Modeling the relationship between the asymmetry in crown display and local environment

Abstract

The asymmetry in crown display was modeled with respect to neighbors and microtopography. The direction and magnitude of the asymmetry were expressed by the ‘crown-vector’, the horizontal two-dimensional vector that joins the stem base position of a focal tree with the centroid of its projected crown area. In the model, the crown-vector of a focal tree was a function of the position and size of its neighbors and the direction and inclination of the slope on which it occurred. Using the model, the effect of repelling behavior of crowns on the spatial pattern of crowns was quantified; spatial patterns of crowns were more regular than those of stem bases. The effects of parameters in the model on the spatial pattern of population were also quantified. The model was applied to the data derived from two study plots: one in cool temperate deciduous broad-leaved forest in northern Japan and the other in warm temperate evergreen broad-leaved forest in central Japan. The least-squares fit of the model accounted for 56% and 73% of the total variance in crown-vector for the two study plots, respectively.