Modeling the Effects of Ecosystem Fragmentation and Restoration: Management Models for Mobile Animals. Volume 2. Appendices 3-7

摘要

Throughout southwestern North America, efforts are under way to reduce the risk of large-scale, high intensity fires and improve forest health through the implementation of forest restoration, a process of timber harvesting and prescribed burns designed to return the ponderosa pine forest ecosystem to a state similar to that in which it existed prior to European settlement of the Southwest. Restoration treatments produce a novel type of habitat edge the edge between treated and untreated forest patches which has the potential to have profound effects on animal abundance in the post- restoration landscape. We studied the influence of the edge between ponderosa pine forest patches that had undergone restoration treatments and those that remained untreated on the abundance of seven passerine bird species. One species, the dark-eyed junco, showed an edge-exploiting response, occurring more frequently at the edge than in either neighboring habitat. Of the six remaining species, none changed in abundance near the structural edge in the treated forest, but four showed significant changes in abundance relative to the edge in the untreated forest. These responses did not conform to a simple null model based on birds integrating changes in habitat preference across the edge. On the other hand, the null model was correctly predicted the direction of all observed edge responses in the untreated habitat. Edge effects on bird abundance mirrored changes in microclimate across the edge. Like the avian responses observed in this study.