Study on the Interspecific Associations in Arbor Layer of Evergreen Monsoon Rainforest in Fangcheng Golden Camellia National Nature Reserve

To reveal interspecific relationships within the evergreen monsoon rainforest communities and explore their community stability in Fangchenggang Golden Camellia National Nature Reserve, this study employed Variance Ratio(VR), χ² test, AC index, Pearson correlation, and Spearman rank correlation coefficient. Additionally, PCA sequencing and the M. Godron community stability analysis method were utilized for interspecific association analysis, ecological species group classification, and community stability assessment of the 16 dominant tree species in the community. The findings are summarized as follows: The overall correlation among dominant species in the tree layer was not significantly negative, indicating a relatively loose community structure. The χ² test shows that the positive and negative connection ratio is abnormal, and the significant rate is 1.6%. The positive and negative connection ratio of AC index is 0.125, but the significant rate is large. In order to determine the interspecific association of the community more comprehensively, the comprehensive quantification should be combined with χ² test and AC index. The results of both Pearson correlation and Spearman rank correlation coefficient tests were consistent, that is, the interspecific relationship is mainly negative correlation, the positive and negative correlation is low, and the significant rate is small. Principal Component Analysis(PCA) categorized the 16 dominant tree layer species into 3 ecological species groups. It is estimated that the first ecological species group is mostly pioneer species that liked light in the early succession and drought tolerance, the second ecological species group is evergreen species with warm and humid climate in the middle succession, and the third ecological species group is evergreen species that like light and humidity in the late succession. The intersection value of the M.Godron stability results is(30.93, 69.07), indicating that the community is in an unstable phase and is in the middle and late period of unstable succession.