南京老山秤锤树空间分布格局及种间关联性

以南京老山1 hm 2样地秤锤树(Sinojackia xylocarpa)天然种群为研究对象,运用成对g(r)函数,选择完全随机模型、异质泊松模型与先决条件零模型,分析秤锤树种群结构和空间分布格局及其空间关联性,从空间格局角度来深入认识其种群结构和分布格局及形成该格局可能存在的机制并提出保护建议。结果表明:(1)秤锤树天然种群中小径个体数量占优,属于增长型种群。(2)种内空间分布研究中,基于完全随机模型分析,秤锤树种群在尺度0~26 m时为聚集分布,尺度29~30 m时为均匀分布;基于异质泊松模型分析,秤锤树种群在0~23 m时为聚集分布,尺度27~30 m时为均匀分布。秤锤树空间分布表现为由聚集分布向均匀分布变化。(3)主要种间关联性研究中,秤锤树与朴树(Celtis sinensis)的种间关联性表现为小尺度下负关联,随着空间尺度的增加变为正关联。秤锤树与黄连木(Pistacia chinensis)和秤锤树与三角槭(Acer buergerianum)的种间关联性大致相同,基本为大尺度下正关联,偶尔出现负关联和无关联。上述结果表明,秤锤树种群更新状况良好,种群空间分布以聚集分布为主,其主要受种间竞争、扩散限制与密度制约的影响。基于种群现状开展就地保护与适当干扰其生存群落,是濒危物种秤锤树的科学有效的保护措施。

Spatial distribution patterns and interspecific correlation of Sinojackia xylocarpa in Laoshan Mountain of Nanjing

The species of Sinojackia xylocarpa in sample plot of 1 hm² in Laoshan Mountain of Nanjing was taken as the object of study. Using the pairing correlation function g(r) and three null models: complete spatial randomness(CSR), heterogeneous Poisson(HP)and antecedent condition(AC)to analyze the relation between the structure and spatial distribution of the population. The potential mechanism of this pattern formation could be deeply recognized from the view of spatial pattern. The results were as follows:(1)The number of individuals of small DBH class in natural S. xylocarpa population was dominant, and it was a growing population.(2)In the study of point pattern analysis, the S. xylocarpa population showed the aggregate distribution at scale 0-26 m, and uniformly distribution at scale 29-30 m based on the CSR; and the S. xylocarpa population showed the aggregate distribution at scale 0-23 m, and uniformly distribution at scale 27-30 m based on the HP. The spatial distribution pattern of S. xylocarpa showed a trend of changing from aggregate distribution to uniformly distribution.(3)In the study of interspecific correlation, the spatial relationship between S. xylocarpa and Celtis sinensis showed from the negative correlation to the positive correlation. The spatial relationship between Sinojackia xylocarpa and Pistacia chinensis and that between Sinojackia xylocarpa and Acer buergerianum were about the same. There were positive correlations between them on a large scale, and occasionally negative correlation and no correlation. The above results indicate that Sinojackia xylocarpa population is in a good regeneration state. The spatial distribution pattern of S. xylocarpa population is basically aggregate distribution, and is mainly affected by interspecific competition, diffusion restriction and density restriction. Based on population status, carrying out in situ protection and appropriately disturbing the community are a scientific and effective protection measure for the endangered species of S. xylocarpa.