Ze Ren , Hongkai Gao, Wei Luo, James J. Elser

Glaciers are among the least explored environments on Earth, especially from a perspective of nutrient stoichiometry. In this study, we documented and compared the nutrient availabilities (concentrations) and composition (stoichiometric ratios) of nutrients (C, N, and P) in six distinct habitats of a glacier terminus in the Yangtze River Source area, 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 forefront soil with well-developed vegetation (VS). The results showed that SI had significantly higher DOC and N concentrations as well as higher C:P and N:P ratios than BI. However, BI had significantly higher SRP than SI. In addition, both SI and BI had very high C:P and N:P ratios, suggesting P-limitation. For sediment/soil in glacier terminus, nitrogen and organic carbon concentrations were significantly lower in BaS, TS, and DS than in VS. Moreover, TP and SRP concentrations were significantly 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 limitation, VS had a significantly higher C:N, C:P, and N:P ratios than BaS, TS, and DS, supporting a long-held biogeochemical and ecological paradigm that ecosystem processes during early successional stages are primarily organic C and N limited but are P-limited in later successional stages. Considering that glaciers cover around 10% of the terrestrial landmass and are experiencing severe retreat, documenting and comparing nutrient contents and stoichiometry in glacier terminus can further our understanding of global biogeochemical cycles under future climate change regimes.