天山云杉天然林群落空间结构异质性分析

为了解天山云杉(Picea schrenkiana var. tianschanica)天然林群落空间结构的变异规律,沿天山山脉由西至东选择5个地点(昭苏、新源、呼图壁、天池、奇台),在每一地点沿海拔布设样带进行天山云杉群落调查,样带海拔区间为1700~2900 m。利用角尺度、大小比数分析其群落空间结构特征。结果表明: (1) 5个样带天山云杉角尺度平均值为0.545,群落呈团状分布格局;大小比数平均值为0.490,群落内林木的生长状态介于亚优势与优势之间。(2) 不同海拔高度天山云杉角尺度的变化显示随海拔高度的增加该群落呈现聚集分布-随机分布-聚集分布-随机分布的交替变化规律;大小比数随海拔高度的变化显示群落中天山云杉林木生长分化特征随海拔的增加呈现出亚优势-中庸-亚优势-劣势的规律。(3) 5个地点天山云杉角尺度平均值随着经度的变化较小,各地点均呈明显的整体团状分布;而林木大小分化由西至东表现为中庸木-亚优势木-中庸木的转变特征。

Spatial Pattern Heterogeneity of Picea schrenkiana var. tianschanica Natural Forest in the Tianshan Mountains,Northwest China

To understand the law of spatial pattern heterogeneity in a Picea schrenkiana var. tianschanica natural forest,five sample plot positions were selected from west to east in the Tianshan Mountains (Zhaosu,Xinyuan,Hutubi,Tianchi,and Qitai) where elevation ranged from 1700 m to 2900 m.Some structure parameters such as uniform angle index and neighborhood comparison were used to analyze the spatial structure characteristics of the P. schrenkiana natural forest.Results showed that,the mean value of the uniform angle index was 0.545 for the P. schrenkiana natural forest in the five sample plots,which indicated reunion distribution for the P. schrenkiana natural forest.The mean value of neighborhood comparison was 0.490,which means that the growth state of the P. schrenkiana natural forest was between sub-dominant and moderate.Uniform angle index changed with the variation in elevation for the five sample plots,suggesting the distribution of P. schrenkiana natural forest exhibited alternating changes from aggregate to random,to aggregate,to random.The variation of neighborhood comparison indicated that the growth state of the P. schrenkiana natural forest changed from sub-dominant to moderate to sub-dominant to poor.Changes in the mean values of the uniform angle indexwere not significant within five sample plots,which showed reunion growth distribution of P. schrenkiana natural forest.But the variation of the mean value of neighborhood comparison had significant changes from moderate to sub-dominant state to moderate within the five sample plots form west to east in the Tianshan Mountains.