Extension of the Optical Diffraction Analysis Technique for Estimating Forest Canopy Geometry.

Abstract

Optical diffraction analysis of in situ ground photographs has previously been used to estimate foliage angle distributions in grassland canopies. These canopies are typically characterized by a single component-leaves-and the foliage is highly linear in nature. In this paper, the diffraction technique is extended to a multicomponent forest canopy containing needles and branches. Additional convolution and coordinate transformations are used to estimate the branch and needle angle frequency distributions for top, middle, and base sections of two lodgepole pine (Pinus contorta) trees. The resulting distributions show that the branch inclination angles tend to increase as one proceeds to the tree tops. The needle inclination angle distribution was relatively constant for all layers, and it is believed that this distribution is characteristic of a large class of needle-bearing species.