cdfr 2005 04 prsnttn borealmosscommunities
DESCRIPTION
https://foothillsri.ca/sites/default/files/null/CDFR_2005_04_Prsnttn_BorealMossCommunities.pdfTRANSCRIPT
Boreal moss communities: succession and implications for
establishment after fire in Alberta’s spruce-dominated forests
Michael SimpsonDepartment of Biological Sciences, University of Alberta
Supervisor: Dr Mark Dale
Polytrichum juniperinum
Funaria hygrometrica
Ceratodon purpureus
Bryum argenteum
Hylocomium splendens
Pleurozium schreberi
Ptilium crista-castrensis
RESEARCH OBJECTIVES
1. Successional change in boreal moss communities – characteristics and controls
A. Describe short-term variations in composition, diversity and species distribution in early-successional communities
B. Test hypotheses about controls on timing of establishment of late-successional feather mosses
C. Generate a model of species change over time
2. Implications for wider forest community• Effects of moss on post-fire recruitment of selected
conifer species
HYPOTHESES
Establishment and growth of feather mosses is controlled by:
• Available substrates– Early successional: mineral-based; high pH, low nutrients, dry
c.f. Late successional: high OM, low pH, high nutrients, moist
• Limited tolerance for low humidity, increased water loss– High exposure in early successional (open) stands
• Reproduction primarily asexual (vegetative propagation); delays dispersal of propagules
• Interactions between substrate, stand age, reproductive strategy
HYPOTHESIS 1: Establishment and growth of feather mosses is controlled by available substrates
1. Compare the establishment potential and growth of fragments of 2 feather mosses on burned and unburned substrates
Pleurozium schreberi
Ptiliumcrista-castrensis
Ash
Humus
Burned moss
Burned mineral soil
2 FRAGMENT SIZES
Small: unbranched, mean lengths: Ptilium5.6 mm Pleurozium 8.2 mm, dislodged using a soil sieve
Large: branching, ~ 4 cm long, cut with scissors
• 2.5” square plastic pots – 24 or 36 = 1 ‘block’
• 5 blocks per stand in:– SMALL frags: 3 early- &
1 late-successional stand
– LARGE frags: 1 late-successional stand
• Sunk into humus on forest floor
• Fragments tied to paper clips
• SMALL - 12 monthsLARGE - 3 months
12221018N =
SUBTYPE
Humus
Mineral soil
CONTROL
Burned moss
Mea
n +-
1 S
E SQ
RT(
leng
th)
5.0
4.5
4.0
3.5
3.0
2.5
SubstrateMea
n to
tal l
engt
h (s
quar
e-ro
ot tr
ans.
dat
a)
12221018N =
SUBTYPE
Humus
Mineral soil
CONTROL
Burned moss
Mea
n +-
1 S
E SQ
RT(
leng
th)
5.0
4.5
4.0
3.5
3.0
2.5
SubstrateMea
n to
tal l
engt
h (s
quar
e-ro
ot tr
ans.
dat
a)
12221018N =
SUBTYPE
Humus
Mineral soil
CONTROL
Burned moss
Mea
n +-
1 S
E SQ
RT(
leng
th)
5.0
4.5
4.0
3.5
3.0
2.5
SubstrateMea
n to
tal l
engt
h (s
quar
e-ro
ot tr
ans.
