Effects of tourism disturbance and altitudinal gradient on leaf and soil ecological stoichiometry of a mountain meadow in Altai Mountains, China

Exploring the variation laws and coupling relationships of carbon (C), nitrogen (N), and phosphorus (P) content and their ratios in plant leaves and soil along altitudinal gradients can provide insight into grassland ecosystem stability and maintenance mechanisms under tourism disturbance. To identify spatial heterogeneity and compare tourism disturbance intensity, we set four group plots (1 300 m, 1 500 m, 1 700 m, and 1 900 m group, each group including tourism disturbance plot and no tourism disturbance plot, totaling 8 plots) from 2015 to 2017 in the Kanas Scenic Area, Xinjiang, China. We investigated the C, N, and P content in leaves and their ratios in the dominant species and main companion species and soil ecological stoichiometry characteristics of the 0 − 20 cm layer, and analyzed the correlation between leaf and soil ecological stoichiometry. The results were as follows: 1) Leaf C, N, and P content decreased, and C/N, C/P, and N/P increased under tourism disturbance. Soil C, N, and P content and their ratios all decreased under tourism disturbance in the 0 − 20 cm layer. However, the decreased ranges of soil N and P content and N/P were not significantly different from those of the no-disturbance plots; 2) Leaf C, N, and P content increased and C/N, C/P, and N/P decreased with increasing altitudinal gradient in the no-disturbance plots. Tourism disturbance altered the changing trends of leaf stoichiometry characteristics. In all plots, soil C content and C/N decreased, soil N content and N/P increased, and soil P content and C/P did not change. However, tourism disturbance barely altered the changing trends of soil stoichiometry characteristics; 3) In all plots, leaf N content was positively correlated with soil C content and C/N. Leaf P content was positively correlated with soil C/P. Leaf C/P was negatively correlated with soil C/P. Leaf C content was not significantly correlated with soil ecological stoichiometry. In high-altitude plots, leaf N/P was negatively correlated with soil C content, C/N, and C/P. With regard to spatial variations of leaf and soil ecological stoichiometry, leaf and soil ecological stoichiometry were correlated along the altitudinal gradient. Tourism disturbance altered the spatial heterogeneity of leaf stoichiometry characteristics along the altitudinal gradient, and the influence on the soil stoichiometry characteristics was negligible. These findings improve our understanding of the influence of tourism disturbance on leaf and soil ecological stoichiometry, stability, as well as the maintenance mechanism of the mountain meadow ecosystem.