Temperature patterns of soil carbon: nitrogen: phosphorus stoichiometry along the 400 mm isohyet in China

Abstract

Responses of terrestrial ecosystems to global warming have gained widespread attention. Soil carbon: nitrogen: phosphorus (C:N:P) stoichiometry regulate various functions and services in terrestrial ecosystems. Investigating the stoichiometric changes of soil C:N:P along the temperature gradient provides valuable insights into the long-term impacts of global warming. However, the inconsistent results were found in previous studies. The collinearity between temperature and precipitation might account for it since the variation in precipitation was rarely limited in previous studies. To make the precipitation effect become minimized, we conducted a 6000-km soil investigation along the 400 mm isohyet in China with a broad mean annual temperature (MAT) range of 14.2 °C. Soil C, N and P concentrations and soil C:N, C:P and N:P ratios all decreased with increasing MAT. Most of these temperature patterns were not affected by vegetation type and soil type, which indicated that the decreasing trends of soil C:N:P stoichiometry with increasing temperature might be common phenomena. MAT is the most important influential factor of soil C and N concentrations and soil C:P and N:P ratios along the temperature gradient; and soil properties, vegetation and soil types also exerted some effects on the changes of soil C and N concentrations and soil C:P and N:P ratios. For soil P, its variation was jointly influenced by MAT, soil properties, vegetation and soil types. The change of soil C:N ratio was mainly influenced by MAT and vegetation type. Furthermore, the decreased soil C:P and N:P ratios with increasing MAT indicated that soil C and N lowered faster than soil P as temperature increased, leading to the imbalanced soil C-N-P.