为选择胸径与缓冲区类竞争指数相关关系的最佳拟合函数,研究用4种简单的初等函数计算7块杉木样地的4种缓冲区类竞争指数.结果表明:幂函数形式能最好地反映胸径与4类竞争指数的关系；各样地的空间相关距不同,相关距大小随着样地的株数密度有所变化;缓冲区距离断面积比和缓冲区断面积比两个竞争指数优于缓冲区距离直径比和缓冲区直径比；在各杉木样地中,4种竞争指数与胸径的关系呈倒“J”型分布,随着4种缓冲区类竞争指数值的增大,胸径逐渐变小,说明随着竞争压力的增大,杉木个体胸径生长受到抑制.%Four kinds of buffer competition indices in seven Chinese fir plots were fitted with four simple functions to choose the best fitting function. Result showed that the power function could best reflect the scatter relationship between four kinds of competition indices and Diameter at Breast Height (DBH). The spatial correlation was different in those seven plots, and the sizes varied with the tree density of different plots. The buffer distance basal area ratio and buffer basal area ratio were superior to the buffer diameter ratio and buffer distance diameter ratio. For those seven plots, the four kinds of competition indices and DBH exhibited an inverted J-shaped relationship. The DBH decreased gradually with increasing competitive indices , indicating that the DBH growth of Chinese fir individual trees was inhibited as the competitive pressures increased.
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