Scale-dependent diversity partitioning of managed grasslands.
Questad, Erin*,1, Foster, Bryan1, Jog, Suneeti1, Kindscher, Kelly1, 1 University of Kansas, Lawrence, KS
ABSTRACT- Agricultural management and habitat fragmentation have altered grassland ecosystems by changing disturbance regimes, eliminating native species, and introducing exotic species. We wanted to better understand how management affects plant diversity at a range of spatial scales. We surveyed 104 managed grasslands in northeastern Kansas and recorded plant community data at three spatial scales within each site (1 m, 10 m, and 20 m). Each site was classified into one of five management categories: native hay, native grazed, exotic hay, exotic grazed, and conservation reserve program (CRP). We examined species richness (-diversity) and community similarity (-diversity) within each site. The scale of measurement and management significantly affected - and -diversity with a significant scale*management interaction. This interaction indicates that native sites have proportionally higher -diversity than non-native sites at small scales. Native sites also have higher -diversity than non-native sites at small scales, but have low -diversity at large scales. We also analyzed community similarity among sites in the same management category and found low similarity among exotic sites, moderate similarity among CRP sites, and high similarity among native sites. Our results suggest that the change in species composition associated with grassland management is due to an overall reduction in native diversity and changes in community heterogeneity associated with exotic species. The effect of management on community structure also appears to be more predictable among native sites, further suggesting that community trajectories are similar when species pools contain many locally-adapted, native species.
Key words: biodiversity, species pool, disturbance, heterogeneity
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