Effects of disturbances on the carbon balance of tropical peat swamp forests

Abstract

Tropical peatlands have accumulated huge soil carbon over millennia. However, the carbon pool is presently disturbed on a large scale by land development and management, and consequently has become vulnerable. Peat degradation occurs most rapidly and massively in Indonesia, because of fires, drainage, and deforestation of swamp forests coexisting with tropical peat. Peat burning releases carbon dioxide (CO2) intensively but occasionally, whereas drainage increases CO2 emission steadily through the acceleration of aerobic peat decomposition. Therefore, tropical peatlands present the threat of switching from a carbon sink to a carbon source to the atmosphere. However, the ecosystem‐scale carbon exchange is still not known in tropical peatlands. A long‐term field experiment in Central Kalimantan, Indonesia showed that tropical peat ecosystems, including a relatively intact peat swamp forest with little drainage (UF), a drained swamp forest (DF), and a drained burnt swamp forest (DB), functioned as net carbon sources. Mean annual net ecosystem CO2 exchange (NEE) (± a standard deviation) for 4 years from July 2004 to July 2008 was 174 ± 203, 328 ± 204 and 499 ± 72 gC m−2 yr−1, respectively, for the UF, DF, and DB sites. The carbon emissions increased according to disturbance degrees. We found that the carbon balance of each ecosystem was chiefly controlled by groundwater level (GWL). The NEE showed a linear relationship with GWL on an annual basis. The relationships suggest that annual CO2 emissions increase by 79–238 gC m−2 every 0.1 m of GWL lowering probably because of the enhancement of oxidative peat decomposition. In addition, CO2 uptake by vegetation photosynthesis was reduced by shading due to dense smoke from peat fires ignited accidentally or for agricultural practices. Our results may indicate that tropical peatland ecosystems are no longer a carbon sink under the pressure of human activities.

Root oxygen loss from Raphia taedigera palms mediates greenhouse gas emissions in lowland neotropical peatlands

“…GWP 20: CH 4 = 86, N 2 O = 268; GWP 100 : CH 4 = 34, N 2 O = 298 observation of CO 2 emissions declining with agricultural land use change contrasts with previous research showing increasing CO 2 emissions in areas were land use change is associated with a lowering of the water table (Furukawa et al 2005;Hatala et al 2012;Hirano et al 2012). This highlights the critical role of the water table regulating CO 2 emissions from tropical peatlands in the context of land use change.…”

Aquatic DOC export from subarctic Atlantic blanket bog in Norway is controlled by seasalt deposition, temperature and precipitation

“…A tool like the combined hydrological-biogeochemical model INCA-C (Futter et al 2007) could be useful in this setting, as there are many studies of peatland NEE where quantification of aquatic carbon export is lacking, thus limiting the possibility to improve peatland NECBs (Aurela et al 2002(Aurela et al , 2007(Aurela et al , 2009Beetz et al 2013;Campbell et al 2014;Elsgaard et al 2012;Hirano et al 2012;Lund et al 2007Lund et al , 2015McVeigh et al 2014;Mezbahuddin et al 2014;Peichl et al 2014;Sagerfors et al 2008). INCA-C can be used for quantification of aquatic DOC fluxes in catchments with limited observations for empirical quantification of DOC fluxes, and has been successfully calibrated for a number for small headwater catchments, with single and mixed land cover in various climate conditions (Futter and de Wit 2008;Futter et al 2009).…”

“…Many more studies have quantified NEE for peatlands, but not aquatic carbon export, i.e., in subarctic (Aurela et al 2002;Lund et al 2015), boreal (Aurela et al 2007(Aurela et al , 2009Peichl et al 2014;Sagerfors et al 2008), tropical (Hirano et al 2012;Mezbahuddin et al 2014), and temperate peatlands (Beetz et al 2013;Campbell et al 2014;Elsgaard et al 2012;Lund et al 2007;McVeigh et al 2014). Despite the lack of quantification of key components of NECB, several studies claimed to quantify the carbon sink strength of these peatlands (Campbell et al 2014;Hirano et al 2012;Hommeltenberg et al 2014).…”

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).…”