天目山针阔混交林林木空间特性

Forest tree spatial characteristics of a coniferous, broad-leaf mixed forest on Mount Tianmu

为了解天目山针阔混交林林木空间的特性,以期对该地区森林可持续经营模式的实践提供理论基础,设置了15块30 m×30 m的固定标准地,采用实测调查法,调查样地内所有胸径≥5 cm的林木特征值。以林木冠幅作为空间分割尺度来生成Voronoi图,确定林木空间结构单元,统计分析林木空间不同尺度上的差异性。结果表明:单株树种的空间面积差异性较大,群组中每株树木周围平均有4~5株树。优势种中苦槠Castanopsis sclerophylla,锥栗Castanea henryi和麻栎Quercus acutissima等树种的空间面积大小较稳定,而马尾松Pinus massoniana,杉木Cunninghamia lanceolata,白栎Quercus fabric和山矾Symplocos caudata等树种空间面积大小差异性较大。林木胸径的大小对其所占空间面积有一定影响,而对其周围邻近木的株数影响不大。目标树的最近邻木株数为3~13株,多数为5~7株,平均为6株。天目山针阔混交林为强度混交林,林分群落结构相对稳定。

To understand characteristics of forest tree spacing in a coniferous, broad-leaf mixed forest on Mount Tianmu and to provide a theoretical basis for sustainable forest management, fifteen 30 m × 30 m fixed plots were established to measure characteristics of all trees over 5 cm DBH. The forest crown was used for a spa- tially segmented scale to generate a Voronoi Diagram, to determine the spatial unit between trees, and for sta- tistical analysis of differences with various scales of tree spacing. Results showed that single tree spacing had large differences, with an average of four to five trees in a group. The spatial area was stable for dominant species of Castanopsis sclerophylla, Castanea henryi, and Quercus acutissima, but large spatial difference were found with Pinus massoniana, Cunninghamia lanceolata, Quercus f^ric, and Symplocos caudata. DBH influ- enced spatial area, but not the nearest-tree number. The range of nearest-tree number for target trees was 3 to 13, with the mode being 5, 6, and 7, and the mean was 6. Overall, Mount Tianmu was a well-established, mixed forest, with a relatively stable community structure. [ Ch, 8 fig. 2 tab. 25 ref. ].