Interspecific associations of Pistacia chinensis community and association index'rank pattern model.

Interspecific association, which reflects the interspecific relationships and community stability,is an important index in the conservation of biodiversity and the sustainable utilization of plant community. Seven indicators, including over all correlation test VR, 字2 statistics test, coupling coefficient AC, point correlation coefficient PCC and matching coefficients of JI, OI, DI, were calculated to indicate the interspecific association of Pistacia chinensis community. At the community level, we analyzed the interspecific association of species and at the population level, we analyzed the association between male and female P. chinensis, male or female P. chinensis and the other species. We also use Spearman's rank correlation models to calculate the relevance between P. chinensis and the other species and find the differences between female and male P. chinensis. The results were shown in the followings: The whole relevance of P. chinensis community was not strong with significantly negative correlation. Significantly negative correlation was found between P. chinensis population and the other species. The positive correlation between male P. chinensis and the other species(72.7%)was higher than that between female P. chinensis and the other species(27.3%). The positive correlation between female P. chinensis and the nitrogen fixation Alnus sibirica and the significantly negative correlation between female P. chinensis and Stephanandra incise with high frequency in the community might be due to the breeding cost and the foraging behaviors. The rank correlation equations of male and female P. chinensis and male P. chinensis were all linear, while that of female P. chinensis was concave curve. The slope of rank correlation equation of three joint index JI, AC and PCC was negative. The absolute value of the slope ranked in the order of female male the whole of female and male P. chinensis. The association index'rank pattern model was first used in the paper, where the absolute value of the slope could reflect the level of tightness between the central species and the others in the community. When the absolute value of the line gradient was larger, the stage of interspecific association was more unstable. This provides a new model to further reveal the interspecific association and a novel idea to analyze the interspecific association of the dioecious plants.