Maintaining Critical Habitat in a Heavily Managed Landscape: Effects of Power Line Corridor Management on Karner Blue Butterfly (Lycaeides melissa samuelis) Habitat

摘要

The Karner blue butterfly (KBB) (Lycaeides melissa samuelis), a federally listed species, has historically been a component of barren and savannah ecosystems in the northeastern and midwestern United States. In New York, it now occurs primarily on managed, early-successional sites such as power line corridors (utility rights-of-way) from Albany to Glens Falls. Blue lupine (Lupinus peren-nis), the exclusive larval food source of the KBB, has been suggested to be the most limiting factor for the butterfly within the eastern portion of its range. Power line corridor management maintains early-successional habitats by suppressing the regrowth of woody species, creating potentially important habitat for the conservation and restoration of the KBB complex. This research compared the effects of several vegetation-clearing methods on Blue lupine populations and associated communities of nectar species for KBB over an 8-year period. Methods evaluated differed in intensity (annual, 4-, or 8-year intervals) and type (herbicide or mechanical). Blue lupine and plant community responses did not significantly differ among the treatment types applied to the power line corridors. However, Blue lupine cover, clump size, and density of stems per clump increased following the application of treatments in general. The number and cover of nectar species, total herbaceous cover, and species richness also responded positively to treatment overall. The percentage of non-native species temporarily increased following treatment but declined to near pre-treatment levels again as woody cover increased. Temporal changes in plant community composition were not related to management methods. The management tools assessed, mowing and herbicide application, will accomplish the goal of halting or reversing succession, maintaining critical habitat for the KBB in a landscape that provides little other suitable habitat.