Asymmetric responses of soil dissolved organic carbon and dissolved organic nitrogen to warming: A meta-analysis

Soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) play pivotal roles in regulating soil carbon and nitrogen cycles. The global effects of experimental warming on DOC and DON concentrations and their relationship (DOC:DON) remain uncertain. This study integrates a dataset containing 321 separate DOC and 187 DON independent experiments to address the magnitude and direction of warming’s impact on DOC and DON, as well as the key driving factors. Our results indicated that while warming did not significantly affect DOC concentrations, it led to a notable increase in DON concentrations (8.84%), consequently reducing DOC:DON ratio by 10.79%. Soil moisture emerged as the most influential factor (19.0%) driving DOC responses to warming, whereas soil nitrate nitrogen was the primary driver (33.2%) of DON responses to warming. Soil ammonium nitrogen exhibited a positive linear relationship with the DOC:DON ratio, while soil nitrate nitrogen responded negatively as the DOC:DON ratio increased. Our results revealed the complex responses of carbon and nitrogen cycles to warming, including their decoupling patterns. This finding highlights the sensitivity and adaptability of soil carbon and nitrogen cycles to experimental warming, uncovers that warming could disrupt the soil carbon and nitrogen balance, potentially affecting ecosystem stability and function.