7.3 Timing of extreme weather events impacts annual carbon and water dynamics in a grassland ecosystem

Thursday, 31 May 2012: 4:15 PM
Alcott Room (Omni Parker House)
Nathaniel A. Brunsell, University of Kansas, Lawrence, KS; and T. Ocheltree and J. B. Nippert

Extreme weather events have profound impacts on water and carbon cycling. However, events of similar magnitude may have very different impacts depending upon the timing of the event in the phenological cycle. We assess these impacts of extreme daily weather events including precipitation, maximum and minimum temperature using data collected from the Konza Prairie Long Term Ecological Research site in the central U.S. We utilize the long term weather and biomass collection data at the LTER site to examine the historical variability of extreme events and the impacts on annual carbon dynamics. We quantify the impacts of the timing and magnitude of extreme events through a Critical Climate Period (CCP) analysis. Results indicate a strong sensitivity to spring precipitation and summer temperature. Using six years of eddy covariance data, we can isolate more of the biophysical mechanisms governing the responses to extreme weather events. Of particular interest is the heat wave of July, 2011, where daily maximum temperatures were over 38 C for 24 consecutive days and resulted in drastically reduced above ground carbon allocation than in previous years. In addition, we employ the Agro-BGC model to assess the biophysical processes responsible for determining the response of water and carbon dynamics to extreme weather events. Developing a more thorough understanding of extreme events and the differential responses due to the timing and magnitude of the events will potentially assist in the mitigation of future climate change.
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