青杄林恢复演替过程中的邻体竞争效应及邻体干扰指数的改进模型

ON NEIGHBOURHOOD EFFECTS IN A SUCCESSIONAL COMMUNITY AND AN IMPROVED INDEX OF NEIGHBOURHOOD INTERFERENCE

本文研究了青杄(Picea wilsonii)个体生长速度与其邻体效应之间的相互关系。结果表明乔木演替初期种山杨、白桦以及青杄自身对青杄生长的影响均为竞争关系。由以基株为中心、两米为半径圆内所有个体所测得的邻体干扰可以解释青杄生长速度变异的百分之三十以上。在本文中,我们还改进了邻体干扰指数,提出应该考虑基株自身的个体大小,由改进的指数模型能够解释青杄生长速度变异的百分之四十五左左。因此可以说改进指数要优于原先的指数。根据本文所得的结果,我们可以断定青杄林恢复演替的动力是优势植物种间的竞争。

This paper deals with the relationship between the growth rate of Picea wilsonii and neighbourhood interference.The significant correlation between Picea individual growth rate and the indices of local interference demonstrates that interference occurs and that the pioneer tree species, Populus davidiana, Betula plat-yphylla,and Picea wi/sonii itself are competitively related with the growth of Picea wilsonii individuals. We are able to account for more than 30% of the variation in plant growth rate of Picea wilsonii as a polynomial function of the size, distance and number of their neighbours within 2 meters.In this study, we have improved the index of neighbourhood interference as follows :where S is the size of subject individual; Si is the size of i-th neighbour; di is the distance to the i-th neighbour; N is the number of neighbours. The improved index can account for 45% of the variation in the growth rate of Picea wilsonii .Since interference occurs and the climax species may establish itself synchronously with the pioneer tree species, it can be reasonably concluded that the main driving force of recovery succession of Picea wilscnii is an interspecies competition among the dominant tree species.