Secondary community characteristics and interspecific associations in alpine meadow areas along the Qinghai-Tibet railway

Species composition and interspecific relationships determine the characteristics and dynamics of a community. In order to explore the influence of the Qinghai-Tibet Railway route on the alpine meadow plant community in the Qinghai-Tibet Plateau–along the Tanggula Mountain to Naqu section–plots were set at 5 m and 300 m, respectively from the railway. On the basis of the community survey of plots, the variance ratio method, the χ² test method and the Spearman rank correlation coefficient test were used to analyze the overall correlation and inter-species correlation of the vegetation community. The results show that: Compared with the non-engineered site, the species composition along the engineered site changed significantly. The number of species in the engineered site was less than that in the non-engineering site, but the number of drought-tolerant species increased in engineered site. The plants at the engineered site belonged to 17 families, 36 genera, and 46 species, whereas the plants at the non-engineered site comprised 18 families, 38 genera, and 54 species. The variance ratio test shows that the community of engineered and non-engineered site statistic W were 51.84 (χ² _0.95(36) = 23.27) and 42.09 ( χ² _0.05(36) = 51.00), indicating that the overall correlation degree of the community in the non-engineered site did not show a significant positive association, while the overall correlation degree of the communities at the engineered site showed a significant positive association. The correlation between the main species showed that compared with that in the non-engineered site, the positive correlation ratio between the species pairs at the engineered site is increased, and the degree of association among the species within the community is also increased. In general, the species composition of the secondary community in the engineered site has been dominated by drought-tolerant and barren-resistant plants in the past 10 years, and it is at a relatively stable stage in the succession process. It is difficult to restore the top alpine meadow community in either theshort- or long-term.