[Interspecific associations of the main tree populations of the Cyclobalanopsis glauca community in Karst hills of Guilin, Southwest China].

Analyzing the interspecific association of major tree populations of Cyclobalanopsis glauca community and revealing the coexistence among the populations would provide theoretical basis for the restoration and reconstruction, management and biodiversity conservation of Karst hills in Gui-lin. Based on field survey, the χ test, association coefficient (AC), co-occurrence percentage (PC), Ochiai index (OI), Dice index (DI), and principal component analysis (PCA) were used to investigate the interspecific association and eco-taxonomic classification of the top 22 tree species in Cyclobalanopsis glauca community in Guilin Karst Rocky Mountains. The results showed that there was a significant positive correlation between the interspecific associations of the 22 main tree populations, indicating that this community was in a stable climax stage. The results of χ test showed that 108 pairs of 231 species pairs had positive associations, 115 species pairs had negative associations, 8 species pairs were unrelated, with the positive and negative linkage ratio being 93.9%. The vast majority of species pairs showed no significant association. The strong indepen-dence between species might be mainly caused by the higher habitat heterogeneity of the Karst hills in Guilin which led to the differentiation of niches between species. The results of AC, PC, OI and DI were basically consistent with that of χ test, indicating that the analysis of interspecific association should be based on the χ test and supplemented by AC, PC, OI and DI indices. According to the PCA and evaluation of interspecific relationships, the 22 main tree species were divided into three ecological groups. The species within each group had the same adaptability to habitat but different ecological requirements.