北京松山自然保护区蒙古栎林的空间结构特征

Spatial structure of Quercus mongolica forest in Beijing Songshan Mountain Nature Reserve

以松山自然保护区面积为0.6hm2样地的调查数据为基础,利用角尺度、大小比数和混交度3个林分空间结构参数,分析了蒙古栎天然林的空间结构特征.结果表明:蒙古栎林乔木层共有10个种群,蒙古栎种群密度和断面积占有明显优势,是乔木层的优势种和建群种;蒙古栎林平均混交度为0.299,林分混交程度低,优势种以零度混交和弱度混交为主,伴生种的混交状况普遍较好;蒙古栎和油松种群在空间结构单元中以优势木、亚优势木和中庸木为主,分别占种群总株数的68%和58%,其他种群的树种优势度不明显,多为被压木;该林分的空间分布格局为聚集分布,但林木聚集程度和聚集规模较低.

Based on the survey data of a 0. 6 hm^2 plot in Songshan Mountain Nature Reserve, and by using the uniform angle index, neighborhood comparison and mingling degree, this paper analyzed the spatial structural characteristics of Quercus mongolica forest in the Reserve. There were 10 populations in the tree layer of the forest, among which, Q. mongolica had the obvious advantage in population density and basal area, being the dominant and constructive species of the tree layer. The average mingling degree of the forest was 0. 299, suggesting the low mingling degree of stands. The dominant species was mainly none- or less-mixed, while the accompanying species were generally well-mixed. In the spatial structural units, Q. mongolica and Pinus tabulaeformis populations were mainly of dominant, sub-dominant, and intermediate trees, accounting for 68% and 58% of the total plants of the populations, respectively, while the advantages of other populations were not obvious, being mostly of suppressed trees. The spatial pattern of the stands was of aggregative distribution, but the aggregation degree was not high and the aggregation scale was not large.