Photosynthetic radiation regime and canopy structure in modeled forest stands.

In modeling canopy structure, a statistical approach is applied to assign the location and orientation of plant parts; the radiation field is described in terms of random variables and their distributions. A comparison of horizontally homogeneous stands and grouped forest stands showed that grouping reduced interception of radiation and increased spatial variation. In conifers, the grouping of needles into shoots and the effect of penumbra had an important influence on the distribution of radiation on the needle area