Drainage and land use impacts on changes in selected peat properties and peat degradation in West Kalimantan Province, Indonesia

Abstract. Degradation of tropical peats is a global concern due to large Carbon emission and loss of biodiversity. The degradation of tropical peats usually starts when the government drains and clears peat forests into open peats used for food crops, oil palm and industrial timber plantations. Major properties of tropical peat forests are high in Water Contents (WC), Loss on Ignition (LOI) and Total Organic Carbon (TOC), and low in peat pH, Dry Bulk Density (DBD), and Total Nitrogen (TN). In this study, we investigated impacts of drainage and land use change on these properties. We collected peat samples from peat forests, logged over peat forest, industrial timber plantation, community agriculture, and oil palms. We used independent t-tests and oneway ANOVA to analyze mean differences of the research variables. We found that peat pH, DBD, and TN tend to increase. A significant decrease of C/N ratio in oil palm and agriculture sites importantly denotes a high rate of peat decompositions. Water contents, LOI, and TOC are relatively constants. We suggest that changes in pH, DBD, TN and atomic C/N ratio are important indicators for assessing tropical peat degradation. We infer that land use change from tropical peat forests into cleared and drained peats used for intensive timber harvesting, oil palms and industrial timber plantations in Indonesia has greatly degraded major ecological function of tropical peats as Carbon storage.