation of native and alien species

above and below ground in the old field habitats. These descriptions of old field communities

providr an understanding of the biological setting in which 1 conducted my experiments, they

help to justify the sets of species used in rny experiments, and they demonstrate that seed banks

and seed biology play a role in the ecology of these meadows.

Prior to the work presented here, little information on the natural history of the site existed and

nothing was in a form readily accessible to university researchers. In addition to outlining the

plant communities which comprised the setting for my research, this chapter and the complete

species lists of vascular plants, birds, mammals, reptiles and nmphibians (Appendices 1 to 5) are

intended to provide baseline data which will be important for future researchers at Joker's Hill. 1

hope they also serve to increase awareness within the University of Toronto community of the

outstanding and rare natural features of the site.

Site overview

The Joker's Hill property, also known as the Koffler Ecological Research Station, occupies 348

ha in King Township, Regional Municipality of York. immediately West of the city of

Newmarket (see map, Figure 2.1). Property boundaries are somewhat irregular, but are contained

within the quadrangle formed by Highway 9 to the north, Bathurst Street to the east, Keele Street

to the West and the 19th Sideroad of King Township (Mulock Drive) to the south. Dufferin Street

cuts north to south through the centre of the site. The property was donated to the University of

Toronto in 1995 by Murray and Marvelle Koffler, in one of the largest single donations of

property ever given to a Crinadian university. The Kofflers acquired approximately 200 ha of the

property in 1969 and then added several peripheral properties in the western end after that (W.

Fox, pers. cornrn.).

CHAPTER 2. JOKER'S HILL: VEGETATlON

Approximately one third of the property is managed as manicured grounds and agncultural land.

Almost al1 of the buildings and anthropogenic habitats are dong and to the West of Dufferin

Street. The largest proportion of the managed grounds are associated with the large boarding

stable operation, which includes three b m s , a reception building, approxirnately 35 ha of active

hay fields, 15 ha of mown show jumping grounds and accomodation for a small number of

employees. Other buildings on the property include a small field house for researchers, seven

rental houses and a large, enclosed gazebo. Aside from the development of an increased network

of trüils and a small maple sugar bush in t 97 1, the remaining two thirds of Joker's Hill were

subject to minimal human disturbance under the Koffler's ownership and are in excellent

condition as a result. Vegetation at Joker's Hill includes unusually extensive and mature

examples of several upland forest types and seepage swarnp communities typicril of the Oak

Ridges Moraine. These very high quality communities are well buffered on most edges by

younger forest. conifer plantation and old field communities. Native species richness is unusually

high for the level of habitat diversity present (S. Varga, OMNR Inventory Specialist, pers.

comm.) and there are numerous significant plant species present (Varga 1999). In 1999, partly as

a result of the work presented here, the Ontario Ministry of Natural Resources (OMNR) has

recognized the exceptional quality of the forest comnunities at Joker's Hill by proposing them as

a Life Science Area of Natural and Scientific Interest (ANSI).

Lnndforms and early human ltistory of ~oker's'fiill

Away from the areas described above, Joker's Hill is predominantly natural forest with a variety

of conifer plantations and old field habitats also present. The site sits in the western portion of

the Oak Ridges Moraine, and contains some of the highest elevations on the moraine. Elevations

range from 260 m dong the creek at the extreme West end of the property to 347 m near the

corner of Dufferin Street and the Wh Sideroad. There are few flat areas on the property; most of

the site, including al1 of the mature forest, is on ruggedly undulating kame deposits (Ontario

Natural Heritage Information Centre 1999). Most of the cleared land in the western third of the

property is on more gently rolling Kettleby and Newmarket Tills. OMNR includes most of the

eastem part of Joker's Hill in the provincially significant Glenville Hills Kame Earth Science

ANS1 because of the excellent representation of kame moraine features, which are uncornmon on the western part of the Oak Ridges Moraine (Ontario Naturd Heritage Information Centre 1999).

The soils on the property are predorninantly fine sandy loarns and silty sand loams, with organic

accumulation in some wet bottomlands (P.M. Kotanen, unpublished data, CSB pers. obs.). One

of the outstanding features of the site is the number of springs and groundwater seepage areas at

the bases of the steep slopes. The groundwater flowing from these areas feeds several small

creeks which flow northward into the Holland River. Two of these creeks have been dammed to

CHAPTER 2. JOKER'S HILL: VEGETATJON

create three small ponds, two in the open land West of Dufferin Street and one in the forest to the

east of Dufferin Street. An additional spring fed pond has been dug along the driveway leading

to the stables.

European settlement began in the area in the early 1800s. Forest cover in King Township was

reduced from >95% before European settlement, to 608 in 1840, to a low of 4.9% of ungrazed

forest in 1938 (Riley and Mohr 1994). With natural reforestation and the developrnent of conifer

plantations, forest cover in the township had recovered to 22% by 199 1 (Riley and Mohr 1994).

The Joker's Hill property itself was likely settled as several small famis. Around 1950. howevcr,

most or al1 of the current property was purchased and developed as an 800 ha hone farm and

estate. Over time. the land base was reduced until purchase the Kofflers (Rasky 1984, W. Fox,

pers. comm.). The fact that the property has been operated primarily as an estate farm for

approximately 50 years, rather than as a srnaller, more typical southem Ontario farm, has been

important in the retention of high quality. old growth forest on site. Woodlots on most profit-

driven southem Ontario farms tend to be logged at fairly regular intervals.

Native plant cornniunitirs: The hisroric serting

Historically, the property would have been almost continuously forested, with the exceptions

discussed below. The rnost mature sugar maple and hernlock dominated forests on site are

probably very typical of the forest types which predominated in pre-European times. Bnsed on

the large number of trees which appear to be in the range of 150 - 200+ years old, core areas of

the forest were only lightly logged and were never cleared.

Much of the most mature forest on site includes a significant proportion of conifers; pnmarily

hemlock and white cedar with some large white pine. Many steep, north facing dopes are

hemlock dominated and the valleys dong the sinall creeks have extensive high quality seepage

swamps of hernlock and white cedar, with some yellow bircb, black ash and red maple. Very

mature examples of hemlock - white cedar seepage swamps occur in the northwestem corner of

the property and to the east of Dufferin Street along the boundary with the Thornton - Bales

Conservation Area. These habitats support species such as Dennstuedtin punctilobula.

Corallorhiza maculata, Oxalis montanu and Vibumum lanranoides which are typical of more

northem forests in Ontario. The small inholding (not owned by the university) within the east

end of the property, dong the Bathurst Street road allowance, is a somewhat different white

cedar - white pine swarnp conaining several additional significant species (Ribes lacustre,

Maluxis monophyllos and Moneses unflora) associated with coniferous forest.

Deciduous forests dominated by sugar maple occur in some areas of intermediate moisture. The

best exarnple is west of Dufferin Street, where kame material meets the richer tills. The old

growth forest there is predominantly sugar maple, with beech, red oak and white ash also

common. This stand is exceptionally mature, with numerous trees over 60 cm dbh. Along with

the more common understory flora, the herbaceous layer in the deciduous forests at Joker's Hill

includes several locally rare or uncommon species typical of very rich-soiled forest sites (e.g..

Dryopteris goldiana, Athyrium thelypteroides, Orchis spectobilis, C. hitchcockiana. C. dhursir~a

ruid Panax quinquifolia).

Open wetlands are nther restncted at Joker's Hill. Diverse marshes dominated by combinations

of Typha lotifolia. Scirpus spp., and Eleocharis erythropoda occur at the forest pond and along a

small creek near the southwest edge of the propeny, and Typhn stands occur around the

perimeter of the gazebo ponds. An unusual fen-like wetland system is also present on a gently

sloping area with extensive groundwater seepage, immediately east of WM. In openings among

white cedür - willow thickets. several fen associated species (Appendix 2) occur among Carex

spp. and Equisetum spp. dominated comrnunities. The presence of certain obligate open wetland

species like Carex iasiocarpu and Solidago uliginosa suggests that this area may have been at

least partly open historically; perhaps as a result of regular windfalls caused by the instability of

the seepage slope.

In the eastern end of the property. soils are very dry kame sands. The forest is mostly well under

100 years old. Red oak and largetooth aspen are dominant with red maple, white pine and some

sugar maple also present. Historically, this area was probably relatively open oak and pine foresi.

On some of the ridge tops which are currently sparsely treed shmb thickets, dry conditions and

reiatively frequent fires may have maintained natural openings. Some herbaceous species typical

of prairies and savannahs (e.g., Calystegia spirhameus, Galium lanceolarum, Solidago arguto

and Symphoricarpos albus) are still present in these areas. These naturatly open sites may have

been the source of some of the nurnerous native, prairie affiliated species which now occur in the

dry old fields of the northeastem corner of the propeny.

Oldfields: The study systern

While the preceding vegetation types probably resemble the original vegetation of the site, old

fields form the focus of this thesis. They were created through human removal of the original

forest and the rnix of native and alien species present reflects the history of human use on site.

Species composition in the numerous old field habitais present at Joker's Hill varies in response

to age since abandonment, intensity and type of agrîcultural use and moisture level. among other

CHAPTER 2. JOKER'S HJLI.: VECiETATION

factors. Open areas represent a continuum frorn active hayfields which are cultivated in dfalfa

(Medicago sativu) and alien pasture grasses. to long abandoned areas which were cleared

historically but probably never ploughed. Much of the land which was once cleared at Joker's

Hill has since reverted to natural forest or been tumed into conifer plantation. The ratio of native

to alien species in the rernaining old fields varies substantially. Mesic, recently abandoned

hayfields tend to be heavily dominated by alien pasture grasses. especially Pon prntensis and

Bromus inermis, with fewer native species. Some of the drier fields are dominated by the native

graminoid species Pou compressa (questionably native. Voss 1972). Dontlmlin spicata,

Sporoholus cryptondrus and Carex pensylvanica.

The native species in old fields at Joker's Hill include some ubiquitous species of open, disturbed

areas such as Solidago canadensis, Rubus strigosus and Erigeron annuus, which likely

previously persistcd in temporary openings created by wind and fire. As suggested by Marks

(1983). however, the native flora of the old fields seems to be primarily made up of species

which specialized in historic times in more persistently open marginal habitats such as

shorelines, rnarshes, dry prairies and savannahs. As discussed above, species of praine and

savannah communities (Riley 1989) are unusually well represented at the site (see also Appendix

3). Many of these species may have invaded artificially cleared areas from dry, open ridge top

communities in the immediate area. Others may have spread from further afield. Patches of time

prairie habitats are present less than 10 km northeast of Joker's Hill at Holland Landing

(Reznicek and Maycock 1983) and prairie remnants become more common further east dong the

Oak Ridges Moraine and southwest toward the western end of Lake Ontario (Catling, Catling

and McKay-Kuja 1992, Catling and Catling 1993). Additionally, many of the common native

species of the wetter old fields likely spread to cleared areas from nearby wetlands. Species such

as Eupntorium macuhtum, E. pr@olintum, Elithamia gmrninifolin. Aster lmtcrolutus and A.

puniceus, among many others, are typical of the open wetlands on site.

Many of the alien species present in the old fields undoubtedly arrived with the first European

settlement, as has been documented elsewhere in North America (Whitney 1994). Forage grasses

and legumes probably were extensively introduced to the site with the onset of farming.

European settlement in North America dso inevitably brought a wide range of unintentional

introductions as a consequence of impure seed mixes and other inadvertant transport (references

in Whitney 1994). The fact that this type of unintentional introduction continues today was

evident in observations of the year to year variation in weed communities in disturbed areas

around the houses and stables on the property (CSB, pers. obs.). Another significant source of

introduction on site is gardening. Historicdly, many herbs probably were introduced by settlers

ÇHAPTER 2. JOKER'S HILL: VEGETAïïON

on site for cooking and medical use, though their distributions today are probably primarily a

consequence of natural dispersal. Currently, ornamental herbs, shmbs and trees are extensively

planted on the property. Some of these have spread to natural communities and represent

potentially problematic invaders (e.g.. Lonicero tatarica and Lonicera x morrowi; Luken 1988).

Survey methods

The local species pool: Overall vascular plant species pool

Beginning in May 1997 and continuing through to July 1999 1 rnaintained a list of vascular plant

species observed on the Joker's Hill property and in the immediately surrounding natural areas.

This list represents the pool of native and exotic species which actually or potentially occur in

my study sites. 1 made a substantial effort to cover al1 pans of the property and every habitat

type. New records were obtained in almost every month of the year, but search effort was

concentrated from May to October. Voucher specimens were collectçd for di fficul t to identi fy

species and for species considered locally significant. Difficult identifications were confirmed

with the help of P.W. Ball, at the Erindale Herbarium (TRTE). Voucher specimens will be

deposited at the Royal Ontario Museum - University of Toronto Herbarium (TRT).

Species presertce and abundunce esstimlrtes for main field sites

Vascular plant species lists for the Dead Man's Curve (DMC) and Wet Meadow (WM) field sites

were developed through careful inspection of the two fields during the growing seasons of 1997

and 1998. This list represents the species which have successfully established in the imrnediate

area of my primary study. Both of these sites are oldfields. DMC is located on a steep ridge in

the north-central area of the property; WM is a more gently sloping and wetter site in the

southwest corner. WM was managed as a hayfield until approximately 10 years ago.

Management of the site during that time consisted of ploughing and seeding the field with a hay

mix (primarily Medicago sativa and Phleum pratense) roughly every four years (W. Fox,

property manager, pers. cornm.). In contrast, DMC has had no significant anthropogenic

disturbance since at least 197 1 (W. Fox, propeny manager, pers. comm.). The steepness of the

dope has probably precluded ploughing over much of the site and some fairly large trees suggest

the site has been left for a considerable time. Stone piles around the more gently sloping lower

part of the field suggest that it may have been histoncally cultivated. The area covered by the

lists is bounded by the corners of the experimental gnds established by P.M. Kotanen on the

DMC and WM sites. The Kotanen grids were made up of rows of 1.5 m by 1.5 m plots. Within a

row, plots were separated by approximately 5 m, and rows were separated by 10 m; thus the

plots themselves covered only a small portion of the total area surveyed. Atypical areas (shadrd

spots under trees, frost hraved areas of low plant cover, rock piles and shmb thickets), which

CHAPTER 2. JOKER'S HU.1.: VEGETATION

were deliberately avoided when placing plots, were searched for species not present elsewhere in

the fields. The experimental treatments performed on some of the Kotanen plots included the

removal of existing vegetation and the addition of seeds of 43 native and 54 alien species, some

of which were not previously present in these fields. Species which appeared naturally only in

the soil disturbance plots were included in the overall species totals, with notation indicating the

origin of the record. Species present in the field only as a result of experimental seed addition,

and species recorded only in indoor seed bank germination trials, were not included in the list.

Species abundance was quantified using the unmanipulated control plots in the Kotanen grids üt

DMC (n=43) and WM (n=4 1). The plots were carefully examined for approximately ten minutes

and every species present was recorded. Abundance for each species was estimated on a scale

with the following categones: 1 - 1 to 9 rarnets present in plot, 2 - 10 to 49 ramets present in

plot, 3 - 50+ ramets present in plot. Two abundance indices were calculated for each species;

first the number of plots in which a species occurred was counted and second the abundance

estimates for each species in each plot was summed.

Seed bank estimation for main field sites

Germinable seed banks at both Joker's Hill field sites were assessed by germinating soil cores in the Erindale College greenhouse. Cylindrical cores 5 cm in diarneter were collected to 10 cm

depth with a bulb planter. The sidrs of the cylindrical cores were cut square to eliminate the

effects of seed movement between the bottom and top layers during collection. This left cores

which were 5 cm x: 5 cm x 10 cm deep. These cores were divided into upper and lower halves.

which were gerrninated separately. Cores were collected in December 1997 (40 cores per site)

and May 1998 (20 cores per site). Soi1 from each half core was spread thinly (m. 0.5 cm) over

soilless potting mix in a 12 cm x 20 cm tray and was kept moist for 90 days under an automatic

sprinkler system. Seedlings were counted and thinned roughly once a rnonth before the final

count after 90 days. In order to determine if seeds were evenly distributed by depth, difference

values were generated for each species in each core, by the formula:

difference = seedlings in top half of core - seedlings in the bottom half of core.

One sarnple sign tests were then conducted on data grouped by; 1) site and trial and 2) species

(within a site and trial), in order to determine whether there were significant differences between

soil fractions.

CHAP'ER 2. JOKER'S HILL: VEGETATION

Results and Discussion Overall vascular plant species pool

As of July 10, 1999,437 native and 166 alien species were identified for the Joker's Hill property

and immediate surroundings (Appendix 1). Almost al1 of these species were recorded within the

Joker's Hill boundaries. Records for only 12 species (0.2% of total) were based on species

recorded only in adjacent areas but not on the property itself. The native species total is a rather

high species richness for southem Ontario. For example, Brownell and Blaney (1995) plotted

native species richness vs. log (area) for 18 natural areas inventoned in the Lower Trent

Watershed in eastern Ontario. The Joker's Hill data point would be well outside the 95%

confidence interval on their graph. The estimated divenity of the site is partly a consequence of

the unusually complete coverage made possible by continual searching over several field

seasons, but also reflects the high quality of the habitats present. The proportion of alien species

on the list (27.3%) is typical or perhaps slightly lower than average for a site with extensive

anthropogenic habitats (S. Varga, pers. cornm.).

Rnre native plant species

Of the 437 native vascular plant species recorded. 57 are significant at some level between local

and national rarity. The list of significant species, with rarity level, status and habitat in the area.

is given in Appendix 2. Again, this total is unusually high among local natural areas (S. Varga,

pers. comm.). Most of the significant species are associated with one of five habitat types.

Sixteen rare species. mostly those typical of southem Ontario prairies. were found dry open

areas. Nine rare species were in cedar - hemlock swamp, seven rare species were in dry red oak

dorninated forest and six rare species were in each of rich deciduous forest, calcareous (fen-like)

seepage marsh and mixed herdock - sugar rnaple forest. The remaining seven rare species were

found in various disturbed habitats.

Species presence and abundance in main field sites

At the DMC field site, 8 1 native and 41 alien species were found in the area of the Kotanen plots

(Table 2.1.). At WM, 62 native and 38 alien species were found (Table 2.1). At the scale of the

single plot, species richness (25.5 spp./plot) was substantially greater at DMC than ai WM (14.5

spp./plot). At DMC, 27 species were found in >50% of al1 plots (Table 2.2), while at WM only 8

species were present in >50% of plots (Table 2.3). At WM Pua pratensis and Solidago

canadensis are uniformly abundant across al1 plots, with just a few other species consistently

present (Table 2.3). Vegetation at DMC was much more heterogeneous. No species were found

in al1 plots and dominant species varied between plots. At DMC, 15 different species were

CHAPTER 2. JOKER'S HILL: VEGETATION

recorded at Ieast once in the >50 ramets/plot abundance category, compared to just 6 species in

the sarne category at WM.

Severai factors contribute to the difference in overall species richness between the DMC and

WM sites. The greater age of DMC is Iikely important, both in allowing time for invasion of

species from sumounding areas and in producing a greater habitat heterogeneity because of the

presence of more trees. Shaded conditions under the larger trees limit the highly cornpetitive

open field grasses and provide a microclimate suitable for a substantial number of forest species

not found in open areas at DMC. The trees also act as foci for the invasion of bird and animal

dispersed species because of their use for perching and shelter. The drought prone nature of

DMC and the naturd disturbance of its steep slopes by soi1 slips and frost heaving appear to be

important in maintaining high species richness, at both the whole field and the plot scales. These

factors prevent formation of the dense stands of Pou pratensis with thick litter layers iypical of

WM, which probably greatly inhibit seedling establishment (Gross and Werner 1982. Rice

1985).

CHAPTER 2. JOKER'S HILL: VEGETATION

Table 2.1. Species present üt Deüd Man's Curve (DMC) and Wet Meadow (WM) field sites, within the area o f the Koianen plots. Species are in taxonomie order and are listed alphabetically within families. Nomenclature and native (N) or alien (A) origin follow Morton and Venn 1990.

Species DMC WM

NPitz~s strobus x

APinus sylvestris x

'Jurr iperus cort~niioiis x

N~uriiperirs virgiriiuria x x

~ h u j a occidenrulis x

A~grost i .~ gigaritea x x

" Festuca aritriùitiacea x x

NC;lyceria striatu x

POO cotripr.~.ssa x x

A POU y rarerisis x x

N~poruliolirs tteglecr~rs x

NC(~rex uureti x x

Cc~r~or cotn twuis x

Species (cont'd) DMC WM

'carex cf: cristutellu x

v a r e x grucillirnu x

N ~ a r e x grariitluris x x

carex leptotierviu x

Netuex pedrricit lura x

carex ymsylvurricu x

N ~ a r e x vulpirioideu x

N~cirpus utrmirens x

'~uricus dirdleyi x x

A~sparngus oficiriulis x

Strlix bebbimilr x

'Sulix discolor x x

'Sulix eriocrplicr lu x

'Salix yetiolrr-is x x

Jrrglnris cirier-eu x

Species (cont'd) DMC WM l l~~ec ies (con t 'd) DMC WM

I ~ M ~ ~ ~ c u ~ o sutiva x

Uhtr us unrericarta x x

ACerasriutri forirariutri x x

Asilene vulgur-is x

N~t~rrriorie cylirtdrica x

N ~ ~ i e r ~ i o n e virgirriarra x x

N~quilegia ca~iadettsis x

A~ariirticirlirs acris x x

intun tu ni clteirarithoides x

"Malus purriilu x x

* Pru r tus serotiria x

Rubirs srrigosus x x

'Sorbus air cirpcrriu x

'Desniodiuni cutiadetise x

'brrts conliculc~tus x

'Metlicugo Irrpitliriu x x

Melilorus alba X X

Trifalium hybriduni x

Vicia cracca

Vicia sariva

Ribes aniericatio x

Ribes rubruni x

II: Agrin~oriia gryposepala x

Atnelurichier laevis x

ACrataegus ttionogynu x

NCratuegus puricruta x

Crataegus sp. X X

N~ragaria virgitiiaria X X

%eitrn allepyiciinr x x

NO-valis sp. x

X

Rhus typliina X X

Toxicodendroti radicaris x

Celasrrus scaradetis x

Seed bank estimation in main field sites

Cornparisons of the total seed bank density with other seed bank studies are complicated by

differences in meihodology. Depth of sampling, season of sampling (and thus the inclusion of the

transient seed bank), and methods of enumerating seeds Vary across studies. Despite these

limitations. the total germinable seed banks recorded at the WM (30800 seeds/rn2 tu 10 cm depth

) and DMC (15730 seeds/m2 to 10 cm depth) sites (Table 2.4) were still within the range that has

k e n reported in other temperate old field sites (Rice 1989). The higher total at WM was

probably reflective of the recent history of hay cultivation on the site, as seed nurnbers are often

larger in arable field seed banks than in old fields (Cavers and Benoit 1989).

The two sites were similar in that species richness detected in the seed bank was much lower

than that above ground (Tables 2.5, 2.6). At DMC, seed bank species richness was 24.1 % of that

above ground while at WM, seed bank species richness was 37.6% of that above ground. This

result was likely largely a consequence of sampling intensity. Above-ground species lists were

developed by thoroughly walking the fields and species lists were reasonabiy complete, while

seed bank sampling probably detected only the common species below-ground.

At both sites, the majonty of species in the seed bank were also found in the above ground

vegetation, and the dominant above ground species (Pou pratensis, Poa compressa and the

Solidago canadensis /S. altissima cornplex) were among the dominant species in the seed bank

(Tables 2.1-2.6). These species made up roughly one third of the total seed bank at each site.

Many of the differences between the sites at the species level are simply reflective of differences

in the current above ground vegetation. Species such as Daucus carota, Hypericum perforatum

and Monardaflstulosa were much more common in both the seed bank and the above ground

vegetation at DMC than at WM while the reverse was true for Erigeron philadelphicus, Juncus

cc dudleyi and Eutharnia grarninifolia. Numerous above-ground species were not detected in the

seed bank, notably Brornus inemis, which was locally dominant at both sites.

ÇHAPTER 2. JOKER'S HILI .: VEGETATION

Table 2.4. Germinable seed banks from top and bottom halves of cores from Dead Man's Curve (DMC) and Wet

Meadow (WM) field sites, fall 1997 and spnng 1998 trials.

Site Trial Total seeds/m2 # cores % in % in Seedlings (10 cm depth) top 5cm bottom 5 cm

DMC Fall 1997 276 2629 42 53.6 46.4

DMC Spring 1998 806 15730 21' 50.3 49.7

'The top half of one core was excluded because of loss during germination. Proportions were adjusted accordingly.

ÇHAFI'ER 2. JOKER'S HILL: VEGETATION

Table 2 5 . Geminable seed bank (menn seeds/m2 to IO cni depth SEM) at the Dead Man's Curve field site. $II

1997 (42 cores) and spnng 1998 (21 cores). Taxonomy and origin follows Morton and Venn ( 1990).

SPECIES OFUGIN F A U 1997 SPRiNG 1998

Hypericum perforarum

' Paaceae sp.

2~olidago sp.

Erigerori strigosus

'~ieraciuni sp.

'~ieraciunr caespiiosuni

'~ieracirtm piloselloides

Cure-r granula ris

Chnxzn therriunl leucarithemuni

'~ol ic ia ,~o nenrarulis

Dartcrrs curota

Porr~ttilla recrtr

Verbascunt thapsus

Melilonts alba

Rudbeckia hirra

Sporohofus ~ieglecrits

Pariicrtnr ucuntinutuni

Euthnntiu grmiirriïi,lia

Awnio~ie cyli~idricdvirgiriica

Muriardu fisttllostr

Medicago lupu lina

Juticus cf: dudleyi

Oenothera biennis

Carex au rea

Patiicunt linearifoliurn

Pruriella vulguris

Aster ri rophyllus

rilien

' --- native

native

nlien

alien

alien

native

id ien

native

al ien

alittn

al ien

alien

native

native

nriti ve

native

native

nriti ve

alien

native

native

native

native

native

native

CHAPTER 2. JOKER'S HTLI .: VEGETATION

Table 2.5. Con tinued.

SPECIES ONGIN FALL 1997 SPRING 1998

Clirtopodiunt vulgare native OIC) 20120

' T ~ p h a sp. native OIO 20120

Phleunl pratertse alien O*O 19120

Anteririaria neglecra native O I O 19120

unknown dicot --- 1 Oh39 195185

SAsreraceae sp.

TOTAL

native 3 8 ~ 2 3 174198

26291457 15730k1375

'Most of the unidentified grasses were Pou mntpressu. (native) with some Asrostis giganfea ( a h ) and Poo

prnrensis (alien).

'~oliciogo catiadrrisis and S. ultissinta were not scpsrated in either trial. Thrse two species were not sepnrated froni

S. trerrmralis in the fall 1997 trial.

'Hiemcium caespitosuni and H. praterzse were noi sepanted in the FaIl 1997 trial. The Hieraciim sp. total in the

spring 1998 trial is the sum of the two species' totals.

'The single îjpka sp. seedling may have resulted from a seed blowing into the greenhousr from outside. No suitable

habitat for the species is present at DMC, although it does occur within 50 m of the site.

'Undifferentiated Asterxeae were primarily Solidago spp. and Erigero~l strigosiu which did not rench an

identifiable size before the final seedlinp count.

CHAPTER 2. JOKER'S HILL: VEGETATION

Table 2.6. Germinsble seed bank (mean seeds/rn2 to I O c m depth I SEM) nt the Wrt Meadow field sia. FiII 1997

(30 cores) and spring 1998 ( 18 cores). Taxonorny and origin follows Morton and Venn (1990).

