Strong climate mitigation potential of rewetting oil palm plantations on tropical peatlands
Nisa Novita, Adibtya Asyhari, Rasis Putra Ritonga, Adi Gangga, Gusti Z. Anshari, Joni Jupesta, Jennifer C. Bowen, Nurul Silva Lestari, J. Boone Kauffman, Alison M. Hoyt, Clarice R. Perryman, Israr Albar, Chandra Agung Septiadi Putra, Wahyu Catur Adinugroho, Bondan Winarno, Miguel Castro, Samantha Yeo, Tryan Budiarna, Eko Yuono, Velyn C. Sianipar
Abstract
For decades, tropical peatlands in Indonesia have been deforested and converted to other land uses, mainly oil palm plantations which now cover one-fourth of the degraded peatland area. Given that the capacity for peatland ecosystems to store carbon depends largely on hydrology, there is a growing interest in rewetting degraded peatlands to shift them back to a carbon sink. Recent estimates suggest that peatland rewetting may contribute up to 13 % of Indonesia's total mitigation potential from natural climate solutions. In this study, we measured CO 2 and CH 4 fluxes, soil temperature, and water table level (WTL) for drained oil palm plantations, rewetted oil palm plantations, and secondary forests located in the Mempawah and Kubu Raya Regencies of West Kalimantan, Indonesia. We found that peatland rewetting significantly reduced peat CO 2 emissions, though CH 4 uptake was not significantly different in rewetted peatland compared to drained peatland. Rewetting drained peatlands on oil palm plantations reduced heterotrophic respiration by 34 % and total respiration by 20 %. Our results suggest that rewetting drained oil palm plantations will not achieve low CO 2 emissions as observed in secondary forests due to differences in vegetation or land management. However, extrapolating our results to the areas of degraded oil palm plantations in West Kalimantan suggests that successful peatland rewetting could still reduce emissions by 3.9 MtCO 2 yr −1 . This result confirms that rewetting oil palm plantations in tropical peatlands is an effective natural climate solution for achieving national emission reduction targets. • Peatland rewetting significantly lowered CO 2 fluxes with no clear shifts in CH 4 . • Rewetting in oil palm plantations reduced heterotrophic respiration by 34 %. • Rewetting in oil palm plantations reduced total soil respiration by 20 %. • In our case, rewetting will not reach the reference CO 2 emissions in the forest. • New country-level emission factors for rewetting can be improved from this study.