Fragmented midwestern forests and songbird populations: where do we go from here?

摘要

The central hardwood forests of the midwestern United States range from extensively forested to highly fragmented. Forest fragmentation is a major conservation issue in the region and affects land-use planning and management (Thompson et al. 1996, Faaborg et al. 1998). Much recent research has addressed the effects of forest fragmentation on songbirds (see reviews by Faaborg et al. 1995, Robinson and Wilcove 1994), and the Midwest has some of the best-documented examples of the effects of fragmentation (Robinson et al 1995). High variability in the reproductive success of songbirds has hampered our understanding of factors affecting populations. The needs for better information on species status, mechanisms for fragmentation effects and the balance of source and sink habitat make it difficult to recommend specific mitigation measures, or to determine if mitigation measures are even necessary. The diverse and sometimes competing habitat needs of wildlife such as forest birds further complicate conservation planning. I compiled some statistics on the levels of fragmentation in the central hardwood region and used data on changes in land use to try and provide some temporal perspective on fragmentation. I reviewed the current state of our knowledgeon the effects of fragmentation on forest birds in the region and suggest conservation and research approaches for mitigating negative effects of fragmentation.