基于Voronoi图的群落优势树种种内种间竞争

在浙江天目山国家级自然保护区内,选择典型常绿阔叶林设置样地,样地大小100m×100m。用全站仪测定每株树木坐标(x,y,z)。首先,用优势度分析法确定群落优势树种。其次,提出基于Voronoi图的V_Hegyi竞争指数,并对Hegyi、APA和V_Hegyi三种竞争指数进行比较分析。最后,采用V_Hegyi竞争指数分析常绿阔叶林的种内、种间竞争关系。结果表明:常绿阔叶林群落共有11个优势树种即细叶青冈(Cyclobalanopsis myrsinaefolia)、青冈(Cyclobalanopsis glauca)、短尾柯(Lithocarpus brevicau-datus)、豹皮樟(Litsea coreana)、白栎(Quercus fabri)、天目木姜子(Litsea auriculata)、黄连木(Pistacia chinensis)、榉树(Zelkovaschneideriana)、杉木(Cunninghamia lanceolata)、枫香(Liquidambar formosana)和黄檀(Dalbergia hupeana)。比较分析认为,V_Hegyi竞争指数既克服了用固定半径圆确定竞争单元的尺度不统一缺陷,又可进行种内、种间竞争分析,并保持竞争排序的稳定性,因此是优于Hegyi和APA的更合适的竞争指数,所以选择V_Hegyi竞争指数进行优势树种竞争分析。常绿阔叶林优势树种的种内竞争比种间竞争激烈。种内竞争最激烈的优势树种细叶青冈、青冈和短尾柯与其它优势树种的种间竞争强度也是最高的。反之,种内、种间竞争都较弱的优势树种包括豹皮樟、白栎、天目木姜子、黄连木、榉树、杉木、枫香和黄檀。多数优势树种存在1个主要竞争树种,很少有超过3个以上的情形。细叶青冈是群落最占优势的树种,具有最强烈的种内竞争。同时,也是所有其它优势树种的最大竞争者。

Intraspecific and Interspecific competition analysis of community dominant plant populations based on Voronoi diagram

One plot that represents typical evergreen broad-leaved forests was established and surveyed in Tianmu Mountain National Nature Reserve, Zhejiang Province, and the plot size was 100 m × 100 m. Each tree was located in terms of x-, y-, and z-coordinates using a total station and the dominant plant populations were determined based on the dominance index analysis method. Then, V_Hegyi competition index based on Voronoi diagram was put forward, and three competition indices including Hegyi, APA and V_Hegyi were compared. Finally, the new competition index V_Hegyi was applied to analyze intraspecific and interspecific competition of dominant species. The results show that in the evergreen broadleaf forest that was studied, there are eleven dominant tree species, including Cyclobalanopsis myrsinaefolia, Cyclobalanopsis glauca, Lithocarpus brevicaudatus, Litsea coreana, Quercus fabri, Litsea auriculata, Pistacia chinensis, Zelkova schneideriana, Cunninghamia lanceolata, Liquidambar formosana and Dalbergia hupeana. The comparison and analysis imply that V_Hegyi not only overcomes the shortcoming in the inconsistency of measure units used to determine the competition based on fixed radius circles, but also can be used to make intraspecific and interspecific competition analysis and leads to stable rank of competition. Thus, V_Hegyi is superior to Hegyi and APA, and applicable for dominant tree species competition analysis. In the evergreen broadleaf forest, the intraspecific competition is fiercer than the interspecific competition. The dominant tree species whose intraspecific competition is the fiercest, Cyclobalanopsis myrsinaefolia, Cyclobalanopsis glauca and Lithocarpus brevicaudatus, also possess the cruelest interspecific competition. On the contrary, both intraspecific and interspecific competition of the tree species including Litsea coreana, Quercus fabri, Litsea auriculata, Pistacia chinensis, Zelkova schneideriana, Cunninghamia lanceolata, Liquidambar formosana and Dalbergia hupeana, are weak. Most of the dominant tree species have one main competitor, but few have more than three. Cyclobalanopsis myrsinaefolia is the absolutely dominant tree species and shows the fiercest intraspecific competition and at the same time, it is also the strongest competitor of other dominant tree species.