Effects of Management and Edges on Prairie Spatial Ecology

Humans have converted most of the tallgrass prairie into agriculture, which has disrupted historical disturbance regimes and increased species losses caused by ecosystem fragmentation. Efforts to recover tallgrass and mixed grass prairies have included both (1) restoration by reintroducing natural disturbances like fire and grazing to remnants and (2) expanding prairie habitat through prairie reconstructions to mitigate the effects of fragmentation.;In the first of my two thesis research projects, I assessed the effects of two different methods of burning and grazing management (patch-burn-grazing (PBG) and uniform burning and grazing (UNI)) on the spatial heterogeneity of vegetation in an Oklahoma tallgrass prairie. I used biomass samples and multispectral imagery as parameters of vegetation heterogeneity. An analysis of variance (ANOVA) indicated that vegetation heterogeneity at the within-patch scale, measured at a 10m2 resolution, was not significantly different between PBG and UNI at P ≤ 0.05. Mean forb biomass was significantly different between patches at the whole-plot treatment level (PBG= 20.7g UNI= 12.0g).;My second research project assessed effects of edge locations on plant species composition and richness of adjacent remnant and reconstructed prairies at six tallgrass or mixed grass prairie sites. The central edge was the internal edge between the remnant prairie and the adjacent reconstructed prairie whereas the outer edge was the edge between the remnant or reconstructed prairie and the adjacent land or road external to the study area. Native and non-native species cover data were collected within a 1.0 m2 quadrat at 5 and 15 meters from each edge location (outer and center). I analyzed cover and richness data using a three-way ANOVA that examined interactions with edge location, distance from edge, and prairie type (remnant and reconstructed). Average native Species Richness (S), excluding native weedy generalists and tree species, was found to be significantly lower at the outer edge of reconstructions than in the center (Outer S = 6.1, Center S = 8.5).