Significant sedge-mediated methane emissions from degraded tropical peatlands

Sedge-mediated gas transport to the atmosphere has been recognized as a significant CH4 pathway in northern peatlands; however, in the Tropics, this pathway remains unquantified. In Southeast Asia, degraded tropical peatlands covered with sedges and ferns have increased to approximately 10% of the total peatland area due to an increased drainage and fires. In view of this, we investigated the role of sedge, Scleria sumatrensis, in CH4 emissions from a fire-degraded tropical peatland in Brunei. At our site, we found that this sedge-mediated transport contributed >70% of the total CH4 emission, making it a significant CH4 emission pathway. We also observed significant seasonal and spatial variation with values ranging from 0.78 +/- 0.14 to 4.86 +/- 0.66 mgCH(4) m(-2) h(-1). This variation was mainly attributed to water table level along with changes in sedge cover and pore-water properties (pH, salinity, cations, and anions). More importantly, these numbers are three times higher when compared to intact peat-swamp forests and 17 times higher when compared to similar degraded tropical peatland covered with shrubs.

Automated summary

The role of sedge in CH4 emissions, especially in degraded tropical peatlands, is significant. Studies have shown that sedge contributes over 70% of total CH4 emissions and displays significant seasonal and spatial variations.