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1 Ecological Restoration of Ravenshill Pond: Aquatic invasive Iris pseudacorus assessment and removal Giorgio Giovinazzo Prepared for: Dr. Val Schaefer ER 390 Restoration of Natural Systems July 2012

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Page 1: Ecological Restoration of Ravenshill Pond: Aquatic ... Technical Series/Giovinazzo.… · Ecological Restoration of Ravenshill Pond: Aquatic invasive Iris pseudacorus assessment and

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Ecological Restoration of Ravenshill Pond: Aquatic invasive Iris

pseudacorus assessment and removal

Giorgio Giovinazzo

Prepared for: Dr. Val Schaefer

ER 390

Restoration of Natural Systems

July 2012

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Acknowledgements

Many thanks to many people are in order. First off, I would like to thank my

friend Jason Slade for putting me contact with Ian Bruce (Environmental Consultant),

second I would like to thank Ian Bruce for putting me in contact with Paul and Adele,

third I would like to thank Paul and Adele on whose property this ecological restoration

project took place. A circle of connections makes the world beautiful. Forth I would like

to thank my love, Miranda Cross for her expertise in plant identification and assistance in

invasive species plant removal. A special thank you goes out to Dr. Val Schaeffer whose

guidance was helpful in relieving the stress of the situation.

Cover Photo: Ravenshill Pond

Abstract

In July 2012 in the district of Sannich, 11 kms from Victoria, BC the invasive species Iris

pseudacorus was assessed and some plants removed/controlled. Also bathymetric

analysis of Ravenshill pond took place in conjunction with ecosystem typing,

aquatic/terrestrial plant survey, pond cores, water data collection, and dam inspection to

assist in the development of a long term invasive Iris eradication/control program.

Bathymetric analysis was conducted to elucidate the ponds features, aquatic and

terrestrial plant survey for future comparative analysis to identify potential invasive

species spreading. Core samples were taken to indentify the underlying ground matrix

and its potential ability to allow heavy machinery into pond area for maintenance,

modification, and control of invasive species. Ecosystem typing was conducted to

confirm that the pond was in fact man made. Water data collected for future

reference/comparative analysis. Bathymetric analysis revealed a max depth of <2m, pond

cores revealed an underlayer of grey clay, ecosystem typing/site series of CwFd-

Kindbergia (Western-Red Cedar, Douglas fir), pond water was slightly acidic, with low

dissolved oxygen. Removal of Iris pseudacorus is labor intensive and requires it is

recommended that machinery be hired to assist in the control/eradication of Iris

pseudacorus.

Introduction

Ravenshill pond acquired its name from a past owner, who modified the wetland

previously on the property by building an earth dam, thereby creating Ravenshill pond

(Ward-Harris, 1979). Ravenshill pond is in the Todd Creek watershed, and water from

the pond drains through a culvert into Bleathman Creek which flows into Prospect Lake.

Ravenshill pond is located in the district of Sannich, on Southern Vancouver Island, BC.

Currently the pond belongs to Paul and Adele who both wish to maintain and create a

habitat where native species flourish. Compromising their wishes is an invasive species

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known as Yellow Flag Iris (Iris pseudacorus), that grows on the wet shores of the pond,

also it creates floating mats which enable it to grow in the shallows of the pond.

This freshwater aquatic ecosystem provides habitat for numerous migratory waterfowl,

and native amphibians. The integrity of this ecosystem needs to be maintained by

controlling invasive species presences. Iris pseudacorus is listed as a noxious invasive

species in British Columbia (IPCBC, 2012). This particular aquatic invasive is

widespread throughout North America, and many areas engage in mechanical removal of

the entire plant, repeated cutting, or the use of herbicides (UoF, 2008). The plant is

believed to displace native species and alter ecosystems. It is suggested that the plant

material be burned, or placed in thick garbage bags for placement in a landfill

(IPCBC,2012).

The objective of this ecological restoration is to map the extent of Iris pseudacorus

within Ravenshill pond, to slow its spread through removal of the plant, and to assess the

conditions for widespread eradication Iris pseudacorus from Ravenshill pond.

2.0 Methods

Study Area

The study area was a 8000m2 subsection of Paul and Adele’s property (Fig. 1, 2), on

southern Vancouver Island within the Coastal Douglas Fir Biogeoclimatic Zone

(Meidinger & Pojar, 1991). This area falls within the Vancouver Island/Olympic

mountain rain-shadow, summers are warm and dry, winters, mild and wet. Average

precipitation varies from 647-1263 mm, with less than 5% as snow (Nuszdorfer et al.

