Pulse Regulation of Terrestrial Trace Gas Fluxes

A Department of Atmospheric and Oceanic Sciences Seminar featuring Dr. G. Darrel Jenerette, Associate Professor, Department of Botany & Plant Sciences, University of California Riverside

Wednesday, October 23, 2013
3:30 PM
MSB 7124

Abstract

Atmosphere-terrestrial exchanges of trace gasses are typically considered as continuous functions of moisture, temperature, and substrates.  However, new paradigms of pulse dynamics are developing that suggests ecosystem metabolism is discontinuous in its sensitivity to cycles of drying and rewetting.  These pulses of ecosystem metabolism have direct implications for atmospheric-terrestrial trace gas exchanges.  We have evaluated ecosystem pulses through combinations of whole ecosystem continuous observations, field and laboratory wetting experiments using manual chamber measurements, and field wetting experiments using continuous in-situ soil sensors directed towards understanding rates of terrestrial CO2 emission.  These studies have clarified a central feature of pulse-dynamics, the sequential limitation of multiple resources.  Wetting provides a trigger for activity, which is immediately followed by regulation through carbon substrate availability. Both the effects of the trigger and substrate availability are further influenced by temperature.  Recently we have begun extending this framework to measurements and models of nitrogen trace gasses, N2O and NOx and are finding strong support for pulse regulated nitrogen cycle dynamics.  These findings are allowing us to generate new algorithms to improve land surface models that emphasize discontinuous ecosystem responses to moisture variability – conditions that will likely increase in future climates.

SEMINAR at 3:30 PM
SEMINAR TEA:  4:30-5:00PM (MSB 7124B)