SPECIES ORIGIN FALL 1997 SPRING 1998

Solidago canaderzsi.~/altissirrm

Etàgeruti philadelphicus

Juncus c$ dudleyi

P oteririlla tioniegica

Plantago major

Carex granularis.

Hypericunt perjoratum

Eutharriia granlinifolia

Erigerm aarinuus

l~,qrostis giganrea

'Pou prurensis

' Pou coniprma

'gras sp.

Chrysarrthentum Ieitcantherntrnt

Carex cf: cristarel la

Rudbeckia hirtu

Oeriathera bietttris

Panicunz capil lare

Verllascuni thapstrs

Asrer riovae-angliae

Cerastitm fontanuni

Carex L$ aurea

Daucus carora

Rubus srrigosus

Capsella bursa-pastoris

Lycopus antericartus

Plart rago laricealara

Vicia crucca

Taraxacurn cf. officinale

Erysimum cheiranthoides

Verorticu serpyllifolia

native

native

native

' ?

alien

native

alien

native

native

al ien

dien

native

' --- alien

native

native

native

native

dien

native

alien

native

alien

native

alien

native

alien

alien

alien

alien

alien

CHAPTER 2. JOKER'S HILL: VEGETATION

Table 2.6. Continued

SPECIES ORIGIN FALL 1997 SPRlNG 1998

Trifoliunz pratertse alien O d 22222

Cirsiunz vulgare alien O I O 22122

Hiemcium caespitosum dien O I 0 22k22

Sorlchus arvensis al ien Ih10 0I0

Mortardu fistutosa native 10I10 O I 0

unknown dicot --- 1 03128 22122

unknown Erigeron/Sdidagn sp. native 153135 O&

TOTAL 4 1 74k4-15 3080Ck43 10

'Pua pratensis (alicn). Poa compresse (native) and Agrostis gigantea (alien) wcrr not sepanteci in the fall 1997 trial.

The grriss sp. total in the spring 1998 trial is the sum of these three species' totals.

'Very similar native and alien foms occur in Nonh Arnerica (Voss 1985); germinated plants were not

distinguishable.

CHAPTER 2. JOKER'S HILL: VEGETATlON

Most seed bank studies find considerable differences between the species composition of the

above ground plant communities and the soil seed bank and this is especially true in successional

grasslands (Major and Pyott 1966, Rice 1989, Thompson 1987, 1992). Above and below ground

differences were present to a much greater extent at WM where 8 cpecies, including the very

common Poteniilla norvegica, were in the seed bank but not present in undisturbed above

ground vegetation. Al1 8 of these species were ruderal annual or biennial species, a pattern well

known in retired arable land (Chippendale and Milton 1934, Dore and Raymond 1942.

Chancellor 1986). At WM the uniformly dense vegetation currently leaves little habitat for

highly ruderal species. The only obvious natural source of bare soil was a smali nuinber (4) of

large ant mounds. The more diverse and numerous rudenl seed bank at WM is presumably

remnant from the period when the site was an periodically ploughed hay field. This type of

disturbance regime is likely to produce large seed banks of ruderal annuals and biennials. These

species reproduce abundantly from the seed bank in the first one or two surnmers after

ploughing, before the perennial grasses become too dense. This sequence was observed in

several currently active Joker's Hill hay fields which were ploughed and seedrd in 1997 and

1998. resulting in an abundünce of annuals such as Panicum capillare. Clze~zopodiii~i rzllm~i and

Anznrnnthus retroflrxus, al1 of which have since become much less common (CSB, pers. obs.).

At DMC, ruderais were less prevalent in the seed bank. Among seed bank species, only the

exotic Verbascuni thapsits was absent above ground. Verbascum thnpsits produces very large

numbers of seeds per plant and is well known for the extreme longevity of its seeds in soil.

Along with V. blnttrtrin, it was the longest lived species in Dr. Beal's 100 year seed bank

experiment (Kivilaan and Bandursky 198 1). A few native ruderal species were present in the

both the seed bank and the above ground vegetation of DMC. Oenotlrem biennis, with a long

lived seed bank (Kivilaan and Bandursky 1973) and biennial life history similar to Verbascurrr,

and the annual grass Sporobolus negiecttts are the best examples. Though this site has not been

ploughed for at least 30 years (if ever), natural soil disturbance is much more substantial at DMC than at WM. The steep, south facing slope at DMC results in occasional soil slips and a high

variance in spring and fall temperatures, which causes frost heaving (Kilburn, unpublished

thesis). These processes leave approximately 15% of the field as bare soi1 or with very low plant

cover. This natural disturbance is the preferred habitat of the native annual grass Sporobolus

nciqlectus (Blaney, pers. obs.) and is probably important in the persistence of the other ruderal

species in the above ground vegetation. The persistent seed bank of Verbascum could be the

result of occasional reproduction in natural disturbances since the field was cleared or could

remain from a single large disturbance (perhaps even the original cleanng of the site) from

greater than 30 years ago.

CHAPTER 2. JOKER'S HTLJ .: VEGETATTON

The relatively even distribution of seeds between the upper and lower halves of the 10 cm deep

cores (Table 2.4) is probably explained ai WM by the history of ploughing (Roberts 198 1). The

occurrence of the same pattern at DMC, where ploughing has not occurred in many years, is

somewhat more surprising given the number of studies where seeds are highly concentrated in

the upper few cm of soi1 (Roberts 1981 and references therein). Historic human disturbance may

have mixed the seeds into the deeper layers, or perhaps the activities of the biota in conibination

with natural soi1 disturbance at DMC are sufficient to rnove seeds or creaie fissures by which

seeds can enter the deeper layers.

The large increase in the total germinable seed bank detected in May 1998. as compared to thnt

detected in December 1997. was somewhat unexpected (Tables 2.4-2.6). It is almost certain thüt

overall seed numbers are highest in the ûuturnn after the shedding of the season's seeds but

before the spring peak of germination. Most seeds produced in 1997 would have been shed from

the parent plants by the December 1997 sarnpling and no seeds of any of the commonly

occurring seed bank species would have been produced before the May 1998 sampling.

Similarly, many of the seeds which were going to germinate in 1998 hûd probably germinated

before the May 1998 sarnpling. Thus the second trial should have been sampling a smaller pool

of seeds. It is likely ihat the spring increase was attributable to reduced dormancy of seeds andor

spring conditions in the green house being more conducive to germination. Further evidence of

the presence of viable but ungerminated seeds in the December 1997 sampling cornes from

observations after the germination penod ended. Some samples were left in the greenhouse after

the December 1997 germination trial was over. No funher seedling counis were done, but in

May and June, nurnerous Ju~icus seedlings emerged frorn the WM samples (CSB, pers. obs.)

from which no J~rncris had yet been recorded.

Seasonal dormancy cycles have been documented in rnany temperate species (well summarized

in Baskin and Baskin 1998). Dormancy cycles have, however, been somewhat overlooked in the

literature exarnining total seed bank communities. In the studies which examine seed banks at the

sarne site over successive seasons. the influx of shed seeds after the growing season is generally

cited as the main reason for seasonal variation in total seed numbers. This may be the case in

certain desert or Mediterranean grassland communities in which the seed bank is dominated by

annuals. however my results indicate that changing dormancy status may cause seasonal

variation of equal or greater magnitude. From a sarnpling perspective, the significance of

dormancy cycles will Vary depending on the germination environment used. The fact that 1 was

looking at the immediately germinable seed bank under natural day lengths in the greenhouse

CHAPTER 2. JOKER'S HILL: VEGETATION

likely accentuated the effeci of dormancy cycling because the short days in winter may have

been insufficient to stimulate germination of some seeds which otherwise would have

grrminated. Also, if newly dispersed seeds were trapped by the upper layers of litter rather than

becoming incorporated into the older litter or soil, they would been underrepresented since

coarse litter was discarded before germination because of its potential inhibitory effects on

germination.

The existence of domancy cycles ernphasizes the need to take more thrn one annual sampie in

assessing the seed bank at a single site. There is no single "correct" time for seed bank

estimation. Seed dispersa1 and germination occur virtually throughout the growing season, so the

seed bank is in constant flux with any atternpt at estimation being just a snapshot of a point in

time. My sampling methodology measured a consistent and biologically meaningful parameter:

the germinable component of the seed bank, rnther than the total seed population.

Conclusions

The Joker's Hill property consists of a mixture of forest, wetland, Field, and oldfield communities

with widely different histories of disturbance and invasion. In particular, the oldfirld

communities comprise a diverse mixture of native and exotic plants drawn from a large local

species pool. Many of these species have persistent seedbanks, but the majority seem unable to

maintain large buried seed populations. These results provide both background data and impetus

for further study into the role that seed banks rnay play in determining which species c m

establish and persist in oldfields.

CHAPTER THREE

EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

CHAPTER 3: EXPERTMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Introduction The structure and composition of many ecosystems have been altered profoundly by biological

invaders: non-native species deliberately or unintentionally introduced by humans into new

regions. Since the 1950s many researchers have tned to develop general rules to help predict

which species make successful invaders (e.g., Elton 1958, Baker 1974, Groves and Burdon 1986,

Mooney and Drake 1986, Drake et al. 1989, Mack 1996) and which communities are susceptible

to invasion (e.g., Crawley 1987, Mack 1989, Rejmanek 1989, Groves and Dicastri 1991). These

effons have produced few, if any, rules with strong predictive value (Lodge 1993, Karieva

1996). One reason for this lack of success is the fact that diens are extremely diverse. Rules

demonstrated to apply to one group (Le.. the genus Pinus, Rejminek 1995) rnay fail when

applied to other groups. Another reason for the difficulty in developing a predictive ecology of

invasions may be the methods used to denve the predictions. Early efforts tended to involve

generalization based on correlative analyses of successful invasions, without much observation

of unsuccessful invasions or resistant communities (Burke and Grime 1996). Some recent

authors have looked at large species pools and used stronger correlational methods (e.g., Mazur

1989, Scott and Panetta 1993, Crawley, Harvey and Purvis 1996, Williamson and Fitter 1996a,

1996b. Kotanen, Bergelson, and Hazlett 1997) but there are still very few explicit, experimental

tests of hypothesized rules about plant invaders. As Burke and Grime ( 1996) state, "There is now

an urgent need for the initiation of field experiments that test sorne of the more important

invasibility hypotheses that have been genented from the study of past case histories."

One hypothesis is that some invaders succeed because they experience low risks frorn natural

enemies (predaton and pathogens). There are two distinct ways this could occur. Both of these

hypotheses argue that a low pest load is important to invasion. The distinction lies in the

mechanism causing this low load. First, invaders rnay lose their natural enemies when they are

transported to a new area (the predator escape hypothesis: Elton 1958, Crawley 1986).

Alternatively, species with intnnsically low rates of seed predation rnay make better invaders

because they are less likely to be elirninated by natural enernies in their new habitat (the predator

filter hypothesis). These two hypotheses are difficult to distinguish, but the escape hypothesis

predicts that invaders should have lower p s t loads in new habitats, while the filter hypothesis

predicts that pest loads are equally low in both original and new areas. As well, the escape

hypothesis refers primarily to the loss of species-specific enemies, while the filter hypothesis is

more likely to apply to generalist enernies.

There is some supporting evidence for both hypotheses. The strong host specificity of many plant pathogens and predators (Harper 1977, Dinoor and Eshed 1984, Crawley 1992) suggests

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALlTY

the potential importance of predator escape for plants arriving in new regions. Most alien plants,

excepting ornamental species, are probably introduced as seed, meaning that that certain types of

predators and pathogens are uniikely to have amved with them. It should be noted, however, that

fungal and other pathogens are often transported on seeds (Neergaard 1977, Aganval and

Sinclair 1997), so invaders may be less likely to escape from specialist seed-borne pathogens.

The concept of predator escape is fundamental to biological control efforts, which often attempt

to replace "lost" predators. Certain spectacularly successful biological control efforts, as with

Oprtntia species in Australia (Mann 1970) and South Africa (Zimmermann et al. I986), and

Hypericum per$orntitni in California (Huffaker and Kennett 1959) strongly suggest it to be true

for sorne plant invaders. However, the fact that most biological control efforts fail (Crawley

1986) suggests that these examples may not be typical. Further evidence links predator escape at

the seed stage to invasiveness. Some invaders have been shown to develop larger seed brinks in

new regions than in their native habitats. Lonsdrile and Segura (1987) found that seed banks of

Mimosa pigra were approximately 100 times larger in Australia than in its native range in

Mexico. Research in coastal shrublands in Mediterranean climate zones of Australia and South

Africa (Weiss and Milton 1984) has shown that seed banks of the reciprocdly invasive Acacia

longifolia (native to Australia) and Chrysanrhernoides monilifera (native to South Africa) were

increased 44 and 13 16 times in new regions.

There has been less investigation of the idea that species subjected to low pest loads make better

invaders; however, the evidence that sorne communities resist invasion (e.g., Pimm 199 l), points

to the possibility that the predator filter hypothesis may apply in some cases. AdditionalIy,

correlations between seed size and predation rates, and between seed size and invasiveness

(Crawley, Harvey and Pagel 1996) suggest that native and alien species rnay have intrinsically

different rates of generalist predation, as predicted by the filter hypothesis.

Several other lines of evidence suggest that the seed stage may be important in understanding

plant invasions. First, many plants (native and exotic) suffer the majority of their mortality at the

seed stage (Harper 1977; Cavers 1983). Second, the seed stage is the primary opportunity most

plants have for dispersal, which is necessary for the invasion of new areas (Harper 1977; Fenner

1985; Leck et al. 1989; Rees 1993). Third. many invaders have long term seed banks. Almost

al1 of the world's worst weeds listed in Holm et al. (1977). for example, produce significant seed

banks. Crawley, Harvey and Purvis (1996) found that British aliens were more likely than

natives to have long term seed banks and Rees and Long (1992) found that 75% of species

currently undergoing range expansion in Britain (both native and alien, but skewed towards

aliens) produce long term seed banks. Seed banks may be important in buffering against the

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

stochastic hazards faced by small populations (Keddy and Reznicek 1982, Venable and Brown

1988, Rees and Long 1992, Rees 1993); invading species generally face these hazards

repeatedly, both at the original site of introduction and with range expansion ris small colonizing

subpopulations are formed (Barrett and Richardson 1986, Barrett and Husband 1990).

Much work has been done on post-dispersal seed predation (well summarized in Thompson

1987, Louda 1989b, Crawley 1992). though there is no published work that has focussed on

differences between wild native and alien species. Rodents and ants are generally both important

post-dispersal seed predators in arid Iandscapes (Reichman 1979, Abramsky 1983, Parmenter et

al. 1984, Heskr, Brown and Guo 1993). In temperate grasslands, post-dispersal seed predation is

genenlly Iess intense. and vertebrates (prinmily rodents) are generally the more important

predators than ants (Mittelbach and Gross 1984, Hulrne 1994). although Reader and Beisner

( 1993) did find significant predation by ants at an old field not far from Joker's Hill. Predator

risks ülso v q with species-specific seed characters. For example, there is strong evidence that

both birds and rodents prefer large seeds (Thompson 1987). Factors such as predator identity,

seed abundance and dispersion and nutritional value can al1 affect the critical size beIow which

seed predation by birds and mammals is reduced. Studies by Kelrick et al. (1986), Mittelbach

and Gross (1984) and Reader (1993), however, suggest that seeds below 1 to 3 mg tend to escape

predation by a wide range of vertebrates. In addition to ants, Collins and Uno (1985) and

Crawley (1992) list seed bugs (Lygaeidae), seed beetles (Bruchidae) and ground beetles ris post-

dispersal seed predators but note there is very little experirnental work exarnining the importance

of these groups.

Although most rnortality likely occurs below ground for many long term seed banking species,

there is strikingly little experirnental work examining the causes of that mortality in natural

systerns (Baskin and Baskin 1998). Both bacteria and fungi in the soi1 are often suggested to be

important in causing seed rnortdity. Paul. Ayres and Wyness (1989) reviewed the potential for

the use of fungicides for experimentation in natural vegetation, but an investigation of fungal

mortality in the seed bank of Minrosa pigra (Lonsdaie 1993) appears to be the first such study.

Lonsdale found that fungicide significantly reduced seed losses by 10 to 16% over seven rnonths,

but concluded that fungi were a less important source of seed mortality than germination

associated with large temperature fluctuations. Crist and Friese (1993) examined survivorship of

five species of seeds over 10 months under Wyoming shmb steppe and found that proportions of O

decomposed seeds ranged from 6% to 93.5% by species. Although some important soil

pathogens appear to be generalists (von Broembsen 1989), there is evidence of soil pathogens

having some degree of host-specificity (Kirkpatrick and Bazzaz 1982. Van der Putten et al.

1993, Mills and Bever 1998), including soine seed pathogens of agricultural plants (Neergaard

1977, Aganval and Sinclair 1997). If species specific fungal pathogens are common in natural

communities, the predator escape hypothesis would predict that natives would be more

susceptible to thrm than aliens, which could have left their specific pathogens behind before

arriva1 in North Amenca. If generalist fungal pathogens are more important, the predator filter

hypothesis is more likely to account for any superionty in fungal resistance observed among

invaders.

The impacts of soi1 fauna on seed populations below ground are understood only slightly better

than are the effects of microorganisms. Crawley (1992) writes, "There is a great scarcity of data

on mortality attributable to predators of dormant seeds in the soil. Protecting buried seeds in

cages with a variety of mesh sizes should enable data on subterranean seed predation rates to be

gathered without much difficulty, but so far as I know, such experiments have not been carried

out." Baskin and Baskin (1998) thoroughly reviewed the literature concerning consumption of

buried seeds by soil fauna. They found references to below ground seed consumption by

mammals, earthworms, ants and slugs but they suggested that a wide range of other soil

arthropods which feed on plant matter may also eat seeds (i.e.. millipedes, isopods, beetles and

termi tes).

In this chapter I cxpenrnentally examine the hypothesis that alien species are less susceptible

than natives to predators and pathogens. If this is indeed the case, either the predator escape

hypothesis of the predator filter hypothesis could provide the explanation. In order to avoid some

of the problems of previous work, 1 perform field experiments using suites of 39 to 43 species of

open upland habitats, evenly divided between native and alien species. 1 focus on seed predation

at two stages; 1) after dispersal but before incorporation into the long term seed bank (soil

surface seed predation experiment) and 2) in the long term soil seed bank (seed bank mortality

experiment). Along with the work outlined in Chapter 4, this is the first study cornparhg either

seed bank or post-dispersal seed mortality over a wide range of CO-occurring native and alien

species. It also represents one of the first attempts to understand the role fungal mortality and

seed predation by soil fauna in soil seed banks.

Methods Study site

Both experirnents were conducted at the Dead Man's Cume field site at the University of

Toronto Joker's Hill field station, Regional hlunicipality of York, Ontario (44O02'25" N,

CHAPTER 3: EXPERIMENTAI. SURVEY OF NATTVE AND ALlEN SEED MORTALITY

79'32'00" W). The site is a dry-mesic old field on a south facing slope and has been abandoned

from any agricultural use for at least 30 years. Soils are sandy and silty loarns. Vegetation is a

diverse (74 native species, 4 1 alien species: Chapter 2) n ix of native and alien species, typical of

southem Ontario old fields (Maycock and Guzikowa 1984, Reader and Best 1989). Tree and

shrub cover is approximateiy 10%. Grasses dorninate the site with the aliens Bromus inernzis and

Poa pratensis important in mesic areas. Drier portions of the site are dominated by the natives

Poa compressa and Danthoniu spicata. Cornmon native herbs inchde Solidngo canadensis, S.

nemoralis, Antennaria neglecta, Aster urophyllus and A. novae-angliae. The most common aiien

herbs are Hieracium piloselloides, H. cnespifosum, Melilotus alba, Medicago lupulina, Daucus

carora. Hypericurn perforatunz and Chrysanrhen~um lruc~znthemum.

Experirwnîal Species

The seed bank mortality experiment used 19 native and 20 alien species; the soi1 surface serd

predation experiment used 22 native and 2 1 alien species (Table 3.1). Species were selected from

a pre-existing collection of southem Ontario seeds. Al1 species are forbs or graminoids with wild

populations occuming in the Regionai Municipülity of York (Riley 1989). Most of the species

occur naturally within the Joker's Hill property (Chapter 2; Appendix 1). With five exceptions,

seeds had been collected from wild populations in southern Ontario between June 1996 and June

1997. Seeds of Andropogon gernrdii, Bromus kalmii, Elytnus trncizycnulus and Sorghastrum

nutans were purchased from the Pterophylla F m . Walsingham, Ontario, where they had been

grown in 1996 from plants originating from local, wild seed stock. Seeds of Digitaria ischneniunz

were from greenhouse plants grown from local, wild seed in 1997. After collection, seeds were

stored dry, in a freezer until use in the expenments. Species were selected to represent a range of

taxonomie groups and for their habitat preference. Al1 species occur primarily or entirely in

open, upland habitats and forest edges.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.1. Experimental species for seed bank niortnlity (SB) and soi1 surface seed predation (SP) experinients. Presence on Joker's Hill research statian property

(JH), and at the Deiid Man's Curve rtiseürch site (DMC) are indicated by "x". Native (N) or alien (A) origin follows Morton and Venn (1990) and nonienclrtture

follows Gleason and Cronquist ( 199 1 ).

Fümily Species Expt. JH DMC

APIACEAE

ASCLEPIADACEAE

ASTERACEAE

ASTERACEAE

ASTERACEAE

ASTERACEAE

ASTERACEAE

ASTERACEAE

ASTERACEAE

BORAGINACEAE

BORAGINACEAE

BRASSICACEAE

BRASSICACEAE

BRASSICACEAE

CARYOPHYLLACEAE

CARYOPHYLLACEAE

CHENOPODIACEAE

A Daucus cri rotcl

NAsclepicis syriwa

A~ rctiirm rriirrirs

rtertiesin cnrtrpestris

Aster ericoides

*Ch~sar~tke~)irr~n leucarirlienirrni

AHierc~cirrt~~ critrtiririwutrr

NHieracirrni sc~brrrrri

Solidago rieniorrrlis

AEcIri~~r~i wigclre

NHackelia virginicm~

* A lyssu rrr alysuides

' A rrrbis glubrrr

AErysi~mm cheircitrtlinides

!Werie aritirriiiria

ASilene vrtlguris

"Cher~c~pndiurr~ ~lbirni

SP, SB

SP, SB

SP. SB

SP, SB

SB

SP, SB

SB

SB

SP, SB

SP, SB

SP, SB

SP

SP

SB

SP

SP, SB

SP. SB

Fririiily Species Expt. JH DMC CY PERACEAE

CY PERACEAE

DIPSACACEAE

FABACEAE

FABACEAE

FABACEAE

FABACEAE

FABACEAE

LAMIACEAE

LAMIACEAE

LAMIACEAE

LAMIACEAE

ONAGRACEAE

PLANTAGINACEAE

PLANTAGINACEAE

POACEAE

POACEAE

POACEAE

' '~ (~rex ~tiu~i~eribergii

"Carex spicata

*~ ipsnc i rs sylvesfris

N~esntodi~rm carraderise

NLespedeza cnpitata

A~edicago Irrpitlirtu

* Melilntus alba

* Vicia craccu

N~edeonia Iiispida

ALeoriurus cardiaeu

"~orrarda jisrulosa

ANepetrr cataria

"~etrothera bientiis

APla~itago n w r

NPlutitugo rugellii

N ~ ~ i d r o p o g o ~ ~ gerardii

N~rorrrus knlriiii

*Brorrrrrs tectoruni

SP

SP

SP, SB

SP, SB

SP. SB

SB

SP* SB

SP, SB

SP. SB

SP, SB

SP, SB

SP, SB

SP, SB

SP, SB

SP, SB

SB

SP, SB

SP

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.1. Continued.

Faniity Specics Expt. JH DMC

POACEAE

POACEAE

POACEAE

POACEAE

POACEAE

POACEAE

POLYGONACEAE

RANUNCULACEAE

RANUNCULACEAE

ROSACEAE

ROSACEAE

ROSACEAE

ROSACEAE

LAMIACEAE

ONAGRACEAE

ADigitcrricr ischuer)ilrt~~

A ~lytr~rrs reperls

N~lyniirs tracl~ycairlirs

NPatiicrrm litieurifoliirni

A ~lrleurrl pruterise

NSnrglic~striir~i rrittclrts

A Rurriex crispus

' ~ w r m r i e cjlittiiri~*u

"~~~~riiriciiliis r/~ontboi&iw

"~eiini aleppicirrn

AGeitnr irrbmiirni

Poterltilla arguta

"uteritillrr recta

A Nepeta catariu

N~rnorlteru bieririis

SP

SP, SB

SP, SB

SP

SB

SP, SB

SP, SB

SP, SI3

SP

SP, SB

SP

SP, SB

SP, SB

SP, SB

SP, SB

Fain ily Species Expt. JH DMC

SCROPHULARIACEAE N ~ e ~ i s t e m r i Iiirsir~irs SP, SB

SCROPHULARIACEAE A Verhmctrnr rliclp.uts SP,SB x x

Soi1 surface seed 43 species 22N 18N 9N

predation experinient 21A 15A 8A

Seed bank inortaliip 39 species 19N I1N 8N

expriment 20A 18A 1IA

Total 25N 16N 9N

25A 22A 13A

50 species

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN E E I ) MORTALITY

Treat ments

Soi1 surface seed predution e x p e h e n t 6 experimental plots, each rneasuring 1.5 m x 6.5 m were established in July 1997, roughly in

phase with the annual cycle of seed dispersal. Plots were distributed evenly dong the elevational

gradient of the site but were otherwise randomly placed. Each plot contained 16 petn dishes.

representing a factorial combination of 4 treatments and 4 seed combinations of 10 or 1 1 species

Seed combinations were generated by randomly dividing the 43 expenmental species into 4

combinations of 10 or 11 species, using selection without replacement. 20 seeds of each of the

species in a combination were placed on 1809 of dry. sterile sand in each 14 cm x 1 cm prtri

dish. This process was repeated for each experimental plot.

The four treatments used were: 1) control, 2) vertebrate exclusion, 3) insect exclusion, 4)

vertebrate + insect exclusion. In the control and vertebnte exclusion treatments, petri dishes

were sunk into the ground leaving the edges flush with the soil surface and allowing easy access

to crawling insects. Vertebrate exclusion was accomplished by enclosing the petri dish in a wire

mesh cage ( 1 cm gauge) secured by ground staples. Insect exclusion was accomplished by

covering the outer edge of the petri dish with Tangle-trap Insect Trap Coating (The Tanglefoot

Company, Grand Rapids, MI, USA) and leaving the petri dish on the soil surface.

The contents of the petri dishes were recovered in August 1997, after a month in the field. New

seedlings of the study species which were present in or imrnediately around the petri dishes were

recorded at the time of seed recovery. Seeds were separated from the rest of the petn dish

contents in the lab with a 0.5 mm sieve, which caught most seeds while letting the sand through.

