Carbon budget and management strategies for conserving carbon in peatland: case study in Kubu Raya and Pontianak districts, West Kalimantan, Indonesia

Peatland of Indonesia is an increasingly important land resource for livelihood and economic development, despite its high carbon storage. While under the natural forest it serves as a carbon sink, it turns into a carbon source once the peat forest is cleared and drained. Therefore, strategies is needed for sustainably manage peatland and reduce emissions. This research, conducted in 2009 in the districts of Kubu Raya and Pontianak, West Kalimantan Province of Indonesia, has the following objectives (i) to evaluate land use changes in the peatland of the two districts, (ii) to assess carbon stock and green house gas emissions from various land use systems, and (iii) to recommend options for mitigating CO2 emission. Satellite imageries of 1986, 2002 and 2008 were used for the evaluation of land use changes. This was followed by field ground truth of land cover, and sampling and determination of carbon stock both in the peat and in the plant biomass, measurement of CO2 flux using a portable gas chromatography. Results showed that peatlands in the two districts, including those of >3 m thick, were used for various purposes such as the traditional slash and burn agriculture for maize, traditional and commercialized pineapple plantation, intensive vegetable agriculture, and plantations of rubber (mostly smallholders) and oil palm. Parts of the land are still forest and shrub, but the peat forest area shrunk from 393,000 ha in 1986 to 329,390 ha in 2008, while the shrubs increased from 9,427 to 23,814 in the same time period. Oil palm plantation and paddy field farming also increased rapidly. Among the various types of land uses, the slash and burn farming systems emitted the highest amount of CO2 per unit area due mainly to burning conducted for nourishing the soil and to emission from peat decomposition. Arson not only increases the emission of CO2 but also causes haze around Pontianak Supadio Airport and thus interrupting flight schedule. Emissions was also high on peat shrub and pineapple plantation and these seems to be attributed to a relatively open field, and thus a rise to the soil temperature. For this area, CO2 emission from oil palm plantation was not any higher than those of other land uses. Emission reduction can be done through various scenarios. Scenario I is compliance to the Minister of Agriculture Decree (Permentan No. 14/2009), which elucidated that in the future, no permit of agricultural land uses be granted on peatland of >3 m thick as well as on land outside of agricultural land allocation (APL). Enforcement of this decree is expected to reduce 5.5±3.5% of 2010 to 2035 cumulative CO2 emission from the 127±42 Mt of the business as usual (BAU) level. Scenario II, application of peat ameliorant such as 5-10 Mg ha-1 fine clay or steel slag for all agricultural and plantation lands on top of the Scenario I, is expected to reduce cumulative CO2 emission as much as 15.5±5.5% compared to the BAU. Scenario III is provision of fertilizer subsidy to replace the traditional burning technique in addition to Scenario II and this is expected to reduce emissions as much as 19±7%. Scenario IV, swapping the future agricultural extensification to mineral soil, is expected to lower the cumulative emissions as much as 19±7%. We recommend that the four scenarios be tested in the area and elsewhere in preparation for Reducing Emissions from Deforestation and Degradation++ (REDD++) scheme which is currently under the United Nations REDD discussions. The test is expected to provide information on the technical, legal, social and economic feasibility of REDD++.