Edwards, Adrienne , Koontz, Jason .
Disturbance-dependent glacial drift hill prairies in forest landscapes: is historical past or recent past more important in determining species composition?
GLACIAL drift hill prairies are isolated grassland habitats on south- to west-facing river bluffs in the Grand Prairie region of the central US. Embedded in a forest matrix, they are vulnerable to woody plant encroachment when not managed with appropriate disturbance. We surveyed the species composition of 21 glacial drift hill prairies to determine if habitat size and quality or proximity to like habitats was more important in determining species composition along a 20 mi stretch of the Illinois River. The prairies all were < 0.6 ha and ranged from high quality to severely degraded. Surprisingly, there was no correlation between size or quality of prairies and species diversity. Rather, there was significant spatial autocorrelation between hill prairie proximity and species composition, indicating that prairie openings found on the same bluff ridges were more likely to share a common propagule pool. The number of species in each prairie opening ranged from 42 – 92 (38-88 native species only), averaging 66 species (62 native only). The most common potential woody invaders were native forest species, (including Acer saccharum, Cercis canadensis, Cornus drummondii, Quercus alba, Q. prinoides and Q. velutina) reflecting the forest matrix in which these prairie openings are embedded. However, a few clonal, bird-dispersed shrubs were aggressive invaders when present (e.g., Cornus drummondii, Eleagnus pungens and Lonicera maackii). High quality remnant habitats are often targeted for protection individually, rather than in clusters of like habitat (regardless of quality) across landscapes. Given the dynamic nature of many habitat islands persisting in less hospitable matrices, it would be wiser to preserve clusters of habitats to allow for migration and extinction across landscapes.
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1 - Illinois Natural History Survey, 1816 S. Oak St., Champaign, Illinois, 61820-6970, USA
2 - Augustana College, Department of Biology, 639 38th Street, Rock Island, Illinois, 61201, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM