F. De Castro et N. Fetcher, The effect of leaf clustering in the interception of light in vegetal canopies: theoretical considerations, ECOL MODEL, 116(2-3), 1999, pp. 125-134
The degree of aggregation or clumping of leaves was often considered to hav
e a significant effect on transmission of light by a plant canopy. We produ
ced simulated distributions of leaves, represented by small circles, with d
egrees of aggregation varying from random to a strongly clumped distributio
n. We calculated the interception of every leaf using different lines to re
present light beams, pointing from the origin to different directions: ever
y 5 degrees in azimuth and elevation. The percentage of lines not intercept
ing any leaf was considered as the transmittance of light. The simulations
considered two factors: leaf area index (LAI) (from 1 to 9) and degree of a
ggregation (from random to 100%). The results for a random distribution fit
the predictions of the negative exponential function. A degree of clumping
of 20% produced significant differences with respect to the predictions of
the negative exponential function. The relationship between relative varia
nce (rv) of the leaves' distribution and degree of clustering is largely in
dependent of LAI for values ranging from 3 to 7. We suggest that result cou
ld be used as a method to estimate the degree of clumping of real canopies,
through the analysis of hemispherical images. (C) 1999 Elsevier Science B.
V. All rights reserved.