Key Processes in CH₄ dynamics in wetlands and possible shifts with climate change

Wetlands are a substantial source of CH ₄ production due to emissions during anaerobic conditions in inundated sediments. Knowledge of the factors that affect CH ₄ flux in wetlands is very important in estimating CH ₄ dynamics and predicting future changes in global climate. This paper reviews approaches for the estimation of the controlling variables of CH ₄ dynamics in wetlands. CH ₄ emissions from wetlands are mainly dependent on the combined effects of temperature, water level, carbon supply, and presence/productivity of vegetation. Changes in temperature affect CH ₄ emission not only by a direct in fluence on methanogens but also by modifying the quantity of carbon substrates from primary production and organic matter decomposition. Water level fluctuation is another key factor affecting CH ₄ flux, which can modify methane dynamics by inhibiting or activating methanogens as well as methanotrophic bacteria. Vegetation functions as a conduit for CH ₄ release and a key carbon supplier for methanogens. Global climate change is expected to modify all of these factors in addition to contributing directly to CO ₂ emission and fertilization effects. The consequences of any changes in CO ₂ emission level from wetlands would be additional shifts in the amount and regional distribution of CH ₄ emissions from wetlands.