2023 article

Nitrogen availability mediates soil carbon cycling response to climate warming: A meta-analysis

Bai, T., Wang, P., Qiu, Y., Zhang, Y., & Hu, S. (2023, February 26). GLOBAL CHANGE BIOLOGY.

By: T. Bai*, P. Wang*, Y. Qiu*, Y. Zhang* & S. Hu n

author keywords: climate warming; meta-analysis; root biomass; soil C stock; soil C; N ratio; soil respiration
MeSH headings : Ecosystem; Soil; Nitrogen / analysis; Carbon Dioxide; Biomass; Carbon
Source: Web Of Science
Added: March 27, 2023

Global climate warming may induce a positive feedback through increasing soil carbon (C) release to the atmosphere. Although warming can affect both C input to and output from soil, direct and convincing evidence illustrating that warming induces a net change in soil C is still lacking. We synthesized the results from field warming experiments at 165 sites across the globe and found that climate warming had no significant effect on soil C stock. On average, warming significantly increased root biomass and soil respiration, but warming effects on root biomass and soil respiration strongly depended on soil nitrogen (N) availability. Under high N availability (soil C:N ratio < 15), warming had no significant effect on root biomass, but promoted the coupling between effect sizes of root biomass and soil C stock. Under relative N limitation (soil C:N ratio > 15), warming significantly enhanced root biomass. However, the enhancement of root biomass did not induce a corresponding C accumulation in soil, possibly because warming promoted microbial CO2 release that offset the increased root C input. Also, reactive N input alleviated warming-induced C loss from soil, but elevated atmospheric CO2 or precipitation increase/reduction did not. Together, our findings indicate that the relative availability of soil C to N (i.e., soil C:N ratio) critically mediates warming effects on soil C dynamics, suggesting that its incorporation into C-climate models may improve the prediction of soil C cycling under future global warming scenarios.