The sensitivity of modeled evapotranspiration to rooting parameters during interstorm periods

Thursday, 18 December 2014
Gajan Sivandran1, Gil Bohrer2, Bryce Rizzo3 and David Soldaini2, (1)Ohio State University, Columbus, OH, United States, (2)Ohio State University Main Campus, Civil, Environmental & Geodetic Engineering, Columbus, OH, United States, (3)Ohio State University Main Campus, Columbus, OH, United States
The most recent series of climate change reports all predict changes in temperature accompanied by changes in precipitation characteristics. The most significant projected change in rainfall characteristics for the Midwest is increases in the length of dry spells on the order of 10-15%. The predicted trends in temperature and precipitation have raised questions about the nature of plant functional responses to changing thermal and water stress, especially given that the rate of projected change is unprecedented with respect to historical pressures on adaptation. However, insights may be gleaned from measured ecosystem response to extreme events from the historical record. The objective of this study was to elucidate the role of root distribution on the hydrodynamic response of vegetation to increasing length of dry spells in the Midwest. By combining soil moisture and eddy flux measurements we test the ability of Feddes- and Jarvis-type water use models to regulate the potential evapotranspiration response during periods of drydown as well as the sensitivity of these models to commonly used rooting parameterization.