1991). Within the study area is Ravenshill pond, which has numerous patches of invasive

Iris pseudacorus growing within it (Fig.8)

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*Scale 1:100000, Scale bar lower left reads 1355m, North indicator arrow displayed upper right

Figure 1. Location of the site in the District of Sannich,Vancouver Island, B.C. (Map

obtained from Sannich GIS, 2012)

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Figure 2. Study Site and Sampling Method Locations (Photo obtained from Sannich GIS,

2012)

Sampling Methods

The study site was squared off with the use of a compass in order to define the study site

and enclose the pond. After study site was defined pond bathymetric analysis, core

samples, ground cover analysis, ecosystem typing, aquatic/terrestrial plant inventory,

yellow flag iris locations mapping took place. Also dissolved oxygen, pH, total dissolved

solids, and temperature of pond water data was collected with a Fisher pH/temperature

tester, Hanna instruments: EC/TDS tester (pH and temperature data was cross referenced

with Hanna instruments pH/temp (for accuracy). Disolved Oxygen data was collected

with Chemetrics Kit.

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Bathymetric analysis was carried out by grid mapping, and measuring the depth of the

pond with a meter stick. Measurements were taken: North/South longitude every 15m,

West/East every 3m in order to create a bathymetric map (Fig. 3.), depths were

categorized as less than 1m, greater than 1m less than 2m (<1m,>1<2 respectively).

Three core samples were taken to be representative of the area (Fig. 2). Core samples

were obtained through the use of a hollow pipe, hammer, and wooden dowel to push core

out (Ian Bruce (Environmental Consultant) suggestion). Three soil pits were dug

and ground information forms (GIF) filled out to ecosystem type the area. GIF

completion followed the procedure outlined in the field guide insert to the Field Manual

for Describing Terrestrial Ecosystems accessed from:

http://www.ilmb.gov.bc.ca/risc/pubs/teecolo/fmdte/gif.htm#ground%20Inspection%20Fo

rm (July 2012). Soil moisture and nutrient regimes (SMR/SNR) data were decoded

using A field Guide for Site Identification and Interpretation for the Vancouver Forest

Region (Green &Klinka, 1994). For the identification of terrestrial and aquatic plant

species Pojar and MacKinnon’s (1994) Plants of Coastal British Columbia was used in

conjunction with the help of Miranda Cross (plant specialist).

To map the locations of Iris pseudacorus a Garmin etrex GPS was used in conjunction

with aerial photographs obtained from Sannich GIS (2012) (Fig. 8, Table 2.)

Ecological Restoration

After Iris pseudacorus patches were mapped (Fig. 8., Appendix A: Table 2), areas

that were accessible by wheel barrel were selected for Iris pseudacorus removal. Other

Iris pseudacorus patches were selected for seed head removal. Due to labor/access

restraints a number of Iris pseudacorus patches are were left in active status (Fig. 5, 8.

Appendix A: Table 1).

Removal of Iris pseudacorus from the shore (Fig.3) required the use of a pitch fork,

shovel, gloves, and patience. The rhizomes of the plant need to be removed to prevent re-

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growth, thus gloves are required since you must reach into the soil to remove rhizomes,

also since plants contain skin irritants protection is necessary (Sutherland, 1990).

Removal of Iris pseudacorus in floating mat (Fig. 4) form required the use of a saw to cut

mat into a manageable size in order for it to be hauled out and disposed of. After

removal, the native cattail Typha latifolia was planted.

Figure 3. Left Iris pseudacorus before removal, Same area Camera facing pond after

planting of native cattail , Typha latifolia.

Figure 4. Left Iris pseudacorus before removal, Same area different camera angle after

planting of native cattail , Typha latifolia.

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Figure 5. Left Yellow Flag Iris In Bloom, Right Some of the Iris, Active State

Figure 6. After a Few Days Hard Work, Some pond areas maintained and a couple Truck

Loads of Iris to dispose of.

Disposal of Iris pseudacorus involved the use of Oak Bay’s waste management services,

where organic matter is hot composted to kill viable seeds/plant material. The hot

composting of the plant material ensures that it will not be spread.

Results and Interpretation

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The results of the bathymetric analysis (Fig. 7) and core samples reveal that some areas

of the pond can be reached by light weight machinery to assist in the mechanical removal

of Iris pseudacorus. In other areas, partial draining of the pond may be required to ensure

safe use of machinery within the pond. The cores revealed a clay matrix, which indicates

that the machinery will not sink into the ground.

