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Published byDiego McFadden Modified over 11 years ago
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Do natural disturbance regimes provide realistic guidelines for managing early-successional habitats in New England forests?
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Major forest types in northern U.S. Lull (1968)
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~ 1880
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~ 1930 >50% of forest vertebrates utilize early-successional stands
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Obligate users RELATIVE USE 0 1.0 102030405060708090100 AGE OF STAND 0.5
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Golden-winged warbler USGS
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FOREST CLEARING FARM ABANDONMENT FOREST MATURATION Relative abundance of early-successional habitats RETURN TO PRE-COLUMBIAN CONDITIONS ?
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How much was there?
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source: Harvard Forest
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Methods to Estimate Natural Disturbance Regimes Lorimer and White (2003) Sedimentary pollen and charcoal Presettlement land surveys Descriptions by early naturalists Reconstruction of disturbance history in old-growth stands Modern records and aerial photos Computer models
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Large-scale fires infrequent in New England, ~800-1,200 years 1790 survey in NY found that 1% of landscape burned or open.
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Small-scale wind storms: kill one to several trees. In eastern U. S., 0.2- 2%/year of all forests are affected by wind throw. At any time, 5-50% of a forest may be affected.
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Large-scale wind storms: hurricanes or tornadoes at irregular intervals (1635, 1788, 1815, 1938, and 1944). 1938 hurricane affected >240,000 ha in New England Boose et al. (2001)
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85 yr 150 yr 380 yr >380 yr Approximate return interval of damaging (F2) hurricanes in New England. Boose et al. (2001)
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Wilson 2005 Lumber Exports (Wilson 2005) vs Witness Trees Projections (Lorimer 1977): very different estimates of the prominence of white pine (>10x), indicating a large difference in the frequency and scale of disturbance in these forests.
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Northern Hardwoods seedling/sapling (1-15 yrs): 1-3% young pole (15-30 yrs): 1-3% 2-6% Pitch Pine- Scrub Oak seedling/sapling: 10-30% young pole: 10-30% 20-60% (Lorimer and White 2003)
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Trani et al. (2001) 9% 4% Early-successional forests in the eastern U.S.
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What About Biotic Disturbances?
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Contemporary Herbivores
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flooded forest pond wet meadow shrubs forest
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Open water areas created by beaver dams on the Kabetogama Peninsula, northern MN. 1940: 1% of area 1986: 13% of area Johnston and Naiman (1990) How large an area affected?
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Northern Hardwoods seedling/sapling 1-3% young pole 1-3% beaver flowages ~3.5% (Gotie and Jenks 1982) 5-11% (Lorimer and White 2003)
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Even if we can accurately estimate HRNV, are these values relevant in contemporary landscapes?
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40/mi 2 1100/mi 2 POPULATION DENSITY
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Hoving (2001) Road Density in the Northeast
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0 20 40 60 80 100 COMPOSITION (%) 0 20 40 60 80 100 120 140 RACCOON/CANID TRACKS CANIDS RACCOONS LANDSCAPE FOR DEV AGR
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2.5 ha 5 ha Winter mortality: 69%35% Patches
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OCTNOVDECJANFEBMARAPRMAY FOOD QUALITY LARGE PATCHES SMALL PATCHES THRESHOLD? CONDITION-SENSITIVE PREDATION
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9 JAN 16 JAN23 JAN 30 JAN 6 FEB 13 FEB20 FEB27 FEB 6 MAR 13 MAR 20 MAR27 MAR 3 APR 10 APR 0 2 4 6 8 10 12 UN:C RATIO 4 3 3 3 4 5 6 3 2 5 13 11 13 12 6 2 9 7 7 8 5 5 5 8 5 4 4
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New approaches needed to provide habitat
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Parcelization or Fragmentation potential to mimic natural disturbances restoration of shrublands/ modified disturbance regime (sliding scale) modified disturbances (large and clustered/connected) limited extreme Forest Age young old
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MANAGING INDUCED METAPOPULATIONS: may require deviating from HRNV ME NH VT NY MA CT RI
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DESCRIBING HABITAT DISTURBANCES SizeFrequencyIntensity
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Do natural disturbance regimes provide realistic guidelines for managing early-successional habitats in New England forests?
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Human-generated disturbances
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Pisgah Forest in southwestern New Hampshire three years after 1938 hurricane.
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