Carbon Dioxide and Methane Fluxes in Drained Tropical Peat Before and After Hydrological Restoration

Abstract

Present tropical peat deposits are the outcome of net carbon removal from the atmosphere and form one of the largest terrestrial organic carbon stores on the Earth. Reclamation of pristine tropical peatland areas in Southeast Asia increased strikingly during the last half of the 20th century. Drainage due to land-use change is one of the main driving factors accelerating carbon loss from the ecosystem. Dams were built in drainage-affected peatland area canals in Central Kalimantan, Indonesia, in order to evaluate major patterns in gaseous carbon dioxide and methane fluxes and in peat hydrology immediately before and after hydrologic restoration. The sites included peat swamp forest and deforested burned area, both affected by drainage for nearly 10 years. Higher annual minimum soil water table levels prevailed on both sites after restoration; the deforested site water table level prevailed considerably longer near the peat surface, and the forest water table level remained for a longer period in the topmost 30 cm peat profile after restoration. Forest soil gas fluxes were clearly higher in comparison to the deforested area. Cumulative forest floor CO2 emissions (7305-7444 g x m(-2) x yr(-1); 166.0-169.2 mol CO2 x m(-2) x yr(-1)) and the deforested site CO2 emissions (2781-2608 g x m(-2) x yr(-1); 63.2-59.3 mol CO2 x m(-2) x yr(-1)) did not markedly reflect the notably differing hydrological conditions the year before and after restoration. The forest floor was a weak CH4 sink (-0.208 to -0.368 g x m(-2) x yr(-1); -13.0 to -22.9 mmol CH4 x m(-2) x yr(-1)) and the deforested site a comparable CH4 source (0.197-0.275 g x m(-2) x yr(-1); 12.3-17.1 mmol CH4 x m(-2) x yr(-1)) in the study period. In general, higher soil water table levels had a relatively small effect on the annual CH4 emission budgets. In the two site types the gas flux response into hydrological conditions in degraded tropical peat can be attributed to differing CO2 and CH4 dynamics, peat physical characteristics, and vegetation.

Methane fluxes from waterlogged and drained Histosols of highland areas

“…In general, the results of CH 4 emission reduction followed by methane consumption fully agree with those of other studies that evaluated the effect of lowering the water-table level by draining in flooded soils in several parts of the world Nykanen et al, 1995;Maljanen et al, 2004;von Arnold et al, 2005;Furukawa et al, 2005;Bridgham et al, 2006;Elder & Lal, 2008;Jauhiainen et al, 2008;Jiang et al, 2009;Huang et al, 2010;Page & Dalal, 2011). All these authors showed that small water-table decreases cause drastic reductions in methane emissions, demonstrating the strong effect of drainage on CH 4 fluxes.…”

“…These processes are regulated by oxygen (O 2 ) supply and availability of labile carbon (C), being methanogenesis predominant under anaerobic conditions. The CH 4 flux in waterlogged areas is controlled by soil properties and processes (Roulet & Moore, 1995;Whalen, 2005;Jauhiainen et al, 2008), by microbiological factors (Le Mer & Roger, 2001;Kögel-Knabner et al, 2010;Page & Dalal, 2011), climatic factors (von Arnold et al, 2005;Dalal & Allen, 2008;Jiang et al, 2009), vegetation Koh et al, 2009) and land management (Elder & Lal, 2008;Huang et al, 2010). Precipitation and air temperature are important climatic factors that can affect soil CH 4 emissions, although with great variability (Le Mer & Roger, 2001;Whalen, 2005;Dalal & Allen, 2008;Koh et al, 2009;Huang et al, 2010).…”

“…The water-table level and its fluctuation alter the intensity and duration of CH 4 production and oxidation processes von Arnold et al, 2005;Jauhiainen et al, 2008). Methane production reaches a maximum near 20 cm below the water-table, while oxidation occurs to a depth of 10 cm (Kettunen et al, 1999).…”

Planning hydrological restoration of peatlands in Indonesia to mitigate carbon dioxide emissions

“…Therefore, one of the most important peatland restoration measures is blocking of drainage canals by dams and thus raising the groundwater level of the surrounding peatland. Damming activities performed in the former Mega Rice Project area, in Sebangau National Park and in Merang peatland of South Sumatra have shown that the water retention upstream of dams could be increased thereby decreasing peat desiccation during the dry season (Suryadiputra et al 2005;CKPP 2008;Jauhiainen et al 2008). Few rehabilitation attempts have been undertaken in the past , however within the context of ongoing discussions concerning climate change tropical peatlands have now been recognised as major sources of greenhouse gas emissions (Rieley and Page 2005;Hooijer et al 2006;Uryu et al 2008).…”

Status of Peatland Degradation and Development in Sumatra and Kalimantan

“…Jauhiainen et al 2005) and disturbed (e.g. Hirano et al 2007;Jauhiainen et al 2008) conditions are needed for estimation of gas emissions with potentially global consequences. However, the results of small-scale studies cannot be reliably propagated to the regional level without large-scale high spatial resolution assessments of the overall status of degradation and development in the peatland areas.…”