Figure 7. Bathymetric Map of Ravenshill Pond (Photo obtained from Sannich GIS, 2012)

Ground cover analysis indicated that study site ground cover is mainly, salal, kindbergia,

trailing blackberry, Oregon grape and bracken fern, with patches of invasive St. John

Wort. Salal had a frequency of 50%, St. Johns wort of 25%, oregon grape of 50%,

bracken fern of 25%, trailing blackberry of 37.5 %, and beaked moss of 12.5%

(Appendix A, Table 1). Results indicate that the invasive St. Johns Wort needs to be

contained and controlled.

The aquatic and terrestrial plant species inventory (Appendix A: Table 5,6.) indicate that

there is a wide assortment of native species, however, there are also some invasive

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species that may require attention in the future, namely ivy, holy, creeping buttercup, and

Scottish broom, at present there numbers/abundance appear to be very low, but that can

change quickly.

Some Iris patches have been removed (Fig.8), and others controlled by seed head

removal, however, active patches still remain and require attention.

Figure 8.Location of Iris pseudacorus within Ravenshill Pond. (Photo obtained from

Sannich GIS, 2012)

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The native cattail species Typha latifolia was planted to promote native species within the

pond, and potentially prevent reestablishment of Iris pseudacorus.

Figure 9. Iris pseudacorus seed heads

Figure 9 above depicts the Iris pseudacorus seed heads which float, and can hide. It is

important to be thorough when plants are removed and no traces can be left behind

because of the high potential of re-colonization by the plant.

Figure 10. Iris pseudacorus Left showing the roots, Right, floating mat hauled

in

Figure 10 shows Iris pseudacorus roots that will form rhizomes and mats that

will infiltrate areas of the aquatic ecosystem, with the potential to displace

native species.

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Ecosystem typing/site series of CwFd-Kindbergia (Western-Red Cedar, Douglas

fir) was revealed through digging soil pits (Fig. 2). The reason soil pits were

dug was to confirm that the pond was manmade, the soil matrix of areas

adjacent to the pond shore reveal that the pond was in fact man made.

Water tests obtained a dissolved oxygen rating of 6ppm for surface and 2-3ppm

for 1m deep, pH was 6.5 at surface and 6.2 at 1m deep, TDS 42 at surface and

46 at 1m deep (Appendix A: Table 3).

Discussion

The ecological restoration of Ravenshill pond involved the assessment of the aquatic

invasive species Iris pseudacorus. To slow its spread the removal of some of the plant

patches was carried out along with the cutting/removal of seed heads. Also a bathymetric

analysis of Ravenshill pond took place in conjunction with ecosystem typing,

aquatic/terrestrial plant survey, pond cores, water data collection, and dam inspection to

assist in the development of a long term invasive Iris eradication/control program.

Bathymetric analysis revealed that the pond is quite shallow, meaning that it has a high

potential for invasive plant invasion, and also native aquatic species clogging. The

analysis suggests that potential dredging of the pond may be necessary to maintain a

diverse habitat for native aquatic waterfowl.

Although the ecological restoration of Ravenshill pond helped remove some of the

invasive iris impacts there are still numerous active patches of iris that need to be

removed/controlled. This is a timely and thus costly endeavor, if funds could be obtained

to hire machinery to assist in the removal, it may prevent further ecological damage to the

area by preventing its spread to nearby areas. Leung et al. (2002) point out that if you

can contain/maintain an invasive species before it gets out of control it is much more cost

effective to deal with. In lines with that train of thought, are Keller et al. that suggest the

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risks of invasive species be assessed in order to delineate solutions that will have less

economic and environmental impacts.

The core analysis revealed a clay matrix, which is important if machinery will be used to

assist in ecological restoration. This observation suggests that if machinery is available it

can be used to assist in some removal of invasive iris because the stable ground matrix

will keep machinery from sinking.

Data gathered on water qualities depicted what is typical of pond water, the slightly

acidic pH reading suggests that the pond is not receiving significant contamination from

human activities, since a negative pH is what would be expected in that particular

ecosystem.

It is important to mention that some of the data collection may not be perfect because of

my human error, and the potential that can be attributed to the instruments used for

analysis. That being said, further research, mapping, and analysis of the area should be

carried out.

Maintenance and monitoring should be a huge part of any ecological restoration.

