Sampling to Estimate Mean Leaf Temperatures and Transpiration Rates in Vegetation Canopies
1971
Miller, P. C. (Philip C.)
The measurement of leaf temperatures at different levels in the canopy is important for clarifying the relative contributions of each level to the energy balance, evapotranspiration, and primary production of the total canopy. Frequently mean leaf temperatures at each level will be adequate for the study. Since individual leaf temperatures vary at each level, more than one leaf temperature must be measured to estimate mean leaf temperature. A procedure is outlined for deciding the number of leaves at each level required to estimate the mean leaf temperature within specified accuracies. The procedure involves first calculating expected in sunlit leaf temperatures due to differing orientation to the sun and leaf resistance, sunlit leaf temperatures with the energy—budget equation, then estimating the variation to be solving for the number of sunlit leaves to be measured, and finally, calculating the total number of leaves to be measured at each level in order to have an adequate sample of both sunlit and shaded leaves. The number of leaves calculated by this procedure should be considered the minimum number of leaves to be measured because of other causes of variation in leaf temperatures.
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