The Effect of Contrasting Wet and Dry Extreme Precipitation on Ecosystem Carbon Fluxes and Water Use Efficiency in the Southern Great Plains, United States

Abstract:

Climate extremes, such as heat waves and heavy precipitation, are more likely to occur with increased warming and simultaneously have profound influences on ecosystem fluxes. Existing studies have already investigated how a single extreme event affects ecosystem dynamics. However, how ecosystems respond to consecutive climate extremes is rarely examined. More heat waves are expected to cause more droughts, while more heavy precipitation could cause more floods. Both may have a negative effect on vegetation growth, although wetter conditions may alternatively stimulate growth. In the southern Great Plains the hydrological year of 2006 was the second-driest year on record, with only 61% of long-term annual precipitation. In contrast, the summer of 2007 was the second-wettest summer, with 121% of the normal annual precipitation. This “pair” provides a unique example to study alternatively contrasting climate extremes and their impacts on ecosystem dynamics. In this study, we aim to assess whether or not this consecutive drought and flood has altered the sensitivity of ecosystem carbon fluxes and water use efficiency. To investigate this question, we parameterized a newly developed process-based terrestrial ecosystem model (TEM-Hydro daily version) and applied the Maurer’s 1/8 degree daily climate datasets. The modeled results are compared against the MODIS datasets and Ameriflux Eddy Covariance observations to determine the mechanism responsible for understanding how extremes in precipitation affect ecosystem functions. The significance of the consecutive climate extremes on ecosystem structures and processes in the southern Great Plains will be discussed.