Monitoring is required to assess the effectiveness of any implemented restoration

activities, if it appears that restoration efforts are not being effective than more

maintenance is required. Hopfensperger et al. (2007) suggest that feasibility studies be

carried out in order to assess whether or not ecological restoration projects should be

conducted in the first place. The reason being is that if the funds or the people (labor) are

not there to support the project, it will just fail, thus compromising the ecological

integrity.

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Conclusions & Recommendations

Ravenshill pond is a unique area and provides great habitat for native species,

unfortunately there are also invasive species present that need to be maintained and

controlled.

Recommendations

Source funding for complete removal of Iris pseudacorus

Machinery should be hired to assist in the control/eradication of Iris pseudacorus.

Tree frog populations estimate: in order to see if species are declining

Conduct Bull frog population estimate

Control/removal of St. Johns Wort & keep a watchful eye on other noted

invasives

References

Ecosytems Working Group, Terrestrial Ecosystems Task Force, and Resources Inventory

Committee. 1998. Standard for Terrestrial Ecosystem Mapping in British Columbia.

Retrieved July 2012 from: www.for.gov.bc.ca/ric

Green,R &Klinka,K. 1994. A field Guide for Site Identification and Interpretation for the

Vancouver Forest Region. Resource Branch, BC. Retrieved July 2012 from:

http://www.for.gov.bc.ca/hfd/pubs/docs/lmh/lmh28.htm

Hopfensperger, K. N., Engelhardt, K. A. M., & Seagle, S. W. (2007). Ecological

feasibility studies in restoration decision making. Environmental Management, 39(6),

843-852.

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Invasive Plant Council of British Columbia (IPCBC). Retrieved July 2012 from:

http://www.thinksalmon.com/reports/Aquatic_Invasive_Plants_Action_Plan_%28Feb_28

_2010%29.pdf

Keller, R. P., Lodge, D. M., & Finnoff, D. C. (2007). Risk assessment for invasive

species produces net bioeconomic benefits. Proceedings of the National Academy of

Sciences of the United States of America, 104(1), 203-207.

Leung, B., Lodge, D. M., Finnoff, D., Shogren, J. F., Lewis, M. A., & Lamberti, G.

(2002). An ounce of prevention or a pound of cure: Bioeconomic risk analysis of

invasive species. Proceedings of the Royal Society of London Series B-Biological

Sciences, 269(1508), 2407-2413.

Meidinger, D., and J. Pojar (1991) Ecosystems of British Columbia. British Columbia

Ministry of Forests, Victoria, British Columbia, Canada.

Pojar, J,& MacKinnon,A. (1994) Plants of Coastal British Columbia, Victoria:British

Columbia Forest Service; Vancouver, Lone Pine Publishing.

Nuszdorfer F.C., Klinka, K. And Demarchi D.A. 1991. Chapter 5 Coastal Douglas-fir

Zone. Ecosystems of British Columbia. BC Ministry of Forests.

Sutherland, W. J. (1990). Iris-pseudoacorus L. Journal of Ecology, 78(3), 833-848.

University of Florida. (2008). Iris pseudacorus: Center for Aquatic and Invasive Plants.

Retrieved July 2012 from: Center for Aquatic and Invasive Plants:

"http://aquat1.ifas.ufl.edu/node/205" http://aquat1.ifas.ufl.edu/node/205

Ward-Harris, J. 1979. Creature Comforts. Toronto: Collins.

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Appendix A

Table 1. Ground Cover Assessment: Eight 1m x 1m Quadrats, July 2012

Presence Frequency Average Coverage

Species (#quadrats) (%) in respective quadrats

(%)

Gaultheria shallon(Salal) 4 50 80

Hypericum perforatum

(St. Johns Wort) 2 25 80

Mahonia aquifolium

(Oregon grape) 4 50 5

Pteridium aquilinum

(Bracken Fern) 2 25 5

Rubus ursinus

(Trailing Blackberry) 3 37.5 5

Kindbergia oregano

(Beaked moss) 1 12.5 100

Table 2. GPS Coordinates of Iris pseuacorus patches, size,type, and status _

Approx.Size Type Status

GPS Cooridinates (m2)

N48° 30.092’

W123°26.695’ <1 shore removed

N48° 30.094’

W123°26.698’ <1 shore removed

N48° 30.100’ floating removed

W123°26.692’ 1 mat

N48° 30.096’ floating

W123°26.678’ 1 mat removed

N48° 30.094’

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W123°26.683’ 4 f/m removed

N48° 30.078’

W123°26.689’ 5 f/m seed heads cut

N48° 30.076’

