| Indonesian peatlands cover ∼21 million ha and estimated to contain a substantial store of above, but especially below ground carbon (∼57.8 Gt). Kalimantan contains 5.9 million ha of peatlands ∼ 11% of Kalimantan's land area. Over the previous three decades, tropical peatland forests have experienced extensive conversion and forest degradation resulting in canopy cover loss that, in turn, affects carbon dynamics in several areas (i.e., source-sink dynamics, pools, and flows. Longitudinal assessments were conducted to investigate peat CO2 respiration within peatland forest, and across three most prominent land covers (drained, selectively logged forest, young oil palm plantation, and recently burned areas). Among the three land cover types, mean monthly CO2 respiration of peatland logged forest, oil palm, and post burned (Mean +/- SE) was 20.8 +/- 1.0; 23.7 +/- 1.3; and, 32.2 +/- 2.3 g CO2 m--2d --1 or 72.6, 86.5, and 117.3 Mg ha--1y --1. CO2 respiration within the logged forest and oil palm plantation area differed significantly from post burn area. Yet overall mean CO2 respiration at logged peatland forest was similar to young oil palm plantation where a constant water table is maintained. Although peat water level was found to significantly alter CO2 respiration at all sites, each land cover type had distinctive suite of environmental factors that significantly affect CO2 respiration.;Aboveground net primary production (ANPP) of tropical peatland forests is required to assess how peatlands function and to best estimate losses from land conversion and fires. Across 12 ha of coastal peatlands in West Kalimantan, aboveground carbon pools, growth and mortality of all stems (>1 cm dbh), fine litterfall, and coarse woody debris (CWD) across a peat depth gradient (2.5--5.4 m deep) was measured from 2005--2011. Soil carbon was quantified from 48 peat cores stratified across this site (i.e., 20 cm to 5m deep peat). In addition to CO2 respiration, we also estimated carbon losses through measured dissolved carbon water export into adjacent streamlets.;Coastal peatland ANPP is relatively high (21.2 +/- 1.0 Mg ha --1y--1) despite relatively low aboveground biomass (124.4 +/- 6.4 Mg ha--1) especially when compared with lowland mixed dipterocarp forest (518 +/- 28 Mg ha --1). Living biomass, CWD (standing and ground), and above ground litter pools combined represent an above ground C pool of 276.6 Mg CO 2-e ha--1. Belowground carbon stock was quantified by peat depth: ∼ 499 Mg ha--1m --1 in 2.6 - 5.4 m deep peat (Range: 1,296.75 to 2,693.25 Mg C ha--1) for an overall mean ∼ 6,400 Mg CO2- e h--1. During the relatively mild 2006 ENSO, rainfall decreased significantly (>3mo with <100mm). Litter production increased 17% -- 24% and a 2-fold increase in CWD occurred when compared with non-ENSO periods (2005 -- 2011). Peat heterotrophic respiration appears to regulate carbon budgets in peatlands contributing ∼91% of carbon loss. Among three categories of canopy cover (closed canopy: 60% gaps) and three peat depth groupings (2.5-3.5m, 3.5-4.5m, and >4.5m), significant interaction effects on CO2 respiration were detected. The highest CO2 respiration rates were recorded on shallow peat and open canopy sites. With 38.3 Mg CO 2-e ha--1y--1 total inputs and 59.6 Mg CO2-e ha--1 y--1 combined outputs, estimated forest carbon flows indicate -21.3 Mg CO2-e ha--1 y--1. This negative balance is projected to cause a loss of at least 3.0 cm peat layer depth per year. Thus, this peatland forest was found to serve as a source of carbon emissions to atmosphere rather than a carbon sink. |