The sünd wüs weighed to provide an independent measure of loss of dish contents due to wind,

min or handling. Very small seeds which passed through the sieve, and any other undrtected

seeds were deiected by incubating samples in the greenhouse. The sand from each petri dish was

spread thinly (ca. 0.25 cm) over potting mix in a 12 cm x 20 cm tray and was kept moist for 3

months under an automatic sprinkler system. Seedlings were recorded after 1.5 months and at 3

months. Seeds were recorded as recovered if seedlings were detected in the field, if seeds were

found in the lab after sieving the recovered sand, or if seedlings were recorded in the recovered

sand in the greenhouse. Petri dishes from the insect exclusion treatments were carefully

examined for seeds which had become stuck in the Tangle-trap coating. These seeds were

excluded from the analyses.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Seed bank mortality experiment

18 experimental plots, 1.5 m x 1.5 m in area, were established in June 1997. Plots were

distnbuted evenly alorig the elevational gradient of the site but were otherwise randornly

positioned. Plots contained 16 small, thin walled peat pots (4 cm x 4 cm x 5 cm depth) filled with

a mixture of seeds and 20 cm3 of local field soil (collected immediately preceding the

establishment of the experiment). The peat pots had 2 cm x 3 cm holes cut in the lower half of

each side and the upper 1 cm removed from one side, in order to allow access by soil biota. A 4

mm drainage hole was also added in the bottom of the pots. These pots were buried just below

the soil surface and allowed to incubate under field conditions. The 16 peat pots represented a

factorial combination of 4 treatments and 4 seed combinations of 9 or 10 of the 29 experimental

species. Seed combinations were randomly generated as described above. Each peat pot

contüined 20 seeds of each of the species in that combination. Neutra1 markers (20 glass beüds)

were also added to each peat pot in order to provide an independent measure of seed recovery.

Quantification of the pre-existing seed bank in the soi1 revealed that seeds of some of the

experimental species were present, but that the pre-existing seed density of rnost of these species

was very small relative to the density of added seeds (Chapter 2).

The four treatments used were: 1) controi, 2) fungicide addition, 3) insect exclusion. 4) fungicide

addition + insect exclusion. For the fungicide addition treatment, 5 ml of a fungicide solution

was added to the soil and seed mix immediately before burial, with identical doses added in the

field by syringe in October 1997, May 1998 and September 1998. The fungicide solution was a

1: 100 solution of a commercial fungicide in water (Maestro 75DF, Zrneca Corp., Stoney Creek,

ON, Canada, active ingredient 75% Captan by weight). This concentration was recommended by

the manufacturer for use as a dip for bulbs and iubers. Captan is a non-systemic heterocyclic

nitrogen fungicide used against a wide range of fungi in the Oomycota, Ascomycota and

Basidiomycotina (S harvelle 196 1. Torgeson 1969. Neergaard 1977) and is noted as being

particularly effective against seed-rotting organisms (Neergaard 1977). If has been shown to

have minimal effects on endomycorrhizal fungi and both positive and negative effects on

ectomycorrhizae development (Vyas 1988), depending on plant species.

Insect exclusion was accomplished by drying soil at 50°C for 48 hours and enclosure of the peat

pot in 1 mm nylon window screening to restrict access by soil fauna The processes of collecting

the soi1 and ueating it undoubtedly reduced both invertebrates and soil fungi in al1 treatments;

the purpose of the invertebrate and fungus exclusion treatments was primarily to restrict the

recolonization of these organisms.

ÇHAPTER 3: EXPERIMENTAL SURVEY OF NATWE AND ALIEN SEED MORTALITY

Six plots each were randornly setected for retneval in November 1997, June 1998 and October

1998 (hereafter called the 4 rnonth, 1 i month and 16 month trials). Peat pots were carefully dug

up with their contents intact, and the plants growing out of the peat pots were recorded. After

recovery, the soil and seeds were spread thinly (field soil depth approximately 0.5 cm) over

potting mix in 15 cm diarneter pots. Pots were kept moist for three months in a greenhouse and

seedlings were recorded monthly until the end of the germination penod. After 1.5 months, the

layer of field soi1 was disturbed to allow buned seeds a better chance at germination. After the

germination penod, the field soil was removed frorn the greenhouse pots and was passed through

a 1 mm sieve to recover glass beads. Seeds were recorded as recovered if they were found as

seedlings in the peat pots in the field, or if they were recorded as seedlings in the greenhouse.

Analysis Data for the seed predation experiment and for each of the three trials of the seed bank

experiment were analyzed similarly. Recovery rates (R) were first corrected for physical losses

of seeds. For the seed predation expenment, sand recovery was used as a measure of physical

losses by the formula: - R ,,,,,, - R ,,,,, / (proportion of sand recovered).

For the seed bank mortality experiment, the recovery by greenhouse germination was corrected

but the recovery by field germination was not, as it was considered independent of soil losses

during sampling. The formula used was: -

Rcomcted - Rgcrmrnïie<l in Acld + [Rprminucd in grccnhousc (p"ponion of beads recovered)].

The corrected seed recovery prrcentages were arcsin trünsformed to improve normality (Kirk

1982). After initial analysis of the entire data set, data were divided by ongin (native or alien)

and by species for separate analyses. Analyses were 3-factor randomized block factorial

ANOVAs with blocking by plot. Some values were missing due to vandalism, loss of pots, and

problems distinguishing certain species when they CO-occurred in a seed combination. Of the

1032 experimental values in the seed predation experiment, 9 were missing. Of the 960

experimental values in each of the 3 trials of the seed bank experiment, 3 1.56 and 15 were

missing. To restore a balanced design, missing values were replaced with the rnean of the

remaining values in that treatment x species combination (Underwood 1997). The number of

degrees of freedom for error was reduced by the number of durnrnied values in each analysis

(Underwood 1997). For d l analyses, a non-interactive mode1 was used, as recommended by

Newman, Bergelson and Grafen (1997). Thus, treatment was treated as a fixed effect, plot was

treated as a random blocking factor, and the residuai was used as the error terrn. Finally, in order

PERlMENTAL SURVEY OF NATWE AND ALIEN SEED MORTAIJTY

Results Soil surface seed predation experiment Overall uncorrected seed recovery rate was 37.46%IQ. 13% (al1 values are mean~SEM) and

overdl sand recovery was 89.5 1 %%iû.90%, resulting in a corrected recovery rate of

41.37%*0.98%. Most seed recovery (3 1.86% of seeds) was accomplished by sieving; 2.73% of

seeds germinated in the field, 0.95% of seeds were recovered outside of petri dishes in the field

and 1.858 of seeds germinated after greenhouse incubation. Recovery rates varied substantially

between species (Table 3.2). with corrected rates varying from 85.45% in Aiternone cyhdricn to

3.96% in Verbascuni tliapsus. As would be expected, recovery by greenhouse germination

tended to decrease as recovery by sieving increased. Five native species, Solidago nemoralis.

Arabis glabra, Penstemon hirsutus. Poten tilln argutn and Artenresia campestris and one exotic.

Verboscum thapsm, were recorded primarily or entirely by greenhouse germination. These were

al1 small seeded species, for which overall recovery was low. Of the ten species with the lowest

recovery rates, five were recorded mainly or entirely through greenhouse germination. The

reduced recovery associated with the small seeded species is not considered a major bias since

the main purpose of the experiment was to make cornpansons within species for examination of

treatment effects. The magnitude of seed removal by seed predators, as measured by the

difference between exclusion and non-exclusion treatments, was considerably lower than that

found in most previous studies. 1 found that excluding vertebrates increased overall seed

recovery by only 8.3% over one month, although increases by species ranged up to 46.4% (Table

3 2). The overall effect of invertebrate exclusion was negligible, although there were species for

which invertebnte exclusion both increased and decreased recovery substantially (Table 3.2).

Seed recovery was spatially variable, with plot having a highly significant effect (Table 3.3). The

vertebrate exclusion treatment resulted in a 10.7% increase in seed recovery rate, which was

highly significant (Table 3.3). Effects of vertebrate exclusion varied significantly between

species (Tables 3.2, 3.3). Contrasts indicated that effects of vertebrate exclusion were positive

for 32 of the 43 expenmental species (Table 3.4). Insect exclusion had no effect overall (Table

3.3, Figure 3.1), but insect exclusion x species interactions were significant (Tables 3.2, 3.3).

Seed recovery was increased as a result of insect exclusion in only 20 of the 43 species (Tables

3.4).

, W E E D MORTALITY

Table 3.2. Results of seed predation experiment: Mean proportional seed recovery * SEM (n=6 repiicates per

species. per treatment. unless otherwise noted in brackets after SEM), by treatment and species. Recovery

percentages are corrected for physical losses. Native species are indicated by "N", and alien species are indicated by

"A".

Species Control Invertebrate Verte braie Invertebrate exclusion exclusion & vertebrate

*A lyssunr a lysnides

*;ltiemo~te cylindrica

rubis glabra

"A rctiuni minus

N~ rtentisia campestris

NAsclepias qriacu

~ronirts kalniii

" Bromus tecronrm

NCarex muhlertbergii

"Cu rex spicata

"Cherrupodium nlbuni

"CCtrysanrheniunt leuca~ithenium

"Daucus carota

"De.vmodium catiadense

*Digitaria ischaemrrni

ADipsacrrs sylvestris

"Echiunt iulgarr

"Qwtus repens

NEly~rtus trachycaulits

NGeum cileppicum

R . 9 ALIEN SEED MORTALITY

Table 3.2. Continued.

Species Control Invertebrate Vcttebrate Invertebrate exclusion exclusion & vertebriite

exclusion - 0.6 l4I0.08 1 (5) 0.75 1 iO.075 (5) "Geuni urbununt

"Huckelia virgiriiarta

Hedeoma hispida

AIRonurus cardicrca

NLespede:a capitata

*Melilotus alba

"Moriarda fistulosa

ANepeta cararia

"Oeriothera biennis

NPanicum lirrearifnl iunr

Perisrenlon hirsutlrs

*Plurztago major

~ l m r a g o rrcgellii

"~oterzrilla arguta

*Potrtitilla recru

"Ruriunculus rlraniboideits

"Runiex crispus

"~ilrrie antirrhirra

Asilerie vulgaris

NSnlidago nemoralis

"Sorghasrncm nutans

AVerbascum rhapsus

"Vicia cracca

ÇHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALlTY

Table 3.3. Results of 3-factor randomized block factorial ANOVAs on overall. native and dien data from seed

predation experiment. Treatment was treated as a fixed effect, plot was treated ris ii mndom effect and the rcsidud

wasusedas theerror t e n . * =Pc0.01, **= P ~ 0 . 0 0 1 , *** =Pc0.0001

SEED PREDATlON EXPERIMENT - OVERALL ANOVA TABLE

Factor d f MS F-vol ue

plot 5 1.698 7.490***

venebrate exclusion I 12.201 53.822***

insect exclusion 1 0.000 0.000

species 32 1 0.563 46.596***

vertebrate exclusion x insect exclusion 1 0.460 2.029

vertebrate exclusion x species 42 0.537 2.413***

insect exclusion x species 42 0.412 1.817**

venebrrite exclusion x species 32 0.256 1.129

errorl 846 0.227

'degrees of freedom for error (= 855 - 9) adjusted for 9 dummied values (Underwoc~d 1997); see methods.

SEED PREDATION EXPERIMENT - NATIVE ANOVA TABLE

Fac cor d f MS F-value

plot 5 0.733 3.4 12**

vertebrrite exclusion I 6.947 32.336***

insect exclusion 1 0.038 O. 177

species 2 1 13.50 1 62.833***

vertebrate exclusion x insect exclusion 1 1.330 6.191*

vertebrate exclusion x species 2 1 0.666 3.100***

insect exclusion x species 2 1 0.444 2.067**

vertebrate exclusion x species 21 0.243 1.131

error' 331 0.215

'degrees of freedom for error (= 43 1 - 4) adjusted for 4 dummied values (Undenvood 1997); see methods.

UPTE. A R 3 , SEED ATTVEORTALlTY

Table 3.3. Continued

SEED PREDATION EXPENMENT - AMEN ANOVA TABLE

Factor d f MS F-value

plot 5 1.131 4.713***

vertebrate exclusion 1 5.335 22.232***

insect exclusion 1 0.033 O. 138

species 20 7.844 32.688***

vertebrate exclusion x insect exclusion I 0.030 O. 167

vertebrrite exclusion x species 20 0.333 1.846*

insect exclusion x species 20 0.393 1.638*

vertebrate exclusion x species 20 0.240 1.000

crrorl 410 0.230

'degrees of freedom for error (= 4 15 - 5 ) adjusted for 5 dummied values (Undewood 1997); see methods.

CHAPTER 3: EXPEUMENTAL SURVEY OF NATNE AND ALIEN SEED MORTALITY

Table 3.4. Seed predation expenrnent; vertebrate exclosure (V.E.) and invertebrate exclosure (LE.) effects on seed

recovery by species, with seed weights. Effect sizes are listed from largest to smallest for V.E and I.E. Seed weights

represent weights of seeds as used in experirnent (one seed plus any accessory structures naturally with seed at time

of dispersal).

= (meanvcncbmtc cxc~usion + meaninvcnehnte and vcrtcbmtccxclusion) / (meanconcd + meaninvcttcbmtc CXC~II,~..)

IeE* = (meaninwnebna exchwion + meminrcncbnie ;uid rcncbncc cielusion) ' (meanconmi + meanvettcb~,~ cxc î~s~on)

V.E. (5%) Species

Elyntus trach~caulus

Sorghastrum riutarts

Rariitriculits rliomboidetcs

Elyntrcs repens

Echiuni viclgare

Pariicitni liriearifoliuni

Rurriex crispus

Carex spicara

Plantago rugellii

Dipsacus q l vestris

Daitcics carom

Asclepias sjriaca

Vicia cracca

Bronilu rectoruni

Clietropodium albuni

Potentilla arguta

Siletze idgaris

Oenothera bienriis

Digitaria ischaemum

Brumirs kalmii

Carex ntuhlenbergii

Solidago nemuralis

Leorrurus cardiaca

Silene antirrhina

I.E. (%) Species

Dipsacus sjlvestris

Chrysaritheniuni leucarztliemuni

Elymus t racltycnulus

Desniodiuni cariadense

A nemisia cnnzpestris

Plan rago major

Digitaria ischaemurn

Anenlotte cyliridrica

Siletie antirrhina

Parlicicni liriea rifol ium

Dortcus caruta

Ranuticrt lus rlzonilzoideus

Hedeoma hispidu

Arcthni minus

A lyssum alysoidrs

Hackelia virginiana

Geum urbanum

Solidago nenioralis

Melilotus alba

Bronlus recto runl

Carex spicata

Elymus repens

Oenothera biennis

Echium vulgare

C e . E EED T

Table 3.4. Continued

V.E. (%) Species seed wt.

A rcriunt nzitws

A rreniisia canrpestris

Hnckelia virgitiiana

Melilotus alba

Desntodiutn cariadettse

Hedmnia hispidn

Geum aleppicunt

Ceuni rrrbntium

A lyssuni al~soides

Atientorie cylirtdrica

Motlarda fistrc iosa

Chtysurrilten~unt leucunrhemum

Lespede:~ capitara

Nrperu c-ataria

Porentilkr recra

Plunrago major

A rahis glabra

Perlsrertlort hirsutits

Vrrbascrinr rhapsus

LE. (5%) Species seed wt. (mg)

Leoriunrs cardiaca

Nepera cnîariu

Silerie rulgaris

Lespede:a capiraia

Planraga rugellii

Asclepias syriaca

Geitni aleppicuni

Ambis glahra

Sorgliastrtrnl rturans

Brnmus kalniii

Vicia cracca

Camr nllrhletiber,qii

Ver6ascunr rltapsus

Chettopadiiini albunt

Porerlîilla recru

Porenrilln argiira

Moriurda fisridosa

Perrsrerrlott Iiir=riirus

Rutnex crispus

CHAPTER 3; EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Wiien analyzed separately. the general pattern of treatment effects did not differ substantially

between natives and aliens (Table 3.3). Irrespective of origin. plot and species had highly

significant effects on seed recovery (Table 3.3). For both natives and aliens, vertebnte exclusion

had a highly significant positive effect on seed recovery and there were significant interactions of

insect exclusion x species and vertebrate exclusion x species (Table 3.3). The rnost substantial

difference with respect to origin was the presence of a significant vertebrate exclusion x insect

exclusion interaction in natives but not in aliens.

Seed bank mortality experiment

Seed recovery. as measured by seedlings counted in the field plus seedlings counted in the

greenhouse. vûried substantially between trials (Figures 3.2-3.4). In the 4 month trial 2 1.7% of

seeds were recovered. This proportion was adjusted to 24.9% after correction for mechanical

losses. as measured by the proportion of glass beads recovered. Rccovery peaked in the 1 1

rnonth trial at 28.7%. corrected to 32.1% recovery. The lowest recovery rates were from the 16

month trial. retrieved in faIl 1998, with an uncorrected rate of 14.9% and a corrected recovery

rate of 16.6% of seeds. Rates of bead recovery remained almost constant through the three

successive trials at 87.4%. 87.01 and 88.4%, strongly suggesting that differences in seed

recovery between the trials were not due to differing levels of mechanical loss. The relative

importance of field and greenhouse recovery chünged over the three trials. The increase in

recovery betwern the 4 month and 1 1 month trials resulted from an increase in seedlings in the

greenhouse rather than in the field, while in 16 month trial, reduced recovery was a result of

reductions in both field and green house germination (Table 3.5).

Figure 3.1. Overall results of the above-ground seed predation expenment: Proportion of seed recovered in controls and predator exclusion treatments + SEM.

insect vertebrate vertebrate + insect exclusion exclusion exclusion

Treatment

Table 3.5. Proportions of total seeds in each trial recovered as seedlings in the field and by

germination in the greenhouse in the seed bank expenment.

Trial Proportion Proportion length Field Greenhouse

4 month 0.067 O. 149

11 month 0.068 0.2 19

16 month 0.036 0.1 12

CHAPTER 3: EXPERIMENTAL SLJRVEY OF NATiVE AND ALIEN SEED MORTAI ITY

Native and dien species responded very similarly to the treatments with no consistent

differences between the three trials (Tables 3.6-3.8; Figures 3.2-3.4). Recovery rates by species

were not significantly different between natives and aliens in any of the three trials (means: 4

month trial, native - 26.5%. alien - 22.5%; 1 1 month trial, native - 35.4%. alien - 29.8%, 16

month trial, native - 17.5 %, aIien - 15.4%). Responses to the treatrnents were similar in direction

for natives and aliens. with sonle differences in strenpth of treatment effects. Fungicide

significantly increased overall seed recovery in al1 trials while invertebrate exclusion did not

produce any significant effects on overall seed recovery (Tables 3.6-3.8). In the 1 1 month trial

however, invertebrate exclusion resulted in a rnarginally significant increaïe in seed recovery

(P=0.06). The strength of the overall fungicide effect was greatest in the four rnonth trial. in

which fungicide significantly increased recovery of both native and alien species when those

species were analyzed as separate groups. In the 1 1 month and the 16 month trials, although

fungicide significantly increased overall recovery, on1 y the alien and not the native species

exhibited significant fungicide effects. The overall fungicide x species interaction was significant

in the 16 month trial. and significant fungicide x species interactions were also found for natives

in the four month trial and for alien species in the 16 month trial. In the I I month trial there was

a significant overall invertebrate exclusion x species effect. Recovery varied significantly with

plot in the 4 month and 16 month trials, but not in the 11 month trial. In the four month trial

fungicide improved recovery for 23 of the 39 experimental species. relative to the controls. and

invertebrate exclusion improved recovery for 17 (Table 3.9). In the 1 1 month trial fungicide

irnproved recovery for 22 species and invertebrate exclusion for 24 species (Table 3. IO), and in the 16 month trial, recovery was respectively improved for 24 and 16 species.

Variation in recovery rates by species were highly significant in each trial (Tables 3.6-3.8).

Lrsprdeia capitnta had the lowest recovery rates in al1 three trials at less than 1 %. Maximum

species recovery rates wcre 61.4% in the four month trial for Elynrus traclzycnuius, 77.7% in the

11 month trial for Ritmex crispus and 53.5% in the 16 month trial for Rumex crispus (Tables 3.9-

3.1 1 ). Patterns of recovery in legumes and grasses were distinct from the rest of the experimental

species. Legumes. except Vicia crctcca in the 1 1 month trial, were recovered at very low rates

and al1 grass species were recovered largely as seedlings in the field, with five of six species

showing maximal recovery in the 4 month trial with declining recovery through the 1 1 and 16

month trials.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.6. Results of 3-factor randomized block factorial ANOVAs on overall data (native + alien). native d m and

alien data for 4 rnonth trial of the seed bank experiment. Treatment was treated as a fixed effect, plot w a treated ris

a random effect and the residual was used ris the error term.

* =P<O.Ol, **=P<O.ool, *** =PcO.O001

SEED BANK EXPERIMENT - FOUR MONTH TRIAL - OVERALL ANOVA TABLE

Factor d f MS F-value Plot 5 0.422 2.433*

fungicide 1 3.122 18.Oo2***

invertebrate exclusion 1 0.031 O. 179

species 38 6.896 39.764***

fungicide x invenebrate exclusion 1 0.059 0.310

fungicide x species 38 0.236 1.361

invenebrate exclusion x species 3 8 O. 164 0.946

fungicide x invertebratc exclusion x species 38 0.198 1.142

error ' 74-4 0.173

'degrees of freedom for error (=775-3 1 ) adjusted for 3 1 dummied values (Underwood 1997): see methods.

SEED BANK EXPERIMENT - FOUR MONTH TRIAL - NATIVE ANOVA TABLE

Frtc tor d f MS F-value Plot 5 0.348 1.850

fungicide 1 2.826 15.025***

invertebrate exclusion 1 0.293 1.563

species 18 7.253 38.562***

fungicide x invertebrate exclusion 1 O. 106 0.563

î'ungicide x species 18 0.305 1.621 * invertebrate exclusion x species 18 O. 160 0.851

fungicide x invertebrate exclusion x species 18 0.121 0.643

error' 360 0.188

'degrees of freedom for error (=375-15) adjusted for 15 dummied values (Underwood 1997); see methods.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATNE AND ALlEN SEED MORTALITY

Table 3.6. Continued

SEED BANK EXPERiMENT - FOUR MONTH TRIAL - ALIEN ANOVA TABLE

Factor d f MS F-value Plot 5 0.326 2.057

fungicide 1 0.687 1.336*

i nvertebrate exclusion 1 0.079 0.499

species 19 6.783 42.813***

fungicide x invenebrate exclusion 1 0.430 2.713

fungicide x species 19 O. 163 1 .O29

invertebrate exclusion x species 19 O. 158 0.997

fungicide x invencbrate exclilsion x species 19 0.256 1.6 16*

errnr' 379 0.158

'deprees of freedom for error (=395-16) ridjusted for 16 durnmied values (Undewood 1997); see mrthods.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.7. Results of 3-factor randomized block factorial ANOVAs on overall data (native + alien), native data and

alien data for the 1 I month uial of the seed bank experiment. Treatment was treated as a tïxed effect. plot wris

treated as a mndom effect and the residual was used as the error term.

*=P<O.Ol, **=P<O.ool. *** = P < O . O I

SEED BANK EXPERIMENT - 1 1 MONTH TRIAL - OVERALL ANOVA TABLE

Factor d f MS F-value Plot 5 0.313 1.495

fungicide I 1.1 12 5.311*

invertebrate exclusion 1 0.773 3.692

species 38 6.909 33.W 1 *** funpicide x invertebrate exclusion 1 0.437 2.087

fungicide x species 3 8 0.224 1.070

invertebrate exclusion x species 3 8 0.292 1.395

fungicidr x invertebrate rr;clusion x species 38 0.2 15 1.027

error ' 719 0.209

'degrees of freedom for error (=775-56) adjusted for 56 dummied values (Underwood 1997); see methods.

SEED BANK EXPERIMENT - 1 I MONTH TRIAL - NATIVE ANOVA TABLE

Factor d f MS F-value Plot 5 0.262 1.096

fungicide 1 0.086 0.360

inverte brate exclusion 1 0.589 2.163

spec ies 18 8.675 36.279***

fungicide x invertebrate exclusion 1 0.323 1.351

fungicide x specirs 18 0.272 1.138

invertebrate exdusion x species 18 0.313 1.309

fungicide x invertebrate exclusion x species 18 O. 193 0.807

error' 345 0.229

'degrees of freedom for error (=375-30) adjusted for 30 dummied values (Underwood 1997); see methods.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATNE AND ALEN SEED MORTALITY

Table 3.7. Continued

SEED BANK EXPERIMENT - 1 1 MONTH TRIAL - ALLEN ANOVA TABLE

Fac cor d f MS F-value Plot 5 0.141 0.768

fungicide 1 1.407 7.683**

invertebrate exclusion 1 0.230 1.256

species 19 5.463 29.827***

fungicide x invertebrate exclusion I O. 136 0.743

fungicide x species 19 O. 170 0.930

invertebrate exclusion x specics 19 0.284 1.551

fungicide x invertebrrite exclusion x species 19 0.236 1.342

error' 369 0.210

'degrees of freedom for error (=375-26) adjusted for 26 dummied values (Underwood 1997); see methods.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALEN SEED MORTALITY

Table 3.11. Results of 3-factor randomized block frictorial ANOVAs on overall data (native + dien). native data and

alirn data for the 14 montb tria1 of the of seed bank cxperiment. Treatment wrts treatcd ris a fixed effect. plot wris

trecited as a nndom effect and the residual was used ris the error term.

* = P < 0.01, ** = P < O.Oo!, *** = P c 0.0001

SEED BANK EXPERIMENT - 14 MONTH TRJAL - OVERALL ANOVA TABLE

Factor d f MS F-val ue Plot 5 1.69 1 8.350* ** fungicide 1 1.156 5.776*

invertebrate exclusion 1 0.052 0.260

species 3 8 3.066 20.3 17***

fungicide x invertebrate exclusion 1 0.023 0.1 15

fungicide x species 38 0.306 1.529*

invenebrate exclusion x species 38 0.139 0.745

fungicide x invertebrate exclusion x species 38 O. 149 0.735

errorl 759 0.200

'degrces of freedom for error (=775- 16) adjusteci for 16 dummied values (Underwood 1997); see methods.

SEED BANK EXPERIMENT - 14 MONTH TRIAL - NATIVE ANOVA TABLE

Factor d f MS F-val ue Plot 5 1.265 5.474***

fungicide 1 0.267 1.155

invertebratr exclusion 1 0.004 0.01 7

species 18 5.111 22.118***

fungicide x invertebrate exclusion 1 0.034 O. 147

fungicide x species 18 0.253 1.095

invertebrate exclusion x species 18 0.181 0.783

fungicide x invertebrate exclusion x species 18 0.2 15 0.930

error ' 370 0.231

'degrees of freedom for error (=375-5) adjusted for 5 dummied values (Underwood 1997); see methods.

CWAPTER 3: EXPERIMENTAL SURVEY OF NATWE AND ALEN SEED MORTALITY

Table 3.8. Continued

SEED BANK EXPERIMENT - 14 MONTH TRIAL - ALIEN ANOVA TABLE

Factor d f MS F-value Plot 5 0.72 1 3.264***

fungicide 1 0.995 5.885*

invertebrite exclusion 1 0.066 0.390

species 19 3.289 19.453*

fungicide x invertebrate exclusion ! 0.001 0.006

fungicide x species 19 0.366 2.165**

invertebrrite exclusion x species 19 0.125 0.739

fungicide x invrrtebrate exclusion x species 19 0.094 0.556

error ' 381 0.169

'degrees of freedom for error (=395- 1 1 ) ridjusted for 1 1 dummied values (Underwood 1997); set: niethods.

Figure 3.2. Results of the four month trial of the seed bank expriment, by method of recovery (germination in field and germination in greenhouse). Proportion of seeds recovered are corrected for physical losses. Results (mean +SEM) are given for al1 species, for native species

only and for aiien species only.

