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Dr. John Stella Anna Harrison 19 th September 2011

Reciprocal Influences of Long-Term Beaver Occupancy on Landscape Factors and Forest Structure (Adirondack Mountains, NY ) . Dr. John Stella Anna Harrison 19 th September 2011. Question 1: What landscape factors maintain suitable habitat for beaver in the long-term?. Maintenance Cost.

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Dr. John Stella Anna Harrison 19 th September 2011

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  1. Reciprocal Influences of Long-Term Beaver Occupancy on Landscape Factors and Forest Structure (Adirondack Mountains, NY) Dr. John Stella Anna Harrison 19th September 2011

  2. Question 1: What landscape factors maintain suitable habitat for beaver in the long-term?

  3. Maintenance Cost Dam Volume Beaver Occupancy Duration Positive Number of Dams Negative Cross Valley Slope Resource Quality & Quantity Hardwood basal area Landscape Capacity Softwood basal area Down Valley Slope Forage Area Total basal area Pond Area Potential site influences on long-term occupancy Expected Relationships 3

  4. Huntington Wildlife Forest • 30-year beaver occupancy dataset • 14 sites stratified by occupancy rate: • Located on stream reach or wetland • Open-canopy wetlands • Evidence of dam • One active colony only • Sites are discrete land areas 4

  5. Forage Area Pond Area Dams and Dam Volume Upland Forest Vegetation 5-m wide belt transects Inventory of tree community Field Sampling 3 9 12 4 5

  6. Landscape Capacity 6

  7. Can calculate total beaver habitat area from pond area

  8. Resource quantity and quality 8

  9. Highly Significant Positive Negative Conceptual Model Summary:Strongest relationships with long-term occupancy Maintenance Cost Dam Volume Dam Volume Beaver Occupancy 30 year dataset Beaver Occupancy Number of Dams Resource Quality & Quantity Cross Valley Slope Cross Valley Slope Total basal area Landscape Capacity Hardwood basal area Hardwood basal area Hardwood basal area Down Valley Slope Down Valley Slope Forage Area Forage Area Forage Area Softwood basal area Pond Area Pond Area

  10. Question 2: How do forest impacts by beaver vary with distance from the pond?

  11. Variety of documented forage preferences Aspen, willow, cottonwood, and alder (Denny 1952) Preferred sizes: <10cm diameter (Pinkowski 1983, Haarberg & Rosell 2006 Raffel et al. 2009) Allows for multiple uses (Barnes and Mallik 1997) Increase selectivity with increased distance from pond (Raffel et al 2009) Known selection processes and beaver preferences Photo: Josh Cousins Josh Cousins

  12. Species selectivity by stem and basal area Selectivity = cut / cut + live (Gallant et al. 2004, Raffel 2009)

  13. Size selectivity along a gradient

  14. Multi-stemmed growth habit

  15. Large area + concentrated impact on forest communities

  16. Large area + concentrated impact on forest communities

  17. Potential landscape area impacted by beaver at HWF

  18. Broad landscape controls on beaver behavior Fine-scale foraging impacts of beaver Results in changes to forest composition and abiotic environment Extensive areas with intense foraging could alter forest composition Implications 3 9 12 4

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