7 research outputs found
Avian Use of Perennial Biomass Feedstocks as Post-Breeding and Migratory Stopover Habitat
Increased production of biomass crops in North America will require new agricultural land, intensify the cultivation of land already under production and introduce new types of biomass crops. Assessing the potential biodiversity impacts of novel agricultural systems is fundamental to the maintenance of biodiversity in agricultural landscapes, yet the consequences of expanded biomass production remain unclear. We evaluate the ability of two candidate second generation biomass feedstocks (switchgrass, Panicum virgatum, and mixed-grass prairie) not currently managed as crops to act as post-breeding and fall migratory stopover habitat for birds. In total, we detected 41 bird species, including grassland specialists and species of state and national conservation concern (e.g. Henslow's Sparrow, Ammodramus henslowii). Avian species richness was generally comparable in switchgrass and prairie and increased with patch size in both patch types. Grassland specialists were less abundant and less likely to occur in patches within highly forested landscapes and were more common and likely to occur in larger patches, indicating that this group is also area-sensitive outside of the breeding season. Variation in the biomass and richness of arthropod food within patches was generally unrelated to richness and abundance metrics. Total bird abundance and that of grassland specialists was higher in patches with greater vegetation structural heterogeneity. Collectively, we find that perennial biomass feedstocks have potential to provide post-breeding and migratory stopover habitat for birds, but that the placement and management of crops will be critical factors in determining their suitability for species of conservation concern. Industrialization of cellulosic bioenergy production that results in reduced crop structural heterogeneity is likely to dramatically reduce the suitability of perennial biomass crops for birds
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An evaluation of the use of the nature conservancy vegetation classification for mapping bird distribution at chincoteague national wildlife refuge
A study was conducted to evaluate the use of the 1995 Nature Conservancy vegetation classification (25 plant alliances recognised) for mapping bird distributions on Chincoteague National Wildlife Refuge, Virginia. 328 point counts were conducted in 10 plant alliances and, using goodness-of-fit tests, the hypothesis that bird species were randomly distributed among plant alliances was tested. Using cluster analysis, similarity in bird species composition among plant alliances was also tested. Of 56 bird species that were abundant enough for analysis, 53 were non-randomly distributed among plant alliances, and of these, 9 bird species selected only one plant alliance. Bird species composition was similar among the 3 tree-dominated plant alliances (Pinus taeda evergreen wetland forest alliance, P. taeda-Quercus nigra mixed evergreen-deciduous forest alliance and Pinus taeda evergreen woodland alliance), as well as among the 3 medium and short grass-dominated alliances (Spartina alterniflora, Ammophila breviligulata and Spartina patens). In contrast, both shrub-dominated alliances (Myrica cerifera and Baccharis halimifolia-Iva frutescens) and one grass-dominated alliance had bird species compositions that were very dissimilar to all other plant alliances. It is suggested that some bird species are habitat specific at the plant alliance level, however, the correspondence between bird species distributions and plant alliances depended partially on the plant alliance under consideration. It is concluded that the Nature Conservancy plant alliances are useful for mapping bird distributions, but that in areas in which the vegetation has not been classified, standard correlational approaches to analysing bird habitat relationships would be equally effective