Effects of Different Disturbance Types on Plant Stoichiometric Characteristics in Subalpine Meadows of Northwest Yunnan

To clarify the effects of different disturbance regimes on plant nutrient balance and limitation characteristics in subalpine meadows, this study took the subalpine meadows in Diqing Prefecture, Yunnan Province as the research object, and analyzed the regulatory effects of five disturbance regimes (grazing, fencing, fencing + burning, fencing + fertilization, and fencing + burning + fertilization) on the ecological stoichiometric characteristics and stoichiometric ratios of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) in grassland plant communities. The results showed that disturbance regimes significantly altered plant nutrient contents (C, N, P, K) and their stoichiometric relationships. The enclosure + fertilization treatment yielded the highest C and N contents. The enclosure + fire + fertilization treatment also increased C, N, and P contents, with the most pronounced increase observed for P. The grazing treatment decreased C, N, and P contents but increased K content. The enclosure + fire treatment reduced all measured plant nutrient contents (C, N, P, K), indicating nutrient loss under both grazing and enclosure with fire. Stoichiometric ratio analysis revealed that the N:P ratio (21.9) and C:P ratio (369.96) of plants in the study area were both higher than the average levels of grassland ecosystems in China, indicating that plant growth is primarily limited by P.Correlation analysis further indicated a highly significant positive correlation between plant C and N, reflecting synergistic accumulation. In contrast, C and N were significantly negatively correlated with K, indicating an antagonistic relationship between the assimilation of C and N and the uptake of K. In summary, disturbance measures significantly regulated plant nutrient accumulation and limitation patterns.Enclosure + fertilization is beneficial for promoting C and N retention in plants, whereas enclosure + fire + fertilization can synergistically enhance C, N, and P contents, effectively alleviating P limitation. These integrated measures represent viable strategies for the restoration and grazing management of local subalpine meadows.