2011 Research Highlights
The Importance of Hydraulic Lift in Maintaining Carbon Assimilation During Drought
Better understanding of carbon-water interactions will lead to improved predictions of ecosystem processes in a changing climate
Scientists with EFETAC have made significant contributions toward and are US leaders of research into carbon-water interactions and their influence on ecosystem processes. Finding from two publications (Domec and others 2010; Noormets and others 2010) were recognized as two of the top ten major developments of the year at the 2011 Annual Ameriflux meeting by Bev Law, Ameriflux Science Chair. Domec and others (2010) quantified the effects of hydraulic lift in forest ecosystems and was recognized as a major scientific advancement in the Forum section of New Phytologist (Katul and Siqueira 2010). While the phenomenon of hydraulic lift is known to contribute to plant water status in dry environments, Center researchers’ findings were the first to (1) demonstrate that it can also play a major role in wet environments in high evaporative demand situations and (2) make a quantitative connection between the additional water obtained due to hydraulic lift and the amount of assimilation that can be maintained due to the available water. Based on scientists’ knowledge, this is the first time that such a link is defined in quantitative terms, and it has major implications for forecasting ecosystem processes under changing climate conditions. Noormets and others (2010) demonstrated that the decline in assimilation efficiency at the canopy level under drought conditions was attributable primarily to declines in hydraulic conductance, and only secondarily to decreased stomatal conductance. In addition, the study found that contrary to expectations, the respiratory costs of primary production decreased during drought conditions.
Contact: Michael Gavazzi, biological scientist, michael.gavazzi@usda.gov
