Effects of different habitats on distribution of invasive alien grasses in Nabanhe River Basin National Nature Reserve, Yunnan Province.
To identify the variance of the distribution of invasive alien grasses and the influencing factors in different habitats, 164 subplots (1 m2) were investigated across five habitats, including natural forest, border of natural forest, rubber tree forest, border of rubber tree forest and farm, in Naban River Basin National Nature Reserve in 2015. Thirty-two invasive alien species were found in the five habitats, and more than 20 grasses were distributed on the border of rubber tree forest and farms. In contrast, only six species were found in natural forests. One-way ANOVA analysis results showed significant variance of diversity index among the five habitats. Based on least-significant difference analysis, species richness index (0.50), Shannon-Winner index (0.15), Simpson index (0.09) and Pielou evenness index (0.16) in natural forests were significantly lower than those in other habitats. Except for the eveness, the other indexes of invasive alien grasses in rubber forests were also significantly different from those in other habitats. The richness index of invasive alien grasses (5.50) in the farm was obviously higher than that in other habitats. The results of canonical correspondence analysis (CCA) showed that the species composition of invasive alien grasses were also different in the five habitats. CCA analysis implied that the distribution of invasive alien grasses was influenced by native tree and shrub richness and altitude.