Unraveling Spatially\nDiverse and Interactive Regulatory\nMechanisms of Wetland Methane Fluxes to Improve Emission Estimation

Methane fluxes (FCH<sub>4</sub>) vary significantly across\nwetland\necosystems due to complex mechanisms, challenging accurate estimations.\nThe interactions among environmental drivers, while crucial in regulating\nFCH<sub>4</sub>, have not been well understood. Here, the interactive\neffects of six environmental drivers on FCH<sub>4</sub> were first\nanalyzed using 396,322 half-hourly measurements from 22 sites across\nvarious wetland types and climate zones. Results reveal that soil\ntemperature, latent heat turbulent flux, and ecosystem respiration\nprimarily exerted direct effects on FCH<sub>4</sub>, while air temperature\nand gross primary productivity mainly exerted indirect effects by\ninteracting with other drivers. Significant spatial variability in\nFCH<sub>4</sub> regulatory mechanisms was highlighted, with different\ndrivers demonstrated varying direct, indirect, and total effects among\nsites. This spatial variability was then linked to site-specific annual-average\nair temperature (17.7%) and water table (9.0%) conditions, allowing\nthe categorization of CH<sub>4</sub> sources into four groups with\nidentified critical drivers. An improved estimation approach using\na random forest model with three critical drivers was consequently\nproposed, offering accurate FCH<sub>4</sub> predictions with fewer\ninput requirements. By explicitly accounting for environmental interactions\nand interpreting spatial variability, this study enhances our understanding\nof the mechanisms regulating CH<sub>4</sub> emissions, contributing\nto more efficient modeling and estimation of wetland FCH<sub>4</sub>.