祁连山青海云杉林动态监测样地更新苗和成树格局的空间变异

Spatial variation of regeneration patterns in a dynamic monitoring plot of Picea crassifolia forest in the Qilian mountains

【目的】研究青海云杉林更新苗和成树的两个重要参数密度和高度的空间异质性程度与变异尺度,并分析其空间分布格局及其与生态学过程之间的内在联系。【方法】利用国家级祁连山森林生态站已建立的340 m×300 m青海云杉林动态监测样地,进行更新苗和成树数量和高度的调查,采用经典统计学和地统计学方法研究密度和高度的空间变异特征。【结果】1)样地更新苗和成树密度的均值分别是5762和2016株·hm-2,对应的高度均值分别是0.30和8.79 m。更新苗密度和高度的变异属强变异,而成树密度和高度的变异属中等变异。2)样地更新苗和成树密度的变异函数值可用球状模型和指数模型描述,变程分别为73.10和45.60 m。更新苗密度空间依赖性较强,而成树密度空间依赖性较小。东北—西南方向上是更新苗密度分布的优势格局,全方位上是成树密度分布的优势格局。更新苗密度斑块之间的连接程度低,成树密度斑块间的连接程度较高。3)样地更新苗高度的变异函数值可用指数模型描述和球状模型描述,变程分别为47.40和23.90 m。东北—西南方向上是更新苗高度分布的优势格局,南北方向上是成树高度分布的优势格局。更新苗高度斑块之间的连接程度低,成树高度斑块间的连接程度较高。【结论】青海云杉林更新苗和成树密度和高度的空间变异性研究有助于解释青海云杉林种群动态背后的潜在规律性,有望为青海云杉林生态系统的可持续管理提供理论依据,也可为退化的青海云杉林生态系统植被生态恢复提供参考。

【Objective】Density and height are two important parameters of regenerated and adult trees.The spatial heterogeneity and variation scale of density and height of regenerated and adult trees in Picea crassifolia forests were studied,and the spatial distribution pattern and its internal relationship with the ecological process were analyzed in this article.【Method】Based on the 340 m×300 m dynamic monitoring plot of the Picea crassifolia forest in the Qilian Mountains,Gansu Province,we investigated the number and height of regenerated and adult trees,and studied the spatial variation characteristics of density and height by using classical statistical and geostatistical methods.【Result】1)The mean density of the regenerated and adult trees in the plot were 5762 and 2016 strains·hm-2,respectively,and the corresponding mean heights were 0.30 and 8.79 m,respectively.The variation of the density and height of regenerated seedlings was strong,while the variation of the density and height of adult trees was moderate.2)The variances of the density of regenerated and adult trees could be described by the spherical model and the exponential model,with a range of 73.10 and 45.60 m,respectively.The spatial dependence of the density of regenerated seedlings was stronger than that of adult trees.From northeast to southwest,there was a dominant pattern of the density distribution of regenerated seedlings,while from all directions,there was a dominant pattern of the density distribution of adult trees.The degree of connection between patches of regenerated seedlings density was low,while that between patches of adult trees density was high.3)The variogram of the height of newly grown seedlings in the sample plot could be described by the exponential model and the spherical model,and the variogram ranges were 47.40 and 23.90 m,respectively.The dominant pattern of height distribution of regenerated seedlings was from northeast to southwest,while the dominant pattern of height distribution of adult trees was from south to north.The degree of connection between the patches of the height of regenerated seedlings was low,while the degree of connection between the patches of the height of adult trees was high.【Conclusion】The spatial variability of density and height of regenerated and adult trees in Picea crassifolia forests helps to explain the underlying laws behind the population dynamics of Picea crassifolia forests.It is expected to provide a theoretical basis for the sustainable management of Picea crassifolia forest ecosystem and the vegetation ecological restoration of the degraded Picea crassifolia forest ecosystem.