0.3

O R S -hW

OP 0 p*mh*.dhgnrihouu

0.15 a-- 0.1

0.05

O

ÇHAPTER 3: EXPERIMENTAL SURVEY OF NATiVE AND ALlEN SEED MORTALITY

Figure 3.3. Results of the 1 I month trial of the seed bank experiment. by method of recovery (germination in field and germination in greenhouse). Proportion of seeds recovered are correcied for physical losses. Results (mean +SEM) are given for al1 species, for native species

only and for alien species only.

Figure 3.4. Results of the 16 month trial of the seed bank experiment, by method of recovery (germination in field and germination in greenhouse). Proportion of seeds recovered are corrected for physical losses. Results (mean +SEM) are given for al1 species, for native species only and for alien species only.

CHAPTER 3: EXPERIMENTAL SURVEY OF NATNE AND ALIEN SEED MORTALITY

Table 3.9. Results of four month trial of seed bank expriment: Mean percentage seed recovery corrected

for soi1 losses. by treatment and species. A SEM (n=6 replicates per species. per treatmcnt. unless utherwise

noted in brackets after SEM). Native species are indicated by "N", and alien species are indicated by "A".

Species Control Invertebrate Fungicide Fungicide & exclusion invenebrate

N~tzdropogon gerurdii

N~ rientane cylindrica

AArcrittnr niinus

Y~neniesia cumpesrris

'v~sclepias syriaca

N~ster - ericoides

'YBronius kalniii

AClie~iopodium album

" Ctinsatithert~unr feucantheniitm A D ~ ~ ~ t l ~ carora

"Desniodiuni cartadense

" Dipsacus sylvestris

A Echiunz vrrlgare

A Elynzus repens

'v~lyrnics rrachycaul us

" Etysimum cheiranrhoides

NGertnt aleppictcnt

'V~ackelia virg irziarta

AHitrrnciitm arr rtltiriacum

NHieracium scabrttm

A L e ~ r i ~ r t c ~ cardiaca

NLespedeza capitatcl

" Medicago lupulina

"Melilorus afba

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.9. Continued.

Species Control Invertebnte Fungicide Fungicide & exclusion invertebrate

exclusion *'Motiarda fistulosn 0.332I0.069 0,328M.063 0.323I0. 1 12 0.315I0.112

ANepera cataria 0.040I0.020 0.06210.026 0.057I0.023 O. 130I0.035

"Oertothera bienriis 0.19 1 I0.060 0. 170M.039 0.32 1 I0.05 1 0.25710.055

'VPe~wremon hirsutits 0.150I0.049 0.223a.026 0.26510.066 0.288I0.057

" Phleilm pratense 0.4 1 2kO.033 (5) 0.123I0.088 ( 5 ) 0.2821t0.080 (5) 0.334a. 125

A Plattrago major 0.56210.072 ( 5 ) 0.44 1 I0.064 (1) 0.5 15d . 127 (5) 0.358I0.126 (5)

VPlari tago rugellii 0.556I0.0(i 1 ( 5 ) 0.462M.064 ( 5 ) 0.446I0.096 (5) 0.507I0.092 (5)

'VPoreritilla argttta 0.258d.060 0.247I0.037 ( 5 ) 0.224M.0.15 0.320I0.057

APoretirilla recta 0.035I0.022 0.02 1 I0.02 1 ( 5 ) 0.03910.025 0.06310.025

ARitrr~ex crispus 0.62810.066 0.493I0,072 ( 5 ) 0.583d. 107 0.699îO.060

"Solidaga nenroralis 0.1 3710.025 0.19~I0.063 0.17410.049 0.268+0.083

"Sorghusrntnz nutriris 0.348d.070 0.34210.1 03 0.32 1 Io. 1 08 0.165I0.073

A Verbascttm tltapsits 0.165H.046 O. 1 1 OI0.045 O. 12210.062 O. 15510.063

" Vicia cracca O. 168I0.029 0.083a.O 17 O.OSOfl.026 0.12310.035

CHAPTER 3: EXPERTMENTAL SURVEY OF NATNE AND GLEN SEED MORTAI-ITY

Table 3.10. Results of I I month trial of seed bank experiment: Mean percentagc secd recovery corrected

for soi1 losses, by treritrnent and species, * SEM (n=6 replicates per species, per treatment, unless otherwise

noted in brûckets after SEM). Native species are indicated by "N', and alien species rire indicated by "A".

Species Control Invertebmte Fungicide Fungicide & exclusion invenebrate

N~tidropogon gerardii

"Atiernone cylindrica

A~ rctium nliws

rtcnzesia canipesrris

'V~sclepias syriaca

' V ~ s t r r ericoides

NBrontits kalrnii

"Cheriopodiun~ alliirnt

A Chnsan fhemim leucanthenium ADaucus carotu

'V~e.sniodiirni carrudense

.' Dipsacus syl vesrris

A Echiunl vulgare

A Elyntrts repens

N ~ i y m u s rrachycaulirs

A Erysimicrn cheiranrhoides

" ~ e l l n i aieppicunt

"~uckel ia virginiutra

" Hieracirrnt aururitiacum

'VHieraciurn scabrum

"Leon~rnrs cardiaca

N~espedeza capitara

A Medicago lupulitta

"Meiilotus allia

" ~ o n a r d a fisrulosa

ÇHAPTER 3: EXPERIMENTAL SI JRVEY OF NATIVE AND ALEN SEED MORTAJ .ITY

Table 3.10. Continued. Species Con trol Invertebrate Fungicide Fungicide &

exclusion invertebrate exci usion

Nepeta ruta ria 0.265I0.070 O. 139I0.029 0.089d.048 0.277iû.025

"Omorhera bienriis 0.707Io. 125 ( 5 ) 0.79OM.MO (5 ) 0.689îû.05 1 0.579dl. 148

'VPlantago rugellii 0.763M. 1 19 (4) 0.603dI.2 12 (4) 0.799I0.075 (4) O.808îû.094 (3)

NPoretitilla arguta 0.234d.028 0.354fl.030 ( 5 ) 0.380d. 12 1 O. 1 70I0.049

A Potentifla recta O. 1 1 1 I0.030 ( 5 ) O. 182I0.03 1 (5) 0.274H.063 0.14310.033

A Runiet crispus 0.67510.094 0.763IQ.099 ( 5 ) 0.779îû.0.19 0.88810.025

ASiletie vulgaris 0.069îû.051 0.103I0.060(5) 0.109I0.062 0.114îû.068

'V~oq/tasrruni rillrutis 0.33610.W 0.347d.W 0,36410.102 0.43010.109 (5)

" Verhmcum thapsus 0.286d.072 0.137I0.075 0.376I0.083 0.539I0.074 ( 5 )

A Vicia cracca 0.383I0.059 ( 5 ) 0.364~0.029 ( 5 ) 0.360i4.037 0.350H.057

ÇHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.11. Results of 16 rnonth trial of seed bmk experiment: Mean percentage seed recovery corrected

for soi1 losses, by treatment and species, * SEM (n=6 replicates pet species, per treatment. unless otherwise

noted in brackets after SEM). Native species rire indicated by "N", and alien species tire indicated by "A".

Species Conuo l Invenebrrite Fungicide Fungicide & exclusion invertetinte

N~ndropogon gerardii

"A liernone cylindrica

" A rctirtni nrinus

NA rtenmia canipestris

sclepias sy riclcw

"Aster ericoides

"~rontus knlmii

AChenopodiunt alhrtm

A Ch rysanrireniirni leucari theni um A Darr cus carota

NDesnindittnt canadense

A Dipsacus sylvestris

A Echium vuigare

A Ely nr us reperls

"El~niirs trachyaldus

A Ensimum cheirclnthoides

"Geunl aleppicunl

"Hackelia virg iriiana

"ieracirrm aurarrtiacunl

"Hieracium scabrrtrri

" Leoriurus cardiaca

"Lespedeza capitora

" Medicago lupulina

A Melilotus alba

NMonarda fistulosa

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND ALIEN SEED MORTALITY

Table 3.1 1. Continued.

Species Conml Invertebnte Fungicide Fungicide & exclusion invertebrate

exclusion " Nepera cararia

"Oenothera bierittis

'VPensrenion hirsrrrus

A Pltierini prarerrse

A Plart rago major

'" Pinrirago riigellii

" Poteririlia arguta

" Porert rilla recta

* Rttniex crisplis

,'Silerie r~rrlgaris

."~oiidago ri entoralis

rVSorslia.~tnrni rtiitaris

A Verbascrint thapsrts

A Vicia craccu

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND AI .W.N SEED MORTALITY

Discussion Soil surface seed predation Predator idenrity

Occasional droppings observed in petri dishes during the experiment indicated the presence of

birds and rodents. Commonly observed seed eating birds at the study site were Field Sparrow

(Spizella pusilla), Song Sparrow (Melospiza meludia), Northern Cardinal (Cardinalis

cardinalis), Indigo Bunting (Passerina cynea) and Amencan Goldfinch (Cardedis tristis). Data

on small mammals were not collected during the experiment, but the onIy seed eating rodents

found in a subsequent srnaIl marnmal trapping program in old fields on site were Meadow Vole

(Microtus pensylvanicus), deer mouse spp. (Perornyscus spp.) and Meadow Jumping-mouse

(Zupirs hudsonius) (P.M. Kotanen, unpublished data). These species are ubiquitous in old field

and forest edge habitats in southern Ontario (Mark Engstrom, R.O.M., pers. corn.) and are

presumed to have been the important rodent seed predators during the study. A single

observation of ants removing seeds was also made, but no attempt was made to identify ants to

species. The common occurrence of droppings, seed husks and damaged seeds in dishes suggests

that many seeds were consumed by birds and rodents on site rather than being criched, as was

found in a similar study in old field habitats (Mittelbach and Gross 1984). Likewise, seeds

removed by ants are presurned to have been consurned. None of the seeds used in the study had

eliasomes, thus any seed removal by ants was likely for consumption of the seed itself.

Field observations shed some light on the presence and behaviour of other invertebrate seed

predators, but their roles remain unclear. Other studies show that earthworms (McRill and Sagar

1973, Grant 1983 and Thompson et al. 1994)- slugs and snaiis (Newell 1967), Carabid (Kjellson

1985) and Bruchid (Janzen 1975) beetles and Lygaeid bugs (Collins and Uno 1985) can feed on

seeds at the soi1 surface. During wet periods. the slime of earthworrns, snails and slugs may have

enabled them to overcome the Tangletrap barrier. In a separate study at the same location, slugs

were observed to occasionally crawl ont0 and eat Tangletrap-coated seed t n p papers, without

becoming entangled. Lygaeids and Carabids were likely not important post-dispersai seed

predators at the site as none were found among the many insects stuck to the Tangletrap-coated

dishes. If these taxa were present in the study area, they would likely have been deterred by the

Tangletrap barriers, as they forage on the ground rather than in flight (Kjellson 1985).

Overnll seed rernoval

The magnitude of seed removal by seed predators, as measured by the difference between

exclusion and non-exclusion treatments, was considerably lower than that found in most

ç H _ A e T E R L E X P E R l M E N T A L E N SEESEED MORTALITY

previous studies. It is not surprising that predation rates were Iower than those found in studies in

arid landscapes. North American and Old World deserts have numerous specialist granivore taxa,

especially rodents and ants, whereas in northeastern North Arnerica, çranivorous ants, rodents

and birds are generalists which rnay switch to other food sources in the summer (Mittelbach and

Gross 1984, and references therein). 1 found that excluding vertebrates increased overnll seed

recovery by only 8.3% over one month, although increases by species ranged up to 46.4%. The

overall effect of insect exclusion was negligible. Mittelbach and Gross (1984) and Hulme ( 1994)

investigated post-dispersal seed predation in oid fields in Michigan and England. They found

predation rates of 5% / d and 24% 1 d over 6 d and 3 d respectively, on seeds of a range of sizes.

The lower rates in my study are probably at least partly attributable to the use of a broad range of

seed sizes, including nurnerous seeds weighing < 1 mg (Table 3.4), as other studies have shown

seeds of this size to have lower risk of predation (Kelrick er al. 1986, Mittelbach and Gross 1984

and Reader 1993).

Another potentially important factor was the > 50% of seeds which were not recovered due to

factors other than seed predators. Seeds lost to the study could not be counted as having been

consumed, even if they were. The corrected rate of seed loss was 54% for dishes protected from

both vertebrates and invertebrates, which theoretically should have lost no seed. Several factors

were likely important in limiting recovery. First, incomplete germination as a result of dormant

or inviable seeds undoubtedly lirnited the recorded recovery rates of small seeded species for

which greenhouse germination was the main source of recovery. Most of these species had

recovery rates well below the overall average. The magnitude of this effect is hard to determine.

Most species had high germination rates (s75%) before the study, but some were significantly

lower. Secondly, the correction factor for physical loss of seeds büsed on the recovery of sand

from each dish was probably an underestimate. Despite the drainage holes, sand and seeds were

observed to have overfiowed from some plates after heavy rains. Seeds were placed on the sand

surface, and it seems likely that the proportion of seeds washed or blown out of the dishes might

exceed that of the sand as a result. Field observations do suggest that although the correction

factor may not have been large enough, it was in the right direction, as sand loss and seed loss

tended to be correlated. Field germination and subsequent death rnay have been an important

source of seed loss for a few species. There were some heavy d n s early in the experirnent which

stimulated germination for some species, followed by dry periods which desiccated the sand in

the petri dishes entirely, killing some seedlings. Dead seedlings were counted as k ing recovered,

but small seeded species which germinated and quickly died could easily have been missed.

Finally, there rnay have been some predation by slugs, mails or other invertebrates which were

able to get around the invertebrate barrier, as described above. These factors only limit the utility

CHAPTER 3: EXPERIMENTAL SURVEY OF NATTVE AND At.IEN SEED MORTAIJTY

of the observed absolute rates of seed loss as estimators of natural predation rates. They do not

significantly affect conclusions about the relative importance of different experimental

treatments.

The presence of a large negative effect of insect exclusion on seed recovery for species such as

Bromus kalmii, Rumex crispus and Verbascuin thapsus is hard to explain. The negative effect on

Verbascu~n tlrapsus could be explained by a failure to detect the species' very smal1 seeds if they

became trapped in the Tangletrap insect barrier. This explanation would not apply to Bror~rus

kalnrii and Rumex crispiis. as their large seeds were easily detected when trapped in the insect

brimer.

Patterns in treatmerzt efSects

As shown by the significant insect exclusion x species and vertebrate exclusion x species

interactions, different species of seeds are subject to different types of predators at the soi1

sudace. Larger seeds were distinctly more susceptible to vertebrate predation. Nine of the ten

species of seeds with the greatest increases in recovery as a result of vertebrate exclusion had

seed weights above the median of 1 .O mg (P=O.OO 1, one sided sign test). This result agrees wel1

with work in shmb steppe by Kelrick et al. (1986), and in old fields by Mittelbach and Gross

(1984) and Reader (1993), who found reduced rodent predation on seeds under 2 or 3 mg.

Contrary to the trend in multi-species seed dish experiments (Thompson 1987). there was no

consistent evidence of selectivity on the basis of seed size by insect seed predators, although the

two species for which insect predation was significant (Dipsacus sylvestris and Desmodi~rni

canadense) were relatively large seeded.

The Mittelbach and Gross (1984) and Reader (1993) papers used a nurnber of the same species

as were in this study and found some different results. Most differences were significant

predation effects found by the other authors, but not in this experiment (Daucus carota in both

studies, Chrysanthemum leucanthemurn in Reader). Mittelbach and Gross, however, also found

that ants (which were significant predators of other species in their study) were not significant

seed predators of Dipsacus sylvestris, while my work found Dipsacus sylvestris to have the highest level of insect predation of any species. My results were in accord with iheirs for

Oenothera biennis, Echiurn vulgare and Verbascurn thapsus. In addition, work by Reader and

Beisner (1991) at the same site as Reader (1993) found that an&, but not rodents or birds, were

significant seed predators, contrary to the findings of my experiment. My results differ from

Reader's despite the fact that the sites are very similar in vegetation and only 75 km apart.

CHAPTER 3: EXPERJMENTAI. SURVEY OF NATlVE AND ALIEN SEED MORTALlTY

One major taxonornic trend in predation rates was evident. Grarninoids were overrepresented

among the favoured seeds for vertebrates. The six species showing significantly increased

recovery with vertebrate exclusion included four grasses and one sedge, out of only 9 grarninoids

in the study. This probably is related to the relatively large size of the experimental graminoid

seeds and likely reflects their comparatively high quality as food items as well.

Seed bank rnorîality

Fung icide addition

My results demonstrate the genenl importance of fungal mortality in the seed bank and seedling

stages. Overall recovery was significantly improved with fungicide addition in al1 three trials.

Fungal effects on seeds and seedlings are well known in agricultural systems, as demonstrated by

the extensive use of fungicide seed coatings (Taylor and Harman 1990) and foliar treatments on

seedlings (Kendrick 1992). Fungal pathogens have also been shown to be important causes of

seed and seedling mortality in natural vegetation. Crist and Fnese (1993) found seed

decomposition rates of 0-93.5% over 10 months in seeds of six shrub-steppe species and their

isolation of seven species of Ascornycete fungi from inside the seeds suggested fungal

involvement. Lonsdale ( 1993) experimentally excluded higher fungi (but not Oomycota) and

found 10% CO 16% increases in seed survival over 7 months for the shmb Mimosa pigrn in

tropical Australia. Augspurger and Kelly ( 1984) demonstrated that darnping-off disease killed O- 9 5 8 of seedlings of 18 tropical tree species and that mortality increased with seedling density,

shade and proximity to the parent tree. As well as decomposition, infection by soil fungi has

been shown, in some species, to inhibit germination without immediately killing the seed

(Kirkpatrick and Bazzaz 1979). to contribute to breaking dormancy of hard seeded species

(Gogue and Emino 1979). to reduce colonization of subsequent microbes and to reduce or

increase seed consumption by animals (Roy and Abney 1977, Janzen 1977, Crist and Friese

1993). Thus the effects of fungicide addition can be complicated and the observed results may be

a combination of several effects in addition to fungal mortality. The results do indicate, however.

that the combined effect of excluding fungi is increased seed survival.

The particular fungi involved in seed decomposition in soil are very poorly understood, but

likely include species of both the primitive "protoctistan fuiigi" (especially the Division

Oomycota) and the Eumycota (Divisions Zygomycota and Dikaryomycota). The Oomycota are

especially important pathogens of young seedlings, with genera such as Pytlzium and

Phytoptliora being the major cause of damping-off diseases and root-rots (Augsburger and Kelly

1984, Paul et al. 1989). Although both traditionally classed as fungi, these two major groups are

H APTER 3- EnERIMENTAL SURVEY OF NATIVE AND AI.EN SEED MORTAJ,ITY C

now classified in separate kingdoms, with the "protoctostan fungi" allied with brown algac in the

Strarnenopiles (Sogin and Patterson 1998). Due to physiological differences, few fungicides are

effective against both groups (Paul et al. 1989). No assays of the fungi in treated and untreated

soil were atternpted in this study but Captan is widely used in agriculture to control species of

oornycetes, ascomycetes and basidiomycetes in the soil and on fruit, leaf and seed surfaces

(Sharvelle 1961, Torgeson 1969, Neergaard 1977). The increases in recovery associated with

fungicide addition in this experiment may well underestimate total fungal mortality, as

fungitoxic effects of Captan are species specific and some pathogens may not have been

controlled by the fungicide (Sharvelle 1961, Torgeson 1969, Neergaard 1977).

Lonsdale (1993), in the only other study which has used fungicide on seeds in field soil, found

that addition of a benomyl fungicide, which is effective against Dikaryomycota, but not

Zygornycota or Oomycota, resul ted in a 10% to 16% increase in relative survival of Mimosa

pigm seeds over 7 rnonths. Lonsdale's measure of fungicide effect was relative to the control

treatment [(% recovery with fungicide - % recovery without fungicide) / (% recovery without

fungicide)]. The same calculation on my data gives a similar percentage increase in recovery;

1 16.2% and 18.1 % in the 4 month. 1 1 month and 16 month trials respectively. The same

value calculated for each species ranged from negative effects (which were non-significant by

ANOVA) to a 299% increase in recovery of Arctium minus in the 16 month trial, indicating

substantial variability in species' susceptibility to fungi.

Invertebrate exclrrsiorz

There was no significant overall effect of invertebrate exclusion in any trial, ihough there was a

marginally non-significant increase (pd.06) in recovery and a marginally non-significant

invertebrate exclusion x species interaction (P=0.06) at the 11 month trial. Of the 7 species in the

three trials for which invertebrate exclusion significantly affected recovery, 5 showed increased

recovery. Significant effects, as a percentagr of non-invertebrate treatments, ranged from a

66.7% decrease in recovery for Medicago lupulina in the 1 1 month trial to a 76.0% increase in

recovery for Artemisia campestris in the 1 1 month trial.

The importance of mammalian seed predation below ground was probably minimal. Rodents are

capable of detecting seeds below ground (Reichmann 1979, Johnson and Jorgenson 198 1 ), but

Hulme (1990, in Crawley 1992) found that seed buriai reduced rodent predation by 90% across a

wide range of species in English grasslands, and no evidence of rodent tunnelling around the pots

was seen. Invertebrates were not quantified but earthworms and ants were the rnost numerous

potential seed consumers noted in the pots after recovery. Neither earthworms nor ants were

ÇHAPTER 3: EXPERIMENTAJ. SWVEY OF NATTVE AND ALEN SEED MORTALITY

completely excluded by the invertebrate exclusion screening, as they were occasionally observed

in the screened pots, but the invertebrate exclusion treaiment probably would have reduced at

least earthworm numbers by making access more difficult for them. The effects of earthworms

on seeds have been relatively well studied (McRill and Sagar 1973, Grant 1983, Thompson et al.

1994). They consume large numbers of small seeds, and have been shown to selectively consume

seeds within soil (Grant 1983). Consumed seeds may be killed. they may be excreted apparently

unchanged, or they may survive with reduced dormancy, which can be fatal for seeds below

ground. The impact of earthworms on seeds is variable. There is an obvious lirnit to the size of

seeds which they can ingest and it seems unlikely that the rather small earthworms observed in

the pots consumed any of the larger seeds in the study. Thompson et al. (1994) found that

virtually al1 seeds in worm casts were less than 0.3 mg, while this size class represented only

20% of the soil seed bnnk ai his site. Earthworms can also be very important in seed movement

within the soil. Some earthworm species will feed below ground and produce casts at the soil

surface, while other species forage on the soil surface and excrete seeds underground (Thoinpson

et al. 1994). Larger soil fauna such as earthworms and ground beetles can also move adhesive

seeds extemally (Kjellson 1986). The few effects of invertebrates rneasured in this study could

therefore include both mortality and seed movement out of the pots in the field. My results

suggest that invertebrates may be an important source of below-ground seed n-iortality for some

species, but that they are less important overall than are soi1 fungi.

Temporal pattern in seed recovery

The changes in recovery rates over time retlect an interaction between increasing mortality and

seasonal shifts in dormancy. The reduction in recovery rates between the 4 month trial and the 16

rnonth trial is likely to be a consequence of seed mortality, as seasonal dormancy effects should

not greatly differ (both were retrieved in fall, 1997 and 1998 respectively). The fact that the

recovery rate was substantially lower in the 4 rnonth trial (retrieved in faIl 1997) as compared to

the 1 1 month trial (retrieved in spring 1998) strongly suggests that seeds were more dormant in

the fa11 than in the spring. This result is not unexpected given that dormancy cycles are likely of

rather general occurence among temperate zone herbs. Baskin and Baskin (1998), in their

comprehensive summary of investigations of dormancy cycles, found that 79 of 95 species

studied exhibited dormancy cycles. Their list of studies included references for 7 of my expenmental species. Chenopodium album (Chnstal et al. 1998), Daucus carota (Pons 199 l),

Oenothera biennis (Baskin and Baskin 1994), Solidago nemoralis (Walck et al. 1997) and

Verbascum rhapsus (Baskin and Baskin 1983) exhibited dormancy cycles, while Potentifla recta

(Baskin and Baskin 1990) and Rurnex crispus (Baskin and Baskin 1985) were shown not to have

dormmcy cycles. Changes in dormancy through the three trials and the difficulty in

ÇHAPTER 3: EXPERiMENTAL SURVEY OF N A W E AND ALEN SEED MORTAJ JTY

distinguishing dead seeds from live but dormant seeds lirnits the extent to which my recovery

values can be considered to represent natural rates of seed survival. This does not, however,

create a problem in comparing treatment means within a species and trial. which is the primary

focus of this work.

Treatment efects vs. seed size

Several recent papers (Thompson et al. 1993, Bekker et al. 1998, Thompson et al. 1998) have

correlated seed size with persistence in the soil for several hundred species in northwest Europe.

including most of the alien species used in this study. These studies found that species with long

term seed banks are generally smaller seeded. Leishman and Westoby (1998), on the other hand.

found no correlation between seed size and longevity for Australian species. In my experiment,

there was no evidence of srnaller seeded species having a greater resistance to fungi, as might be

expected if they tended to be longer tem seed bankers. There are both small and large seeded

species among those for which fungicide addition and invertebrate exclusion improved recovery.

Regressions of fungicide and invertebrate effects by species vs. seed weight were non-significant

for al1 three trials. with slopes generally close to O. Seed banking requires a suite of

morphological and physiological characters in addition to disease resistance (Leck et al. 1989,

Fenner 1985, Baskin and Baskin 1998). If a relationship between seed size and dormancy dors

exist, it may be better explained by germination charactenstics than by fungal resistance.

Tuonumic paftern

Severai taxonomie patterns were obvious in the data. The very low recovery rates (40%) of al1

the legumes except for Vicia crncca (Desmodium canadense, Medicago lupulina, and MeLilotus

cilbu), were expected given the hard, impermeablr seed coats typical of the farnily (Baskin and

Baskin 1998). Imbibition and germination in these species does not occur until the seed coat

breaks down. Sieving the soil after the germination period revealed that the legume seeds were

still present. In post-experiment germination tests these seeds were highly viable when the seed

coats were scarified. Sirnilarly, the pattem of recovery among the grasses was quite distinct from

the rernainder of the species. Al1 gras species were recovered Iargely as seedlings in the field.

with that pattem especially pronounced in the aliens Elymus repens and Phleum pratense and the

native Elymus rrachycaulus. Within the grasses. five of six species showed maximal recovery in

the 4 month trial with declining recovery through the 11 and 16 month trials. This strongly

contrasted with the forb species; al1 forbs were recovered pnmvily by greenhouse germination

and 26 of 33 species reached maximum recovery rates in the 11 month trial. This pattem can be

attributed to two factors. First is the tendency for grasses to have limited seed dormancy and to

be less likely to produce long term seed banks than herbs (Thompson et al. 1998, Baskin and

CHAPTER 3: EXPERIMENTAL SURVEY OF NATIVE AND A I E N SEED MORTALITY

Baskin 1998). Second, the relatively large seeds of most of the grasses in the study were likely

important in allowifig seedlings to push through several cm of soil to the surface and survive to

be counted where smaller seeded species might have perished.

Aliens vs. natives

Neither experiment produced evidence that aliens benefitted from a reduced rate of seed

predation. as predicted by both the predator filter and predator escape hypotheses. In the soil surface experiment. patterns in predation rates with respect to treatment. plot, seed size. and taxa

were generally consistent between natives and aliens. Overall responses to insect and vertebrate

exclusion were similar for natives and aliens. The only differential response with respect to

origin was the presence of a significant vertebrate exclusion x insect exclusion interaction for

native species. with insect exclusion producing no effect by itself, but resulting in a slight

increase in seed recovery when in combination with vertebrate exclusion. For aliens, insect

exclusion effects were negligible with or without vertebrate exclusion. Natives and aliens also

responded similarly to soil pathogens. Where observed, di fferences between native and alien

species were inconsistent between the three trials.

