Estimation of seasonal change in leaf area index for a Chamaecyparis obtusa stand
2001
Utsugi, H. (Forestry and Forest Products Research Inst., Sapporo (Japan). Hokkaido Research Center) | Araki, M. | Kawasaki, T. | Ishizuka, M.
Many researchers have found that forest production correlates well with the radiation intercepted by the foliage. Therefore, it is important to estimate seasonal variations in foliage area in order to clarify the function of the canopy in the exchange of energy budgets throughout the year. In this study, we estimate the seasonal change in leaf area index (LAI) of a stand of Chamaecyparis obtusa, using a hemispherical photographic technique and a direct destructive sampling method. The dynamics of shoot and defoliation influences on the effective leaf area index (LAIef) are estimated from the hemispherical photographs. The relationship between LAIef and DOY (the day of the year) was approximated by a trigonometric function. The value of LAI was given by LAIef multiplied by the clumping factor. The seasonal change in penetration of global radiation through the canopy was calculated using a model that contained LAI and other canopy architectures as parameters. The calculation result was about 32% smaller than the measured data in each month, and the pattern of seasonal fluctuation agreed with the measured value.
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