Edge effects on the tallgrass prairie plant community

Background/Question/Methods

Peripheral zones of fragmented forests have altered plant species composition due to climatic factors (e.g., solar radiation, wind) that are buffered within forest interiors.  However, less attention has been directed towards the effects of fragmentation on vegetative composition of native grasslands, specifically fragmentation by wooded hedge rows or blocks of forest.  We examined biomass and species composition of tallgrass prairie in relation to distance and directional aspect from wooded edges of prairie fragments in eastern Kansas.  Our measurements were taken three times through the growing season of 2011 at 14 sites.  We estimated aboveground biomass, species richness, and soil moisture every 2 m (range 2 - 20 m), from wooded edges.

Results/Conclusions

We found an index of biomass (vertical visual obstruction) to increase with distance from edges and, unexpectedly, to decrease over the growing season.  Species richness and soil moisture did not vary significantly with distance from wooded edges.  Biomass, species richness, and soil moisture did not vary significantly among aspects from wooded edges.  Our results must be qualified by the drought conditions during the growing season, which might have explained a seasonal decrease in the biomass index.  We found an apparent increase in prairie biomass with distance from edges, which might indicate a negative effect of wooded edges on primary productivity in tallgrass prairie.  Further research on this topic in years of average precipitation, and in other grasslands systems, would be productive.