基于4株相邻木关系的林分空间结构多样性测度方法研究

Research on the measurement method of forest spatial structure diversity based on 4 neighborhood tree relationship

【目的】深入剖析林分空间结构参数四元分布的生态意义,构筑基于相邻木关系的林分空间结构多样性综合评价指数,为制订有的放矢的森林结构调整策略提供理论依据。【方法】基于生物多样性概念,以参照树与其最近的4株相邻木组成的结构单元为对象,有机整合结构参数角尺度、混交度、大小比数和密集度的四元分布及结构单元树种数和林层数,运用遗传绝对距离公式、自然对数分别表达结构单元类型均匀性和丰富度,构造表达林分空间结构多样性测度指数,并运用长期定位监测样地数据进行验证。【结果】运用本研究提出的林分空间结构多样性指数(D_(FS))对处于不同气候带或不同起源的森林类型的空间结构多样性测度表明,锐齿栎天然林的D_(FS)值(0.854)与阔叶红松林的D_(FS)值(0.852)几乎相等,二者具有相似的空间结构多样性。侧柏人工林结构参数四元分布类型较多,高于锐齿栎天然林和红松阔叶林,但其空间结构多样性为3个林分类型中最低的(D_(FS)=0.382),主要原因是其垂直结构(D_(FSv)=0.369)和水平结构(D_(FSh)=0.562)多样性方面都比两类天然林低。结构单元中的平均树种数表现为天然林高于人工林,锐齿栎天然林为4.23,阔叶红松天然林为4.09,而侧柏人工林则为1.98,结构单元树种数能充分体现结构单元树种丰富程度。【结论】林分空间结构参数四元分布、结构单元树种数和林层数3者的有机整合是构造有效的林分空间结构多样性指数的基石。基于生物多样性概念提出的林分空间结构多样性指数D_(FS),既是对结构参数四元分布合适的量化表达,也是对结构参数四元分布生态意义恰当的诠释,更是对林分空间结构多样性的科学综合评价,能够测度出不同林分类型林分空间结构多样性的差异。

[Objective]The ecological significance of 4-variate distribution of stand spatial structure parameters was deeply analyzed and a comprehensive evaluation index of stand spatial structure diversity based on the relationship between adjacent trees was constructed to provide a theoretical basis for formulating targeted forest structure adjustment strategies.[Method]Based on the concept of biodiversity,taking the structural unit which was composed by reference tree and its nearest four adjacent trees as the object,organically integrating the 4-variate distribution of structural parameters of uniform angle index,mingling,neighborhood comparison and crowding,as well as the number of structural unit trees and forest layers,the genetic absolute distance formula and natural logarithm were used to express the evenness and richness of structural unit types,respectively,and the stand spatial structure diversity index was constructed.The validity of index was verified by long-term positioning monitoring sample plot data.[Result]Using the stand spatial structure diversity index(D_(FS))proposed in this study to measure the spatial structure diversity of forest types in different climatic zones or different origins,it was showed that the D_(FS) values of Quercus aliena var.acutiserrata natural forest(0.854)and broadleaved Pinus koraiensis forest(0.852)were almost the same,indicating that the two forest stands had similar spatial structural diversity.The 4-variate distribution types of Platycladus orientalis plantation were higher than other natural forest,however,its spatial structural diversity(D_(FS)=0.382)was the lowest in the three stand types,mainly due to its lower diversity in both vertical(D_(FSv)=0.369)and horizontal(D_(FSh)=0.562)structure than the two natural forest stands.The average number of tree species in the structural units was higher in natural forest than in plantation,with 4.23 in Quercus aliena var.acutiserrata forest,4.09 in Pinus koraiensis forest,and 1.98 in Platycladus orientalis plantation.The number of tree species in a structural unit fully demonstrated species richness of the structural unit.[Conclusion]The integration of the three numbers including 4-variate distribution of stand spatial structure parameters,the number of tree species and number of forest layers in structure unit lay the foundation for constructing a valid spatial structure diversity index for forest stands.The stand spatial structural diversity index(D_(FS)),based on the concept of biodiversity,is not only a feasible quantitative expression of the 4-variate distribution of structural parameters,but also is an appropriate interpretation of the ecological significance of the 4-variate distribution of structural parameters,and a comprehensive scientific evaluation of the spatial structural diversity of the stand.The index is able to measure the difference of stand spatial structure diversity of different stand types.