97th ESA Annual Meeting (August 5 -- 10, 2012)

COS 177-6 - Testing simple new conductance models that are derived from a process model and can be parameterised by gas exchange

Friday, August 10, 2012: 9:50 AM
F150, Oregon Convention Center

ABSTRACT WITHDRAWN

Thomas N. Buckley1, Tarryn L. Turnbull2 and Mark A. Adams2, (1)Faculty of Agriculture and Environment, University of Sydney, Narrabri, NSW, Australia, (2)Centre for Carbon Water and Food, University of Sydney, Sydney, Australia
Thomas N. Buckley, University of Sydney; Tarryn L. Turnbull, University of Sydney; Mark A. Adams, University of Sydney

Background/Question/Methods

Representation of stomatal physiology in models of plant-atmosphere gas exchange is minimal, and direct application of process-based models is limited by difficulty of parameter estimation.  We derived simple models of stomatal conductance from a recent process-based model, and cross-validated them against measurements of sap flux in mature and post-fire regrowth stands of Eucalyptus delegatensis and E. pauciflorain the mountains of southeastern Australia. 

Results/Conclusions

The derived models – which are driven by irradiance and evaporative demand and have 2-4 parameters that represent sums and products of biophysical parameters in the process model – reproduced a median 83-89% of observed variance in half-hourly and diurnally averaged sap flux, and performed similarly whether fitted using a random sample of all data or using one month of data from spring or autumn.  Our simple models are an advance in predicting plant water use because their parameters – which can be estimated by gas exchange – are transparently related to reduced processes and properties, enabling easy accommodation of improved knowledge about how those parameters respond to environmental change and differ among species.