A synthesis of methane emissions from 71 northern, temperate, and subtropical wetlands

摘要: Wetlands are the largest natural source of atmospheric methane. Here, we assess controls on methane flux using a database approximately 19 000 instantaneous measurements from 71 wetland sites located across subtropical, temperate, and northern high latitude regions. Our analyses confirm general emissions soil temperature, water table, vegetation, but also show that these relationships modified depending type (bog, fen, or swamp), region (subarctic to temperate), disturbance. Fen was more sensitive vegetation less temperature than bog swamp fluxes. The optimal table for consistently below peat surface in bogs, close poor fens, above rich fens. However, bogs occurred when dry 30-day averaged antecedent conditions were followed by wet conditions, while fens swamps, both current wet. Drained wetlands exhibited distinct characteristics, e.g. absence large following warm suggesting same functional between environmental cannot be used pristine disturbed wetlands. Together, our results suggest dominant other processes, such as vascular transport have potential partially override effect types. Because types vary controls, ecosystems need considered separately yield reliable estimates global release.