Effects of Simulated Climate Conditions on Phosphorus Cycling in an Annual Grassland Ecosystem

Abstract:

The Jasper Ridge Global Change Experiment is a long-term study of the effects of simulated climate change conditions on an annual grassland ecosystem. The different treatments consist of elevated atmospheric CO₂ levels, enhanced nitrate deposition, as well as higher temperatures and precipitation rates. A representative portion of the above ground vegetation from each plot is harvested. The aim of this study is to investigate the effects of different climate conditions on the phosphorus content and phosphorus cycling in terrestrial plants. Since phosphorus only has one stable isotope, the δ¹⁸O signature in phosphate is used as a proxy to investigate phosphorus cycling. Although this technique has been successful in determining phosphorous cycling in aquatic systems, only a few studies have used this approach for terrestrial ecosystems. We analyzed the δ¹⁸O of the most abundant grass from each of the plots and treatments. The δ¹⁸O values of each sample are compared to elemental budgets of carbon, nitrogen, and phosphorous for correlation as well as soil enzyme activities. and the combination of measures are assessed as indicators for phosphorus limitation in each respective treatment site and provide a better understanding of phosphorus cycling in annual grasslands and the potential effects of climate change on phosphorus cycling.