Tuesday, 18 November 2003: 3:30 PM
Vegetation responses to fire created edges in a Douglas-fir/hardwood forest
We investigated the vegetation responses at forest edges next to high-severity burned patches of Douglas-fir/hardwood forests in the Klamath Mountains, California. Edges adjacent to salvage logged and unsalvaged forest patches were compared fourteen years after a wildfire. Fire has strongly influenced development patterns of forests in this area. A frequent, low- to moderate-severity fire regime created a mosaic of species and age classes across the landscape, with considerable patchiness and forest edge. Species richness and Shannon-Wiener diversity decreased toward the forest interior for both salvaged and unsalvaged transects. Shrub, forb, and graminoid cover increased near the burned patches of both unsalvaged and salvaged sites. Shrub cover was greater on unsalvaged sites compared to salvaged sites, whereas forb and tree cover were greater near edges of salvaged sites. A depth of edge influence was determined for common species that exhibited a preference for the edge or forest interior. Depth of edge influence (0 - 60m) was comparable to studies conducted in other forest types. Most species reacted similarly along both the salvage logged and unsalvaged transects, but edge influence was generally 15-30 m deeper into the forest interior adjacent to salvaged patches. An analysis of species composition, classified by two-way indicator species analysis (TWINSPAN), showed similar results. Only two common species showed a significant reduction in abundance near burned patches. Our results suggest that species are adapted to the historic patchiness of the landscape, but that salvage logging increases the depth of edge influence in forests adjacent to burned patches.