Effects of rewetting of peatlands on GHG fluxes from the soils with different land-cover types

Deforestation followed by draining of tropical peat swamp forests are the most common disturbance regimes before further land development takes place. The severity and extent depend on a number of drivers that dictate how restoration should be performed. The permanent plots were established to monitor total ecosystem carbon stocks and greenhouse gases (CO₂, CH₄, N₂O) emissions from peatland under different vegetation cover, namely forest tree species, oil pal, and rubber plantations, and evaluate the effect of rewetting by blocking the drainage canals on GHG fluxes. We found that the mean total ecosystem carbon stocks at a reforested area, rubber and oil palm were 3983 + 318 Mg C ha^-1, 3363 + 207 Mg C ha^-1 and 3523 + 253 Mg C ha^-1 respectively. The average total soil emission of CO₂ during conditions before canal blocking in reforested areas, oil palm and rubber plantations were 10.93 Mg CO₂ ha^-1yr^-1, 16.66 Mg CO₂ ha^-1yr^-1 and 23.70 Mg CO₂ ha^-1yr^-1. After the canals were blocked, the average total CO2 emissions were 3.57 Mg CO₂ ha^-1yr^-1 in reforested area, 10.47 Mg CO₂ ha^-1yr^-1 in oil palm and 15.27 57 Mg CO₂ ha^-1yr^-1 in rubber plantation.

Methane (CH4) flux before blocking were (-0.10 + 0.84), (0.34 + 4.52), and (0.50 + 2.70) mg m^-2 hr^-1 in reforested area, oil palm and rubber plantation respectively, while the fluxes after blocking were (8.02 + 3.28), (5.36 + 6.13), and (0.64 + 1.19) mg m^-2 hr^-1 respectively. The increasing trends after blocking suggests that methanogenic bacteria were active in anaerobic. On the other hand, N2O decreased from (0.40 + 0.84), (0.40 + 0.84), and 0.40 + 0.84) mg m^-2 hr^-1 in forested area, oil palm and rubber plantations to (-0.20 + 0.27), (-0.45 + 2.08), and (2.15 + 0.25) mg m^-2 hr^-1 respectively.