C:N:P stoichiometry in six distinct habitats of a glacier terminus in the source area of the Yangtze River

Glaciers are among the least explored environments on Earth, especially from a perspective of nutrient stoichiometry. Here, we documented and compared the nutrient concentrations and stoichiometric ratios in six distinct habitats of a glacier terminus in the source area of the Yangtze River, including surface ice (SI), basal ice (BI), basal sediment (BaS), newly exposed forefront soil close to glacial terminus (TS), soil at increasing distances from glacier terminus (DS), and soil with well-developed vegetation (VS). The results showed that SI had higher dissolve organic carbon (DOC) and nitrogen (N) concentrations as well as higher C:P (carbon:phosphorus) and N:P ratios than BI. However, BI had higher soluble reactive P (SRP) than SI. In addition, both SI and BI had very high C:P and N:P ratios, suggesting P-limitation. For sediment/soil along the chronosequence, total N (TN) and organic carbon (SOC) concentrations were lower in BaS, TS, and DS than in VS. Moreover, SRP concentration was higher in BaS and VS than in TS and DS. These nutrient patterns could be explained by differences in biotic influence in soil development or by changes in soil physical properties. With regard to nutrient stoichiometry, BaS, TS, and DS had low SOC:TN ratios but high dissolved inorganic N (DIN):SRP ratios. Considering both nutrient concentrations (high SOC and N but very low SRP) and stoichiometric ratios (low SOC:TN but high DIN:SRP), our data support an interpretation that P-limitation is dominant along the entire chronosequence following deglaciation. Considering that glaciers are experiencing severe retreat, this study can further our understanding and prediction of global biogeochemical cycles under future climate change.