The predator escape hypothesis requires the existence of species specific natural enemies. In

contrast. the predator filter hypothesis does not require specialist pathogens - only that successful

exotics tend to be more pathogen-resistant than species that fail to establish. Most of the seed

predators in this experiment probably were generalists (birds. rodents, and eanhworms).

Although many fungal plant pathogens are gçneralists (von Broembsen 1993), host specitkity

among seed pathogens is known in agricultural plants (Neergaard 1977, Agarwal and Sinclair

1997). and there is some evidence that natural fungal communities associated with different

species of seeds Vary within the sarne habitat (Kirkpatrick and Bazzaz 1979. Harman 1983. van

der Putten et al. 1993). The most likely explanation for the sirnilar responses of native and alien

species in these experirnents is that both soil fungi and seed predators were sufficiently

indiscriminate generalists that they did not distinguish between native and alien seeds. It is also

plausible that some species specific pathogens of alien seeds have already been inadvertently

introduced to the New World on seeds or in soil, or that pathogens specific to native species have

become adapted to alien congeners since the mival of the aliens. In either case, the results

indicate that predator escape by alien seeds is not a general phenornenon at the seed stage.

The taxonomic composition of the native vs. exotic experimental species was relatively

balanced, though not completely so. There were, for exarnple, four native grass species and only

two alien grass species in the seed bank mortality experiment. The presence of strong taxonomic

CHAPTER 3: EXPERIMENTAL SURVEY OF NATNE AND ALEN SEED MORTALITY

patterns within the recovery rates and treatment effects, and the correlation of these patterns with

further taxonomic pattern in factors such as seed size, suggests that phylogenetic correction

methods may be necessary to extricate the causes of any differences between natives and aliens;

otherwise, large but irrelevant differences between unrelated taxa rnay obscure rnodest

differences between native and exotic species. In the experiment described in Chapter 4, the

effects of fungi in the seed bank are investigated further and effects of phylogeny are controlled

by the use of phylogenetically independent native-alien contrasts.

CHAPTER FOUR

COMPARATIVE EXPERIMENTS ON FUNGAL AND HABITAT EFFECTS O N SEED

BANK MORTALITY

CHAPTER 4: COMPARATWE EXPERIMENTS

Introduction The literature concerning seed banks is enormous (major reviews in Heydecker 1973, Cook

1980, Roberts 198 1, Thompson 1987, 1992, Leck et al. 1989, Chambers and MacMahon 1994,

Fenner 1985, Fenner 1992, Baskin and Baskin 1998). It includes studies in many different

disciplines covering a wide range of related subjects and representing efforts in almost al1 types

of plant corrmunities and locations. The importance of seed banks in relation to population

persistence, to recovery of plant communities following disturbance, to restoration ecology, to

management of rare species and communities, and to weed control are among the many topics

which have been addressed.

Seed banks also may play an important role in biological invasions. Substantial evidence

suggests that the presence of seed banks is important in buffering against the stochastic hazards

faced by small populations (Keddy and Reznicek 1982, Venable and Brown 1988, Rees and

Long 1992, Rees 1993). Invading species generally face these hazards repeatedly, both at the

original site of introduction and with range expansion as small colonizing subpopulations are

formed (Barretl and Richardson 1986, Barrett and Husband 1990). It follows that invasiveness

may be enhanced in species able to produce persistent seed banks, and there is some evidence

that is the case. For example, almost al1 of the world's worst weeds listed in Holm et al. (1977)

produce significant seed banks and the presence of persistent seed banks is cited as being one of

the most important factors in limi ting the success of biological weed control programs

(Holloway 1964, Dahlsten 1986). Crawley, Harvey and Purvis ( 1996) found that British aliens

were more likely than natives to have long term seed banks. Finally, Rees and Long (1992)

found that 75% of species undergoing range expansion in Britain (both native and alien, but

skewed towards üliens) produced long term seed banks.

For a plant to produce a persistent seed bank, its seeds must be able to survive in the soil for

extended periods of time. However, little is known of the factors responsible for mortality in the seed bank (Cavers 1983, Cavers and Benoit 1989, Crawley 1992, Chambers and MacMahon

1994, Baskin and Baskin 1998). Bacteria and fungi in the soil are often suggested to be important

in causing seed mortality, but very few field experiments have addressed their roles specifically

(Baskin and Baskin 1998). Crist and Friese (1993) found that proportions of decomposed seeds

arnong 5 shb-steppe species ranged from 4% to 93.5% over 10 months. They implicated fun@

as a causal agent by isolating 7 fungal species from the retrieved seeds. Lonsdaie (1993) is the

lone study to have demonstrated increased seed survival after experimentally reducing soil fungi

in the field, finding that fungicide addition resulted in a 10- 16% increase in seed survival over 7

months for the exotic Mimosa pigrn in northem Australia. Finaiiy, the demonstrated

CHAPTER 4: C W A R A T I V E EXPERIMENTS

effectiveness and extensive use of fungicidal seed coatings in agriculture (Taylor and H m a n

1990). points to the potentially importance of fungal seed rnortality in other community types.

If fungi are an important source of seed rnortality in soil, and if seed banking is especially

important for invasive species. then invaders may gain a significant advantage if their seeds

rarely suffer fungal attack. There are two distinct mechanisms by which this could occur. Both of

these hypotheses argue that a low pest Ioad is important to invasion; the distinction lies in how

this low load is achieved. First. invaders rnay lose their pathogens when they are transported to a

new area (the predator escape hypothesis: Elton 1958, Crawley 1986). Second, perhaps species

resistant to diseüse make better invaders because they are less likely to be eliminated by natural

enemies in their new habitat (the predator filter hypothesis). These two hypotheses are difficult

to distinguish, but the escape hypothesis predicts that invaders should have lower pest loads in

new habitats, while the filter hypothesis predicts that pest loads are equally low in both original

and new areas. As well. the escape hypothesis relies on the loss of species-specific enemies,

while the filter hypothesis is more likely to apply to generalist enemies.

These hypotheses are not exclusive, and both rnay apply sirnultaneously. There is some evidence

to support at lrast the predator escape model. Many important soil pathogens appear to be

generalists (von Broembsen 1989), but there is also evidence of soil pathogens with some degree

of host-specificity (Kirkpatrick and Bazzaz 1982. Van der Putten et al. 1993, Mills and Bever

1998). including some seed pathogens of agricultural plants (Neergaard 1977, Agarwal and

Sinclair 1997). A few studies have demonstrated that invaders develop larger seed banks in new

regions than in their native habitats, suggesting that escape from seed predators could be

occurring. Lonsdale and Segura ( 1987) found that seed banks of Mimosa pigru were

approximately 100 times larger in Australia than in its native range in Mexico. Research in

coastal shrublands in Mediterranean climate zones of Australia and South Africa (Weiss and

Milton 1984) has shown that seed banks of the reciprocally invasive Acacia longifolia (native to

Australia) and Chrysanthemoides ~nonilifern (native to South Africa) were increased 44 to 13 16

times in new regions. For Acacia longifolin this was attributed primarily to lower seed

production in its native range because of the presence of a seed eating weevil. For

Chrysanthemoides rnonilifera seed production only differed between the two regions by a factor

of two, but survival in the soil was greatly reduced in its native South Africa.

It is unclear if these cases are exceptional, or reflect general niles. Another study comparing 39

locally-occumng native and alien species (Chapter 3) found significant fungal rnortality, but no

consistent differences between natives and aliens. This dernonstrates that natives and diens need

CHAP'ïER 4: COMPARATNE EXPERIMENTS

not behave in fundamentally different fashions, but the interpretation of these results is made

difficult by the fact that native and alien species within the floras of particular areas invariably

have different taxonomie distributions (Heywood 1989, Crawley, Harvey and Purvis 1996). This

can lead to problems of interpretation, for two reasons. First, relatively subtle native-alien

differences may be lost in the "noise" created by the inclusion of very different species in the

same dataset. Second, if a significant result is obtained, there is the danger that it may be an

artefact produced by phylogenetic confounding, as in the following example.

Suppose we were trying to determine the importance of disease resistance for alien species and

we find that the average alien species has significantly greater resistance than the average native.

This result suggests that disease-resistant species are more frequent invaders. This is an

important conclusion, but this TIP approach (i.e., no phylogenetic correction) cannot eliminate

the possibility that differences in disease resistance between natives and aliens are merely

characteristics of the phylogenetic groups to which they predominantly belong, and are unrelated

to the characters w hich actually lead to invasiveness. The effects of origin are confounded w ith

al1 other traits which are conservative with respect to phylogeny (Felsenstein 1985; Harvey and

Pagel 1991; Gittleman and Luh 1992; Miles and Dunham 1993). The solution to these problems

is to adopt a PIC (phylogenetically independent contrast) approach (Felsenstein 1985; Harvey

and Pagel 199 1; Gittlemm and Luh 1992; Miles and Dunham 1993). PICS control for

phylogenetic correlation by contrasting native and alien clades which are more closely related to

each other than to any other clades in the species set. They describe what aliens do, relative to

othenvise similar relatives. In doing this, they reduce both irrelevent phylogenetic noise and the

risk that any effects detected are actually spurious correlations. If the PIC approach were used

and it was still found that aliens had greater disease resistance than natives, the result would be

unlikely to be a consequence of some confounding trait shared by related invaders but unrelated

to invasiveness. Some studies already have applied the PIC approach to cornparisons of native

and alien floras (Crawley, Harvey and Purvis 1996, Kotanen, BergeIson and Hazlett 1998).

In this chapter, 1 address the questions: 1) Does fungal mortality influence seed persistence in the

soi1 seed bank? 2) Does fungal mortality Vary between wetland and upland meadows? and 3)

Does fungal rnortality vary between closely related natives and diens? This work adds to that

descnbed in Chapter 3 by using congeneric pairs of native and alien species to control for

phylogeny, by adding moisture level as a factor, and by increasing spatial replication. By using a

PIC approach, 1 am able to reduce the problem of phylogenetic confounding, and to look for

subtle effects despite using a wide range of species. As well, this approach suggests the

mechanism involved if exotics have low pest loads: since CO-occumng congenerics are likely to

CHAPTER 4: COMPARATiVE E?@J32IMF.NTS

share their generalist enemies. a difference between natives and exotics is more likely to reflect

specialist enemies, and therefore argues for the escape hypothesis. Along with the work outlined

in Chapter 3, this is the first study to expenmentally compare seed bank monality over a wide

range of CO-occurring native and alien species. It is also one of a very small number of papers to

experirnentally examine the roles of soil fungi and soil moisture on seed bank persistence.

Methods Shtdy site The experiment wm conducted in 10 upland and 10 open wetland plots widely spread around the

347.6 ha University of Toronto Joker's Hill field station, Regional Municipality of York. Ontario

(44"02* N, 79"3 1 ' W). Plots were matched for moisture level, openness and vegetation type and

were separated by at least lOOm but were arbitrarily chosen within those bounds. The upland

plots were in open, dry, sandy old field habitats, with some combination of Bromus inemis, Pon

prntensis and Pua compressa dominant. The wetland plots were in open, permanently wet

meadows, dominated by species such as Eupatorium rnaculatum and E. pe@bliatum, Agrostis

stolonifera, Impatiens capensis, Onoclea sensibilis, Glyceriu stria fa, Equisetzlm arvense and E.

fluviatile.

Experimentul Species Thiny herbaceous species which occur pnmarily or entirely in open, upland areas were selected

from a pre-existing seed collection. These species were made up of 15 congeneric pairs of one

native and one alien species (Table 4.1). WiId populations of üli the experimental species occur

in the Regional Municipality of York (Riley 1989), and most of the species occur naiurally

within the Joker's Hill property (Chapter 2). Seeds were collected from wild populations in

southem Ontario in 1997, with the exception of Ely>nus trachycaulus. This species was

purchased from the Pterophylla F m , Waisingham, Ontario, where seeds were grown in 1996

from plants originating from local, wild seed stock. After collection, seeds were stored dry, in a

freezer until use in the experiments.

CHAPTER 4: COMPARATWE EXPERIMENTS

Treatments Field soil for the wetland and upland seed bags was collected irnmediately before the

experiment. from one wetland and one upland plot respectively. Soi1 was partially dned and

sieved but otherwise untreated before use. Seed bags. made from a knee high nylon stocking cut

in thirds, were filled with 20 seeds of a single species mixed with 20 ml of field soil and then tied

shut. Seed bags were subjected to one of two treatments: 1) control - seed bag saturated in water

before burial and 2) fungicide addition - seed bag saturated in fungicide solution before burial.

The fungicide solution was a 1 : 100 solution of Maestro 75DF in water (active ingredient Captan

- 75% by weight, Zeneca Corp., Stoney Creek, ON, Canada). This concentration was

recommended by the manufacturer for use as a dip for bulbs and tubers. Captan is a non-

systemic heterocyclic nitrogen fungicide used against a wide range of fungi in the Oomycota,

Ascomycota and Basidiomycotina (Sharvelle 196 1. Torgeson 1969. Neergaard 1977) and is

noted as being panicularly effective against seed-rotting fungi (Neergaard 1977). It has been

shown to have minimal effects on endomyconhizal fungi and both positive and negative effecis

on ec tornyconhizae development (Vyas 1 WB), depending on plant species.

At each experimental site a 2.5 m by 3.5 m plot was established. Within each plot a 10 x 6 grid

was set up with points separated by 0.5 m. At each point. one seed bag was buried 5cm below the

soil surface, so that each plot contained al1 30 species subjected to the two treatments. Seed bags

were buried in the field in June 1998, early in the natural cycle of seed dispersal, and were

recovrred in laie October 1998, at the end of the growing season. After recovery, seed bags were

opened and their contents spread over potting mix in lOcm square pots. In a very small number

of bags. one or two Bromuî or Efymus seedlings had germinated and forced their way through

the bag to the soil surface. These seedlings were added to the total number of seedlings

germjnated in the greenhouse. The pots were kept moist in the greenhouse for 3 months. After

1.5 rnonths, seedlings were counted and soi1 was disturbed to allow the more deeply buried seeds

a better chance to germinate. A final count of germinating seedlings was done at the end of the 3

month germination penod.

CHAPE-R 4: COMPARATIVE EXPERIMFNTS

Table 4.1. Experirnental species for the seed bank - habitat experirnent. Presence on Joker's Hill research station

property (JH) is indicated by an "x" (Chapter 2). Native or alien origin follows Morton and Venn (1990) and

nomenclature follows Glertson and Cronquist ( 199 1 ).

Congeneric pair Spccies Origin JH ASTERACEAE 1

ASTERACEAE 2

BRASSICACEAE

CAMPANULACEAE

CARYOPHYLLACEAE

CARYOPHYLLACEAE

CHENOPODIACEAE

CYPERACEAE

PLANTAGINACEAE

POACEAE 1

POACEAE 2

POLYGONACEAE

ROSACEAE 1

ROSACEAE 2

RUBiACEAE

Lactrica canadensis

Lacruca serriola

Setiecio pauperculus

Senecio vulgaris

Lepidiunt campestre

Lepidiunt densiflorum

Cunipnriula rapiinculoides

Canipartula rcltri~tdifolia

Cerastium arvense

Cerastiunt fontanunt

Silene antirrhina

Silerie viilgnris

Cliertopodium albunz

Chenopodium simplex

Carex niuhlenbergii

Carex spicata

Plantago major

Plarzrago rtigellii

Brontus itiemis

Brornus kalmii

Elyrntts repens

Elyntus rruchycaulus

Polygonum cilittode

Polygonum corivolvulits

Geum aleppicum

Geum urbanum

Poren rilla arguta

Porentilla recta

Galiurn boreale

native

alien

native

alien

alien

native

al ien

native

native

alien

native

dien

alien

native

native

alien

dien

native

alien

native

alicn

native

native

alien

native

alien

native

alien

native

Galiurn verum aiien Total 30 species 15 native 10 native

15 dien 13 alien

CHAPTER 4; COMPARATlVE EXPERIMENTS

Analysis Wetland and upland habitats were analyzed separately. Germination percentage values for each

species at each plot were arcsin transformed to improve normality (Kirk 1982). A 2-factor

randomized block factorial ANOVA was performed on these transformed germination

percentage values, blocking by plot, to test for overall fungicide effect.

Origin (nativeMien) effects were investigated in two ways. First, a 3-factor randornized block

factorial ANOVA, with origin as a factor and blocking by plot. was performed on the

transformed germination percentage data. This is not a PIC analysis since it does not restrict

analyses to intrageneric cornparisons; however, it can be used to indicate whether a PIC anülysis

is required: the presence of a significant fungicide x origin x genus interaction would indicate

that the importance of pathogens to aliens is taxon-dependent. and thus that phylogenetic

detrending rnay be required.

Second, origin (native/aIien) effects were investigated with 2-factor randornized block factorhl

ANOVAs performed on nativehlien PICS. Two problems with PICS are that most methods

require a reliable phylogeny, and that they may result in a substantial reduction in statistical

power, especially if done n posteriori (Harvey and Pagel 199 1; Harvey and Purvis 199 1; Lord et

al. 1995; Westoby et al. 1995a.b). To avoid these problems. 1 developed PICS a priori

(Armstrong and Westoby 1993), and avoided the need for a full phylogeny by simply matching

congenenc pairs of one native and one alien species. Each contrast was generated by subtracting

alien from native germination values for members of a congenenc pair under the same treatment.

at the same plot. For these tests, a significant fungicide effect would indicate that fungi have

effects on the relative performance of native and aiien members of the same genus, and hence a

phylogenetically-independent fungicide effect.

Of the 600 experimental values (species x treatment x replication combinations) in each of the

upland and wetland expenments, 3 and 17 respectively were missing because of seed bags which

were not relocated. To restore a balanced design, rnissing values were replaced with the mean of

the remaining values in that treatment x species combination (Underwood 1997). The number of

degrees of freedom for error in each analysis was reduced by the number of dummied values

(Underwood 1997). For ail analyses, a non-interactive mode1 was used, as recornmended by Newman, Bergelson and Grafen (1997). Thus, treatment was treated as a fixed effect, plot was

treated as a random blocking effect and the residual was used as the error term.

Results Overall seed recovery

Overall seed recovery rates were significantly lower in wetland (mean~SEM: 20.21 1 .O%) than in

upland habitats (mean+SEM: 28.4t1.246). Plot effects were significant in upland, but not

wetland areas (Table 4.2). Examination of totals by plot highlights the very consistent nature of

the reduction in seed recovery associated with wetland plots. The ranges of mean plot recovery

rates obtained in upland and wetland tnals did not overlap. Recovery rates for the 10 wetland

plots ranged from 16.9% to 22.6% and the 9 upland rates ranged from 24.8% to 3 1.3%. The

reduced recovery rates in the wetland trial were iilso fairly consistent across species, with 22 of

30 species having greater recovery rates in the upland trial (Tables 4.3.4.4).

O v e r d effects of fungicide addition

The results suggest that seeds in wetland plots were subject to higher levels of fungal attack, and

that this contributed to the reduced seed recovery rates from wetlands. Fungicide addition

significantly improved seed recovery in the wetland trial (Table 4.2) from 18.01 1.3% to

22.41 1.5%, but had no effec t on recovery in the upland trial (28 .h 1.7% control vs. X 6 t 1.7%

fungicide addition) (Table 4.2). Fungicide addition thus improved recovery in the wetland trial

from 63.6% to 78.3% of that in the upland trial. In upland plots, fungicide improved recovery of

15 of the 30 experimental species; in wetlands, 25 of 30 species benefitted. Fungicide effects per

plot were significantly larger in wetland plots than in upland plots (unpaired t-test. P=0.03).

Recovery was increased with fungicide addition in 9 of the 10 wetland plots and mean fungicide

effect per plot was a 25.6% increase in recovery. Fungicide increased recovery in only 4 of 9

upland plots, and al1 increases or decreases were by less thün 7.1%. Mean fungicide effect per

upland plot was a 0.6% decrease in recovery.

APTER 4: COMPARATIVE EXPERIMEPS

Table 4.2. Results of 2-factor randomized block factorial ANOVAs (fungicide treatment x species) on recovery data

for the upland and wetland trials of the seed bank - habitat experiment. Treatment was treated as a fixed effect. plot

was treated as a random effect and the residual was used as the error term.

*=P<O.Ol, **=Pc0.001, ***= P < 0 . m 1

SEED BANK - HABITAT EXPERIMENT -- UPLAND TRIAL

Factor d f MS F-value

plot 8 0.4 14 3.540***

fungicide treatment 1 0.004 0.034

species 29 8.985 76.823***

fungicide tmt. x species 29 0.167 1.428

error' 369 0.1 17

'degrees of fieedom for error (= 472 - 3) adjusted for 3 dummied values (Underwood 1997); see methods.

SEED BANK - HABITAT EXPERIMENT -- WETLAND TRIAL

Factor d f MS F-value

plot 9 0.1 88 1.359

fungiçidr treatment 1 3.039 21.968***

species 29 7.038 50.877***

fungicide tmt. x species 29 0.154 1.113

erro? 514 0.138

ldegrees of fieedorn for error (= 53 1 - 17) adjusted for 17 dummied values (Undenvood 1997); see methods.

CHAPTER 4: COMPARATIVE EXPERIMENTS

Variation in seed recovery between species

Recovery varied significantly with species in both habitats (Table 4.2). In the upland trial,

recovery rates for 6 species were less than 5% while recovery rates exceeded 50% for 7 species.

Highest recovery rates were obtained for Lepidilcm densiflorum (84.7%) and Senecio vulgaris

(81.7%) (Table 3.3). in the wetland trial 10 species had recovery rates below 5% (the same 6

species as in the upland trial plus 4 additional species) (Table 4.4). Only Chenopodium album

(59.8%), Lcpidiurn dens~gorum (58.9%) and Serlecio vulgaris (52.8%) had recovery rates above

50%.

Varicrtion in recovery by origiti

In 3-factor (non-PIC) ANOVAs, there werz no three-way interactions, implying that relationship

did not influence origin x treatment interactions in either habitat (Table 4.5). These origin x

treatment interactions were non-significant in both habitats, indicating that native and dien

species generally behaved similarly in their responses to fungicide addition. In the upland trial,

response to fungicide addition was non-significant, with native recovery drcreasing by 2.4% and

alien recovery increasing by 4.2% (Figure 4.1). In the wetland trial, fungicide addition produced

a significant increase in recovery. Native recovery increased 22.4% and alien recovery increased

by 26.3%.An unexpected result was the evidence that recovery of native seed was less negatively

affected by wetland conditions than chat of aliens. Aliens were recovered at a greater rate overall

in both the upland and wetland trials but the difference was less pronounced in the wetland trial

(Figure 4.1). The difference in recovery between natives and aliens was significant in the upland

habitat, but not in the wetland habitat (Table 4.5).

The 2-factor (PIC) ANOVAS, did not significantly alter this interpretation. No effect of

fungicide addition on native vs. dien contrast values was detected (Le., natives and aliens

responded to fungicide addition similarly; Table 4.6). This result may be expected from the

absence of a 3-way interaction, as described above.

CHAPTER 4: COMPARATIVE EXPERIMENTS

Table 4.3. Seed bank - habitat expenment. upland trial: Mean + SEM percentrige seed recovery, by treatnient and

species (n=9 replicates per species. per treatment, unless othenvise noted). Native species rire indicated by " N . and

dien species are indicated by "A".

Species Control Fungiçide MeankSEM Mean~sEM

A Broniiis inermis

'Bromus kalmii

ACampanula raput~culoides

"~antpatiula rorurid~olia

* Cu re-r spicara

"Carex naultlenbergii

ACera.~tiunt foritarium

'VCeru~t i~m arvertse

A Cheriopoiiium album

"~herro~odiurn sinaplex

A E l y us repens

NEl~nius rrachpcaulus

AGaliuna verunl

'VGaliir~~i boreale

*Certrtt it rb~ttrtnr

"Geunl uleppicunt

*L.uciuca serriola

NLuctucu canadensis

* Lepidutn carnpestre

"Lepidum deruijlontm

A Platirago rriajor

"~latitago rugellii

A~olygonum convolvulus

"Polyganum cilinode

A Poterttilla recta

"Poteniilla arguta

*4Setiecio vulgaris

'vSenecio pauperculrts

"Silette vulgaris

NSilerie an firrhina

CHAPTER 4: COMPARATIVE EXPERTMENTS

Table 4.4. Seed bank - habitat experiment. wetland trial: Mean I SEM percentüge seed recovery, by treritment and

species (n=10 replicates per species, per treaunent, unless otherwise noted). Native species rire indicated by "N", and

alien species are indicated by "A".

Species Control Fungicide MeaniSEM MeankSEM

A Bronrus inemis

'"~ronius kalmii

A Campanula rapuncnloides

~v~a~npurrrtla rorundi$olia

* Carex spicata

NCare.t ntuhlenbergii

ACer~t iurn fontanuni

" ~ e r a s t ium arverise

AChe~iopodiunt albunt

NChenopodiunr sinrplex

A EIynius repens

N ~ l J ~ t ~ ~ tractiycaulus

A ~ a l i u m verum

"Galium boreale

"eunt urbanum

%eunt aleppicum

"Luçrucu serriolu

NLacti4ca cattdensis

A Lepidium campesrre

N~epidit4m densiflorim

*Plantago major

"Plantago rugellii

A Polugonum convolvulus

"Poljgonum cilinode

" Porentilla recta

'"~otertrilla arguta

"Senecio vulgaris

NSenecio pauperculus

"Silene vulgaris

%ilene antirrhina

CHAPTER 4: COMPARATIVE EXPERTMENTS

Table 4.5. Resutts of 3-factor randomized bIock factorid ANOVA (fungicide treatment x origin x genus) on the

recovery data for the upland trial of the seed bank - habitat experiment. Treatment wu treated as ri fixed effect, plot

was treated as a random effect and the residual was used as the error term.

* = Pc 0.01, ** = P < 0.001. *** = P<0.0001

SEED BANK - HABITAT EXPERIMENT -- UPLAND TRIAL

Factor d f MS F-Value

plot

fungicide treatrnent

oripin

genus

fungicide treatment x origin

fungicide treatrnent x genus

origin x genus

fung. tmt. x origin x genus

errorl

'degrers of freedom for error (= 53 1 - 17) adjusted for 3 dummied values (Underwood 1997); see methods.

SEED BANK - HABITAT EXPERIMENT -- WETLAND TRIAL

Fric tor d f MS F-Value

plot

fungicide treatment

origin

genus

fungicide treatment x origin

fungicide treatment x genus

origin x genus

fung. tmt. x origin x genus

erroi

'degrees of freedom for error (= 53 1- 17) adjusted for 17 dumrnied values (Underwood 1997); see methods.

CHAPTER 4: COMPARATIVE EXPERIMENTS

Figure 4.1. Results of seed bank - habitat experiment; proportion of seed recovered in upland ÿnd wetland habitats, for native and aiien species, under control and fungicide addition

treatments. Error bars are 11 SEM.

