TY  - JOUR
A1  - Dommain, René
A1  - Frolking, Steve
A1  - Jeltsch-Thömmes, Aurich
A1  - Joos, Fortunat Ulrich
A1  - Couwenberg, John
A1  - Glaser, Paul H.
T1  - A radiative forcing analysis of tropical peatlands before and after their conversion to agricultural plantations
JF  - Global change biology
N2  - The tropical peat swamp forests of South-East Asia are being rapidly converted to agricultural plantations of oil palm and Acacia creating a significant global “hot-spot” for CO2 emissions. However, the effect of this major perturbation has yet to be quantified in terms of global warming potential (GWP) and the Earth's radiative budget. We used a GWP analysis and an impulse-response model of radiative forcing to quantify the climate forcing of this shift from a long-term carbon sink to a net source of greenhouse gases (CO2 and CH4). In the GWP analysis, five tropical peatlands were sinks in terms of their CO2 equivalent fluxes while they remained undisturbed. However, their drainage and conversion to oil palm and Acacia plantations produced a dramatic shift to very strong net CO2-equivalent sources. The induced losses of peat carbon are ~20× greater than the natural CO2 sequestration rates. In contrast, a radiative forcing model indicates that the magnitude of this shift from a net cooling to warming effect is ultimately related to the size of an individual peatland's carbon pool. The continuous accumulation of carbon in pristine tropical peatlands produced a progressively negative radiative forcing (i.e., cooling) that ranged from −2.1 to −6.7 nW/m2 per hectare peatland by 2010 CE, referenced to zero at the time of peat initiation. Peatland conversion to plantations leads to an immediate shift from negative to positive trend in radiative forcing (i.e., warming). If drainage persists, peak warming ranges from +3.3 to +8.7 nW/m2 per hectare of drained peatland. More importantly, this net warming impact on the Earth's radiation budget will persist for centuries to millennia after all the peat has been oxidized to CO2. This previously unreported and undesirable impact on the Earth's radiative balance provides a scientific rationale for conserving tropical peatlands in their pristine state.
KW  - Acacia plantation
KW  - CO2 emissions
KW  - drainage-based land use
KW  - global warming potential
KW  - oil palm plantation
KW  - radiative forcing
KW  - tropical peatland
Y1  - 2018
U6  - https://doi.org/10.1111/gcb.14400
SN  - 1354-1013
SN  - 1365-2486
VL  - 24
IS  - 11
SP  - 5518
EP  - 5533
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Brothers, Soren M.
A1  - Hilt, Sabine
A1  - Attermeyer, Katrin
A1  - Grossart, Hans-Peter
A1  - Kosten, Sarian
A1  - Lischke, Betty
A1  - Mehner, Thomas
A1  - Meyer, Nils
A1  - Scharnweber, Inga Kristin
A1  - Köhler, Jan
T1  - A regime shift from macrophyte to phytoplankton dominance enhances carbon burial in a shallow, eutrophic lake
JF  - Ecosphere : the magazine of the International Ecology University
N2  - Ecological regime shifts and carbon cycling in aquatic systems have both been subject to increasing attention in recent years, yet the direct connection between these topics has remained poorly understood. A four-fold increase in sedimentation rates was observed within the past 50 years in a shallow eutrophic lake with no surface in-or outflows. This change coincided with an ecological regime shift involving the complete loss of submerged macrophytes, leading to a more turbid, phytoplankton-dominated state. To determine whether the increase in carbon (C) burial resulted from a comprehensive transformation of C cycling pathways in parallel to this regime shift, we compared the annual C balances (mass balance and ecosystem budget) of this turbid lake to a similar nearby lake with submerged macrophytes, a higher transparency, and similar nutrient concentrations. C balances indicated that roughly 80% of the C input was permanently buried in the turbid lake sediments, compared to 40% in the clearer macrophyte-dominated lake. This was due to a higher measured C burial efficiency in the turbid lake, which could be explained by lower benthic C mineralization rates. These lower mineralization rates were associated with a decrease in benthic oxygen availability coinciding with the loss of submerged macrophytes. In contrast to previous assumptions that a regime shift to phytoplankton dominance decreases lake heterotrophy by boosting whole-lake primary production, our results suggest that an equivalent net metabolic shift may also result from lower C mineralization rates in a shallow, turbid lake. The widespread occurrence of such shifts may thus fundamentally alter the role of shallow lakes in the global C cycle, away from channeling terrestrial C to the atmosphere and towards burying an increasing amount of C.
KW  - calcite precipitation
KW  - CO2 emissions
KW  - global carbon cycle
KW  - metabolism
KW  - regime shift
KW  - sedimentation
KW  - submerged macrophytes
KW  - temperate zone
KW  - trophic status
Y1  - 2013
U6  - https://doi.org/10.1890/ES13-00247.1
SN  - 2150-8925
VL  - 4
IS  - 11
PB  - Wiley
CY  - Washington
ER  -