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    亮叶水青冈次生林种间分离特征的研究

    Characteristics of interspecific segregation in Fagus lucida secondary forest.

    • 摘要: 采用最近邻体列联表法和计算主要树种混交度的方法,研究亮叶水青冈天然次生林不同树种的种间分离特征。结果表明:1)亮叶水青冈空间分布格局为聚集型,该群落中随机毗邻种对的数量占优势(比例达69.89%),正分离种对较少(比例为29.88%),负分离种对极少(仅为0.23%)。星座图清晰显示种间分离在不同种之间存在一定的差异。2)随着亮叶水青冈在群落中的重要值增大,亮叶水青冈与其他树种发生正分离的种对也增加;随着亮叶水青冈径阶增大,与其他树种的分离关系逐渐接近自然状态,即以随机毗邻为主,正分离次之,负分离不存在。3)群落的平均混交度较高,取值集中在0.5~0.75,说明整体上树种之间的隔离程度较大;亮叶水青冈的混交度值为0.34,处于弱度与中度混交之间,趋向于聚集分布;茅栗、四照花等主要伴生树种的混交度在0.75左右,可以视为强度混交。种间分离类型比例和主要树种混交度的取值分析均说明该亮叶水青冈群落的稳定性较强。

       

      Abstract: In order to better understand the characteristics of interspecific segregation in Fagus lucida community, we investigated 15 plots in F. lucida secondary forest in the National Dalaoling Forest Park, Yichang City of Hubei Province, central China. The interspecific segregation was studied with an N×N nearestneighbor contingency table and a 2×2 nearestneighbor contingency subtable. Mingling was also used to analyze the spatial isolation of major tree species in the community. The results showed that: 1) the dominant speciespairs were randomly segregated (accounting for 69.89%), some speciespairs were positively segregated (29.88%), and only a few were negatively segregated (0.23%). The constellation diagrams indicated clear differences in interspecific segregation among various species. 2) As the importance values of F. lucida in the plots increased, the number of positive segregation between F. lucida and other tree species also increased. For F. lucida trees in different diameter classes, the proportion of random segregation remained dominant, followed by that of negative segregation, meanwhile the proportion of negative segregation declined sharply to 0. 3) The average mingling degree of F. lucida plots was about 0.5~0.75, suggesting the relatively high mingling degree of stands. The value of mingling of dominant species was 0.34, indicating that F. lucida trees were mainly less and middlemixed, tending to be in a clumped distribution. The mingling degrees of some important companion species (such as Castanea seguinii and Dendrobenthamia japonica) were around 0.75, indicating they were well mixed. The proportion of interspecific segregation and the mingling of main tree species suggested that F. lucida community in the study area was in a steady stage.

       

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