Stocks and fluxes of carbon associated with land use change in Southeast Asian tropical peatlands: A review

Abstract

[1] The increasing and alarming trend of degradation and deforestation of tropical peat swamp forests may contribute greatly to climate change. Estimates of carbon (C) losses associated with land use change in tropical peatlands are needed. To assess these losses we examined C stocks and peat C fluxes in virgin peat swamp forests and tropical peatlands affected by six common types of land use. Phytomass C loss from the conversion of virgin peat swamp forest to logged forest, fire-damaged forest, mixed croplands and shrublands, rice field, oil palm plantation, and Acacia plantation were calculated using the stock difference method and estimated at 116.9 ± 39.8, 151.6 ± 36.0, 204.1 ± 28.6, 214.9 ± 28.4, 188.1 ± 29.8, and 191.7 ± 28.5 Mg C ha −1 , respectively. Total C loss from uncontrolled fires ranged from 289.5 ± 68.1 Mg C ha −1 in rice fields to 436.2 ± 77.0 Mg C ha −1 in virgin peat swamp forest. We assessed the effects of land use change on C stocks in the peat by looking at how the change in vegetation cover altered the main C inputs (litterfall and root mortality) and outputs (heterotrophic respiration, CH 4 flux, fires, and soluble and physical removal) before and after conversion. The difference between the soil input-output balances in the virgin peat swamp forest and in the oil palm plantation gave an estimate of peat C loss of 10.8 ± 3.5 Mg C ha −1 yr −1 . Peat C loss from other land use conversions could not be assessed due to lack of data, principally on soil heterotrophic respiration rates. Over 25 years, the conversion of tropical virgin peat swamp forest into oil palm plantation represents a total C loss from both biomass and peat of 427.2 ± 90.7 Mg C ha −1 or 17.1 ± 3.6 Mg C ha. In all situations, peat C loss contributed more than 63% to total C loss, demonstrating the urgent need in terms of the atmospheric greenhouse gas burden to protect tropical virgin peat swamp forests from land use change and fires.

Carbon dioxide emissions from an <i>Acacia</i> plantation on peatland in Sumatra, Indonesia

“…The autotrophic respiration contribution of 21 % to the total CO 2 emission in mature tree stands is much lower than the previous values suggested for oil palm plantations on peatland, which range from 46 % (Melling et al, 2007), to 36 % (Murdiyarso et al, 2010) and29 % (Hergoualc'h andVerchot, 2011). This difference may be caused by the fact that these earlier studies and reviews were based on very small numbers of measurements (at only one location in the case of Murdiyarso et al (2010) referring to work by Melling et al, 2005), that were not specifically set up to separate autotrophic from heterotrophic CO 2 emissions, i.e.…”

Potential climate forcing of land use and land cover change

“…We assume that natural CH 4 emissions remain unchanged from 1850 through 2100 for all scenarios. Finally, there is a source of CO 2 from deforestation and forest degradation in tropical peat swamp forests that has only recently been widely recognized (Hergoualc'h and Verchot, 2011), although it is thought that contributions from this source to current global CO 2 concentrations are small .…”

Observing and understanding the Southeast Asian aerosol system by remote sensing: An initial review and analysis for the Seven Southeast Asian Studies (7SEAS) program

“…Geochemical cycles: Aerosol particles are a significant component to a host of geochemical cycles, such as carbon , and trace elements (Langmann and Graf, 2003;He and Balasubramanian, 2009a). The carbon pools of SEA, especially in relation to peatland, are tremendous (Hergoualch and Verchot, 2011). Tracers: Used as imagery or tracer products, aerosol particles are indicators of air-mass types, magnitude and transport mechanisms (Gutman et al, 2000;Ji and Stocker, 2002;Duncan et al, 2003b;Lin et al, 2007;Xian et al, 2013-this issue).…”