Upland

Control Fungicide

Wetland 0.35 ,

Native

Alien

Native

Alien

Control Fungicide

CHAPTER 4: COMPARATIVE EXPERIMENTS

Table 4.6. Results of PIC ANOVAs (fungicide treatment x genus) on native vs. alien contrast data for the upland

and wetland trials of the seed bmk - habitat experiment. Treatment was treated as a fixed effect, plot was treated ris

a random effect and the residual was used as the error term. * = P < 0.01, ** = P c 0 . 0 I , *** = P c 0.000 1

SEED BANK - HABITAT EXPERIMENT -- UPLAND TRIAL

Factor d f MS F-Value

plot 8 0.287 1.352

fungicide treatment 1 0.233 I .O48

genus 14 14.338 64.482***

fungicide treatment x genus 14 0.184 0.827

error' 229 50.920 0.222

'degrees of freedom for error (= 232 - 3) iidjusted for 3 dummied values (Underwood 1997); see methods.

SEED BANK - HABITAT EXPEIUMENT -- WETLAND TRIAL

Factor d f MS F-Value

plot 9 O. 153 0.566

funsicide treatment 1 0.250 0.925

genus 14 1 1.858 43.898***

fungicide treritment x penus 14 0.305 1.129

error? 244 0.270

'degrees of freedom for error (= 26 1-1 7) adjusted for 17 dummied values (Underwood 1997): see methods.

CHAPTER 4: COMPARATIVE EXPERMENTS

Discussion Dues furtgal rnorrality influence seed persistence in the soif seed bank?

As in the seed bank mortality expenment in Chapter 3, this experiment clearly shows that

restriction of soil fungi c m increase seed survival. In this investigation, the fungicide effect was

habitat dependent; fungicide significantly increased recovery in wetland meadows while 110

effect was found in upland meadows, at least dunng the relatively short duration of this

experirnent. In the wetland habitats, the fungicide effect was somewhat more consistent across

species than that in the seed bank mortality experiment in Chapter 3, which was performed in ri

dry, upiand site. Given the broad taxonomie range of the experimentai species and the fact that

the wetland plots were widely separated, these results demonstrate that in certain habitats fungal

mortality of seeds in soil is a significant and general phenornenon.

Soil fungi have often been suggested to cause mortality of seeds in seed banks. There are a

number of lines of evidence suggesting the importance of fungi to soil serd banks in natural

habitats. Soil fungi (including Eumycota, the true fungi and the "protoctistan fungi" (Kendrick

1992), including Ooniycotü, which are now classified with brown algars in the Stramenopilcs

(Sogin and Patterson 1998) are ubiquitous, abundant and include many important decomposers

with the ability to secrete extracellular celluiase and proteolytic enzymes (Crist and Friese 1993).

Many fungal piant pathogens, including some which can have significant community level

effects (Kliejunas and Ko 1976, von Broembsen and Kruger 1984. Augspurger and Kelly 1981)

are also soil borne (Garrett 1970). Additionally, the importance of fungicidal seed coatings in

agriculture (Taylor and Harman 1990). the fungal scarification of some seeds with hard seed

coats (Gogue and Ernino 1979, van Leeuwen 1981, Guttridge et al. 1984) and the presence of

fungal-inhibiting compounds in seed coats (refrrences for 8 species given in Baskin and Baskin

1998) al1 suggest that fungi are likely to be an important source of seed mortality in soil. Despite these lines of evidence, my results (including Chapter 3) are among the first which demonstrate

the occurrence of fungal mortality in soil seed banks in natural plant communities; Crist and

Friese (1993) and Lonsdale (1993) are two rare exceptions.

The particular fungi involved in seed decomposition in soil are very poorly undentood, although

those causing seed rots of agricultural plants are comparatively well researched (Neergaard 1977,

Agstnval and Sinclair 1997). Important species likely include rnembers of both the primitive

Mastigomycota (especially the Division Oornycota) and the Eumycota (Divisions Zygomycota

and Dikaryomycota). Due to physiological differences, few fungicides are effective against both

groups (Paul et al. 1989). No assays of the fungi in treated and untreated soil were attempted in

this study but Captan is widely used in agriculture to convol species of oomycetes, ascomycetes

CHAPTER 4: COMPARATIVE EXPERIMENTS

and basidiomycetes in the soil and on fruit, Ieaf and seed surfaces (Sharvelle 196 1, Torgeson

1969, Neergaard 1977). The increases in recovery associated with fungicide addition in this

experiment may well underestimate total fungal mortality. as fungitoxic effects of Cüptan are

species specific and some pathogens may not have been controlled by the fungicide (Sharvelle

196 1. Torgeson 1969. Neergaard 1977).

Do seed recovery aridfirngal rnortality vnry between wetlnnd and rlpland rneadows?

Seed recovery was consistently higher in upland sites, but not al1 of the difference in recovery

between habitats can be attributed higher fungal mortality in wetland habitats. Recovery wüs still

lower in wetland habitats when fungi were experimentally excluded. The fact that a significant

fungicide effect was found in wetland but not upland meadows does strongly suggests that some

of this difference was associated with a higher Ievel of fungal mortality in wetlands. With

fungicide addition, the difference between upland and wetland recovery wüs reduced by 39.8%

relative to the difference between upland and wetland recovery under the control. It is this

portion of the upland and wetland difference that is probably attributable to increased fungal

mortality in wetlands.

Several factors may account for the lower rates of recovery in wetlands beyond that which cm be

attributed to fungi. The most important of these is likely a greater stimulation of germination

below ground in wetland habitats associated with the higher soil moisture. A lower rate of

recovery for the wetland trial would result fiom this effect because below ground germination

was likely fatal for almost all seeds in the experiment due to the bürrier presented by the nylon

bags in combination with 5 cm of soil. As described in the Methods, a few grass seedlings with

their relativrly large seed reserves and narrowly pointed cotyledons were able to push tlirough

the mesh seed bag and survive until recovery, but it is unlikely that smaller seeded species and

those with wider cotyledons (most or dl dicots) would have been able to reach the surface. Even

among the grasses, most seedlings which germinated in the field did not survive until recovery.

Many Elymus and Brumus seeds were observed after recovery to have germinated and died.

Reduced wetland recovery could also result if drier conditions induced dormancy in the field,

thus preventing fatal germination, and donnancy was then broken in the greenhouse. Laboratory

experiments using solutions of low osmotic potentials to simulate water potentials in dry soils

have shown effects of this type in some species, including two congeners of experirnental species

(Chenopodium bonrts-henricus and Lactuca sariva) (Baskin and Baskin 1998). Conversely,

higher moisture level may stimulate some species of seeds into deeper donnancy (Baskin and

Baskin 1998). If dormancy was induced in some seeds in the wetland trial and was not broken in

the greenhouse germination period, the pattern of reduced recovery in wetlands could also be

CHAPTER 4: COMPARATiVE EXPERIMENTS

produced. These types of effects limit the extent to which overall recovery rates reflect natural

survival rates, but do not significantly affect comparisons between treatments. Finally, wetlands

may have a greater concentration of fungal and non-fungal pathogens which were not excluded

by the fungicide in the wetland soil, thus reducing wetland recovery. There is evidence that

fungal pathogens are genenlly more prevalent in moist soils than in dry soils. The best example

cornes from Augspurger (1983) and Augspurger and Kelly (1984), whose extensive studies of

spatial variation in the rates of damping off mortality in tropical tree seedlings showed that

mortality was greüter in darker areas with higher soi1 moisture and humidity. Rotem (1978) also suggests that this is a general trend which may apply to non-fungal plant pathogens as well.

Very few studies have examined the effects of moisture content of soil on seed bank survival in

natural plant communities (Leck 1996). The available evidence suggests that seeds generally

survive best in the moisture range in which they typically occur. Moist, high temperature

conditions decrease seed survival for many species in controlled storage (Villiers 1972, Ibrahim

et al. 1983) but seeds of many aquatic species lose viability when stored dry (Bewley and Black

1982, Bai et al. 1995). Morinaga (1926, cited in Bekker, Oomes and Bakker 1998) found that

submergence negatively influenced the survival of seeds of many upland species. In a mesocosm

experiment using turfs collected from the field, Bekker, Oomes and Bakker (1998) found that

among seeds for which moisture level affected survival. seeds of species typical of wet

grasslands tended to survive best in a high water treatment while dry grassland species survived

best in a low water treatment. Two of the species found in their study were also used in this

experiment. Bekker et al. found that Cerastium fo~ita~tum seeds survived better under the low

water treatment. This finding matches my results well, as Cerastiurn fonrariunt showed the

greatest reduction in recovery between upland and wetland trials of any species. Bekker et c d .

found no effect, however, of water level on Plantago major seed survival, while 1 found

significantly reduced recovery of Plantago major in the wetland trial. The relatively small

number of Plantago seeds detected in the Bekker et al. study (21 in total) may have precluded

detection of significant effects of water level. Overall, my results are in accord with the

hypothesis that seeds will survive better in the range of moisture levels they typically encounter.

The upland plots included populations of a number of the study species and were typical of the

habitats in which most of the experimental species commonly occur. Few of the experimental

species were present in the wetland plots and, with the exception of Geum aleppicum, none of

the expenmental species tend to occur regularly in Ontario wet meadows of the type used in the

study (CSB, pers. obs.).

CHAPTER 4: COMPARATlVE E m . N T S

Does fungal mortali~y vary between closely related natives and aliens?

Responses to fungicide addition were not significantly different between native and alien

species. Native and alien responses to fungicide addition were of a very similar magnitude in both the wetland and upland habitats, and there were no treatment effects on contrast values.

Having controlled the effects of phylogeny by using a PIC approach, the fact tbat the congeneric

pain of native and alien species behaved similarly in this experiment indicates that alien status

perse does not confer resistance to fungi. This result does not eliminate the possibility that alien

species as a whole may be more resistant to fungi. If the larger set of alien species tended to

corne frorn resistant genera or families, a priori sefection of congeneric pairs would tend to

obscure differences between natives and aliens. The failure to detect significant differences

between natives and aliens in the TIP analysis of the seed bank mortality experirnent in Chapter

3, however, suggests that this is not the case.

Results agree with those of Chapter 3 in that there was no difference in the response of native

and alien species to the reduction of soil fungi. The predator escape hypothesis requires the

existence of species specific pathogens for both natives and aliens. Although many fungal plant

pathogens are generalists (von Broembsen 1993), host specificity among seed pathogens is

known in agriculturai plants (Neergaard 1977, Agarwal and Sinclair 1997), and there is sonie

evidence that natural fungal communities associated with different species of seeds Vary within

the sarne habitat (Kirkpatrick and Bazzaz 1979, Harman 1983). The most likely explanaiion for

the similiir responses of native and alien species to restriction of soil fungi is that the important

pathogens of seeds in soil were generalist fungi which do not distinguish between native and

alien seeds. It is also plausible that some species specific pathogens of alien seeds have already

been inadvertantly introduced to the New World, or that pathogens specific to native species

have become adapted to alien congeners since the arriva1 of the aiiens. The Iack of differential

response also suggests that the filter hypothesis does not apply. In either case, the results indicate

that predator escape by alien seeds is not a general phenomenon at the seed bank stage.

Aliens suffered a slightly greater reduction in recovery between upland and wetland habitats than

did natives. The increase in native recovery relative to that of aliens was sufficient to reduce the

significant difference between native and alien recovery in the upland trial to non-significance in

the wetland triai, although the absolute recovery rate was greater for aliens in both triais. The

greater relative performance of natives in the wetland trial was opposite to rny expectation, based

on experience with the habitats of the experimental species. Except for Geum aleppicum, none of

the experimental species occur with any frequency in Ontario meadows as wet as the wetland

habitats in the study (CSB, pers. obs.). The natives in this study are distinctly less abundant in

the agricultural part of southem Ontario than are the aliens. The alien species are mostly

widespread and very common in old fields and ruderal areas. The native species include two

abundant ruderal species (Lepidium dens~florum and Plantago rugellii) and d l do occur in old

fields to some extent. Most of the native species used, however, are relatively uncornmon in

intensively disturbed areas and they achieve their greatest abundance within southern Ontario in

specialized and uncommon communities; dry, sandy prairie remnants and prairie-like old fields,

or rock outcrops and limestone pavements (alvan) which were relatively open areas historically

due to regular summer drought and frequent fires (Catling, Catling and McKay-Kuja 1992,

Catling and Catling 1993, Catling 1995, Catling and Brownell 1995). My prediction, therefore,

was that the apparent drought tolennce of natives might corne at the expense of overall niche

breadth, resulting in reduced tolerance of wet conditions, while aliens would have a broader

range of tolerances. The results reject these hypotheses.

The different results between upland and wetland trials show that habitat is important in

determining pathogen effects. The strong differences in recovery between habitats and their very

consistent effects across locations and species provide good evidence that seed mortality could

be important in restricting the distribution of upland plants in wetlands and in defining wetland

boundaries. If the recovery rates from this study translate to increases in recruitment from seed,

the observation of changing relative performances of natives and alirns implies that aliens are

more likely to have an advantage at the seed stage in upland habitats than in wetland habitats, at

least among species of upland habitats.

CHAPTER FIVE

GENERAL CONCLUSIONS

CHAPTER 5 - GENERAL CONCLUSION S

b) to determine whether seeds suffer significant losses to predators before incorporation into the seed bank (Chapter 3) Seeds of both natives and exotics suffered highly significant losses to above-ground predators.

Vertebrates (birds and rodents) were generally more important thm invertebrates as seed

predators, as is generally the case in temperate old fields. Overall predation rates were lower than

most other studies, but rnay have been underestimated because of diffïculties in recovering

surviving seeds.

c) to determine whether seeds suffer significant tosses to seed predators and pathogens in the seed bank (Chapter 3) Pathogens generally were significant sources of mortality below ground, but invertebrate

predators were not. Fungal mortality affected both natives and exotics over a very wide

taxonornic range, indicating that fungal rnonality in the soi1 seed bank is of very general

signi fîcance. The presence of significant fungicide effects over the relative l y short experimental

periods suggests that fungi may be very important when compounded over the long periods that

many species remain in the seed bank. These are the first field studies to demonstrate a fungal

effect on the seed bank survival of a wide range of species.

d) to discover whether seed losses to natural enemies differ among species (Chapter 3) Different species showed different susceptibility to natural enemies. Above-ground. losses to

seed predators strongly differed among species. Losses were linked to seed size, with larger

seeds tending to suffer greater predation. Below-ground, losses to fungi also varied significantly

among species, with rates of loss showing some variation by taxa but no consistent variation by

seed size.

e) to determine whether seed losses to natural enemies differ between habitats (Chapter

4) Only the effects of fungi were investigated, but the result was striking: fungal mortality was

consistently higher in the wet sites than in upland areas. These results show that habitat is

important in detennining pathogen effects. and provide good evidence that seed rnortality may

be important in restricting the distribution of upland plants in wetlands and in defining the

boundaries of wetland plant communities.

f ) to determine whether seeds of native and alien species differ in their susceptibility to natural enemies (Chapter 3,4)

Aliens and natives did not consistently differ in their response to predators and pathogens. The

likely explanation is that both above-ground predators and below-ground pathogens were

sufficiently generalist that differences between native and alien seeds (if any) did not alter

predation and disease risks. These results argue against both the predator escape and predator

filter hypotheses, and suggest natural enemies of seeds do not as a general rule determine

invasive ability.

g) to determine whether differences in seed losses between natives and aliens occur independent of their phylogenetic relationship (Chapter 4) Phylogenetically Independent Contrasts failed to reveai significant differences between natives

and exotics with respect to fungal mortality. These results provide further evidence that alien

status is not associated with fungal resistance. and particularly provide evidence against the

predator escape h ypothesis.

Limitations of the work

As with any study, the work outlined in this thesis is subject to certain limitations. The seed

bank quantification in Chapter 2 was a minor component of the study. If, however, more

detailed seed bank quantification was required in the future, my work could be improved upon

by increasing the number of sampling points within a field and the total amount of soil sampled.

Ter Heerdt et al. ( 1996) outline a successful and efficient method for concentrating soi1 samplcs

for seed bank quantification, without greatly increasing space requirements for germination.

Sampling more soi1 from a greater proportion of a field's surface area would help to reduce the

variation caused by the very patchy distribution of seeds in the seed bank. An increased

frequency of sampling over a longer period would also be useful to improve the understanding of

within and between year flux in seed bank composition and abundance. Additionnlly, future

work should incorporate an effort to quantify and/or control the effects of seasonal dormmcy

cycles, which were large enough to obscure seasonal patterns of seed input and loss in my work.

This could be done by using consistent, controlled environments for germination coupIed with

separating seeds from the soil for viability testing.

A few limitations were comrnon to al1 of the experiments outlined in Chapters 3 and 4. The

longest period experimental seeds remained in the field was 16 months, whereas seeds are

capable of lasting much longer in natural conditions. The link between seed mortality and

rnoisture level demonstrated in Chapter 4 also points to a strong potential mechmism for

105

CHA PTm 5 - GENERAI. CONCLU-

between-year variation in seed mortality. This could only be quantified with longer term studies.

In al1 experiments, seed mortality was inferred indirectly, when seeds failed to germinate. As

shown with the seed bank quantification, germination is strongly influenced by seasonal

dormancy cycles in many species. Use of consistent and controlled germination conditions and

making a greater effort to directly track the viability of individual seeds would help control

dormancy effects. No effort was made to identify the specific organisms causing seed mortality.

Fungal mortality was inferred by the presence of increased seed recovery associated with

fungicide addition. Isolation of fungi, from soi1 and from seeds, using as diverse a variety of

media as possible, would rectify this shortcoming. Understanding the fungal species involved in

seed mortality would also help to clarify which seeds have species-specific pathogens, an

important issue reiared to the predator filter and predator escape hypotheses of rilien advantage.

Finally, my work suggests that finding consistent differences between native and alien species is

likely to be difficult when looking across a moderately broad taxonomic range. General

differences, if present, may tend to be subtle enough to be masked by the large variation present

between taxa irrespective of origin. Future studies may have more success in finding native and

alien differences by focussing on a narrower taxonomic range (Le. one or a few genera within a

family) or by devising a study which can include a very large proportion of the species within a

particular reg ion.

General Conclusions Together, the results indicate seed mortality is important. both imrnediately after dispersal and in

the seed bank. Species differ, but aliens on average do not differ from natives (with or without

effects of phylogeny controlled). Thus the results demonstrate that the predator escape and

predator filter hypotheses are not general rules among invaders. This does not meün that these

rules never apply; indeed, the limited evidence available suggests some invaders may benefit

from reduced populations of seed predators and pathogens. However, such studies have generally

focussed on abundant problem species. It may be that, while most invaders do not enjoy reduced

seed losses, those that do are more likely to becorne senous problems. By demonstrating that

most invaders do not benefit from reduced populations of natural enemies, this research may

suggest one important distinction between the rnajority of invaders which do not represent

serious environmental threats, and the minority which do.

LITERATURE CITED

ABRAMSKY, 2. 1983. Experiments on seed predation by rodents and ants in the lsraeli desert.

Oecologia, 57: 328-332.

AGARWAL, V.K. and J.B. SINCLAIR. 1997. Principles of Seed Pathology, Second Edition.

CRC Press, Boca Raton, F'L.

AGRIOS, G.N. 1978. Plant Pathology, Second Edition. Academic Press, New York.

ARMSTRONG, D.P. and M. WESTOBY. 1993. Seedlings from large seeds tolerate defoliation

better: a test using phylogeneticaily independent contrasts. Ecology. 74: 1092-1 100.

AUGSPURGER, C.K. 1983. Seed dispersal of the tropical tree Plutypodiuni elegcrns, and the

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APPENDICES

ArmhmxI VASCULAR PLANTS OF JOKER'S HILL

King Township, Regiond Municipality of York

C. Sean Blaney. July 1999.

The following list is compiled primarily from the observations and collections of the author made between 1997 and 1999, with a few records from other sources. Approximately 190 species (indicated by 9 ) are documented by specimens which will be deposited at the Royal Ontario Museum - University of Toronto herbarium (TRT). The remainder of listed species are included on the basis of the authoris sight records, with three exceptions. Steve Varga. OMNR Aurora, provided field notes from 3 1983 visit to the site, which added Corallarhiza trifidu and Vaccinium angustijhliuni to the list. Ongoing research by Richard Joos, University of Toronto Department of Botany, added D~opter i s goldiana, and my lab colleague, Marc Johnson was responsible for several new records i n 1999.1 have been quite careful to include only species which have been identified with cenainty. and have collected voucher specimens for any difficult identifications. Very little investigation of the flora of the site Iiad been carriecl out pnor ta its donation to the University of Toronto. The eastern half of the property is almost entirely included by the Ontario Ministry of Natural Resources within the Glenville Hills Kames Earth Science Area of Natural and Scientitic Interest. The Natural Heritage Information Centre at the OMNR office i n Peterborough supplied two sources of botanical information on this ANSI. These were a list of 5 locally rare plant species in an environnitntally significant areas study prepared for the South Lake Simcoe Conservation Authority (Ecologistics. 1982) and a partial list of plants found at the adjacent Thornton Bales Conservation Area (South Lake Simcoe Conservation Authority, undated report). These reports included problernatic records and did not note whether species werr recorded on the Joker's Hill property. Due to these difficulties the list below was started from scratch.

The list includes al1 species known to be growing outside of cultivation within the Joker's Hill property. Also listed are native species found in land adjacent to the Joker's Hill property, but not yet found on the site (sçientitic name preceded by "*" - 12 species). A total of 603 taxa (specics and hybrids) are listed. 337 taxa are considered native tu Joker's Hill (those listed i n bold typeface) and 166 are considered non-native (listed i n repular typeface). Determining native versus non-native status required a few rather arbitrriry judgements.

Several people assisted in the preparation of this list. Peter Ball of the University of Toronto at Mississauga assisted with a number of difticult identifications, especially in the Cyperaceae. Tim Dickinson and Jenny Bull of the Royal Ontario Museum identified the native Crataegus specimens. Peter Kotanen of the University of Toronto at Mississauga offered uscful comments, corrections and encouragement and formatted the document for the world wide web - htt~://www.crin.utsronto.cd-w3~koW~Iants.~. Jarmo Jalava of the Ontario Natural Heritage Information Center compiled the pre-existing information on the site. Steve Varga, Ontario Ministry of Natural Resources and Richard Joos, University of Toronto provided records for species not previously recorded.

Taxonomy, with only ri few exceptions, follows Morton and Venn ( 1990). Wherc widely used synonyms or other potentially confusing alternate binomials exist, these are listed below the species' scientific name. As there are n o standard English names for plant species, common names have been taken from a vririety of sources. Afthougli 1 have visited al1 parts of the property looking for plants, mnny additional species will still be found with further tield work. Information on any additional species (preferably documented with specimens) or other comments on the list woufd be welcomed by the author or P.M. Kotanen.

EQUISETA CEA E (Horsetail Family )

Equisetum atvense L. Equisetum flu viatile L. Equisetum hyemale L. § Equisetum pratense Ehrh. Equisetum scirpoides Michx. 5 Equisetum syl vaticurn L. Equisetum variegatum Schleich.

LYCOPODIACEAE (Club-moss Family)

Lympodium clavatum L. Lycopodium digirutum A. Braun

(L Jkrbelliforme) Lycopodium lucidulum Mic hx. fi Lycopodium obscurum L. (sst.) 5 Lycopodium rristachyum Pursh

O PHIOGLOSSACEA E (Grape-fern Fam ily )

$Bofrychium dissccturn Spreng. (B. obliquum)

Botrychium multifiduum (Gmel.) Rupr. Botrycliium virginianurn (L.) Sw.

OSMUNDACEA E (Flowering-fern Fami ly)

Osmunda cinnamomea L. Osmunda clay~oniano L. Osmunda regalis L.

PTERIDACEAE (Spleenwort Fsmily)

Adhnfum pedatum L.

POL YPODiA C l 3 E (Polypody Family )

DENNSTA EDTIA CEAE (Brac ken-fern Family )

§Dennstaedtia punctifobula (Michx.) T. Moore Pteridium aquifinum (L.) Kuhn

THELYPTERIDACEAE (Marsh-fern Famil y)

§ Phegopteris connectilis (Michx.) Watt fjThelypieris noveboracensis (L.) Nieuwl. Thelypteris paluscris (Salisb.) Schott.

ASPLENIACEAE (Spleenwort Fatnily) SAsplenium p&yneuron (L.) BSP.

Field Horsetail Water Horsetail Rough Horsetail Meadow Horsetail Dwarf Scouring-rush Woodland Horsetail Variegated Horsetail

Staghorn Clubmoss Running Ground-cedar

Shining Clubmoss Tree Clubmoss Ground-cedar

Dissected G rapc-îern

Lea t he ry G ra pe-fe rn Rattlesnoke Fern

Cinnûmon Fern Interrupted Fem Royal Fern

Maidenhair Fern

Rock Polypody

Hay-scented Fern Bracken Fern

Nort hem Beech-fern New York Fern Marsh Fern

Ebony Spleenwort

I - VASCULAR PLANTS OF JOW.R'S

DRYOPTERIDACEAE (Wood-fem Family)

Athyriumfilk-femina (L.) Roth. SAthyrium thelypteroides (Michx.) Desv. Cystopteris bulbifera (L.) Bernh. Cystopteris tenuis ( Michx.) Desv. §Dryopteris x boottii (Tuckeman) Underw.

(D. intermedia x D. cristata) Dryopteris carthusiana (Vill.) H.P. Fuchs

(D. spinulosa var. spinulosa) Dryopteris cristaro (L.) A. Gray Dryopteris goldiana (Hook) A. Gray Dryopteris intermedia (Muhl.) A. Gray

(D. spinulosa var. intennedia) Dryopteris marginalis (L.) A. Gray 3 Dryopteh x triploidea W herry

(D. intennedia x D. carthusiana) Gymnocarpium dry opteris (L.) Newm. Matteuccia struthiopteris (L.) Todûro Onoclea sensibilis L. Polystichum acrostichoides (Michx.) Schott

TAXACEAE (Yew Family)

Tarus canadensis Ma rsh.

Lurir laricina (Du Roi) K. Koch Picea glauca (Moench) Voss Pinus strobtrs L. Pirtus s~lvestris L. Tsuga canadensis ( L.) Carr.

CUPRESSACEA E (Cy press Family )

§Juniperus communis L. §Junipenrs virginiana L. Thuja occidentalis L.

TYPHACEAE (Cat-tail Family )

Typha angustifolia L. Typha latqolùa L.

SPARGANIACEAE (Bur-reed Family)

SSparganium chlorocarpum Ryd b.

POTAMOGETONACEAE (Pondweed Family)

g Potamogeton pectinatus L.

Lady Fern Silvery Glade-fern Bulblet Fern McKay's Fragile Fern Boott's Wood-lem

Spinulose Wood-fern

Crcsted Fern Goldie's Fern Intermediate Wood-fern

Marginal Shield-fern Triploid Wood-fern

Oak Fern Ostrich Fern Sensitive Fern Christmas Fcrn

Canada Yew

Tama rack White Spruce White Pine Scots Pine Eastern Hemlock

Cornmon Juniper Eastern Red Cedar Eastern White Cedar

Green Bur-reed

Sago Pondweed

NAJADACEAE (Naiad Family)

III

Najasflexifis (Willd.) Rostkov & W. Schmidt

AUSMATACEAE (Water-plantain Family)

Alisma plontago-aquatica L. (A. triviale)

gsagittaria ht$olia W illd.

POACEAE (Grass Family)

5Agrosti.s gigantea Roth. Agrostis scabra Willd.

(A. hyemaiis) Agroslis stolonifera L. §Alopecurus aequalis Sobol. §A venu saîiva L. *Brachyehtrum erectum (Schreber) Beauv. #Bromus ciliatus L. Bronlus inennis Leyss. Calamagrosris canadensis (Michx.) Beauv. #Cinna lrztifofia (Trev.) Griscb. Dactylis glonrerata L. Danthonia spicda (L.) Beauv. Digitaria ischaemunr (Schreb. ) Schreb. 5 Digitaria sanguirralis (L. ) Scop. 4 Echinochloa crusgalli ( L . ) Beauv. #Ecliinochloa wiegandii (Fasset) McNeil & Dore El~nitis repens (L.) Gould

(Agropy-on repens) §Elymus vüginkus L. Festuca arundinacea Schr.

