Impact of Extreme Weather Events and Fire On Grassland NEP and Greenhouse Gas Fluxes.

Extreme weather events such as droughts result in large net losses of carbon from grassland systems, while above normal rainfall causes net increases ecosystem carbon levels. These responses to changes in precipitation have been observed using eddy covariance data and ecosystem model result for grassland systems. This paper will use DayCent model results from US Great Plains agroecosysem to show how extreme weather events have impacted net ecosystem production and trace gas fluxes during the last 150 years. The results show that extreme droughts( eg 1930's drought ) result in large losses of carbon, while above normal wet periods store carbon in the plant soil ecosystem. Model results suggest the net loss of carbon during droughts results from decreased amounts of live plant carbon, while increases during the wet periods are result of increased live plant biomass. Dry periods cause increases in soil carbon, while wet period cause decreases in soil carbon. This paper will also show the impact fire events on net carbon storage and trace gas fluxes in the tallgrass prairie.