Land-use change in tropical peatland potentially results in a large amount of carbon dioxide (CO) emissions owing to drainage, which lowers groundwater level (GWL) and consequently enhances oxidative peat decomposition. However, field information on carbon balance is lacking for rubber plantations, which are expanding into Indonesia's peatlands. To assess soil CO emissions from an eight-year-old rubber plantation established on peat after compaction, soil CO efflux was measured monthly using a closed chamber system from December 2014 to December 2015, in which a strong El Niño event occurred, and consequently GWL lowered deeply. Total soil respiration (SR) and oxidative peat decomposition (PD) were separately quantified by trenching. In addition, peat surface elevation was measured to determine annual subsidence along with GWL. With GWL, SR showed a negative logarithmic relationship (p<0.01), whereas PD showed a strong negative linearity (p<0.001). Using the significant relationships, annual SR and PD were calculated from hourly GWL data to be 3293±1039 and 1408±214gCmyr (mean±1 standard deviation), respectively. PD accounted for 43% of SR on an annual basis. SR showed no significant difference between near and far positions from rubber trees (p>0.05). Peat surface elevation varied seasonally in almost parallel with GWL. After correcting for GWL difference, annual total subsidence was determined at 5.64±3.20 and 5.96±0.43cmyr outside and inside the trenching, respectively. Annual subsidence only through peat oxidation that was calculated from the annual PD, peat bulk density and peat carbon content was 1.50cmyr. As a result, oxidative peat decomposition accounted for 25% of total subsidence (5.96cmyr) on average on an annual basis. The contribution of peat oxidation was lower than those of previous studies probably because of compaction through land preparation.

The conservation measures of peat or peat maintain under natural conditions many proposed to address the increase in carbon emissions from land use change and efforts to minimize of fire, but it can not entirely implemented due to peat land has the potential for development of the agricultural commodities is supported by extensive area. Peatlands can be productive agricultural land with appropriate methods. Water management is required to regulate groundwater levels which is suitable for plants, nature conservation and restore hydrological conditions, such as reducing the vulnerability to fire. The percentage of water content vertically and functional groups of organic materials that have both hydrophilic and hydro phobic properties can be an indicator of vulner ability to fire. This research was conducted by survey method and then field sampling on land use rubber. Water management carried out with the installation of water-gate in the drainage channels (Tabat System). There are two experimental units in peatland, namely: 1) the drainage channel is equipped with the water-gate/Tabat (KST), Tabat size adjusted to the channel dimensions, and 2) there are no water-gate on the drainage channel (KNT). The parameters are observed of CO2 fluxes, ground water levels, water content and functional groups of organic matter. The purpose of this study was to determine the role of “tabat system” in mitigating CO2 emission sand vulner ability tofire. The results showed that the water management “tabat system” can reduce CO2 emissions by 47.6%, reducing hydrophobic properties of peat (0-50 cm soil depth) of 6.6% and is able to prevent loss of water-holding ability of fibric peat by 26.6%. This indicates that water management measures is required as one effort to maintain of peat to remain moist condition, so that changes in peat properties of hydrophilic become hydrophobic can be prevented, and reduce peat vulnerability to fire.Keywords: Carbon dioxide emissions, Peatland, Vulner ability to fire, Water management [How to Cite: Siti Nurzakiah, Nurita and Dedi Nursyamsi. 2016. Water Management “Tabat System” in Carbon Dioxide Mitigation and Vulnerability to Fire On Peatland. J Trop Soils 21: 41-47. Doi: 10.5400/jts.2016.21.1.41]

Peatland describes the typology of tidal and freshwater swamplands. Peatlands are affected by tidal activity; the water level fluctuation causes the peat to dry out and then get wet, which affects the soil’s water content and carbon emissions. Additionally, mineral enrichment from river overflows affects soil fertility and peat stability. Peat stability is importantly related to the peatland management for agriculture. Functional groups in the peat, such as carboxyl and hydroxyl, are volatile and easily transform, decomposing from CHO bonds into CO₂ under aerobic conditions. The characteristics of functional groups can be changed from polar to non-polar at the organic colloid surface, leading to hydrophobicity. This study evaluated carbon dioxide emissions and peat hydrophobicity. The research was conducted by survey and field sampling on two differently managed plots of peatlands: a rubber-and-pineapple intercrop plot and a traditionally-managed rubber plot. Parameters measured were CO₂ flux, groundwater levels, water content, and peat hydrophobicity. Peat hydrophobicity was assessed by analyzing certain functional groups using a Fourier-Transform Infrared (FTIR) spectrophotometer. The results showed that CO₂ emissions were 21.78 ± 5.44 (mg ha^-1yr^-1) for the rubber-and-pineapple intercrop and 19.15 ± 5.18 (mg ha^-1 yr^-1) for the traditionally-managed rubber plot. Peat hydrophobicity for both plots decreased with increasing soil depth, indicating that peat on the surface layer (0–50 cm) is more vulnerable to drought and fires, especially if there is no water management.

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Agricultural development on peatland in Indonesia has been constrained by the presence of environment issues in relation to the release of greenhouse gases (GHGs) particularly carbon dioxide (CO2) and methane (CH4) to the atmosphere. This study was aimed to predict the potential carbon emission based on carbon stocks in acrotelmic and catotelmic peats with the reference of groundwater level of peatland.  The results showed that groundwater levels have played an important  role  in  carbon  release, which  has  close  relationship  with  water  regime  of  the upper  layer  of  peats  that influenced by oxidative and reductive conditions of the land.  From the layer that having groundwater level fluctuations during the period from rainy to dry season (acrotelmic peat), the emissions were mostly dominated by CO2 release, while from permanent reductive-layer (catotelmic peat) was not detected.  The decrease of groundwater level from -49.6 to -109 cm has clearly influenced carbon emission.  From each decreasing 1.0 cm groundwater level, CO2 emission measured during the period of February - October 2013 was calculated to yield about 0.37 Mg ha-1 yr-1.Keywords: Acrotelmic and catotelmic peat, carbon emission, groundwater level [How to Cite: Siti N, S Sabiham, B Nugroho and Di Nursyamsi. 2014. Estimation of the Potential Carbon Emission from Acrotelmic and Catotelmic Peats. J Trop Soils 19(2): 91-99. Doi: 10.5400/jts.2014.19.2.91]