dat
a)
a aa
b
132220N =
Substrate
Humus
Mineral soil
Burned moss
#SHO
OTS
10
8
6
4
2
0
399
327
Med
ian
num
ber o
f sho
ots
per f
ragm
ent
Substrate
132220N =
Substrate
Humus
Mineral soil
Burned moss
#SHO
OTS
10
8
6
4
2
0
399
327
Med
ian
num
ber o
f sho
ots
per f
ragm
ent
Substrate
132220N =
Substrate
Humus
Mineral soil
Burned moss
#SHO
OTS
10
8
6
4
2
0
399
327
Med
ian
num
ber o
f sho
ots
per f
ragm
ent
Substrate
# shoots per fragment– Few shoots; no difference
between substrates
SMALL: Total length of fragments with living shoots– Only 2 Pleurozium fragments on
ash and 2 Ptilium fragments total with growth
– Fragments on all substrates significantly longer than initial length (P<0.05)
11715109N =
Substrate
Humus
Mineral soil
CONTROL
Burned moss
Ash
Squa
re ro
ot o
f mea
n LM
A8.0
7.5
7.0
6.5
6.0
5.5
91115108N =
Substrate
Humus
Mineral soil
CONTROL
Burned moss
Ash
Squa
re ro
ot o
f mea
n LM
A
7.4
7.2
7.0
6.8
6.6
6.4
6.2
6.0
5.8
Ptilium
Pleurozium
Mea
n le
ngth
of m
ain
axis
(mm
) (sq
uare
-root
tran
sfor
med
dat
a)
Substrate
b
a
a a a
a
bb
ab ab
11715109N =
Substrate
Humus
Mineral soil
CONTROL
Burned moss
Ash
Squa
re ro
ot o
f mea
n LM
A8.0
7.5
7.0
6.5
6.0
5.5
91115108N =
Substrate
Humus
Mineral soil
CONTROL
Burned moss
Ash
Squa
re ro
ot o
f mea
n LM
A
7.4
7.2
7.0
6.8
6.6
6.4
6.2
6.0
5.8
Ptilium
Pleurozium
Mea
n le
ngth
of m
ain
axis
(mm
) (sq
uare
-root
tran
sfor
med
dat
a)
Substrate
b
a
a a a
a
bb
ab ab
11715109N =
Substrate
Humus
Mineral soil
CONTROL
Burned moss
Ash
Num
ber o
f firs
t-ord
er s
ide
shoo
ts
7
6
5
4
3
2
1
0
-1
3117
168
162
185
91115108N =
Substrate
Humus
Mineral soil
CONTROL
Burned moss
Ash
Num
ber o
f firs
t-ord
er s
ide
shoo
ts
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
40
169
Ptilium
Pleurozium
Med
ian
num
ber o
f firs
t-ord
er s
ide
shoo
ts
Substrate
a
bbcdc
d
a
bc ab c ab
HYPOTHESIS 2: Establishment and growth of feather mosses is controlled by limited tolerance for exposure (low humidity, increased water loss)
1. Compare the establishment potential and growth of fragments of 2 species sown in recently burned (open) stands
2. Test for differences between 3 fragment sizes
• LARGE, SMALL, MULCH
• Soil surface excavated to ~ 2.5 cm and replaced with humus
• 5 blocks in 5 stands– 4 recently burned (open)– 1 late-successional
• 4 x 4 blocks marked out using plastic frame
• Fragments pinned/spread within squares
• Number of fragments with living shoots recorded after 12 months
Number of Pleurozium fragments recovered, and number of fragments found with shoots across all stands (August 2004)
38
4
46
43
15
40
5
10
15
20
25
30
35
40
45
50
BRANCHES MULCH SHOOT TIPS
Fragment size
Num
ber o
f fra
gmen
ts
0
5
10
15
20
25
30
35
40
45
50Number of fragments recovered
Number of fragments with shoots
Number of Ptilium fragments recovered, and number of fragments found with shoots (August 2004)
39
46
0
40
0 10
5
10
15
20
25
30
35
40
45
50
BRANCHES MULCH SHOOT TIPS
Fragment size
Num
ber o
f fra
gmen
ts
0
5
10
15
20
25
30
35
40
45
Number of fragments recovered
Number of fragments with shoots
43
15
4
40
1
46
4
38
46
39
0
Number of Ptilium fragments recovered, and number of fragments found with shoots (August 2004)
39
46
0
40
0 10
5
10
15
20
25
30
35
40
45
50
BRANCHES MULCH SHOOT TIPS
Fragment size
Num
ber o
f fra
gmen
ts
0
5
10
15
20
25
30
35
40
45
Number of fragments recovered
Number of fragments with shoots
39
46
0
40
0 10
5
10
15
20
25
30
35
40
45
BRANCHES MULCH SHOOT TIPS
Fragment size
Num
ber o
f fra
gmen
ts
0
5
10
15
20
25
30
35
40
Number of fragments recovered
Number of fragments with shootsNumber of Pleurozium fragments recovered after 12 months
and number of recovered fragments with living shoots
Number of Ptilium fragments recovered after 12 months and number of recovered fragments with living shoots
Living shoots (all stands)• Growth found in few
MULCH replicates• Few SMALL fragments
had living shoots• Almost all LARGE
fragments had living shoots
Number of fragments recovered
Number of fragments with shoots
OBJECTIVE 1: PRELIMINARY CONCLUSIONS
• Establishment and growth on burned/mineral substrates and in open stands possible
Therefore…• Timing of establishment of feather mosses
primarily a function of dispersal limitation, but…• Exposure and substrate influence timing
thorough interactions with fragment size– Larger fragments likely to be more successful, but…– Fewer of them– Long distance saltation dispersal = long process
(which may be accompanied by loss of viability)– Other vectors may be quicker – rare event?
