Tropical Peatland of the World
In the tropics peat occurs mostly in sub coastal lowlands and is formed from rainforest trees and associated higher plants. There are regional differences in the plant species involved and there are also changes with increase in altitude with a tendency to lower growing and more low temperature tolerant plants. The best estimate of the area of tropical peatland is 441,025 km2 which is about 11 of the global peatland resource, although there is a wide range of estimate from 387,201 to 657, 430 km2 depending upon whether or not all Histosols and shallow organic soils are included. Current inventories of peatland area, peat thickness and carbon stores leave much to be desired and their accuracy varies not only from region to region but also country to country. The largest area of tropical peatland and peat carbon store is in Southeast Asia with 56 of the former and 77 of the latter owing to the large extent of peatlands and the considerable thickness of peat (regularly exceeding 10 m) in this region. Following Southeast Asia, South America contains the next largest area (24 of peatland but a smaller proportion of the global tropical peatland carbon store because of the thinner peat deposits. Africa contributes 13 of the global area and 8 of the carbon store, while Central America and the Caribbean, Mainland Asia and Australia and the Pacific contribute only 5 1 and <1 respectively and only 3 of the carbon store, collectively. Tropical peatlands are now being subjected to intensive land use change and conversion to forms of agriculture including commercial plantations. This is well advanced in Southeast Asia, especially Indonesia and Malaysia where most of the peatland area has already been deforested, drained and converted often using fire as a land clearance tool. Apart from losses of biodiversity there have been immense emissions of greenhouse gases and large losses of carbon from the peat store, contributing to climate change processes. Other regions are further behind in these environmentally damaging impacts on the tropical peatland resource.