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

Abstract

Tropical peatlands are a significant carbon store and contribute to global carbon dioxide (CO 2) and methane (CH 4) emissions. Tropical peatlands are threatened by both land use and climate change, including the alteration of regional precipitation patterns, and the 3-4°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 CO 2 and CH 4 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 CO 2 and CH 4 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 CO 2 and CH 4 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 CO 2 or CH 4 production or significantly affect the Q 10 of either gas. These findings demonstrate that the production of CO 2 and CH 4 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. Keywords Tropical peat Á Carbon dioxide Á Methane Á Root exudates Á Land use change Á Temperature sensitivity

Peat Properties, Dominant Vegetation Type and Microbial Community Structure in a Tropical Peatland

“…2a). High methanotroph abundance would also imply large CH 4 production, which has previously been reported from both in situ and ex situ studies of CH 4 production/ fluxes (Girkin et al 2018b;Girkin et al, 2018;Sjögersten et al 2011).…”

Spatial variability of surface peat properties and carbon emissions in a tropical peatland oil palm monoculture during a dry season

“…Redox potential is lower in Proximal than in Distal areas, which may be related to increased need of oxygen for living cells in oil palm rhizosphere (Husson, 2013). Redox potential in all the sampling zones in this study was higher than have been observed in a pristine tropical peatland in Peninsular Malaysia (Girkin et al, 2020a), and only the Ditch zone had higher redox potential than oil palm and pineapple intercropping system in the same region (Girkin et al, 2020a). The higher Redox potential in the ditch may be because of the higher water and oxygen availability in that zone (Figure 3).…”

Root oxygen mitigates methane fluxes in tropical peatlands

“…Root inputs of oxygen varied significantly between species which, combined with different litter chemistry, exerts a key limitation on rates of decomposition. Differences between species are significant in the context of global land use and climate change, as shifts in peatland plant community composition may alter regional patterns of GHG fluxes through changes in root oxygen inputs, and elevated temperatures can drive substantial increases in CH 4 production [45,46]. As a consequence, we propose that plants have an important role in reducing peat CH 4 fluxes through root inputs of oxygen, and should be included in future models of GHG emissions from tropical peatlands.…”