(F. elatior. in part) Festuca rubra L. 9 Festuca subverticillata (Pers.) A. Alex.

(F. obtusa) Fesruca brevipila Trricey

( F. trachyphylla, F. ovina) Glyceriu grandis S. Wats. Glycerio striata (Lam.) Hitchc. Leersia orytoides (L.) Sw. Laliurn perenne L. gMilium effusum L. Muhlenbergia mexicunu (L.) Trin. Oryzopsis asperifulici Michx. §Panicum acuminatum Sw.

(P. lanuginosum, Dkhanthelium acuminatum) Panicum capiiiare L. §Panicum depauperatum Muhl. Q Panicum linearifolium Scrib. Phalaris arundinacea L. Phleunt pratense L. Phragmites austraiîs (Cav.) Trin.

(P. cornmunis)

Flexible Naiad

Watcr-plantain

Common Arrowhead

Redtop Tickle Grass

Creeping Bent Grass Short-awn Foxtail Oats Bearded Shorthusk Fringed Brome Awnless Brome Canada Blucjoint Drooping Woodreed Orchard Grass Poverty Grriss Smooth Crab-gras Large Crab-grass Barnyûrd Grass Western Barnyard Grass Quac k Grass

Virginia Wild-rye Fall Fescue

Red Fescue Nodding Fescue

Sheep Fescue

Tall Manna-gras Fowl Mannci-grass Rice Cut -gras Rye Grass Wild Millet Mexican Muhly-gras Rough-leaved Mountain-rice Tufted Panic-gras

Common Witch Grass Depauperate Panic-gras Linear-leaved Panic-grriss Reed Canary Grass Timothy Common Reed-gras

IX 1 - VASCULAR Pl .ANTS OF JOKER'S

Pua annua L. Poa compressa L. Poa palustris L. Poa prarensis L. §Pou ahodes L. Schizacline purpurascens (Torr.) Swallen. §Setaria pumila (Poiret) Schultes

(S. glauca) §Setaria viridis (L.) Beauv. §Sphenophalis intemedia (Rydb.) Rydb. Sporobolus cryptandrus (Torr.) A. Gray Sporobolus neglectus Nash Sporobolus vaginiflorus (Torr.) Torr.

CYPERACEAE (Sedze Family)

$Carex albursina E. Sheldon $Carex aqiralilis Wahl. Cares arctahz Roo t t Carex aurea Nutî. *§Carex backii Boott §Carex bebbii (Baiiey) Fern. §Carex blanda Dewey Carex cephaloplrora Mu hl.

§Carex cornmunis Bailey §Carex cris&tella Britt. Carex deweyana Schwein. 5 Carex dispenna Dewey ljcarexflpva L. Carex gracillimu Schwein. Carex granularis Mu hl. *§Carex lrirtifolio Mack. $Carex hitchcockiana Dewey $Carex hystericina Mu h l $Carex interior Bailey *$Carex intumescens Rudge §Carex laevivaginata (Kuk.) Mûck. $Carex hiocarpa E hrh. §Carex laxiflora Lam. Carex ieptalea Wahl. §Carex leptonervia (Fern.) Fern. §Carex lupulina Mu hl. §Carex muhlenbergii Schk. §Carex peckii Howe Carex peduncuhta Muhl. Carex pensylvanica Lam. Carex phntaginea Lam. Carex platyphylia J. Carey 5 Carex pseudo-cyperus L. §Carex radicrla (Wahl.) Small Carex retrom Schwein. §Carex rosea Schk.

(C. con valuta) SCarex rugosperma Mack

Annual Bluegrass Canada Bluegrass Swamp Bluegrass Kentucky Bluegms Woodland Bluegrass False Melic Grass White Foxtail

Green Foxtail Slender Wedge Grass Sand Dropseeâ Overlooked Dropseed Ensheat hed Dropseed

Broad-leaved Sedge Aquatic Sedge Compressed Sedge Golden-fruitcd Sedge Back's Scdge Bebb's Sedge White Sedge One-headed Sedge Common Sedge Crested Sedge Dewey's Sedge Two-secded Sedge Yellow Sedge Filiform Sedge Granular Scdge Hûiry-leaved Sedge Hitchcock's Sedge Porcupine Sedge Interior Sedgc Bladder Sedge Smooth-sheathed Sedge Slender Sedge Lme-flowered Sedge Bristle-stal ked Sdge Finel y -nerved Sedge Hop Sedge Muhlenbcrg's Sedge Peck's Sedge Peduncled Sedge Pennsylvania Sedge Plan tain-leaved Sedge Broad-leaved Sedge False-cyperus Sedge Radiate Sedge Backward Sedge Rose Sedge

Carex scabdu Schwein. Carer sparganioides W illd. §Carex spicata Hudson * §Carex sprengellii Dewey Carex stipata Muhl. Carex vul;pinoidea Michx. Cyperus bipartilus Torrey

(C. rivuloris) §Cyperirs lupulinus (Sprengel) Mrircks

(C. filiculmis) Efeocharis erythropoda Steud. $Eieocharis obtusa (Willd.) Schultes Scirpus tatrovirens Willd. Scirpus cyperinus (L.) Kunth Scirpus microcarpus Presl.

(S. rubrotinctus) Scirpus vafidus L. (SA)

ARACEAE (Arum Family)

Arisaema triphylium (L.) Schott

LEMNACEA E (Duckweed Family)

Lemnu minor L. Spirodela po ly rhb (L.) Schteid. Worffm columbirrna Karst.

JUNCACEAE (Rush Family)

§Juncus articulatus L. 9 Juncus brevicaudatus (Engelm.) Fern. OJuncus contpressus Jacq. Juncus bufonius L. 5 Juncus dudleyi W ieg. luncus effusus L. $Juncus nodosus L. Juncus tenuis Willd. Juncus torreyi Cov.

LIWACEAE (Lily Family)

Aflium îricoccum Ait. Asparagus oficinalis L. Clintonia borealis (Ait.) Raf. Erythronium americanurn Ker Gawler Hemerocallisjiulva L. Maianthemum canadense Desf. Maianthemum racernosa (L.) Link

(Srnilacina racernosa) §Maianthemunt stelhaîum (L.) Link

(Srnilacina steüàta) Medeoh virgincOna L. Polygonatum pubescens (Willd.) Pursh

Rough Sedge Bur-reed Sedge Spiked Sedge Sprengel's Sedge Crowded Sedge Foxtail Sedge River Cypenis

Red-foot Spikerush Blunt Spikerush Blackish Bulrush Wool-gras Red-sheathed Bulrush

Soft-stem Bulrush

Lesser Duckweed Greater Duckweed Water-meol

Jointed Rush Short-tailed Rush Campressed Rush Toad Rush Dudley's Rush Soft-stem Rush Knotted Rush Slender Rush Torrey 's Rush

Wüd Leek Asparagus Bluebead Lily Yellow Trout-lily Day Lily Canada Maflower FaIse Solomon's-seal

Indian Cucumber-root Hairy Solomon's-seal

APPENDIX 1 - VASCI JLAR PLANTS OF J O W ' S HILL

Smilar herbacea L. gSmilar hispkfu Torr. Streptopus roseus Michx. Trillium erecturn L. Trillium grandiF,rurn (Michx.) Salisb. Uvularia grandiira Sm.

IRIDA CEA E (Iris Family )

Iris versicolor L. Sisyrinchium montanurn Greene

ORCHIDACEAE (Orchid Famil y )

*Corallorhb cf. maculaia (Ra f.) Ra f. Corallorhira trifida Chat. Cypripedium cakeolus L. Cypripedium reginae Walter Epipactis helleborine (L.) Crûntz $Caleuris spectabiiîs (L.) Raf. fiparis loeselii (L.) Richard * §Malaris monopyllos (L.) Swallen Pldanthera hyperborea (L.) Lindley Spiranthes cernua (L.) Rich

SALICACEAE (Willow Family )

Populus bahmgera L. Populus grandidenta fa Mic hx. P opulus tremuloides Michx. Salix amygdaloides Anderss. Salir bebbiana Ssrg. Salir discolor Muhl. §Salk exigua Nutt. $Salk eriocepliala Michx. $SalLr cf: x mbens Schrrin k

(S. fragilis x S. alba) Salk lucida Muhl. Salir petiolrrris Smith $Salk serissima (L. Bailey) Fern.

JUGLANDACEAE (Walnut Frtmily)

Caqa cordfownis (Wangenh.) K. Koch Juglans cinerea L.

BETULACME (Birch Family)

Betula allegheniensis B ritton Betula papynyera Marsh. Carpinus caroliniana \Val t Corylus cornuta Marsh. Oshya virginirina (Miller) K. Koch

Carrion Flower Bristly Greenbrier Rose Twisted-stalk Red Trillium White Trillium brge-flowered Bellwort

Blue Fias Blue-eyeà Grass

Spotted Coralroot Early Comlroot Yellow Lady's-slipper Showy Lady 's-slippcr Helleborine Showy Orchis Loesel's Twayblade White Adder's-mouth Northen Green Orchid Nodding Ladies'-tresses

Balsam Poplar Large-toothed Aspen Trembling Aspen Peach-leaved Willow Beaked Willow Pussy Willow Sandbar WiHow Stiff WiHow Hybrid Willow

Shining Willow Slender Willow Autumn Willow

Bittemut Hickory Butternut

Yellow Birch White Birch Blue Beech Beaked Hazel Hop Hornbeam

FAGACEAE (Beech Farnily)

Fagus grandifolka Ehr h. Querciis aiba L. Quercus macrocatpa Michx. Quercus rubm L.

ULMACEAE ( E h Family)

URTICACEAE (Nettlc Family)

Boehme& cylindrica (L.) Sw. Loporîea canadensis (L.) Wedd. 5 Parietarkz pensyl vanica Mu hl. §Piles fontana (Lunell) Rydb. Pilea pumila (L.) A. Gray U&a dwica L. ssp. gracilis Ait.

POLYGONACEAE (Buckwheat Family)

Polygonunr achoreum Blake Poljgorium aviculare L. Polygonum convolvulus L. §Poljgonunt hydropiper L. Polygonum hpathifolium L. Polygonum persicaria L, Rumex acerosella L. Run1e.r crispus L. Runiex obatsifolius L. Rumex orbicuhus Gray

CHENOPODIACEAE (Goosefoot Frirnily )

Atriplex patula L. Chenopodium album L. §Chenopodium glaucurn L. 5 Chenopodium rubrurn L. 9 Chenopodium simpkx (Torrey) Ra f.

AMARANTHACEAE (Amaranth Famil y)

PORTUUCEAE (Purslane Famil y )

Claytonia caroliniana Michx. Portulaco okmcea L.

CARYOPHYLUCEAE (Pink Family)

American Bcech White Oak Bur Oak Red Oak

American Elm

False Nettle Wood Nettle Pellitory Dark-seeded Cleanveed Cleanveed Tall Nettle

Homeless Knotweed Prostrate Knotwced Black Bindweed Water Pepper Nodding Smartweed Lady 's-thumb Sheep Sorrel Curled Dock Bitter Dock Great Water Dock

Spearscale Lamb's Quarters Oak-leaved Goosefoot Coast Blite Maple-leaved Goosefoot

Tumbleweed Redroot Pigweed

Wide-leaved Spring Beauty Purslane

Arenaria serpyllifolia L. Thyme-leaved Sandwort

Cerustium fonranum Baumg. (C. vulgatum)

Diarithus armeria L. Sapotlaria oficinalis L. Silene antirrhina L. Silene larifalia Poiret

(S . alba. Lychnis ulba) Silene nocriflora L. Silene vulgatis (Moench) Garc ke §Srellaria grarninea L. $StellaM longiJoli0 Willd Srellana media (L.) Cyrillo

RANUNCULACEA E (Crowfoot Family )

Actaea pachypoda (L.) Mill. Actaea rubra (Ait.) Willd. 9Ac)aea x ludovici Boivin

(A. pachypoda x A. rubra) Anemone cylindrica A. Gray Anemone virginiuna L. $AquilegÙz canadonsis L. gAquilegia vulgaris L. Caùha palustris L. Clemaîis vùginiana L. Coptis triifdia (L.) Salisb. Hepatica acutiloba DC. Ranunculus abortivus L. Runuricrilus acris L. Ranunculus recurvatus Poiret Ranunculus sceleratus L, Thalictrum dioicum L. Thlictrum pubescens Pu rsh

BERBERIDACEAE (Barberry Family)

Berberis thunbergii DC. Caulophyllum thalictroides (L.) Michx. P odophyllum peltatum L.

PA PA VERACEA E (Poppy Famil y )

Chelidoniuni majus L. Sangtrinaria canadensir L.

FUMA RIA CEAE (Corydal is Family )

Dicenîra canoderrsis (L.) Bernh.

CAPPARACEAE (Caper Family)

5 Cleome hmsleriana Chodat (C. spinosa)

Mouse-ear Chic kweed

Deptford Pink Bauncing Bet Sleepy Catchfly White Campion

Night-fiowering Catchfly Bladder Campion Grass-lcaved Stitchwort Long-leaveà Stitchwort Common Chickweed

White Baneberry Red Baneberry Hybrid Baneberry

Long-fruited Anemone Thimbleweed Wild Columbine Garden Colurnbine Marsh Marigold Virgin's Bower Goldthread Sharp-lobed Hepatica Kidney-leaved Buttercup Common Buttercup Hooked Buttercup Cursed Buttercup Early Meadow Rue Tall Meadow-rue

Japanese Barbeny Blue Cohosh May-apple

Celandine Bloodmt

Squirrel Corn

Spider Fiower

BRASSICACEAE (Mustard Family)

Alliaria petiolata (M. Bieb.) Cav. & Gr. (A. oficinalis)

Alyssum alysoides (L.) L. Arabis gWm (L.) Bemh. Barbarea vulgaris R. Br. SCamelina microcarpu Andrz. Capsella bursa-pastoris (L.) Medi k. Cardamine dîphylla (Michx.) A. Wood

(Dentriria diphylla) Cardamine pensylvanica Muhl. Erysiniurn cheiranthoides L. Wesperis matrunalis L. Lepidium densiflorum Schrad. Naturtium oncinale R. Br. 4 Ron@pa palustris ( L.) B-r

ssp hispida (Desv.) Jansell Siriapis amensis L.

(Brassica kaber) Sysimbrium oncinale (L.) Scop. Thlarpi arvense L.

CRASSULACEAE (Orpine F~imily)

Sedum telephiuni L.

SAXIFRAGACEAE (Saxifrage Family)

§Chrysospleniurn americanum Hoo ker Mdella diphylla L. Mitella nuda L. Tiarella cordgolia L.

§ Ribes alpi~iurn L. Ribes americonum Mill. Ribes cynosbati L. 9Ribes hùîellum Michx. *$Ribes lacusîte (Pers.) Poir. Ribes rubrum L. Ribes triste Pallas

HAMAMELIDACEAE (Witch-hazel Famify)

ROSACEAE (Rose FamiIy)

Agrimonia gtyposepala Wallr. §Ame&nchier k v i s Weig. §Amelanchier interior Nielson Crataegus nwnogyna Jacq.

Yellow Alyssum Smooth Rock-mess Yellow Rocket SrnaIl-seeded False-flax Shepherd's Purse Toothwort

Pennsylvania Bitter-cress Worrnseed Mustard Dame's Roc ket Peppergms Water-cress

Marsh Yellow-cress Charlock

Hedge Mustard Field Penny-cress

Golden Saxifrage Bishop's-cap Mitrewort Naked hiitrewort Foamflower

Alpine Currant Wild Black Currant Prickly Gooseberry Hairy Gooseberry Bristly Black Curront European Red Currant Swamp Red Currant

Hooked Agrimony Srnooth Servicebemy Interior Seniceberry English Hawthom

APPENDIX 1 - VASCUI,AR PJ .mTS OF JOKER'S HILL

Crrrtaegus punctcrca Jacq. Crataegus macracantha Lodd

(C. succulenta var. macracantha) Crataegus sect Coccineae F r a g a ~ vesca L. Fragaria vwginiana Dechesne Geum akppicum Jacq. Geum canadense Jacq. $Geurn laciniclrum Murr. OGeurn rivale L. Malus pumila Miller

( P y m malus) Q PotentiUa orguta Pursh Potentilla norvegica L. Poteritilla recta L. Prunus nigra Ait. Prunus pensylvanica L.f. Prunus serotina Ehrh. Prunus virgininna L. Pyrus conin~unis L. Rusa bhnda Ait. $Rosa carolina L. Rosa nrultiflora Thunb. Rubus allegheniensis Porter Rubus idaeus var. strigosus L.

(R. strigosus) Rubus occidentalis L. Rubus odoratus L. Rubus pubescens Raf. Sorbus aucuparin L. $ Waldsteinia fragarioides (Michx.) Tratt.

FABACEAE (Bean Family )

Amp hicarpueu bracteatu (L.) Fern. Desmodium canadense (L.) DC. Desmodium glutinosum (Muhl.) Wood QLathyrus tuberosus L. Lotus corniculatus L. Medicago lupulina L. Medicago sativa L.

ssp. sativa ssp. falcata (L.) Arcangeli

Melilotus alba Medikus Melilorur oflcinalis (L.) Pallas Robinia pseudo-acacia L. Trifalium campestre Schr.

(T. procumbenr) Trifalium hybridum L. Tnfolium pratense L. Tnyolium repens L. Vicia cracca L. Vicia sativa L. Vicia tetraspermu (L.) Moench

Dotted Hawthorn Large-thorned Hawt horn

hawthorn sp. - section Coccineae Woodland Strawberry Wild Strawberry Yellow Avens White Avens Slashed Avens Water Avens A P P ~ ~

Tall Cinquefoil Rough Cinquefoil Sulphur Cinquefoil Canada Plun Pin Cherry Black Cherry Choke Cherry Pear Smmth Wild Rose Pasture Rose Multiflora Rose Common Blackberry Red Raspberry

Black Raspberry Purpie-fiowering Rospberry Dwarf Raspberry European Mountain-ash Barren Strawberry

Hog-peanut Showy Tick Trefoil Glutinous Tick-trefoil Tuberous Vetchling Bird's-foot Trefoil Blrick Medick

Alfalfa Yellow Lucerne White Sweet Clover Yellow Sweet Clover Black Locust Pinnate-leaved Hop Clover

Alsike Clover Red Clover White Clover Cow Vetch Spring Vetch S p m w Vetch

OXAUDACEAE (Wood Sorrel Family )

gOxalis metosella L. Oxalis s&icto L.

(O. foniana, O. europaea)

GERANIACEAE (Geranium Family )

Geranium robertianum L.

EUPHORBIACEAE (Spurge Frimily)

Acalypha virginica Raf. (A. rhomboidea)

#Chaniaesyce gljprospernra (En gel m. ) S m d l (Eupho rbia g ljptosperma)

§Chamaesyce maculola (L.) Small (Euphorbia supina, E. macula&)

Euphorbia cyparissias L.

POLYGALACEAE (Polygala Family)

ANACARDIACEAE (Cashew Frimily)

Rlzus radicans L. (Toxicodendron radieans)

Rhus typhina L

CELASTRACEAE (Bittersweet Ftimily )

Ce(astrus scandens L. QEuonymus aiatus (Thunb.) Siebold

ACERACEAE (Maple Family )

SAcer ginnala Maxim. Acer neglrndo L. *§Acer nigrum Michx. f. Acer plaranoides L. Acer rubrum L, Acer sacchan'num L. Acer saccharum Marsh. Acer spkatum Lam.

BALSAMINACEAE (Touch-Me-Not Family)

Impatiens capensis Meerb.

RHAMNACEA E (Buckhorn Family )

Wood Sorrel YePow Sorrel

Herb Robert

Three-seeded Mercury

Engraved Spurge

Spotted Spurge

Cypress Spurge

Poison Ivy

Staghorn Sumac

Bittersweet Winged Euonymus

Amur Maple Manitoba Maple Black Maple Norway Maple Red Maple Silver Maple Sugar Maple Mountain Mapte

Spotted Touch-Me-Not

Common Buckthorn

XII

APPENDIX 1 - VASCULAR PI-ANTS OF JOKFP'S HI1.L

VlTACEA E (Vine Farnily)

Parthenocissus inserta (Kerner) Fritsch (P. vbcea)

Vitis riparia Michx.

TIWACEAE (Linden Fiunily)

Tilia americana L. § Tilia cordara Mil 1.

MALVACEAE (Mallow Family)

CLUSIACEAE (St. Johnswort Family)

Hypericum pe~oratum L. 3 Hypericum punctatum Lam.

CISTA CEA E (Rock-rose Family )

$Lecheu intermedia Britt.

VIOLACEAE (Violet Family)

5 Viola bhn& Willd. Viola canadensis L. Q Viola conspersa Reich. Viola cucullata Ait. §Viola mackfoskeyi F. Lloyd Viola pubescens Ait.

(incl. V. pensyf vanica, V. eriocarpa) Vioh renifolia Gray

Viola rostmîa Pursh 5 Viola seikirkii Purs h Viola sororiiz Willd. (s.L)

TH YMELAEACEA E (Mezereum Famil y)

LYTHRACEA E (Loosestrife Frimily )

Lythrum salicaria L.

ONAGRACEAE (Evening Primrose Family)

Circaea alpim L. Circaea lutetirrna L.

(C. quadrisukaîa) Epilobium cilicltum Rd.

(inci. E. adenocaulon, E. glandulosum)

Virginia Creeper

Wild G rape

Basswood Little-leaf Linden

Common Mallow

Comrnon St. Johnswort Dotted St. Johnswort

Intermediate Pinweed

Sweet White Violet Canada Violet Dog Violet Marsh Blue Violet Northern White Violet Downy Yellow Violet

Kidney-leaved Violet Long-spurred Violet Selkirk's Violet Wooly Blue Violet

Purple Loosestrife

SmaH Enchanter's-nightshade Tall Enchanter's-nightshnde

Northern Willow-herb

APPENDIX 1 - VASCULAR PI-ANTS OF-

~Epilobium hirsutuni L. 5 Epilobium leptophyllum Ra f. Epilobium parviflorum Sc hre ber ~Epilobium strictum Spreng. Oenothera biennis t. (s.L) $Oenothera perennis L.

ARAWACEAE (Ginseng Family)

Aralia nudicaulk L. Aralia racernosa L. Panax quinqu$olius L.

A PIACEAE (Parsley Family)

Cryptotaenia canadensis (L.) DC. Daucus carota L. Hydrocotyle americana L. Osrnorhiza chytoni (Michx.) C. B. Clarke Sium suave Walter Sanicuiu marilandica L.

CORNACEAE (Dogwood Famify)

Cornus alternifolk L. f. §Cornus canadensis L. Cornus rugosa Lam. Cornus stolonvera M ichx.

PYROLACEAE (Pyrolri Frimily)

§Chimaphila urnbellata (L.) Bart. SMoneses uniflora (L.) Gray 5 Pyrola americana Sweet

(Pyroiu rotundifolia var. americana) 8 Pyrola asar~olia Mic hx. Pyrola elliptka Nutt.

MONOTROPACEAE (Pinesap Family)

§Monotropa hypopithys L. Monotropa unif2ora L.

ERICACEAE (Heath Family)

G a u l t h e ~ procumbens L. Voccimium angustifolium Ait.

P RIMULA CEAE (Primrose FamiIy )

Lysimachia ciliala L. Trientalis borealis Raf.

Hairy Willowherb Narrow-leaved Willowherb Small-flowered Willowherb Downy Willowherb Evening-primrose Sundrops

Wild Sarsaparilla Spikenard American Ginseng

Honewort Queen Anne's Lace Water Pennywort Sweet Cicely Water Parsnip Black Snakeroot

Alternate-leaved Dogwood Bunchberry Round-leaved Dogwood Red-osier Dogwood

Pipsissewa One-flowered Wintergreen Round-leaved Pyrolo

Pink Pyrola Shinleaf

Pinesap Indian Pipe

Wintergreen Low Biueberry

OLEACEAE (Olive Family )

Fraxinus urnericana L. Fraxinus nigra Marsh. 5 Frarinus pensylvanica Marsh. Syringa vulgaris L.

GENTIANACEAE (Gentian Farnily)

A POCYNACEAE (Dogbane Family)

Apocynum androsaem~ulium L. Apocynum cannabinum L.

ASCLEPIADACEAE (Milkweed Family)

Asclepios incarnata L. Asclepias s y ~ c a L. rjCynartchuni rossicurn (Kleopov) Borh.

( Vincetoxicum niedium l

CONVOLVULACEA E (Bindweed Frimily)

Calystegia sepium (L.) R. Br. (Con volvulus sepium)

§ Calystegia spithamaea (L. ) Pursh Convolvulw arverisis L. S Cuscuta gronovii Willd.

H YDROPHYLLACEAE (Waterleaf Frtmily)

* 9 Hydrophyllum canadense L. Hydrophyllum virginiana (L.) Johnst.

BORAGINA CEAE (Borage Family )

Cynoglossum oficirtale L. Echium vulgare L. DHackelia virginiana (L.) Johnst. myosotis scorpioides L. 5 Myosotis sylvatico Ho ffm.

PItryma kptostachya L. Verbena hastkzta L. Q Verbena stricu Vent. Verbena urticifolia L.

White Ash BIack Ash Red Ash Lilac

Clased Gentian Fringed Gentian

Spreading Dogbane Indian Hemp

Swamp Milkweed Common Milkweed Swallowwort

R d g e Bindweed

Low Bindweeà Field Bindweed Dodder

Crincida Waterleaf Virginia Waterleaf

Hound's Tongue Viper's Bugloss Virginia Stickseed Watet Forget-me-not Woodland Forget-me-not

Lopseed Blue Vewain Hoary Vervain White Vervain

LAMIA CEAE (Mint Family)

Cfinopodium vulgare L. (Satureja vulgaris)

Galeopsis tetrahit L. Glechoma hederucea L. 5 Hedeoma hispida Pu rsh Leorutrus cardiaca L. Lycopus americanus Mu hl. Lycopus uniflurus Michx. Mentha arvensis L. Menrha x piperita L.

(M. aquatica x M. spicasal Monarda fitubsa L. Nepeta cararia L. Prunelin vulgaris L. Scutellaria latetifloru L.

SOLANACEAE (Nightshade Farnily)

Physalis heteropiaylla Nees §Solarium tuberosum L. Solarium dulcanuira L. §Solarium nigrurn L. (s.1.)

SCROPHULARIACEAE (Figwort Family)

Chaenorrhinurn mirius (L . ) Longe Chelone glabra L. $Gratiola neglecta Torr. Linaria vulgaris H il1 Mimulus tingens L. 9 Penstemon digitah Nuit. Verbuscum thupsiw L. Veronica americana (Raf.) Schw. Vernriica arvensis L. Veronica officinalis L. Veronica peregrina L. ssp. peregrina Veronica serpyllifolia L.

OROBA NCHA CEA E (Broom-npe Family )

Epvagus virginiana (L.) Bart.

PLANTAGINACEA E (Plantain Family)

Plantago major L. Plantago lanceoluta L. Plantago rugelii Decne.

RUBIACEAE (Madder FamiIy)

Galium aparine L. $Galium boreale L. Galium circaezans blichx.

