Interspecific Associations among Dominant Plant Populations in Keteleeria hainanensis Communities in Bawangling,Hainan Island

Based on 2×2 contingency tables,a series of parameters including X² test,percentage of co-occurrence(PC),association coefficient(AC) and variance ratio(VR) were used to analyze the characteristics of interspecific associations among nineteen main plant populations in Keteleeria hainanensis communities.The results showed the association was nonsignificant positive correlation among the nineteen main populations.Among the 171 species pairs,87 pairs were positively correlated,82 pairs were negatively correlated,and 2 pairs showed no correlation.The X² test indicated that six positively correlated pairs and five negatively correlated pairs were significant or very significant.The percentage co-occurrence(PC) value for 144 species pairs was less than 40 percent,for 21 species pairs was equal or more than 40 percent,and for 6 species pairs was 0,indicating that a relatively low correlation existed among these species pairs.The more intense the positive association,the larger the value of niche overlap.The more intense the negative association,the smaller the value of niche overlap.In different dominant tree populations,the interspecific associations were different,but in the dominant species of Lithocarpus fenzelianus and K.hainanensis,the community showed high interspecific association and was more stable.Overall,K.hainanensis had the largest positive association with Psychotria rubra.