基于Voronoi图的阔叶红松林空间结构特征分析

Quantitative analysis of spatial structural characteristics of broadleaved Korean pine forest based on Voronoi diagram

【目的】森林空间结构是森林生物物理过程和动态演替的结果,又决定着森林的生长过程和生态服务功能的发挥。小兴安岭地区作为多样性保护与水源涵养的重要生态功能区,森林退化已经非常严重,有必要对现存的地带性顶极群落的结构特征进行分析,为退化森林的结构优化与调整提供理论支撑,促进其发挥应有的森林生态服务功能。【方法】本文以细鳞河国家级自然保护区内阔叶红松林为研究对象,根据野外调查数据,利用ArcGIS软件建立Voronoi多边形,确定空间结构单元,计算聚集指数、大小比数、竞争指数、多样性混交度等空间结构参数,分析阔叶红松林的空间结构特征。【结果】阔叶红松林林分水平格局为聚集分布,聚集指数与Voronoi多边形边数标准差的判定结果一致;针叶树比阔叶树有更大的竞争优势,阔叶树的种内竞争更激烈,但Hegyi竞争指数与大小比数二者结果并不完全一致;树种多样性混交度表明林分处于中度混交的水平,但每一树种的多样性混交度并不相同,针叶树的树种隔离程度比阔叶树的要高,并且这种隔离程度的强弱与树种在林分中的丰度没有直接关系。【结论】小兴安岭地区阔叶红松林以聚集分布、混交程度中等、竞争程度中等为其特征。红松与冷杉所在的结构单元混交度高、二者在各自结构单元内有明显的竞争优势;而枫桦、青楷槭、暴马丁香所在的结构单元混交度低,他们受到的竞争压力大,更多表现为种内竞争,尤以暴马丁香最具代表性。这些特征与文献报道的长白山区阔叶红松林的不尽相同,这既有选用参数不同的原因,也可能是地形气候差异的自然选择结果,还需要进一步调查研究。

[Objective]Forest spatial structure is the result of forest biophysical processes and dynamic succession,and determines the growth process of forests and the function of ecological services.The Xiaoxing’anling Mountains are important ecological function area for diversity protection and water conservation,but their forest degradation is already very serious.In order to provide theoretical support for the structural optimization and adjustment of degraded forests and promote the forest to play their due roles in forest ecological services,it is necessary to analyze the structural characteristics of existing zonal climax communities.[Method]In this paper,the broadleaved Korean pine forest in the Xilinhe National Nature Reserve was taken as the research object. Based on field survey data, the Voronoi polygons were establishedusing ArcMap software to determine spatial structural units. By the spatial structural units, several spatialstructural parameters such as Clark’s clustering index, size differentiation, Hegyi’s competition index, anddiversity mingling were calculated. According to them, the spatial structural characteristics were furtheranalyzed. [Result] The horizontal pattern of broadleaved Korean pine forest stand appeared aggregateddistribution, and the results derived from Clark’s clustering index were consistent with those resulted fromthe standard deviation of Voronoi polygon edge number. The coniferous trees had greater competitiveadvantages than the broadleaved trees, and the broadleaved trees presented more intense intraspecificcompetition. However, the trends of Hegyi’s competition index and the size differentiation index were notcompletely consistent. The species diversity mingling indicated that the forest stand was at a moderate level,and the isolation of conifers was higher than that of broadleaved trees. Furthermore, the extent of isolationwas not directly related to the abundance of tree species in the stand. [Conclusion] The broadleaved Koreanpine forest in the Xiaoxing’anling Mountains is characterized by aggregated distribution, moderate mingling,and moderate competition. The structural units of Korean pine and Fabers fir have a high degree of mixing,and the Korean pine and Fabers fir have obvious competitive advantages in their respective structural units;while the structural units of Chinese birch, Manchustripe maple, and Amur lilac are low mixed, respectively.These three species are under great competitive pressure, and more manifested as intra-species competition,among them the Amur lilac is the most representative. These characteristics are not the same as those of thebroadleaved Korean pine forest in the Changbai Mountains reported in the literatures. This maybe due todifferent parameters selected or the result of natural selection of topographic and climatic differences.Further investigation and research are needed.