崇州林场柳杉人工林空间结构研究

A Study of the Spatial Structure of Cryptomeria fortunei Plantation in Chongzhou Forest Farm

崇州林场的植被主要是柳杉(Cryptomeria fortunei)人工纯林。为了定量地描述林分的空间结构,调查共设置6个50 m×50 m固定标准样地,对样地中的林木进行每木检尺并绘出它们的坐标位置。研究运用了角尺度参数来量化林木分布的均匀性(即空间分布格局);大小比数来测度树木间的优势度分化,也为种群在林分中的相对地位提供了有益的信息。而混交度则通过参照树周围最近的几株相邻木与其不同种个体所占的比例,来表征林分的物种多样性。借此以单木为基础的结构参数所描述的林分空间混交度、林木大小(胸径)分化程度以及群聚程度,使得定量比较那些具有复杂结构的林分也变得简单易行。这无疑有助于林地的可持续经营和生态管护。

In this paper, an analysis is made of forest spatial structure and diversity in the Chongzhou Forest Farm where the majority of the forests consist of pure stands. A detailed analysis of forest spatial structure was made, based on six one-quarter-hectare plots where all the trees and their coordinates had been assessed. The objective of the study was to provide a quantitative description of the spatial structure of the plots, using new parameters of spatial diversity i. e. neighborhood pattern, neighborhood comparison and mingling, and to present a method for comparative analysis of the six forest sites. The tree-based neighborhood pattern Wi can be used to characterize the spatial distribution of tree positions. It describes the degree of regularity of the spatial distribution of the four trees nearest to a reference tree i based on the classification of the angles aj between the neighboring trees. The dominance which measures the proportion of n nearest neighbors of a given reference tree which are smaller than the reference tree, provides information about the relative status of a species within the population. Species diversity is evaluated by the tree attribute mingling which measures the proportion of the n nearest neighbors that do not belong to the same species as the reference tree. The variables described the distributions of spatial mingling, size differentiation and contagion, which could be easily interpreted allowing quantitative comparisons between complex forest structures. This approach undoubtedly offered great potential for conservation and sustainable woodland management.