Management Strategies to Increase Structural Complexity and Enhance Biodiversity in Mixed Forests of Alaska, Japan, and central Europe Robert Deal, USFS, PNW Research Station, Portland, OR USA T. Yoshida, Uryu Experimental Forest, Hokkaido, University, Japan M. Noguchi, Shikoku Research Center, FFPRI, Kochi, Japan Andrej Boncina, University of Ljubljana, Ljubljana, Slovenia Gabriel Duduman,, University of Suceava,, Romania
Overview Working Ho: Stands with greater complexity will have greater biodiversity then structurally simple stands. Few brief examples from Japan and Europe. Focus on two case studies from southeast Alaska. Potential solutions for management of both oldgrowth and younger forests. Synthesis of research.
Uniform, single-species plantation in Black forest
Multi-layered mixed species stands in Slovenia
Simple, uniform single-species plantation
Selectively harvested older stand in Scotland
Even-aged Hinoki plantations in Japan
Two storied Hinoki stands, Honshu, Japan
40 year old hemlock-spruce stand in SE Alaska Stem exclusion Greatly reduced biodiversity
40-year-oldalder-conifer stands, SE Alaska
Uneven-aged forests of Sitka spruce and western hemlock
Stand structure of old-growth forests
Even-aged forests
Reproduction following clearcutting Natural regeneration Dense uniform stands
Stand Development Stem exclusion Greatly reduced biodiversity
Stand development Stem exclusion Greatly reduced biodiversity
Wildlife Implications
Partial Cutting?
Concerns with Partial Cutting Changes in tree species composition. Residual trees of poor quality, low vigor. Increased dwarf mistletoe in hemlock. Increased wounding of residual trees. Windthrow is common.
Four Major Areas of Research Stand Structure and Growth Conifer Regeneration Patterns of Mortality, Wounding and Disease Plant Community Response
50-Year Year-Old Even-Aged Stand 1,067 500 400 Hemlock Spruce Trees/ha 300 200 100 0 10 20 30 40 50 60 70 80 90 100 Diameter class (cm)
Trees/ha 100 50 High-Site Partially Cut Stands 50 years since cutting Deal, Heithecker, Zenner, 2010 Hemlock Other Spruce 0 10 20 30 40 50 60 70 80 90 100 Diameter class (cm)
Hemlock stand 76 years after cutting
Spruce stand 85 years after cutting
Effects of Partial Cutting on Stand Structure and Plant Communities Current stand structure and growth is dominated by residual trees left after cutting. Size structure of partial cut stands (>50 yrs) was similar to uncut old-growth forests. Plant diversity very high in partially cut stands and similar to uncut stands. No significant changes in plant community structures following partial cutting.
Possibility of using silvicultural systems based on partial cutting in southeast Alaska We did not detect large changes in tree species composition, greatly reduced stand growth, increased hemlock dwarf mistletoe infection, or higher incidence of tree wounding, decay and mortality with partial cuts. Stand structural diversity, plant species diversity and abundance were all much higher than in young-growth growth stands developing after clearcutting.
Stand Dynamics of Mixed Red Alder-Conifer Forests of Southeast Alaska Robert Deal 1 Paul Hennon 2, Ewa Orlikowska 2, David D Amore 2 Pacific Northwest Research Station USDA Forest Service Portland, OR Juneau, AK
Forest vegetation Effect of increasing proportions of alder Stand development Stand structure Tree size distribution
Forest vegetation Effect of increasing density of alder: Understory plant biomass. Wildlife habitat.
700 600 500 a) alder conifer Tree Density (Stems/ha) 400 300 200 100 0 500 400 300 200 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 6 5 7 0 7 5 8 0 Diam eter Class (cm ) b) alder conifer 100 0 2.5 7.5 12.5 17.5 22.5 27.5 32.5 37.5 42.5 Height Class (m )
180 160 140 120 100 80 60 40 20 0 Herbs Shrubs r2 =0.758 r2 =0.855 0 10 20 30 40 50 60 70 80 90 100 Percentage red alder Total net production (kg/ha)
Hanley et al, (CJFR, 2006) Deer days per hectare 140 120 100 80 60 40 20 0 Summer Winter r2 =0.864 r2 = 0.2 4 6 0 10 20 30 40 50 60 70 80 90 100 Percentage red alder
Summary and management implications Multiple food web components responding to red alder
Synthesis of Research Two potential solutions for increasing complexity, biodiversity. Partial cutting of older forests-focus on what stand structures are left, avoid high grading. In younger forests, encourage establishment of red alder and mixed broadleaf-conifer forests. Collaborative project in northern Japan, Alaska, PNW and central Europe