Ecological stoichiometry and driving factors of soil carbon, nitrogen, and phosphorus in the alpine marsh wetlands of Qinghai Qilian Mountain National Park

Alpine marsh wetlands in the Qilian Mountain National Park of Qinghai are important components in the ecosystem of the Qinghai-Xizang Plateau． Ecological stoichiometries of soil carbon (C), nitrogen (N), and phosphorus (P) in this region are crucial to the understanding of alpine wetland ecological processes and nutrient cycling mechanisms. In this study, 54 soil samples with different degrees of degradation and from varied soil depths were collected． One-way ANOVA was used to evaluate effects of degradation degree and soil layer depth on C, N, and P content and their ecological stoichiometric ratios． Multiple regression and hierarchical segmentation methods were used to explore driving mechanisms of topography, climate, soil, and vegetation factors on ecological stoichiometric characteristics． As wetland degradation intensifies, soil organic carbon, total nitrogen, and total phosphorus content decrease by 28.1%, 36.6%, and 36.3%, respectively, with n(C)/n(P) and n(N)/n(P) ratios decreasing but n(C)/n(N) ratios increasing． Both element content and stoichiometric ratios were found to decrease with increasing soil depth． n(C)/n(N) and n(N)/n(P) ratios suggest nitrogen limitation in the soil, while the n(C)/n(P) ratio indicates relatively sufficient phosphorus． Soil ecological stoichiometric characteristics are driven by multiple factors, with n(C)/n(N) being primarily influenced by soil properties (35.19% contribution), n(C)/n(P) regulated by vegetation-soil interactions (29.12% and 28.17%), and n(N)/n(P) mainly controlled by climate factors (34.78%)． In summary, nutrient element cycling characteristics in alpine marsh wetland ecosystems are identified, insights into the coupled relationships of C, N, and P in alpine wetland ecosystems, nutrient limitation mechanisms, and ecological responses are provided．