Characteristics of interspecific segregation in Fagus lucida secondary forest.

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.