Carbon dioxide emissions through oxidative peat decomposition on a burnt tropical peatland

Abstract

In Southeast Asia, a huge amount of peat has accumulated under swamp forests over millennia. Fires have been widely used for land clearing after timber extraction, thus land conversion and land management with logging and drainage are strongly associated with fire activity. During recent El Niño years, tropical peatlands have been severely fire-affected and peatland fires enlarged. To investigate the impact of peat fires on the regional and global carbon balances, it is crucial to assess not only direct carbon emissions through peat combustion but also oxidative peat decomposition after fires. However, there is little information on the carbon dynamics of tropical peat damaged by fires. Therefore, we continuously measured soil CO2 efflux [peat respiration (RP)] through oxidative peat decomposition using six automated chambers on a burnt peat area, from which about 0.7 m of the upper peat had been lost during two fires, in Central Kalimantan, Indonesia. The RP showed a clear seasonal variation with higher values in the dry season. The RP increased logarithmically as groundwater level (GWL) lowered. Temperature sensitivity or Q10 of RP decreased as GWL lowered, mainly because the vertical distribution of RP would shift downward with the expansion of an unsaturated soil zone. Although soil temperature at the burnt open area was higher than that in a near peat swamp forest, model simulation suggests that the effect of temperature rise on RP is small. Annual gap-filled RP was 382 ± 82 (the mean ± 1 SD of six chambers) and 362 ± 74 gC m(-2) yr(-1) during 2004-2005 and during 2005-2006 years, respectively. Simulated RP showed a significant negative relationship with GWL on an annual basis, which suggests that every GWL lowering by 0.1 m causes additional RP of 89 gC m(-2) yr(-1) . The RP accounted for 21-24% of ecosystem respiration on an annual basis.

Comparison of Gross Primary Productivity Derived from GIMMS NDVI3g, GIMMS, and MODIS in Southeast Asia

“…The observations for eight forest sites across Southeast Asia (Table 1 [ [65][66][67][68][69][70][71][72][73][74], Figure 2) were used to assess the performance of the modeled GPP and the remote sensing based FPAR in this study. (1) GPP Validation Data GPP validation was conducted for two levels: (1) seasonal variability using the daily GPP data from the Qianyanzhou (QYZ) site of ChinaFlux and the Palangkaraya (PDF) site of AsiaFlux; (2) annual GPP magnitude with data derived from the literature for eight flux towers ( Table 1).…”

Tropical peat decomposability expressed through physical, chemical and biological properties under varying land management intensities

“…At PSFs, dead tree roots, stems and branches are major contributors to peat formation (Andriesse 1988;Wüst et al 2008;Hoyos-Santillan et al 2015), while the most important factor regulating peat decomposition is a high water table level (WTL) that limits oxygen availability for aerobic decomposers (Clymo 1984;Laiho 2006;Jauhiainen et al 2016a). Decomposition is most efficient in the surface peat above the WTL, where recent litter deposits and sufficient oxygen availability support aerobic decomposition (Clymo 1984;Yule & Gomez 2009;Sundari et al 2012;Hirano et al 2014;Hoyos-Santillan et al 2016). Litter modified progressively by decomposition processes close to the surface will eventually be topped by more recent litter, and subsequently become buried deeper in the peat profile.…”

“…Drainage is a requirement for the successful growth of most cultivated plants, because a lower WTL improves aeration in the rooting zone, while also potentiating aerobic decomposition deeper in the peat profile (Sundari et al 2012;Hirano et al 2014;Jauhiainen et al 2016a). Decomposition process releases nutrients for use of vegetation and soil biota, but enhanced nutrient release in aerobic conditions also increase CO2 emission.…”

“…Additionally, as a consequence of drainage and strong El Niño years leading to prolonged droughts, wild fires have become one of the greatest modifiers of peat in large areas of Southeast Asia during the past decades (Konecny et al 2016;Page et al 2016). The recurrent fire events surfaces progressively older peat from the deeper depths in the peat profile, as the topmost peat is impacted and consumed in the burning processes (Hoscilo et al 2011;Hirano et al 2014). However, peat physical properties have not been systematically compared for several differing land management types.…”

Environmental Biophysics and CO2 Emission in Bare Peatland for Sustainable Biomass Production

“…Faktor-faktor lingkungan yang sangat berpengaruh terhadap besarnya emisi karbon dari lahan gambut adalah suhu dan kelembapan tanah, serta electrical conductivity (EC), atau daya hantar listrik (Saiz et al 2007;Setia et al 2011). Ketiga faktor ini sangat berfluktuasi dari hari ke hari tergantung dari faktor iklim dan hidrologis sehingga berdampak pada tingginya fluktuasi emisi karbon (Hirano et al 2014;Jauhiainen et al 2014;Marwanto & Agus 2014). Untuk itu diperlukan usahausaha untuk melakukan pengukuran dan monitoring emisi CO 2 dari lahan gambut dan parameter lingkungan biofisik yang memengaruhinya.…”