ENERGY BUDGET AND PHOTOSYNTHESIS OF CANOPY LEAVES.

PHOTOSYNTHESIS; PLANT canopies; ENERGY metabolism; SOLAR radiation; LEAF temperature; TROPICAL conditions

The relation between leaves (broad and needle leaves) in a canopy and parts of the soil-atmosphere environment is modeled and analyzed. The parameters examined are concerned with short and longwave radiation, reradiation, and latent and convectional heat fluxes at the leaf level. The resulting leaf energy budget is empirically linked to a generalized model of potential photosynthesis whose major inputs are solar radiation and leaf temperature. The predictions of the combined process-response system do not attempt to portray existing plants, but are used to infer the trend of the major forcing and response functions of leaves in general when exposed to a great variety of environmental conditions. Leaves in the topmost canopy exhibit the highest Bowen ratios and highest potential photosynthesis, whereas the opposite is the rule among interior leaves. During the growing season many middle latitude climate show higher potential productivity than moist, tropical climates. [ABSTRACT FROM AUTHOR]

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