OBJECTIVE 1 – PRELIMINARY CONCLUSIONS
• Suggests establishment by fragments is increasingly rare at greater distances from fire boundary– Spread from boundaries of fire and residuals limited– In the middle of large burns, post-fire recolonisation
likely to be slow• Do distant colonies establish from fragments?
– may occur primarily through spores• Recolonisation likely to be faster post-logging
– source of propagules in situ– would compress intermediate successional stages
and constrain opportunities of species associated with them
RESEARCH OBJECTIVES
1. Successional dynamics in boreal moss communities
A. Describe short-term variations in composition, diversity and species distribution in early-successional communities
B. Test hypotheses about controls on timing of establishment of late-successional feather mosses
C. Generate a model of species change over time
2. Implications for wider forest community• Effects of moss on post-fire recruitment of selected
conifer species
RESEARCH OBJECTIVES
Post-fire recruitment is influenced by early successional conditions
• Burned feather moss remains = ‘biological legacy’• ‘persisting living and dead structures’ left by disturbances’
(Franklin et al. 2002)
RESEARCH OBJECTIVES
Post-fire recruitment is influenced by early successional conditions
• Burned feather moss remains = ‘biological legacy’• ‘persisting living and dead structures’ left by disturbances’
(Franklin et al. 2002)• Dry; elevate seeds and seedlings
RESEARCH OBJECTIVES
Post-fire recruitment is influenced by early successional conditions
• Burned feather moss remains = ‘biological legacy’• ‘persisting living and dead structures’ left by disturbances
(Franklin et al. 2002)• Dry; elevate seeds and seedlings
• Previous studies indicate living moss carpets can enhance seed germination and seedling survival
• Moist; cover; moss-cyanobacteria associations might enhance seedling growth compared with open soil – N fixation
• Potential influence on understory and canopy spatial structure and composition
Assess the impact of:– BURNED MOSS– LIVING CARPETS OF EARLY SUCCESSIONAL MOSS
…on seed germination, and short-term survival and growth of seedlings of selected boreal tree species
BURNED MOSS - METHODS (SEEDLINGS)
• Seeds of Picea glauca and Larix laricina pre-germinated on moist filter paper in Petri plates.
• 10 germinants per species planted in 20 4-inch pots of burned moss, mineral soil or humus subsoil
• Pots in a growth chamber, watered every 3 days.
