Precipitation overrides warming with additive effects on greenhouse gas fluxes in an alpine meadow

Ecosystem greenhouse gas (GHG) fluxes are strongly regulated by climate change, particularly global warming and precipitation changes. However, their combined effects on carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) fluxes in alpine meadows remain unknown. Therefore, a two-factor experiment with six treatments: control (CK), decreased precipitation by 50% (0.5P), increased precipitation by 50% (1.5P), decreased precipitation by 50% and warming (0.5PW), warming (W), increased precipitation by 50% and warming (1.5PW) was adopted for the alpine meadow. Our two-year observations revealed that warming significantly enhanced the cumulative CH₄ uptake while showing no significant effects on ecosystem respiration (ER) or N₂O fluxes. Precipitation changes markedly influenced ER and cumulative CH₄ fluxes: increased precipitation enhanced ER while decreased precipitation reduced it, whereas CH₄ flux responses depended strongly on inherent soil moisture conditions. Neither warming nor precipitation changes significantly influenced N₂O fluxes. Soil moisture was significantly correlated with all GHG fluxes, including ER, indicating its crucial role in regulating emissions. Interactive effects between precipitation changes and warming generally exhibited additive patterns across the three GHGs, except for the combination of increased precipitation and warming which demonstrated antagonistic effects on ER in 2024. While additive interactions suggest single-factor studies provide valuable insights for multifactor scenarios, this assumption may not hold in years of highly erratic precipitation.