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Forest management changes microclimate and bryophyte diversity in the Cascade Mountains of western Washington. Presented by Martin Dovciak at the "Perth II: Global Change and the World's Mountains" conference in Perth, Scotland in September 2010.
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Martin Dovčiak, Charles B. Halpern, Shelley A. Evans, & Troy D. Heithecker
SUNY ESF, Univ. of Washington, USDA Forest Service
Forest management changes
microclimate & bryophyte diversity
in the Cascade Mts. of western Washington
Photo by Rick Droker
Working Forest Landscapes Original forest cover Current forest cover
Intact Forest Landscapes
Source: World Resources Institute / South Dakota State University, 2009
Global changes in land use
Land use changes threaten biodiversity
Sala et al. (Science 287, 2000): Global Biodiversity Scenarios for the Year 2100
Biodiversity loss may affect ecosystem stability
Tilman et al. (Nature 441, 2006)
E
co
syste
m sta
bili
ty (
μ/σ
)
Realized species number
Dovčiak & Halpern (Ecol. Lett. 13, 2010)
Me
an
po
pu
latio
n s
tab
ility
Mean Richness 5 10 15
0.3
0.6
0.9
A. Syred
Individual species important for ecosystem function
M. Vieira
www.stevesforums.com
Significance of forest trees for bryophytes
Forest canopy reduces solar radiation
and thus affects microclimate
temperature
moisture
Trees provide important microhabitats
Decaying logs Tree trunks Forest Floor
Forest management in Pacific Northwest
Policy: Northwest Forest Plan (NWFP) in 1994
No clear-cuts on federal lands
At least 15% of canopy trees retained in harvested areas
to mediate environmental changes due to harvest
Science: DEMO Study in 1994
(Demonstration of Ecosystem Management Options)
Examine effects of canopy removal on forest species Vascular plants
Bryophytes
Fungi
Birds
Small mammals
Insects
Study hypotheses
Bryophytes can be negatively affected by canopy removal
(Dovčiak et al. Can. J. For. Res. 36, 2006)
H-1. Bryophytes negatively affected on longer time scales
richness, abundance, and liverwort proportion
H-2. Bryophytes negatively affected in all microhabitats
forest floor, decayed logs, and tree bases (NE vs. SW)
H-3. Patterns of bryophyte decline are consistent with
microclimatic changes caused by canopy removal
Study area – Cascade Mts., western Washington
3 sites
mid-elevations (825-1280 m)
mature forests (70-170 years)
Douglas-fir dominated (Pseudotsuga menziesii)
Mt. Adams
Mt. St. Helens
40% 15% 100% ( control)
Treatment (retention level)
Experimental design
Total of 576 quadrats (20 × 50 cm) 16 quadrats per microhabitat and treatment unit
Sampled 8 years after canopy removal
3 treatments
4 microhabitats Forest floor
Decaying logs
Tree bases
(NE & SW)
3 sites (blocks)
40% 15%
Canopy structure after treatments
100% (control)
Treatment (retention level)
Effects of canopy structure on microclimate
Adapted from Heithecker & Halpern (For. Ecol. Manage. 226, 2006)
Canopy retention (%)
Ba
sa
l a
rea
(m
2h
a-1
)
0
40
80
20
60
100 40 15 0
a
b
c
c
25
35
20
30
Air te
mp
. m
ax. (º
C)
100 40 15 0
a
ab
b b
PP
FD
(m
ols
m-2
da
y-1
)
100 40 15 0
a
a
b
c
20
40
10
30
0
Canopy retention (%)
a b c
Forest floor
Canopy retention (%)1 3 5
0
1
2
3
4
5
6n.s.
100 40 15
Tree bases
Canopy retention (%)1 3 5
0
1
2
3
4
5
6
a
b
c
P < 0.0001
100 40 15
Richness of bryophytes
Decaying logs
Canopy retention (%)1 3 5
No
. o
f sp
p.
pe
r q
ua
dra
t
0
1
2
3
4
5
6a
b
c
P < 0.0001
100 40 15
a b c
Forest floor
Canopy retention (%)1 3 5
P < 0.01
a
ab
b
100 40 15
Tree bases
Canopy retention (%)1 3 5
a
bb
P < 0.0001
100 40 15
Decaying logs
Canopy retention (%)1 3 5
Cover
(%)
0
10
20
30
40
50 a
b
c
P < 0.0001
100 40 15
Abundance of bryophytes
Response of liverworts vs. mosses
Mosses
More resilient to
drought & heat stress
Liverworts
Less resilient to
drought & heat stress
Hylocomium splendens Scapania bolanderi
Forest floor
Canopy retention (%)1 3 5
n.s.
100 40 15
Tree bases
Canopy retention (%)1 3 5
n.s.
100 40 15
Decaying logs
Canopy retention (%)1 3 5
Liv
erw
ort
s (
%)
0
10
20
30
a
b b
P < 0.001
100 40 15
Proportion of liverworts in bryophyte community
Richness difference
Canopy retention (%)1 3 5
Diff. in
no
. o
f sp
p.
(N
E m
inu
s S
W)
0
1
2
3
4
a
b b
P < 0.0001
100 40 15
Aspect effects on tree bases on richness
Southwest
Canopy retention (%)1 3 5
No
. o
f sp
p. p
er
qu
ad
rat
0
1
2
3
4
5
6
a
b
c
P < 0.0001
100 40 15
Northeast
Canopy retention (%)1 3 5
No
. o
f sp
p. p
er
qu
ad
rat
0
1
2
3
4
5
6
a a
b
P < 0.02
100 40 15
Hypotheses revisited
H-1. Bryophytes negatively affected over longer time scales
Yes: even after 8 years after logging
H-2. Bryophytes negatively affected in all microhabitats
Yes: decayed logs > tree trunks > forest floor
Yes: SW > NE side of tree trunks
H-3. Patterns of bryophyte decline are consistent with
microclimatic changes caused by canopy removal
Yes: for differences among treatments
Yes: for differences among aspects of tree trunks
Conclusions & implications
Canopy retention under 40% does not preserve overall bryophyte diversity and abundance
Current management prescription to retain ≥ 15% of canopy is not sufficient
Global climate change (warming, droughts) is likely to exacerbate the effects of timber harvest
Photos by Rick Droker
Funding: USDA Forest Service and PNW Research Station
DEMO research partners:
USDA Forest Service Region 6
Pacific Northwest Research Station
University of Washington
Oregon State University
University of Oregon
Gifford Pinchot and Umpqua N.F.
Washington DNR
Web site: http://www.fs.fed.us/pnw/rmp/demo/
Acknowledgements
Rick Droker