Vertical Distribution of Leaf Area in Larix occidentalis : A Comparison of Two Estimation Methods

1989

6 Abb., 4 Lit. Ang.

Unselbständiges Werk

9716

200088375

Total leaf-area index and the vertical distribution of leaf-area index were described for an unthinned stand (density 11 250 stems/ha) and a thinned stand (density 1660 stems/ha) of 30-year-old Larix occidentalis Nutt. Two independent methods were used to estimate leaf-area index in each of two stands. The first method is based on allometric relationships that are applied to stem measurements, and the second method is based on gap-fraction analysis of fisheye photographs. Leaf-area index estimates obtained by the two method were nor significantly different. The gap-fraction method provides a desirable alternative because much less fieldwork is required, however, use of this method is limited to canopies where the light-blocking elements are randomly displayed. Total leaf-area index values for the unthinned and thinned stands were 50 and 3.6, respectively. The vertical distributin of leaf-area index in the unthinned stand resembled a normal distribution. The vertical distribution of leaf-area index in the thinned stand would have resembled a nomal distribution, except that thinning operations resulted in a truncated distribution of leaf-area index at the canopy base.