ON USING ECOPHYSIOLOGICAL, MICROMETEOROLOGICAL AND BIOGEOCHEMICAL THEORY TO EVALUATE CARBON-DIOXIDE, WATER-VAPOR AND TRACE GAS FLUXES OVER VEGETATION - A PERSPECTIVE

How eco-physiological, biogeochemical and micrometeorological theory c an be used to compute biosphere-atmosphere, trace gas exchange rates i s discussed within the framework of a process model. The accuracy of t he theory is tested by comparing computations of mass and energy flux densities (water vapor, sensible heat, CO2 and ozone) against eddy cov ariance measurements over five distinct canopies (wheat, potato and so ybean crops and a temperate broad-leaved and a boreal conifer forest). Once tested, the theory is used to evaluate how interactions between climate and vegetation might influence leaf area and photosynthetic ca pacity and, in turn, alter energy balance partitioning and the transfe r rates of CO2 and other trace eases over vegetation canopies, Model p arameters, derived from biogeochemical and eco-physiological, principl es, enabled the model to estimate rates of mass and energy exchange wi th reasonable fidelity. In particular, the theory reproduced the magni tudes and distinct diurnal patterns associated with mass and energy fl uxes over a spectrum of vegetation types. Model sensitivity tests reve aled that variations in leaf area index and photosynthetic capacity in teracted to increase rates of evaporation and carbon dioxide and pollu tant uptake, greatly, and in a curvilinear manner. Finally, we conclud e that the assignment of many model parameters according to plant func tional type has much potential for use in global and regional scale ec osystem, climate and biogeochemistry models. Published by Elsevier Sci ence B.V.