Study: Rewetting in Oil Palm Plantations Has the Potential to Reduce Emissions

Peatland restoration efforts through rewetting bring positive impacts for climate change mitigation “Our research also found that rewetting interventions through the construction of canal blocks in oil palm plantations on peatlands significantly reduce carbon dioxide emissions with no effect on methane emissions,” said Nisa Novita, the lead researcher and Senior Manager of Forest Carbon and Climate at Yayasan Konservasi Alam Nusantara (YKAN), in Jakarta, September 11, 2024.

This data is the result of research conducted by YKAN in collaboration with Tanjungpura University, IPB University, the National Research and Innovation Agency (BRIN), the Ministry of Environment and Forestry, Stanford University, the United Nations University, Oregon State University, and The Nature Conservancy. The results have been published in the journal *Science of The Total Environment* under the title "Strong Climate Mitigation Potential of Rewetting Oil Palm Plantations on Tropical Peatlands," which was published on August 26, 2024 (https://doi.org/10.1016/j.scitotenv.2024.175829).

The research stems from several decades during which tropical peatlands in Indonesia have experienced deforestation and conversion to other land uses, primarily oil palm plantations. Peatlands are known to be the largest carbon sink in the soil compared to tropical forests on mineral lands or mangroves. Drained and degraded peatlands are estimated to contribute up to 5 percent of global greenhouse gas emissions caused by human activities.

Wahyu Catur Adinugroho, Principal Expert at the Center for Ecology and Ethnobiology-BRIN and one of the researchers involved, stated that while several studies have examined the impact of rewetting degraded peatlands, there has been limited research on measuring emissions reductions from these activities. Therefore, the quantification of rewetting interventions’ contributions to nationally determined emission reductions (NDCs) is still lacking. The second FRL Indonesia report (2022) also did not include the mitigation potential of peatland restoration interventions due to limited available data. FRL stands for Forest Reference Level, which indicates the performance of Emissions Reductions from Deforestation and Forest Degradation Plus (REDD+).

Building on this experience, the research aimed to accurately measure the emissions reductions from these efforts. “We conducted this study to precisely calculate the emissions reductions from rewetting degraded peatlands,” Wahyu Catur said on a separate occasion.

The researchers conducted their study in three different areas: drained oil palm plantations, rewet oil palm plantations, and secondary forests that have regrown after damage. The research locations were in Mempawah and Kubu Raya regencies, West Kalimantan. The researchers measured greenhouse gas fluxes in the form of carbon dioxide and methane using dynamic closed chamber methods, including measuring soil temperature, groundwater levels, and other climate parameters.

“Our study found that rewetting through canal block construction can reduce peat decomposition rates by 34 percent compared to non-rewet peatlands,” Wahyu Catur said. However, he added, rewetting in oil palm plantations did not increase methane emissions.

This study is a positive development for Indonesia as it strives to meet its emission reduction targets, especially through natural climate solutions. Natural climate solutions are a series of mitigation efforts based on natural resources, including forest and wetland protection, improved forest management, and ecosystem restoration of forests, peatlands, and mangroves.

The researchers estimate that the contribution to emission reductions could reach 13 percent of the total potential for natural climate solutions mitigation. “Indeed, intact peatlands bring far more climate benefits compared to the restoration of degraded peatlands. But this rewetting effort has already proven beneficial. Thus, it is expected to contribute to achieving the national emission reduction targets,” Nisa concluded.