EGU25-11170, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-11170
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Evaluating soil CO2 fluxes during the transition from peat swamp forest to an oil palm plantation
Nur Azima Busman1, Muhammad Zarul Shazreen1, Faustina E. Sangok1, Akira Watanabe2, and Lulie Melling
Nur Azima Busman et al.
  • 1Sarawak Tropical Peat Research Institute, Kota Samarahan, Malaysia
  • 2Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan

The conversion of tropical peat swamp forests to oil palm plantations has significant implications for soil CO2 emissions. However, the extent of these changes remains highly uncertain, particularly across different stages of land-use conversion at a single site. Therefore, in this study, we present continuous measurements of soil CO2 flux, environmental conditions, and soil chemical properties from a peat swamp forest in Malaysia undergoing conversion to an oil palm plantation. The study, conducted from January 2011 to April 2022, encompasses three distinct phases: peat swamp forest (Jan 2011–Feb 2017), land preparation involving drainage, land clearing, and mechanical compaction (Mar 2017–Apr 2018), and oil palm plantation (May 2018–Apr 2022). Soil CO2 flux was measured on a monthly basis using the manual chamber method, and variations in environmental and soil chemical properties were also measured. Drainage during land preparation lowered the groundwater level (GWL) from −6.4 cm before conversion to −83.5 cm. The GWL further dropped to −112.8 cm in the first year of planting, then gradually increased from the second to the fourth year, reaching −65.7 cm. Air and soil temperatures also increased following conversion, peaking during the second year before starting to decrease in the third year of planting, possibly due to the growing of oil palm canopy. Soil total carbon and nitrogen contents remained unchanged throughout the study period, while the degree of humification and ash content increased after planting. Soil CO2 fluxes before conversion ranged from 30 to 403 mg C m−2 h−1, with no significant changes observed during land preparation (136–397 mg C m−2 h−1). However, soil CO2 fluxes increased during the first to the third year of oil palm planting (140–619 mg C m−2 h−1), followed by a decrease in the fourth year (140–368 mg C m−2 h−1). This decline may suggest that most of the labile carbon may have been lost during the first three years after planting. However, as this trend was observed only over one year, continued monitoring should be done. Soil CO2 flux showed a negative correlation with GWL before the conversion, but no such correlation was observed after conversion. This is likely due to the smaller variation in GWL following conversion, which is maintained by plantation management practices. Overall, our long-term measurements provide valuable insights into the temporal dynamics of soil CO2 flux during the conversion of tropical peat swamp forests to oil palm plantations, allowing for a more robust evaluation of the impacts of conversion.

How to cite: Busman, N. A., Shazreen, M. Z., Sangok, F. E., Watanabe, A., and Melling, L.: Evaluating soil CO2 fluxes during the transition from peat swamp forest to an oil palm plantation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11170, https://doi.org/10.5194/egusphere-egu25-11170, 2025.