黑河上游天老池流域青海云杉树冠分形维数时空变化特征

Temporal and spatial variation characteristics of fractal dimensions of Qinghai spruce canopy in Tianlaochi catchment in the upper reaches of Heihe River

以青海云杉为研究对象,选取不同海拔相同径级、相同海拔不同径级的树木对其树冠的分形维数进行计算,以叶面积指数为参数估算树冠分形维数,揭示青海云杉树冠分形维数的时空变化特征.结果显示:相同径级,高、中、低3个海拔梯度上树冠的分形维数分别为1.81、1.88、0.95,生长在中等海拔地区的青海云杉具有最高的树冠分形维数;相同海拔4个径级梯度5~10、10~20、20~35、35~45 cm的树冠分形维数分别为1.81、0.76、1.68、1.50.随着径级的增大,树冠的分形维数呈减小趋势(10~20 cm例外),2014年青海云杉树冠分形维数相比2013年是增加的.

In order to reveal the temporal and spatial variation characteristics of fractal dimensions about Qinghai spruce （Picea crassifolia）, different altitude gradients and the same sampled trees with different diameters, the same altitude gradients and different sampled trees with different diameters were selected, their fractal dimensions of canopy were calculated. Leaf area indexes （LAI） of the species were measured. The fractal dimensions of canopy were calculated by LAI. The results showed that the fractal di- mensions were 1.81, 1.88 and 0.95 on the high, middle, low altitude, respectively, meaning that the frac tal dimensions of the middle elevation were the highest. At the same altitude, the fractal dimensions in four diameter classes, i.e., 5-10, 10-20, 20-35 and 35-45 cm, were 1.81, 0.76, 1.68 and 1.50, respectively, expressing a decrease of the fractal dimensions with the increase of dimeter at breast height, with 10- 20 cm being an exception. The fractal dimensions of Qinghai spruce in 2014 increased than that in 2013.