南京方山国家地质公园朴树群落特征

Community character of Celtis sinensis of Fangshan National Geological Park in Nanjing

关键词:  方山  朴树  群落特征  种群结构  分布格局

Key words:  Fangshan  Celtis sinensis  community character  population structure  distribution pattern

摘要:

采用样地调查法对南京方山国家地质公园朴树群落特征进行研究。结果表明：(1)群落中朴树的优势地位突出，其重要值为44.481%，是该群落的第1优势种；主要伴生树种有构树、茅栗、榉树、麻栎、榔榆、刺槐等；群落成层现象明显，可分为乔木层、灌木层(含下木层)和草本层，但地被层不发达；(2)群落垂直结构较为简单，乔木层共有木本植物15种。乔木层丰富度指数(S)、Shannon Wiener指数(H′)、Simpson指数(D)、种间相遇机率(PIE)、Pielou均匀度指数(J)分别为7.429、1.406、0.696、0.054、0.723，物种多样性总体偏低；(3)朴树种群年龄结构表现为Ⅰ、Ⅱ级幼苗普遍较少，幼苗贮备严重不足，种群自身更新不良，整体处于衰退之中；(4)采用扩散系数(C)、负二项参数(K)、扩散型指数(Iδ)、Cassie指标(Ca)、丛生指标(I)、平均拥挤度指数(m*)和聚块性指标(m*/m)进行分析，朴树种群的空间分布格局均为集群分布，但不同样地中的种群集聚程度因生境的变化而存在一定差异。

Abstract:

The community character of Celtis sinensis of Fangshan National Geological Park in Nanjing was studied using quadrat survey. The results were as followed:(1)the dominant species of the community was C.sinensis，of which the important value was 44.481%，and there were Broussonetia papyrifera，Castanea seguinii，Zelkova serrata，Quercus acutissima，Ulmus parvifolia and Robinia pseudoacacia in upper layer as main companion tree species； (2)the population structure was simple and there were 15 arborous species at upper layer，and the species diversity indexes of the tree layer were a bit low by analyzed five indices，species richness(S)，Shannon Wiener index(H′)，Simpson index(D)，PIE index，Pielou evenness index(J)，and these indexes were 7.429，1.406，0.696，0.054，0.723 by calculation； (3)the diameter class structure of C.sinensis population showed the seedlings numbers of class Ⅰ and Ⅱ were less，so that the young seedlings reservoir was not seriously enough. The ability of self renewing of the population was bad，so they tended to atrophy quantitatively and were in the decline； (4)the spatial pattern of seven sampling plots were aggregative distribution through testing cluster intensity coefficient for instance K value of negative binomial，dispersal index(C)，index of dispersion pattern(Iδ)，Cassie index(Ca)，clumping index(I)，index of mean crowding(m*)and index of patchiness(m*/m)，but there were certain difference among seven sampling quadrats in their aggregative degree.