森林群落波动的探讨

Fluctuation of forest community.

植物群落的波动是森林动态的一种表现形式,是指由于群落中复合生态因子逐年逐季的不同,引起群落在固有的季节性和逐年性变化上的差异。波动不改变群落的总体物种组成结构和群落性质。植物群落的波动具有可逆性和方向性。正向波动促使群落具更优化结构,负向波动则反之。本文组建了测度植物群落波动强度的公式:并将森林群落波动的基本类型分为树木生长速度的波动、结实率以及幼苗多度的波动、叶量的波动和植物季节性发育周期的波动4种类型。

The fluctuation of plant community means the seasonal or annual fluctuation of plant commumty but not of its characters caused by the seasonal or annual changes of ecological factors. The fluctuation possesses reversibility and direction. Positive fluctuation makes community advantageous, and negative one disadvantageous. The measuring formula of fluctuation intensity is built as follows: FI=(n-sum from i=1 to s((n_i/s)-A))/sum from i=1 to s((n,/s)), When FI is positive, it means the positeve fluctuation, and when FI is negative, it means the negative one. The fluctuation of forest community has the following main types: that of growth rate, of hearing fruit and seedling, of seasonal development and of community structure. The fluctuation deffers from that of grassland.