Carbon Dioxide emissions from Tropical Peat swamp Forests: A review of Processes and Controls with special emphasis to Indonesia

Abstract

The paper in hand is a review of research findings focusing on emission of GHG especially CO2 both in natural and manmade settings across topical peat swamp forests. Since the inception of Kyoto protocol there has been growing interest to maintain and restore C-Stocks at Ecosystem scale (Forest, Savanna, Grasslands, and Peatlands etc.). Therefore avoiding degradation and over exploitation of carbon reservoirs in unsustainable ways has been research focus of scientist across the world. In this paper we conclude the state of the art research by discussing the ecosystem processes contributing to Peatlands both as source and sinks of CO2, the debate of methodological issues pertaining to CO2 emission calculation i.e. distinguishing soil, root respiration, fire and decomposition emitted CO2 (being natural ecosystem functions) from carbon lost in drainage, subsidence, land use change (as manmade scenarios), differentiating C-loss from CO2 emission and finally discussing the opportunities and threats to Indonesian Peatlands being potential carbon pools i.e. the carbon dynamics in a land use change scenario from Peatlands to other land uses such as palm oil, rubber, acacia, rice etc. has been discussed across the country. The paper concludes by recommending soil and biomass carbon stock difference approach as proxy to be the most reliable and convenient method for GHG estimation. Introduction Globally, peatlands cover an area of 400 million hectare, which is equivalent to 3% of the Earth's land area. These ecosystems store a large fraction of terrestrial carbon, as much as 528 Pg (Pg ¼ 1 × 1015 g), or one-third of global soil carbon (Murdiyarso., et al 2010). Lowland peatlands in Southeast Asia cover 24.78 Million hectares (Mha), which is 56% of the tropical and 6% of the global peatland area (Jauhiainen., et al 2012). Forested tropical peatlands in Southeast Asia store at least 42,000 Million metric tons (Mt) of soil carbon(Hooijer., et al 2010). Tropical peatland forests are changing rapidly to meet the food demands of the growing population and economic development (Inubushi., et al 2007). Their high peat carbon density, however, gives rise to the large regional peat carbon store of 68.5 Gt, equivalent to 77% of the tropical and 11% of the global carbon store.One-third of the carbon stored in peatlands (191 Pg) is located in the tropics,of which 60% is in Southeast Asia with an estimated area of 25 million hectare (Mha). The majority (84%) of Southeast Asian peatlands are found in Indonesia (around 21 Mha), whereas Malaysia harbors 2–2.5 Mha. Thailand has around 45,000 ha, and relatively small areas are found in Vietnam, Brunei, and the Philippines (Murdiyarso., et al 2010). Page., et al 2011 estimated tropical peatland area to be 439,238 km2 (~11% of global peatland area) of which 247,778 km2 (57%) is in Southeast Asia; volume of tropical peat as 1,756 Gm3 (~22-33% of global peat volume) with the highest share in Southeast Asia (77%).This new assessment reveals a larger tropical peatland carbon pool than past estimates, with a best estimate of 88.5 Gt (range 81.5-91.8 Gt) equal to 17-19% of the global