PARENT SESSION
Poster Session # 7: Restoration, Resource Management, and Conservation.
Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Effects of experimental nutrient manipulations on a restored grassland community.
Karel, Irene*,1, Smith, Val1, Foster, Bryan1, Brothers, Amanda2, Ramspott, Matthew1, Price, Kevin 1, 1 University of Kansas, Lawrence, KS, USA2 Kent State University, Kent, OH, USA
ABSTRACT- Tallgrass prairie was once widespread in North America, but human activity has reduced it to a small fraction of its former distribution. In recent years, the threatened status of tallgrass prairies has inspired an interest in the restoration of this habitat type. Here, we examine the effects of manipulation of nitrogen and phosphorus levels on the diversity and composition of restored prairie plant communities at the Nelson Environmental Studies Area (University of Kansas). Fifty-four separate 16m2 plots were sown with prairie species in 1996, and we applied two levels of nitrogen depletion, six levels of nitrogen enrichment, and a phosphorus enrichment treatment in a factorial design. The plots are burned each spring to discourage the invasion of woody species. In 2002, we found that species diversity increased significantly in response to nitrogen enrichment. Andropogon gerardii, a native C4 perennial grass, responded negatively to nitrogen addition, while Sorghastrum nutans was unaffected. Setaria faberii, an abundant non-native annual grass, increased significantly in response to nitrogen addition, while leguminous forbs decreased significantly. Seasonally integrated NDVI (Normalized Difference Vegetation Index) values derived from high-resolution spectral images of the site reveal a gradient of green biomass and growth activity between the different treatments. In summary, nitrogen addition affected overall species diversity, and has caused shifts in species composition away from native prairie species and towards weedy species.
Key words: prairie, restoration, nitrogen, Andropogon gerardii