W123°26.689’ 8 f/m seed heads cut

N48° 30.072’

W123°26.693’ 2 f/m seed heads cut

N48° 30.061’

W123°26.705’ 3 f/m active

N48° 30.058’

W123°26.706’ 3 f/m active

N48° 30.055’

W123°26.711’ <1 f/m active

N48° 30.55’

W123°26.713’ 5 f/m active

N48° 30.055’

W123°26.713’ 4 f/m active

N48° 30.056’

W123°26.712’ 1 f/m active

N48° 30.058’

W123°26.711’ 2 f/m active

N48° 30.061’

W123°26.709’ 4 f/m active

N48° 30.061’ <1 f/m active

W123°26.711’

N48° 30.062’

W123°26.716’ <1 shore active

N48° 30.061’

W123°26.718’ 4 f/m active

N48° 30.049’

W123°26.718’ 8 f/m active adjacent to willow Islands

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N48° 30.048’

W123°26.718’ 2 f/m active adjacent to willow Islands

N48° 30.054’

W123°26.720’ 5 f/m active adjacent to willow Islands,

decomposing canada goose

egg seen

N48° 30.052’

W123°26.723’ <1 f/m active adjacent to willow Islands

Table 3. Ravenshill Pond pH, TDS, and Temperature____________________

Status

Depth Disolved Oxygen pH TDS Temperature

(m) (ppm) (ppm) (C°)

0 6 6.5 42 22.3*, 18.9**

1 3 6.2 46 19.5*

Notes on temperature: *In sun, **In Shade

Table 4. Wildlife Observed On Within Study Sited, July 2012___________________

Eagle

Hawk

Red Squirrel

Dragon Fly(many species)

Numerous Birds

Raven

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Table 5. Teresterial Plant Species Inventory of Ravenshill Study Site, July2012

Latin Name Common name

Thuja plicata Western Red Cedar

Pseudotsuga menziesii Douglas Fir

Alnus rubra Red Alder

Lonicera involucrate Twin Berry

Spiraea douglasii Hardhack

Pteridium aquilinum Bracken Fern

Gaultheria shallon Salal

Rubus ursinus Trailing Blackberry

Cornus sericea Red Osier Dogwood

Fragaria vesca Woodland strawberry

Rubus spectabilis Salmon berry

Trientalis latifolia Western Star Flower

Holodiscus discolor Ocean spray

Mahonia aquifolium Oregon grape

Rosa nutkana Nootka Rose

Monotropa uniflora Indian pipe

Physocarpus capitatus Pacific nine bark

Polystichum munitum Swordfern

Malus fusca Pacific Crab Apple

Ranunculus occidentalis Western Buttercup

Prunella vulgaris Heal-all

Leucanthemum vulgare Oxeye daisy

Digitalis purpurea Foxglove

Salix scouleriana Scoulers Willow

Lonicera ciliosa Honey Suckle

Acer macrophyllum Big Leaf Maple

Populus tremuloides Trembling Aspen

Lysichiton americanus Skunk Cabbage

Vaccinium parvifolium Red Huckleberry

Galium aparine Cleavers

Juncus effusus Common Rush

Brodiaea elegans Harvest Lily

Fritillaria affinis Chocolate Lily

Quercus garryana Garry Oak

Amelanchier alnifolia Saskatoon berry

Salix cordata Furry Willow

Claytonia sibirica Siberian miners lettuce

Oenanthe sarmentosa Water Parsley

Salix lucida Pacific Willow

Kindbergia oregano Beaked moss

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Oemleria cerasiformis Indian Plum

Tsuga heterophylla W. Hemlock

Betula papyrifera Paper Birch

Ilex aquifolium L.* Holly

Hypericum perforatum* St. Johns Wort

Hedera helix* English Ivy

Cytisus scoparius* Scottish Broom

Cirsium arvense* Canada Thistle

Ranumculus occidentalis Western Buttercup

Ranumculus repens* Creeping Buttercup

Notes: *Invasive species

Table 6.Aquatic Species Inventory of Ravenshill Pond Study Site, July 2012

Latin Name Common name

Nuphar polysepalum Yellow Pond Lily

Potamogeton natans Floating-Leaved Pondweed

Lemna minor Common Duckweed

Myriophyllum spicatumz Water-Milfoil

Iris pseudacorus Yellow Flag Iris

Appendix B

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Figure 11. Earth Dam Inspection Path (Cut July,2012)

Figure 12. Evidence of Beaver ecosystem modification (engineering), purported to be

invasive