Impacts of Different Environmental Forcings and Drought on Grassland Water and Carbon Fluxes

Abstract

Vegetation has profound impacts on the local and regional water and carbon cycles. Classifying different environments and analyzing the response to drought allows us to assess the impacts on the water and carbon fluxes. For classifying the different environments, self-organizing maps are utilized using different environmental forcing variables with a land-surface model, Noah-MP. Quantitative statistics and wavelets are used to evaluate the influence that different vegetation cover has on the local and regional responses and temporal dynamics on the water and carbon variables. The heterogeneous vegetation cover impacted the results from the self-organizing maps in demonstrating the local changes in the water and carbon fluxes induced by differences between the model. The wavelets demonstrated that the temporal dynamics of these land covers vary little and tend to have higher coherence with environments the vegetation tend to thrive in. The 2012 drought illustrated the response of the water and carbon fluxes with an extreme event case. During the drought year, a large reduction in precipitation, evapotranspiration, and net ecosystem exchange occurred. However, one year following the drought, a strong increase in evapotranspiration and net ecosystem exchange is shown. Two years after drought the water and carbon fluxes showed to return back to pre-drought conditions. This research increases our knowledge of water and carbon fluxes response to different classified environments and drought impact.