Warming increases microbial residue contribution to soil organic carbon in an alpine meadow

Abstract

The contribution of microbial residues to soil organic carbon (SOC) is a process highly influenced by soil properties. We evaluated the presence of microbial amino sugar residues in soil (0–50 cm) of control and warmed plots in an alpine meadow on the Qinghai-Tibet Plateau. Alpine grasslands in the Qinghai-Tibet Plateau store large amounts of soil C and are highly vulnerable to climate change. Results showed that warming significantly increased total microbial residues across the 0–50 cm soil depth. The proportion of microbial-derived C to SOC significantly increased in warmed plots (52% on average) by soil depth compared to the control (38%). Higher microbial turnover and selective preservation into organo-mineral complexes likely explains the observed result. Given insignificant change in total SOC, our results infer an alteration of the SOC source configuration (microbial-derived vs. plant-derived). The observed greater magnitude of warming effects on fungal residues compared to bacterial illustrate a distinct community response to warming. We conclude that warming has the potential to influence soil C sequestration through increased microbial residue inputs, consequently altering its composition and source configuration. Our work provides valuable insights at the molecular level to identify mechanisms of microbial-mediated C processes that are influenced by climate change in high elevation ecosystems.