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植物个体大小差异在植物种群中普遍存在,研究其与群落生产力及物种多样性的相关关系对天然次生林的生态抚育具有重要意义。本文在江苏省南京市溧水县林场选取7块有一定代表性的天然次生林样地作为研究对象,对群落中立木高度、立木径级的变异系数与地上生物量、物种多样性指数(Shannon指数)的相关关系进行了研究。结果发现:(1)立木高度的变异系数总体上小于立木胸径的变异系数,但其对群落地上生物量及群落物种多样性的影响总体上高于立木胸径差异性的影响;(2)郁闭度较低的松-阔混交林中林木个体大小的变异系数与群落地上生物量水平呈正相关,而在郁闭度较高的落叶阔叶林及杉-阔混交林中呈负相关;(3)立木个体大小的差异性与群落物种多样性指数均呈正相关,但在郁闭度相对较小的群落(松-阔混交林)中相关性较小。总体上,个体大小差异性的增加有利于增加群落的物种多样性,并对郁闭度较小群落的地上生物量水平有一定的促进作用。
Differences in plant size are common in plant populations. It is of great significance to study the relationship between plant size and community productivity and species diversity in ecological restoration of natural secondary forests. Seven representative natural secondary forest samples were selected from the forest farm of Lishui County, Nanjing City, Jiangsu Province to study the relationship between height of standing tree, coefficient of variation of stand diameter and aboveground biomass, species diversity index (Shannon index) The relationship between the research. The results showed that: (1) The coefficient of variation of stand height was generally smaller than that of stand diameter, but the effect on community aboveground biomass and community species diversity was generally higher than that of standing diameter; (2) The coefficient of variation (CV) of individual tree size in the coniferous and broad-leaved mixed forest was positively correlated with the aboveground biomass, but negatively correlated with the deciduous broad-leaved forest and the fir-broad mixed forest with higher canopy density. There was a positive correlation between individual size differences and community species diversity index, but the correlation was not significant among the communities with relatively low canopy density (Pinus densiflora and broad-leaved mixed forest). In general, the increase of individual size difference is conducive to increasing the species diversity of the community and promoting the aboveground biomass of the community with smaller canopy density.