Verification of the stem CH₄ flux compilation of Zhao et al. (2026): corrected rows, training tables and code

Every entry of the stem CH₄ flux compilation deposited by Zhao et al. (2026; figshare 10.6084/m9.figshare.32050950) checked against its primary source, with our verdict, corrected values and the source of each correction; per-study decisions; random-forest training tables; and R code that rebuilds the tables, reconstructs the published model, performs the upscaling and tests the wetland estimates. Supports the Comment by Gewirtzman et al. on Zhao et al. (2026, Global Biogeochemical Cycles). See README.md.