How does land use change impact tropical peatland surface elevation changes?

Tropical peat swamp deforestation followed by extensive drainage and recurrence of fires leads to peat subsidence and subsequently carbon release to the atmosphere. While many previous studies have assessed the positive relationship between greenhouse gas (GHG) emissions and peat subsidence, an accurate field-based measurement of peat subsidence remains methodologically challenging. Between 2015 and 2020, we monitored peat subsidence (surface elevation change) in tropical peatlands of Central Kalimantan by using Rod Surface Elevation Table (RSET) installed across 22 locations representing range of land use types, including natural forest as reference. We observed that the largest net surface elevation loss was found in burned areas of -35.1 ± 87.2 mm yr^-1, followed by the drained peatland sites with -11.1 ± 16.9 mm yr^-1 and the agricultural impacted sites with -6.3 ± 13.1 mm yr^-1. Further, we observed substantial net surface elevation loss in secondary protected forests by -12.1 ± 77.2 mm yr^-1. By contrast, natural forest reference experienced net surface elevation loss as much as -8.8 ± 24.4 mm yr-¹. Our findings suggest that all the study sites in the tropical peatlands of Central Kalimantan have experienced net surface elevation loss with their degree of losses vary depending on past land use and current land management.

Keywords: peat subsidence, peat compaction, peat drainage, peat conversion, GHG emission