Interactions between labile carbon, temperature and land use regulate carbon dioxide and methane production in tropical peat

Tropical peatlands are a significant carbon store and contribute to global carbon dioxide (CO2) and methane (CH4) emissions. Tropical peatlands are threatened by both land use and climate change, including the alteration of regional precipitation patterns, and the 3-4 degrees C predicted warming by 2100. Plant communities in tropical peatlands can regulate greenhouse gas (GHG) fluxes through labile carbon inputs, but the extent to which these inputs regulate the temperature response of CO2 and CH4 production in tropical peat remains unclear. We conducted an anoxic incubation experiment using three peat types of contrasting botanical origin to assess how carbon addition affects the temperature response (Q(10)) of CO2 and CH4 production. Peats from forested peatlands in Panama and Malaysia, and a converted oil palm and pineapple intercropping system in Malaysia, differed significantly in redox potential, total carbon and carbon: nitrogen ratio. The production of CO2 and CH4 varied significantly among peat types and increased with increasing temperature, with Q(10)s for both gases of 1.4. Carbon addition further increased gas fluxes, but did not influence the Q(10) for CO2 or CH4 production or significantly affect the Q(10) of either gas. These findings demonstrate that the production of CO2 and CH4 in tropical peat is sensitive to warming and varies among peat types, but that the effect of root inputs in altering Q(10) appears to be limited.