Methods to Estimate Natural Disturbance Regimes Lorimer and White (2003) <ul><li>Sedimentary pollen and charcoal </li></ul><ul><li>Presettlement land surveys </li></ul><ul><li>Descriptions by early naturalists </li></ul><ul><li>Reconstruction of disturbance history in old-growth stands </li></ul><ul><li>Modern records and aerial photos </li></ul><ul><li>Computer models </li></ul>
Large-scale fires infrequent in New England, ~800-1,200 years 1790 survey in NY found that 1% of landscape burned or open.
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.
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)
Approximate return interval of damaging (F2) hurricanes in New England. Boose et al. (2001) 85 yr 150 yr 380 yr >380 yr
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.
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)
Trani et al. (2001) Early-successional forests in the eastern U.S. 9% 4%
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
MANAGING INDUCED METAPOPULATIONS: may require deviating from HRNV ME NH VT NY MA CT RI
DESCRIBING HABITAT DISTURBANCES Size Frequency Intensity
Do natural disturbance regimes provide realistic guidelines for managing early-successional habitats in New England forests?