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.
Forest management changes microclimate and bryophyte diversity in the Cascade Mountains of western Washington [Martin Dovciak]
1. Forest management changes
microclimate & bryophyte diversity
in the Cascade Mts. of western Washington
Martin Dovčiak, Charles B. Halpern, Shelley A. Evans, & Troy D. Heithecker
SUNY ESF, Univ. of Washington, USDA Forest Service
Photo by Rick Droker
2. Global changes in land use
Source: World Resources Institute / South Dakota State University, 2009
Intact Forest Landscapes
Working Forest Landscapes
Original forest cover
Current
3. Land use changes threaten biodiversity
Sala et al. (Science 287, 2000): Global Biodiversity Scenarios for the Year 2100
4. Biodiversity loss may affect ecosystem stability
Tilman et al. (Nature 441, 2006) Dovčiak & Halpern (Ecol. Lett. 13, 2010)
0.9
Mean population stability
Ecosystem stability (μ/σ)
0.6
0.3
5 10 15
Realized species number Mean Richness
6. 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
7. 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
8. 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
9. Study area – Cascade Mts., western Washington
3 sites
mid-elevations
(825-1280 m)
mature forests
(70-170 years)
Douglas-fir dominated
(Pseudotsuga menziesii)
Mt. St. Helens
Mt. Adams
10. Experimental design
3 sites (blocks) Treatment (retention level)
100% ( control) 40% 15%
3 treatments
Tree bases
Decaying logs (NE & SW)
4 microhabitats Forest floor
Total of 576 quadrats (20 × 50 cm)
16 quadrats per microhabitat and treatment unit
Sampled 8 years after canopy removal
12. Effects of canopy structure on microclimate
PPFD (mols m-2 day-1)
Basal area (m2ha-1)
Air temp. max. (ºC)
80 35
a
40 b b
c
ab
60 30
30 b a
40 b
20 a 25
20 c a
10 20
c
0
0
100 40 15 0 100 40 15 0 100 40 15 0
Canopy retention (%) Canopy retention (%)
Adapted from Heithecker & Halpern (For. Ecol. Manage. 226, 2006)
13. Richness of bryophytes
Decaying logs Tree bases Forest floor
No. of spp. per quadrat
6 6 6
a P < 0.0001 P < 0.0001 a b cn.s.
5 5 5
4 b 4 4
a
3 c 3 b 3
2 2 c 2
1 1 1
0 0 0
100
1 40
3 15
5 100
1 40
3 15
5 100
1 40
3 15
5
Canopy retention (%) Canopy retention (%) Canopy retention (%)
14. Abundance of bryophytes
Decaying logs Tree bases Forest floor
50 a P < 0.0001 P < 0.0001 a b P <c
0.01
40
Cover (%)
30
a
20
b a
ab
b
10 b
b
c
0
100
1 40
3 15
5 100
1 40
3 15
5 100
1 40
3 15
5
Canopy retention (%) Canopy retention (%) Canopy retention (%)
15. Response of liverworts vs. mosses
Liverworts Mosses
Less resilient to More resilient to
drought & heat stress drought & heat stress
Scapania bolanderi Hylocomium splendens
16. Proportion of liverworts in bryophyte community
Decaying logs Tree bases Forest floor
Liverworts (%)
30
P < 0.001 n.s. n.s.
20
a
10 b b
0
100
1 40
3 15
5 100
1 40
3 15
5 100
1 40
3 15
5
Canopy retention (%) Canopy retention (%) Canopy retention (%)
17. Aspect effects on tree bases on richness
Northeast Southwest
No. of spp. per quadrat
No. of spp. per quadrat
6 6
P < 0.02 P < 0.0001
5 5
4 4 a
a a
3 b 3
2 2 b
1 1 c
0 0
100
1 40
3 15
5 100
1 40
3 15
5
Canopy retention (%) Canopy retention (%)
Richness difference
Diff. in no. of spp.
4
(NE minus SW)
P < 0.0001
3
b b
2
1
a
0
100
1 40
3 15
5
Canopy retention (%)
18. 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
19. 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
20. Acknowledgements
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 Rick Droker
Web site: http://www.fs.fed.us/pnw/rmp/demo/