Assessment of variability of peat physico-chemical properties, subsidence and their interactions within Selangor forests

Tropical peat swamp forests are carbon rich ecosystems both above- and below-ground, which play a major role in the climate balance of the earth. The majority of the world’s tropical peat forest cover is located in Southeast Asia and is increasingly threatened by anthropogenic disturbances. Despite their importance for biodiversity conservation and climatic balance of the earth, pristine peatlands are almost extinct in many parts of Southeast Asia. Peninsular Malaysia is one such region, where there are no undisturbed peatlands left in the west coast. We studied the largest peat forest area in the west coast of Malaysia, located in the state of Selangor. We evaluated variability of peat subsidence (for 1 year), peat physico-chemical properties and macronutrient contents between forest regions and between different depths (not for subsidence) covering the top 50 cm, and the complex interactions between them. We found that there was significant peat subsidence in all the studied regions, however there was no significant difference in subsidence between different forest regions. Physico-chemical properties such as peat moisture, pH and C content, and all macronutrient contents except P, either varied between regions, or showed significant interactions between region and depth in Selangor peat forests. All the measured peat physico-chemical properties varied with depth. Among macronutrients, only N, P, and Ca showed significant change with depth, while there were no changes with depth for S, K and Mg contents. These changes in each peat physico-chemical property and macronutrient contents correlated with changes in other peat-physicochemical properties and nutrient contents, however there is a need for controlled experiments to further understand these significant interactions. The findings show continued carbon loss in secondary peat swamp forests through subsidence, indicating the long-term impact of selective logging and associated historical drainage. The significant variability of peat physico-chemical properties and macronutrient contents with region and depth, also show the need for intensive sampling to characterise large secondary peat swamp forests