• Survival recorded periodically; mean dry weight and height after 97 days
Surviving Picea glauca and Larix laricina seedlings 92-97 days after sowing, as a proportion of seeds sown (N=150)
0.71
0.64
0.530.48
0.73
0.20
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
BURNED MINERAL SOIL SUB-SOIL BURNED MOSS
Substrate
Prop
ortio
n of
see
ds s
own
Picea glaucaLarix laricina
0.49
0.73
0.20
0.710.64
0.53
Surviving P. glauca and L. laricina seedlings 92-97 days after sowing, as a proportion of seeds sown (N=150)
Surviving Picea glauca and Larix laricina seedlings 23-28 days after sowing, as a proportion of seeds sown (N=150)
0.78 0.79
0.70
0.77
0.93
0.51
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
BURNED MINERAL SOIL SUB-SOIL BURNED MOSS
Substrate
Prop
ortio
n of
see
ds s
own
Picea glaucaLarix laricina
0.77
0.93
0.51
0.78 0.79
0.70
Surviving P. glauca and L. laricina seedlings 23-28 days after sowing, as a proportion of seeds sown (N=150)
SEEDLING SURVIVALBetween 28 and 97 days
after sowing:• For both species, survival
declined most on burned moss– L. laricina 51% to 20%– P. glauca 70% to 53%
At 97 days:• L. laricina survival lowest on
burned moss, highest on humus
• P. glauca survival lowest on burned moss, highest on mineral soil
126138124N =
Treatment
HumusMineral soilBurned moss
95%
CI l
og(W
t)
-2.0
-2.1
-2.2
-2.3
Picea glaucaa
ab
b
1489842N =
Treatment
HumusMineral soilBurned moss
95%
CI l
og(W
t)
-1.8
-1.9
-2.0
-2.1
-2.2
-2.3
-2.4
-2.5
Mea
n dr
y w
eigh
t (g)
(log
tran
sfor
med
dat
a)
Substrate
a
bb
Larix laricina
SEEDLING GROWTH
Mean dry weight• Both species: burned moss
significantly different from humus but not mineral soil (P<0.01)
Mean height• P. glauca - no significant
difference between substrates• L. laricina: burned moss
significantly different from humus but not mineral soil (P<0.01)
PRELIMINARY CONCLUSIONS
• Burned feather mosses are a poor substrate for survival of seedlings, esp. of L. laricina.– Conditions more amenable in growth
chamber?– NO SEEDLINGS on burned moss in field
trial!• Optimum growth of successful germinants will
not occur on burned moss • L. laricina likely to form minor component of
canopy in stands where burned moss had high cover
LIVE MOSS - METHODS
• Pilot study in field – low germination• Seeds of P. glauca, L. laricina and P. mariana
(black spruce) sown in trays on 3 treatments:– Moss present– Moss cleared– Open soil
• Controls sown on filter paper and Jiffy Pots©
• Germination and survival data collected weekly (ongoing)
Survival of Picea mariana seedlings as a proportion of seeds sown
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
7 14 21 28 35 42 49 56 63 70 77 84
Time since sowing (days)
Prop
ortio
n
Moss removedMoss presentOpen soilControl 2 (JP)
Survival of Larix laricina seedlings as a proportion of seeds sown
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
7 14 21 28 35 42 49 56 63 70 77 84
Time since sowing (days)
Prop
ortio
n
Moss removedMoss presentOpen soilControl 2 (JP)
Survival of L. laricina seedlings up to 84 days after sowing as a proportion of seeds sown
Survival of P. mariana seedlings up to 84 days after sowing as a proportion of seeds sown
Germination – All species• Very high on all treatments• Little difference between
treatments
Seedling survival• Little difference between
treatments for P. glauca• L. laricina – germination
highest but survival lowest on Open soil
• P. mariana – germination highest but survival lowest on Moss present
PRELIMINARY CONCLUSIONS
• Little difference between treatments– No effect on germination and survival?– Differences moderated in growth chamber?
• Effects on growth to be determined…• Mortality of L. laricina seedlings might be
lower in presence of early successional moss carpets?
• Mortality of P. mariana seedlings might be greater in moss patches?
ACKNOWLEDGEMENTS
• Dr. Mark Dale, Dr. J. F. Cahill, Dr. Dennis Gignac
• Chisholm-Dogrib Fire Research Initiative (Foothills Model Forest, Alberta), Alberta Conservation Association Grants for Biodiversity Research
• Alberta Sustainable Resource Development (Alberta Tree Improvement & Seed Centre)
• Devonian Botanic Garden• Steve Morse, Lindsay Elliot,
Alexandra Rutherford, Chris Drake, Jess Leatherdale, Rose Muto
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