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.

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

5. Individual species important for ecosystem function
M. Vieira
www.stevesforums.com
A. Syred

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

11. Canopy structure after treatments
Treatment (retention level)
100% (control) 40% 15%

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/