I evaluated the effects of past and future forest management on habitat supply and probability of occurrence for Canada lynx ( Lynx canadensis) and American martens (Martes americana). I used timber harvest and forest composition information derived from Landsat satellite imagery to develop spatially-explicit time series of habitat for lynx and martens (1970-2007) across 1.62 million hectares of commercial forestland in Maine. Timber harvesting was widespread with 55% of the forestlands receiving a harvest 1970–2007, which ultimately resulted in the broad-scale loss of marten habitat (>435,000 ha) and the increase of lynx foraging habitat (∼189,000 ha). Rapid declines in habitat supply and probability of occurrence for martens occurred 1975-1991, as large blocks of spruce-fir forest were salvage logged in response to the 1973-1985 spruce budworm (Choristoneura fumiferana) outbreak. As regenerating forest created during this period began to reach 16 years post-harvest there was a rapid increase in lynx foraging habitat and the mean density of snowshoe hares (Lepus americanus) within potential lynx home ranges, 1985-2007. Probability of occurrence for lynx increased during this period in areas of increased hare density. Marten habitat continued to decline in the 1990s and 2000s, which coincided with shifts in timber harvesting patterns that resulted from new forest policies implemented in 1991.
To provide a better understanding of how past forest management legacy (1970–2007) will influence outcomes of future forest management, I developed alternative forest management scenarios to model the effects on habitat supply and population density for lynx and martens, 2007-2032, across 14 townships with diverse legacies. The worst scenario for future lynx and marten habitat was a continuation of recent (2001-2007) trends in harvest rates, including an aspatial limit (∼4% of total acreage harvested) on clearcut harvesting to mimic the effects of current forest policies in Maine. Removing the limit on clearcut harvesting provided some limited benefit to both species; under all harvest scenarios, however, habitat supply and densities for both species are expected to decline from current levels as a result of past forest management legacies. Conservation planning for these species needs to incorporate the anticipated loss of habitat supply in the future.
|Advisers||Daniel J. Harrison; William B. Krohn|
|School||THE UNIVERSITY OF MAINE|
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