Abstract:

Based on destructive measurements, box-counting dimensions of branching patterns and fractal dimension of the crown of Populus×xiaozhuanica were estimated. Branching orientation were uniform distribution and branching angle were normal distribution. Fractal dimensions of Populus×xiaozhuanica branching patterns were between 1.510～1.733. The highest correlation coefficients were found between biomass of organs and diameter-at-breast-height (DHB) and height using models W=a(D²_1.3H)^b. The two-surface method allows one to calculate fractal dimension from the regression of foliage area (mass) on the area (or volume) of the crown. Fractal dimensions of tree crown calculated by foliage mass and crown volume were 2.065～2.765. In defoliation period fractal dimensions of tree crown were 2.003～2.464, which were calculated by biomass of branch and crown volume. This paper investigated the relationship between the fractal dimension of crown and foliage mass and crown volume. The results show that when the foliage mass is small, fractal dimensions of tree crown increase significantly with the increase of foliage mass, this influence becomes weak until foliage mass increasing to a certain value. There is a certain foliage mass for each different volume to maintain its surface area, there also exists an optimum value, after which the fractal dimension will not change with the increase of foliage mass.

Key words: Populus×, xiaozhuanica, tree crown, fractal dimension, tree architecture, optimum structure