基于林木竞争关系的闽楠人工林目标树密度研究

Study on the Target Tree Density of Phoebe Bournei Plantation Based on Competition Relationship of Forest Trees

为了培育珍贵树种大径材,如何确定目标树密度,使其既利于目标树的生长、又能充分发挥林地生产力是闽楠人工林经营的关键。在金洞林场,选择具有代表性的14a生闽楠人工林,设置3块20m×30m的标准地,根据近自然经营的目标树选择标准选择备选目标树,1,2,3号标准地确定的备选目标树分别为11,15,14株。借助Arc GIS软件,依据林木的空间位置生成Voronoi图确定每株备选目标树的竞争单元,计算每株备选目标树的V-Hegyi竞争指数和大小比数。依据备选目标树V-Hegyi竞争指数与大小比数数值的变化范围将V-Hegyi竞争指数和大小比数划分为3个等级,V-Hegyi竞争指数与大小比数均为第一等级的确定为最终目标树。3个标准地确定的最终目标树株数分别为8,10,9株。即目标树密度分别为120,150,135株/hm^2。由此得到金洞林场闽楠人工林当前阶段目标树密度为135株/hm^2。这为金洞林场闽楠人工林近自然经营目标树的确定提供了理论依据。

In order to cultivate precious tree species of large diameter timber,the key is to manage Phoebe Bournei artificial pure forest and to determine the target tree density so that it can be beneficial to the growth of the target trees and to give full play to the productivity of the forest. In Jindong Forest Farm,the representative of the 14 year old Phoebe Bournei plantation was selected,and three sample spots （20m ×30m） were set. In these three sample spots,respectively, 11,15 and 14 trees were selected as alternative target trees according to the target tree selection criteria based on near natural operation. ArcGIS was used to generate voronoi diagram according to the spatial position of forest trees. The competitive unit of each alternative target tree is determined based on the generated Voronoichart. And by determining the compet- itive unit the V-Hegyi competitive index and neighborhood comparison of each alternative target tree were calculated. V-Hegyi competitive index and the degree of neighborhood comparison are divided into 3 lev-els, according to the variation range of the V-Hegyi competition index and the neighborhood comparison degree. Trees with both indexes at the first level were determined to be final target trees. The number of target trees in these three sample spots would be 8,10 and 9 respectively. That is,the final target tree den-sity was 120,150 and 135/hm2 respectively. So the target tree density of the average of Phoebe Bournei in Jindong forest farm was 135/hm2. This paper provides the theoretical basis for the near natural manage-ment of artificial pure Phoebe Bournei forest of Jindong Forest Farm.