Diversity of tropical peat characteristics in intact peatland forest, under the influence of forest type, peat thickness, and position of peat deposit

The peatland ecosystem plays an important role and has unique ecological functions, such as carbon storage, supply and retention of water, landscape stabilisation, and biological habitats. Peatland is a fragile ecosystem, which is sensitive to disturbance. However, on the other hand, peatland in most areas has been developed for settlement and agriculture, especially in the tropical region. Development of peatland has changed those ecological functions, and subsequently has caused environmental damage. Prior to understanding degradation of peatland ecological function, peat characteristics should be fully understood. The peat characteristics depend on condition of parent material, under layer materials, and hydrology factors, which in natural condition, can be reflected by condition of vegetation, topographical landscape and thickness of peat accumulation. In this study peat samples were collected using the transect method along a logging extraction railway in the upper Sebangau catchment area, Central Kalimantan in both dry and wet seasons. Peat sampling locations were based on distance from river, forest type, and thickness of the peat deposit. Depth of water table and litter accumulation were measured during peat sampling. The peat samples were analysed for physical properties (moisture content, fiber content, bulk density, particle density, porosity, permeability, COLE value, and pF curve) and chemical properties (ash content, organic matter and organic carbon contents, pH, total N and total P contents, total cation and base saturation, and content of some trace elements). Study results showed that some peat properties could be used to explain peat characteristics in its natural condition, such as fibre content, bulk densiy and particle density, water retention curve, organic matter and organic carbon content. These parameters seem not to easily change under natural condition. However, changes in these properties were recorded with depth around the peat dome area under mixed swamp forest and low pole forest. Fibre content of shallow peat under riverine forest at the edge of the peat dome area was usually lower than that of medium and deep peat under mixed swamp and low pole forests at distance of 2-12 km from River Sebangau. The ash contents for shallow peats under riverine forest and mixed swamp forest near River Sebangau were higher than those of medium and deep peat in the middle area of the peat dome where the forest types were transition and low pole forests. The mean value of bulk density for shallow peat was lower than that of medium and deep peats. Organic matter contents for medium and deep peats were usually higher than those of shallow peat, which have maximum value of 56.75 to 57.22 percent by dry weight. Moisture content at low suction (pF=0) was 400 percent to 500 percent by dry weight