C, N, P Stoichiometric Characteristics and Influencing Factors of Plants and Soils in Altai Wetland, Xinjiang, China

To investigate the ecological stoichiometric relationship between plant and soil carbon, nitrogen, and phosphorus content, as well as their association with environmental factors in Altai Wetland, Xinjiang, we conducted field investigations, sampling, measurements, and analyses in both alpine marsh and plain marsh areas. The findings can be summarized as follows: (1) Soil organic carbon, total nitrogen, carbon-to-phosphorus ratio, and nitrogen-to-phosphorus ratio in the Altai mountain marsh soil were significantly higher than those in the plain marsh soil. However, the carbon, nitrogen and phosphorus in plants and their stoichiometric ratios did not show similar patterns. (2) In Altai, the growth of wetland plants was primarily limited by nitrogen, while alpine marsh soil was predominantly limited by phosphorus, and plain marsh soil exhibited a relative shortage of both nitrogen and phosphorus. (3) Soil environmental factors regulated plant phosphorus content, carbon-to-phosphorus ratio, and nitrogen-to-phosphorus ratio. Phosphorus content showed a significant positive correlation with soil water content and precipitation, but a negative correlation with temperature. (4) Air temperature, precipitation, soil bulk density, and soil water content had significant impacts on soil organic carbon, total nitrogen, total phosphorus, carbon-to-phosphorus ratio, and nitrogen-to-phosphorus ratio. All these elements and their stoichiometric ratios were significantly and negatively correlated with soil bulk density and air temperature, while showing a significantly positive correlation with soil water content and precipitation. (5) Stoichiometric interactions of carbon, nitrogen and phosphorus were observed in the plant-soil system of Altai Wetland, with soil elements regulating plant phosphorus content. The findings provide significant implications for understanding the vegetation and soil nutrient status, as well as the limiting factors in different types of wetlands in the region. Moreover, this research provides a scientific basis for the regulation of nutrients in the wetland ecosystem in the area.