Document: DIA-3-64-2

Changes in nitrogen cycling across a 25-year chronosequence of tallgrass prairie restoration sites.

LANE, D.R.* and H.BASSIRIRAD

University of Illinois at Chicago, Chicago, IL 60607 USA ¹

Abstract:
Restoration of tallgrass prairie on land previously used for agriculture is occurring across the Midwestern United States. Little is known, however, about the effect of prairie restoration on important belowground processes. We took advantage of a unique 25-year chronosequence of prairie restoration sites at FermiLab outside of Chicago, IL to examine changes in nutrient cycling over time. We measured nitrogen availability and total nitrogen in the soil, and foliar nitrogen concentration of two dominant species, at restoration plots ranging in age from 2 to 25 years old. Both available and total soil nitrogen increased significantly with increasing restoration age. Available nitrogen doubled from the youngest to the oldest restoration plot, while total nitrogen increased by 85%. The ratio of available to total nitrogen was highest at the intermediate aged plots (6 and 14 years old). Despite the significant increase in soil nitrogen with increasing restoration age, tissue nitrogen in green and senesced foliage of Andropogon gerardii remained unchanged. For the perennial forb Solidago canadensis, foliar nitrogen concentration was significantly higher at the 14 year old plot compared to the youngest and oldest plots. These preliminary results suggest that organic nitrogen accumulates in the soil as restoration proceeds, but nitrogen availability may decline. Ongoing research at FermiLab site will continue to improve our understanding of the mechanisms by which restoration affects ecosystem processes.

Keywords: Restoration, Tallgrass Prairie, Nitrogen Cycling

This abstract is being presented at: 3:30 PM in session:
Poster Session #15: Nutrient Cycling.