Nitrous oxide fluxes from tropical peat with different disturbance history and management

[摘要] Tropical peatlands are one of the most important terrestrial ecosystems interms of impact on the atmospheric greenhouse gas composition. Currently,greenhouse gas emissions from tropical peatlands following disturbances dueto deforestation, drainage or wildfire are substantial. We quantified in situnitrous oxide (N₂O) fluxes during both dry and wet seasons using aclosed chamber method at sites that represented differing land uses and landuse change intensities in Central Kalimantan, Indonesia. Cumulative N₂Ofluxes were compared with carbon dioxide (CO₂) and methane (CH₄)fluxes.

The mean N₂O flux rates (N₂O-N ±: SD, mg m⁻² h⁻¹)varied as follows: drained forest (0.112 ± 0.293) > agricultural peatat the Kalampangan site (0.012 ± 0.026) > drained burned peat(0.011 ± 0.018) > agricultural peat at the Marang site (0.0072 ± 0.028) >undrained forest (0.0025 ± 0.053) > clear-felled, drained,recovering forest (0.0022 ± 0.021). The widest N₂O flux range wasdetected in the drained forest (max. 2.312 andmin. −0.043 mg N₂O-N m⁻² h⁻¹). At the other flux monitoring sites the flux rangesremained at about one tenth that of the drained forest site. The highestN₂O emission rates were observed at water tables close to the peatsurface where also the flux range was widest. Annual cumulative peatsurface N₂O emissions (expressed in CO₂ equivalents as apercentage of the total greenhouse gas (N₂O, CO₂ and CH₄)emissions) were 9.2 % at highest, but typically ~1 %. AverageN₂O fluxes and also the total of monitored GHG emissions were highestin drainage-affected forest which is characterized by continuous labilenitrogen availability from vegetation, and water tables typically below thesurface.

[学科分类] 地球化学与岩石