Niche and Interspecific Association of Species of Taxus yunnanensis Communities in Northwest Yunnan Province

Field data collection was based on 3200 m² plots (including 8 subplots) in Taxus yunnanensis communities distributed in northwest Yunnan province.Methods including niche breadth,niche overlap,chi-square test,and association coefficient (AC) based on a 2× 2 contingency table were used for analyzing the interaction between the species population.Results showed significant positive correlation (p<0.001) between the importance value and corresponding niche breadth.The niche breadth of Taxus yunnanensis,Tsuga forrestii,and Helwingia japonica were larger than other populations.The niche overlap of 48.16% of species pairs was 0 in 1225 species pairs and 4% of species pairs showed neutral association in chi-square test,which indicated a stronger resource utilization competition on different populations.Simultaneously,niche breadth increased with niche overlap.The niche overlap of species pair of between Taxus yunnanensis and Tsuga forrestii was larger than species pairs between Taxus yunnanensis and other populations.The Schoener index was 0.875.Chi-square results showed that there was no association between Taxus yunnanensis and other populations.For AC,the proportion of negative association was more than positive association,which showed that the community had a larger external disturbance.There was a significant positive correlation between association coefficient and niche overlap and the model was Cubic index.