Wild Basil

Hemp Nettte Ground Ivy Hairy Pennyroyal Cammon Motherwort Cut-leaved Bugleweeed Northern Bugleweed Common Mint Peppermint

Wild Bergamot Catnip Heal-al1 Mad-dog Skullcap

Clammy Ground-cherry Potrito Bittersweet Nightshade Black Nightshade

Dwarf Snlipdragon Turtlchead Clammy Hedge-hyssop Common Toadflax Square-stemmed Monkeyflower Fox-glove Beard-tongue Common Mullein Americnn Brooklime Corn Speedwell Comnion Speedwell Purslane SpeedweII Thyme-leaved S peedwell

Common Plantain English Plantain Rugel's Plantain

Cleavers Northern Bedstraw White Wild Licorice

Galium mollugo L. #Galium lanceoiaîum Torr. 5 Cafium palustre L. §Gdium tinctorium L. *§Galium tn~idum L. Galium tnflonrm Michx. Galium verum L. Mitcheh repens L.

CA PRIFOLIACEAE (Honeysuckle Family )

Diewilh lonicera Mill. §Linnaeu borealis L Lonicera canadensis Bartr. Lonicera dioica L. &Lotiicera x bella Zribel

(L. tatarica x L, niorrorvii) .iLonicera hirsuta Eaton $Lotlice ru tata nca L.

Sambucus canadensis L. Sambucus racemosa L.

(S. pubens) Symphoricarpos albus (L.) Blake Triosteum aurantiacum Bich. Viburnum aceri$olium L. 3 Viburrium cassinaides L. $ Vibumum lanratia L. 5 Viburnum lantancrides M ichx.

(V. aln~olium) Viburnum lentago L. $ Vibumum opulus L. *$ Viburnum trilobum Marsh.

(Viburnum opulus var. americatta)

CUCURBITACEAE (Gourd Farnily)

§Cucurbita sp. Ecirinocystis lobata (Michx.) T.& G.

CAMPANULACEA E (Bluebell Family )

Campanula aparinoides Pursh (C. uliginosa)

Campanula rapunculoides L. Lobelia in- L, Lobelia siphilitka L. §Lobelia spicrra Lam.

ASTERACEAE (Composite Fmily)

AchiUea miUefolium L. Ambrosia artemisiifolia L. Anaphalis mugarhcea (L.) Benth. & Hook

Wild Madder Yellow Wild Licoricc Marsh Bedstraw Dyer's Bedstraw Small Bedstraw Frsgrant Bedstraw Yellow Bedstraw Partridgeberry

Northern Bush Honeysuckle Twiriflower Canada Honeysucklc Glaucous Honeysuckie Hybrid Honeysuckle

Hairy Honeysuckie Tartariiin Honeyusuckle

Common Elder Red-berried Elder

Snow berry Wild Coffee Maple-leaved Viburnum Wild Raisin Wayfaring Tree Hobblebush

Nannyberry Guelder Rose Highbush Crrinberry

domestic gourd species Wild Cucumbcr

Marsh Bellfiower

Common Bellflower Indian Tobacco Great Lobelia Spiked Lobelia

Common Yarrow Common Ragweed Pearly Everlasting

APPENDIX 1 - VASCULAR PLANTS OF JOKER'S

§Antennaria neglecta Greene Antennaria parlinii Fem. Arctium minus (Hill) Bernh. §A rtemisiu ludoviciana Nu tt. SArternisia biennis Willd. §Aster x amethystinus Nutt.

(A. ericoides r A. novae-angliae) Aster cord$oliUs L. Aster ericoides L.

(Virgulus erkoides) Aster lanceolatus W il Id.

(A. simplcx) Aster Iareriflorus (L.) Britt. Aster macrophyllus L. Aster novae-angliae L.

(Virgulus novae-angliae) Aster oolentangiensis Riddell

(A. azureus) §Aster pilosus Willd. Aster puniceus L. $Aster uropltyllus Lind. Biàens cernua L. Biàens frondosa L. Bidens tripartifa L. (s.1.)

(B. comosa, B. connata) §Bidens vulgata Greene Carduus acanrhoides L. Cenraicsea jacea L. Chrysanthentum leitcanrhen~um L. Cichoriunz intybus L. Cirsiuni arverise (L . ) Scop. Cirsiunt vulgare (Sav i ) Tenore Cunyza canadensis (L. ) Cron. Crepis teetoruni L Erigerm annuus (L.) Pers. Erigeron phiiadelphicus L. 8 Erigeron pukhellus Michx. Erigeron sttigosus Muhl. Eupatorium maculatum L, Eupcrtorium perfoliatum L. Eupcrtorium rugosuna Houtt. Eutlurmia graminifolk (L.) Salisb.

(Solidogo graminifolk) Galinsoga quadriradiata Ruiz & Pwon Cnaplrctlium obtus~oIium L. Hieracium auranriacurn L. Hieracium caespitosurn Dumort.

(H. pratense) Hieracium pilosella L. Hieracium piloselloides V ill.

( H. flo renrirt um) lnula heleniurn L. Lactuca biennis (Moench) Fern. Lactuca canadensis L.

Field Pussytoes Plantain-leaved Pussytoes Common Burdock Western Sage Biennial Wormwood Amethyst Aster

Hcart-leaved Aster Many-nowered Aster

Panicled Aster

Calico Aster Large-leaved Aster New England Aster

Azurc Aster

Heath Aster Purple-stemmed Aster Arrow-leaved Aster Bur-rnarigold Beggar's-ticks Stick-tight

Tall Beggar's-ticks Plumeless Thistle Brown Knapweed Ox-eye Daisy Comrnon Chicory Canada Thistle Bull Thistle Horseweed Narrow-leaved Hawk's-beard Daisy Fleribrine Philadelphia Fleabane Robinfs Plantain Rough Fleabane S potted Joe- Pye- Weed Boneset White Snakeroot Grass-leaved Goldenrod

Quic kweed Sweet Everlasting Orange Hawkweed Field Hawkweed

Mouse-ear Hawkweed King Devi1

Eiecampane Tall Blue Lettuce Canada Wild Lettuce

Lactuca sem'ola L. Matricaria matricadides (Less. ) Porter Prenanthes alrissima L. Rudbeckia hirio L.

(R. serotina) Rudbeckia iriloba L. SSenecw aureus L. EjSenecio i~iscosus L. Senecio vulgaris L. Solidogo alrissima L. *Solidago arguta Ait. Solidago caesia L. Solidago canaàensis L. Solidago flexicaulis L. Solidago gigantea Ait. Solidago nemomlis Ait. Solidago rugosa Ait. QSolÙiago uliginosa Nutî. Sonchus arvensis L. Sortchus asper (L.) Hill Sonchus oleraceus L. 8 Tanacetum vulgare L. §Tararacum erythrospennum Anderz. ex Besser Taruxacum palustre (Lyons) DC. (S. 1. )

{T. turfosurn) Taraxacurn opcinale Weber Tragopogon dubius Sco p. Tragopogon pratertsis L. Tussilago farfara L.

Prickly Lettuce Pineappleweed Tall White Lettuce Black-eyed Susan

Brown-eyed Susan Golden Ragwort Sticky Groundsel Common Groundsel Tall Coldenrod Sharp-leaved Goldenrod Blue-stemmed Goldenrod Canada Goldenrod Zig-zag Goldenrod Late Goldenrod Gray Goldenrod Rough-stemmed Goldenrod Bog Goldenrod Field Sow Thistle Spiny-leaved Sow Thistle Annual Sow-thistle Common Tansy Red-seeded Dandelion M m h Dandelion

Common Dandelion Goat's- beard Yellow Goat's-beard Colt's-foot

Rare native plants of Joker's Hill and immediate surroundings

C. Sean Blaney, 1999.

The following native species are considered rare at some level between local and national. A number of the species listed as locally rare in Riley (1989) have probably since been removed frorn the OMNR rare list as their status has become better understood. An updated version cf this list will be prepared after consultation with the OMNR. The list includes only records based on specimens 1 have seen. One additional locally rare species, Juglans nigrn (Black Walnut). was reported for the Glenville Hills Environmentally Signifiant Area (which includes rnuch of the Joker's Hill property) in Ecologistics (1982). If correctly identificd, this record is very likely based on an introduction or adventive record, rather than a native occurrence in the area. Numerous JrlgIutzs rtigrn are planted in the western portion of the farm, and the site is north of the species' recognized native range (Farrar 1995).

Codes: * - The record for the species is supported by a specimen (to be deposited at TRTE). N - rare in Canada (National Museum of Natural Sciences 1988). P - rare in Ontario (Oldham 1996) R - rare in the former OMNR Central Region (Riley 1989). Y - rare in Metropolitan Toronto and York Regional Municipality (Riley 1989). ' - not previously recorded in Mrtropolitün Toronto and York Regional Municipality (Riley 1989). ' - recorded outside the boundaries of the Joker's Hill propeny, but nearby ' - collected by Richard Joos. a graduate student icndsr Terry Carleton. Specimen seen by CSB.

Lycopodiuni obsc~rrttrtl L. ( . u t ) Qcopodium rristachyuni Purs h Equiserrrm pratensr Ehrh. Botrychium dissectirin Spreng. Dennstaedtia punctilobiïln (Michx.) Moore Asplertirrm plarynewon (L.) Oakes Dryopteris gokiiana ( Hoo k . ) Gray Polypoditrm virgirziclnunl L. Jrcniperrts contrnunis L. lrmiperrrs virginicrntr L. Fesruca subverticillata (Purs.) E . Alexeev

(F. obtr~sa Biehl.) Panicum ùepauperatwn Mu h 1. Panicum linearijiolium Bri tt. Sporobolris vaginif or us (Torre y ) Torre y Carex cephalophora Muhl. CarexJlava L. Carex hitchcockiana Dewey Carex lasiocarpa E hrh. Carex muhlenbergii Schk. Carex rugosperma Mack. Cyperrrs lupulinus (Spreng.) Marcks Juncus brevicaudarus (Engel m.) Fern. Corailorhita cf: rnacrtlatn (Raf.) Raf. Malaris monophyllos (L.) Sw. Pilea fontana (Lunnell) Rydberg Chrysospienium arnericanrtm Hooker Ribes lacustre (Pers.) Poir. Geum laciniatum Mumay Potentifla arguta Pursh Rosa carolina L.

Ground-pine Ground-cedar Meadow Horsetai l Dissected Grripe-fem Hay-scented Fern Ebony Spleenwort Goldie's Fern Rock Polypody Common Juniper Eastern Red Cedar Nodding Fescue

Depauperate Panic Grass Narrow-leaved Panic Grass Ensheathed Dropseed One-headed Sedge Yellow Sedge Hitchcock's Sedge Wooly-fruited Sedge Muhien berg's Sedge Rough-seeded Sedge CY pems. Short-tailed Rush Spotted Coralroot White Adder's-rnout h Dark-seeded Clearweed Golden Saxifrage Bristly Black Currant Slashed Avens Ta11 Cinquefoil Pasture Rose

APPENDIX II - RARE NATIVE PLANTS OF JO-

*RY *Y *Y *Y *Y NPR *Y

Oxalis acetosellla L. Hypericum punctatum Lam. Epilobium strictum Spreng. Oenothera perennis L. P a m quinquijiolius L. Lechea intermedia Legg . Monotropa hypopithys L. Chimuphila wnbellata (L.) Bartr. Moneses uniflora (L.) Gray Pyroia amencana S weet

( P. rorundifolia var. americana) Gentiana andrewsii Griseb. Gentianopsis crinita (Froel.) Ma Hydrophyllum canadense L. Verbena stricta Vent. Hedeoma hispida Pursh Galium circaerans Mic hx . Galium lanceolatum Tor. Galium tinctorium L. Lonicera hirsuta Eaton Vibumum cassinoides L. Viburnum lantanoides Mic hx.

( V. alnifoliurn Marsh.) Lobelia spicata Lam. Aster pilosus WiIld. Aster urophyllus Lindl. Bidens vulgata Greene Erigerorr pulchellus Michx. Solidago arguta Ait. Senecio aureus L.

Wood Sorrel Dotted St. John's-wort Downy Willowherb Sundrops American Ginseng Intermediate Pinweed Pinesap Pipsissewa One-flowered Wintergreen Round-Ieaved Pyrola

Closed Gentian Fringed Gentian Canada Wate rleaf Hoary Vervain Mock Pennyroyal Wild Licorice Yellow Wild Licorice Dyer's Bedstraw Hairy Honeysuckle Wild Raisin Hobblebush

Spiked Lobelia Pringle's Aster Arrow-leaved Aster Ta11 Beggar's-ticks Robin's Plantain S harp-leaved Goldenrod Golden Ragwort

APPENDIX II - R w NATIVE PI-ANTS OF J O m ' S

Birds of Joker's Hill, King Township, Regional Municipality of York

C. Sean Blaney, July 1999

This tist is a compilation of 1997-99 observations of the author, P.M. Kotanen, W. Kilburn, R. Joos and M.T. Johnson and the observations of property manager William Fox from 1971 to the present. Al1 species on the main list were observed from within the Joker's Hill property boundaries. As this work was secondary to our main research only a low percentage of the species actually breeding on the site were recorded in the confirmed category. Almost al1 species in the possible (PO) and probable (P) breeding categories likely do breed on the site. The status codes listed below are a slightly modified version of those used in the Ontario Breeding Bird Atlas (Cadman et al. 1987):

O - Observed without evidence of breeding M - observed only as a migrant or winter resideiit X - observed during the species' breeding season without evidence of breeding PO - breeding possible SH - observed in suitable habitat during breeding season SM - singing male observed in suitable habitat dunng breeding season P - breeding probable P -pair observed in suitable habitat during breeding season T - singing male observed in the same area on visits separated by at least two weeks A - agitated behaviour D - breeding display or intraspecies hostility N - nest building CO - breeding confirmed DD - distraction display NU - used nest AE - adult entering presumed nest site FS - adult carrying food or faecai sac NE- nest with eggs NY - nest with young FY - flightless or dependent young

Common Loon Pied-billed Grebe Arnerican Bittern Great Blue Heron Green Heron Canada Goose Wood Duck Green-winged Teal Mallard Blue-winged Teal Ring-necked Duck Bufflehead Hooded Merganser Common Merganser Turkey Vulture Northem Hanier Sharp-shinned Hawk Cooper's Hawk Broad-winged Hawk Red-shouldered hawk Red-tailed Hawk Ametican Kestrel Ruffed Grouse

Gavia irnrner (Brunnich) Podilyrnbus podiceps (Li nnaeus) Botaurus [enriginosus (Racken) Ardea herodias Linnaeus Butorides striatus (Linnaeus) Branra canadensis (Linnaeus) Aix sponsa (Linnaeus) Anas crecca Linnaeus Anas platyrhynchos Linnaeus Anas discors Linnaeus Aythya collaris (Donovan) Bucephala albeola (Linnaeus) Lophodytes cucullatus (Linnaeus) Mergus merganser Linnaeus Cathartes aura (Linnaeus) Circus cyaneus (Linnaeus) Accipiter srriatus Vieillot Accipiter cooperii (Bonaparte) Buteo platyptems (Vieillot) Buteo lineatus (Gmelin) Buteo jamaicensis (Gmelin) Falco sparverius Linnaeus Bonasa umbellanis (Linnaeus)

O-M O-M O-M O-X O-X P-P P-P O-M P-P O-M O-M O-M O-M O-M O-X O-X PO-SH CO-FS P-T CO-NY P- A PO-SH P-T

Wild Turkey American Coot Killdeer Solitary Sandpiper Spotted Sandpiper Common Snipe American Woodcock Ring-billed Gu11 Hening Gull Rock Dove Mourning Dove Black-billed Cuckoo Eastern Screech-Owl Great Horned Owl Barred Owl Snowy Owl Common Nighthawk Whip-poor-will Ruby-throated Hummingbird Belted Kingfisher Yellow-bellied Sapsucker Downy Woodpecker Hniry Woodpecker Northern Flicker Pileated Woodpecker Olive-sided Flycatcher Eastern Wood-Pewee Yellow-bellied Flycatcher Alder Flycatcher Least Flycatcher hs tern Phoebe Great Crested Flycatcher Eastern Kingbird Horned Lark Purple Martin Tree Swallow Northern Rough-winged Swallow Bank Swallow Cliff Swailow Barn Swallow Blue Jay American Crow Blac k-capped Chickadee Red-breasted Nuthatc h White-breasted Nuthatch Brown Creeper House Wren Winter Wren Golden-crowned Kinglet Ruby-crowned Kinglet Eastern Bluebird Veery Hennit Thrush Wood Thnish American Robin Gray Catbird Brown Thrasher

Meleugris gallopavo Linnaeus Fulica nmericana Gmelin C h racirius vociferus Linnaeus Tringa solitaria Wilson Actitis macula ria (L innaeus) Gallinago gallinago (Linnaeus) Scolopav mirtor Gme lin Larus delawarensis Ord Lnnis argenteus Pontoppidan Columba livia G rnel in ïenaida macroura (Linnaeus) Coccy:rrs erythropthalmus (Linnaeus) Otus asio (Linnaeus) Bitbu virginianrc Grnetin Strix varia Barton Nyctclea scaridiaca (Linnaeus) Chortieiles minor (Forster) Caprimulgus vociferus Wilson Archiloclirls colrrbris (Linnaeus) Ceryle alcyon (Linnaeus) Spltyrapiclrs wrius ( Linnaeus) Picoides pirbescens (Linnaeus) Picoides villosus (Lin naeus) Colaptes auratus (Linnaeus) Drycopus pileutus (Li nnaeus) Coritopirs borealis (S wainson) Contoprrs virens (Linnaeus) Empidonaxj7aviventris (Baird and Baird) Empidonar alnorrrm Brewster Empidortcrx minimus (Baird and Baird) Sayornis phoebe (Latham) Myiarcltrcs crinitus (Linnaeus) Tyrannits tyrnnnus (Linnaeus) Erernophila alpestris (Linnaeus) Progrte subis (Linnaeus) Tachjrineta bicolor (Vieil lot) Stelgidopteryx serripennis (Audubon) Riparicr riparia (Linnaeus) Hirundo pyrronota Viei Ilot Hinrndo rusticci Linnaeus Cyanocirta cristata (Linn aeus) Corvus brcrchyrhynchos Brehm Parus atricapillus Linnaeus Sitta canadensis Linnaeus Sitta carolinensis Latham Cenhia americana Bonaparte Troglodytes aedort Vieillot Troglodytes trodglodytes (Linnaeus) Regrtlrrs sarrapa Lichtenstein Regulus calendula (Linnaeus) Sialia sialis (Linnaeus) Catharus frrscescens (S tephens) Catharus guttatus (Pallas) Hyfocichla mustelina (Gmelin) Turdus migratorius Linnaeus Dumetella carolinensis (Linnaeus) Toxostoma rufitm (Linnaeus)

CO-FY O-M P-T O-M PO-SH P-T PO-S H O-X O-X CO-AE P-T P-T P-T P-T P-T O-M O-X PO-SM P-T O-X CO-AE P-P CO-NY CO-ET P-T O-M P-D O-M P-T P-T P-P P-D CO-NE PO-SM O-X P-T O-X O-X O-X CO-NY CO-FY CO-FY CO-FY CO-FY CO-FY P-T CO-FY P-T P-T O-M PO-SH P-T O-M P-T CO-FS P-T PO-SM

American Pipit Anthus rubescens (Tunstall) Cedar Waxwing Bombycilla cedrorum Vieillot Bohemian Waxwing Bombycilla garruius Vieillot European Starling Sturnus vulgaris Linnaeus Solitary Vireo Vireo solitarius (Wilson) Warbling Vireo Vireo gilvus (Vieillot) Philadclphia Vireo Vireo philodelphicm (Cassin ) Red-eyed Vireo Vireo olivaceus (Linnaeus) Blue-winged Warbler Vennivora pinus (Linnaeus) Golden-winged Warbler Vemivora chrysoptera (Linnaeus) "Brewster's" Warbler Vennivora chrysoptera (Linnaeus) x

(Golden-winged x Blue-winged Warbler) Vennivora pinus (Linnaeus) Tennessee Warbler Vemivora peregrina (Wilson) Orange-crowned Warbler Vermivora celata (Say) Nashville Warbler Vennivora nrficapilla (Wilson) Nonhem Panila Parula nrnericana (Linnaeus) Yellow Warbler Dendroica petechia (Linnaeus) Chestnut-sided Warbler Dendroica pensylvonica (Linnaeus) Magnolia Warbler Dendroica magnolia (Wilson) Cape May Warbler Dendroicn tigrina (Grnelin) Black-throated Blue Warbler Dendroictz caerulescens (Grnelin) Yellow-rumped Warbler Dendroica coronata (Linnaeus) Black-throilted Green Warbler Dendroica virens (Grnelin) Blackbumian Warbler Dendroica fusca (Muller) Pine Warbler Dendroiccz pinus (Wilson) Palm Warbler Dendroica palmarrrrn (Grnelin) Bay-breasted Warbler Dendroica castanea (Wilson) Blackpoll Warbler Dendroict! striata (Fors ter) Black-and-white Warbler Mniotiltn varia (Linnaeus) American Redstart Setophaga rutacilla (Linnaeus) Ovenbird Seiurus nrrrocapillrrs (Linnaeus) Nonhem Waterthrush Seittnrs noveboracensis (Gmelin) Mourning Warbler Opororrzis philadelphia (Wilson) Common Yellowthroat Geothlypis trichas (Linnaeus) Hooded Warbler Wilsonicr citrina (Boddaert ) Wilson's Warbler Wilsonia prrsilla (Wilson) Canada Warbler Wilsonia canadensis (Linnaeus) Scarlet Tanager Pirangn olivacea (Gmelin) Northem Cardinal Cardinalis cardinalis (Linnaeus) Rose-breasted Grosbeak Pheucticus ludovicianus (Linnaeus) Indigo Bunting Pizsserina cyanea (Linnaeus) Rufous-sided Towhee Pipilo erythopthalmus (Linnaeus) American Tree S parrow Spizella arborea (Wilson) Chipping Spmow Spizella passerina (Bechstein) Field Sparrow Spizella pusilla (Wilson) Vesper Sparrow Pooecetes gramineus (Grnelin) Savannah Sparrow Passerculus sandwichensis (Gmel in) Grasshopper Sparrow Amniodramus savannumm (Grnelin) Fox Sparrow Passerella iliaca (Merrem) Song Sparrow Mefospiza nielodia (Wilson) Swamp Sparrow Melospiza georgiana (Latham) White-throated Sparrow Zoriotrichia albicollis (Grnelin) Dark-eyed Junco Junco hyemalis (Linnaeus) Snow Bunting Plectrophenax nivalis (Linnaeus) Bobolink Dolichonyx oryzivorus (Linnaeus)

O-M P-P O-M CO-NY P-T P-T O-M CO-FS CO-FS CO-FS' CO-FS'

O-M O-M P-N O-M P-P PO-SM P-T O-M O-M P-T P-T P-T P-T O-M O-M O-M PO-SM O-M CO-FY PO-SM P-T CO-FS O-M O-M PO-SM CO-FY P-T P-T CO-FY P-T O-M CO-FY CO-NE PO-SH CO-FS O-M O-M CO-NE P-T P-T O-M O-M P-T

' A male Brewster's Warbler paired with a female Golden-winged Warbler were seen together sevenl times betwetn late May and late June 1998, when the pair was observed carrying food and exhibiting agitated behaviour.

Red-winged Blackbird Eastern Meadowlark Rusty Blackbird Common Grackle Brown-headed Cowbird Northern Oriole Pine Grosbeak Purple Finch House Finch Red Crossbill White-winged Crossbill Common Redpoll Pine Siskin American Goldfinch Evening Grosbeak House Sparrow

Agelaius phoeniceus (Linnaeus) Stumella magna (Linnaeus) Euphagrts carolinus (Muller) Quiscalus quiscula (Linnaeus) Molothrus atcr (Boddaert) lcterus galbula (Linnaeus) Pinicola enucleator (Linnaeus) Carpodacus purpureus (Grnelin) Carpodacus mexicanur (Muller) Loxia curvirostra Linnaeus Loxia lerrcoptera Gmel in CardeulisJkrmmea (Linnaeus) Cardeulis pinus (Wilson) Carduelis tristis (Linnaeus) Cocco th rausres vespertinus (Cooper) Passer domesticus ( Linnaeus)

Clay-coloured Sparrow Spitella pallida (Swainson) - observed just outside property boundaries, to the northwest

P- A P-T O-M CO-FS P-P P-T O-M P-P P-T O-X O-X O-M O-M CO-NE O-M O-X

Mammals of Joker's Hill, King Township, Regionai Municipality of York

C.S. Blaney and W. Fox, 1998

The following list includes al1 wild mammals observed by property manager William Fox between 197 1 and 1999, as well as those recorded dunng field work in 1997 and 1998 and those recovered in small mammal trapping in 1999 (P.M. Kotanen, unpublished data). Ali observations were incidental ones made during other work. A systematic program of nocturnal bat detection would undoubtedly reveal a nurnber of additional species. Virginiz Opossum and Beaver were observed just north of the property boundary.

Dùielphimomhia O~ossums Didelphis virginiana Virginia Opossum

Insectivora Shrews and Moles Blarina brevicaudara Short-tailed Shrew Sorex cinereus Masked Shrew Condylura crisrata S tar-nased Mole

Chiro~tera Bats C - Eptesicus ~ U S C U S Big Brown Bat (indentification probable only)

La~ornomha Rabbits and Hares Syl vilagus floridana Eastern Cottontail Lepus europaeirs European Hare

Rodeniia Rodents Tamias stria rus Eastern Chipmunk Marmota monax Woodchuck Sciurus carolinensis Gray Squirrel Tarniasciurus hudsorlicus Red Squirrel Glaucomys sp. flying squirrel sp. Castor canadensis Beaver Zapus hudsonius Meadow Jumping-mouse Peromyscus leucopus White-footed Mouse Microtus pennsylvanicus Meadow Vole Ondatra ziberhicus Muskrat Rattus norvegicus Norway Rat Mus musculus House Mouse Erithizon dorsatum Porcupine

Carnivora Carnivores Canis latrans Coyote Vulpes vulpes Red Fox Procyon lotor Raccoon Mustela ermina Ermine Mustela vison Mink Mephiris mephitis Striped Skunk

&îiodacîyia Deer Odocoileus virginianus White-tailed Deer

APPENDIX V

Amphibians and Reptiles of Joker's Hill, King Township, Regional Municipality of York

C. Sean Blaney, 1999.

The following species were recorded during in 1997 or 1999 by C.S. Blaney, and P.M. Kotanen, or by property manager William Fox between 1971 and the present.

AMPHIBIANS Ambystomatidae Arnbystorna macvlatum

Salamandridae Notopthalmus viridescens

Pletitodontidne Phhodort cinereus

Hy Iidae Pserrdacris crucifer Hyla versicolor

Ranidae Rana catesbiana Rana clamitans Rnna pipiens Rana sylvatica

Bufonidae Brlfo americana

REPTILES Ch elydridae Chelyra serperitina

Enry didae Chrysernys picta

Colubtùiae Thamnophis sirtalis Storeria occipitornaculata Diadophus punctatus

Mole Salamanders Spotted Salamander

Newts Red-spotted Newt

Lungless Salamanders Red-backed SaIamander

Treefrogs Spring Peeper Gray Treefrog

Tme Frogs Bull Frog Green Frog Leopard Frog Wood Frog

Toads American Toad

Snapping Turtles Snapping Turtle

Box and Water Turtles Painted Turtle

Colubrid Snakes Garter Snake Red-bellied Snake Ring-necked Snake