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| Titel |
Net soil respiration and greenhouse gas balance along a sequence of forest disturbance to smallholder rubber and oil palm plantations in Sumatra |
| VerfasserIn |
Fitri Khusyu Aini, Kristell Hergoualc'h, Jo Smith, Louis Verchot, Christopher Martius |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250153813
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| Publikation (Nr.) |
 EGU/EGU2017-18836.pdf |
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| Zusammenfassung |
| The rapid increase in demand for land to establish oil palm and rubber plantations has led to
the conversion of forests, with potential impacts on greenhouse gas emissions and on
climate change. This study evaluates the net greenhouse gas balance following
forest change to other land uses, i.e. one year rubber plantation, twenty-year rubber
plantation and eight year oil palm plantation on Sumatran mineral soils. None of
the plantations had ever been fertilized previously. During this study they were
fertilized to provide nitrogen at the recommended rate used by farmers (33.3 kg
N ha−1 y−1). The ecosystem stores carbon in litterfall, standing litter biomass
(undergrowth vegetation, leaves, twigs, litter on the soil surface), soil organic matter, root
biomass, and standing tree biomass. It releases carbon to the atmosphere through
soil respiration fluxes, negative values indicating that carbon is stored by the land
use change and positive values indicating emissions to the atmosphere. Net soil
respiration was assessed using a mass balance approach: standing litter and tree biomass
were measured once; the rate of carbon accumulation from standing litter and tree
biomass was calculated by dividing the stock by the age of plantation or the time since
logging started in the disturbed forest. The carbon accumulation in standing litter, tree
biomass in the forest and soil organic matter for all land-uses was estimated from
available in the literature. Root biomass for each land-use system was calculated
using the root:shoot ratio. The net soil respiration of carbon dioxide from the forest,
disturbed forest, one year rubber plantation, twenty-year rubber plantation and oil palm
plantation were calculated to be -6 (± 5), 12 (± 6), 11 (± 15), 10 (± 5), 39 (± 7) Mg
ha−1 y−1, respectively. Soil nitrous oxide, methane and litterfall were measured for
14 months and respiration fluxes were measured for 5 months across land uses
and different seasons. The measured emissions of greenhouse gases were similar
across land use systems; for nitrous oxide in the forest, disturbed forest, one year
rubber plantation, twenty-year rubber plantation and eight year oil palm plantation,
respectively, 17.3 (± 0.2), 1.2 (± 0.1), 1.3 (± 0.2), 1.0 (± 0.1) and 1.0 (± 0.2) kg N ha−1
y−1; for methane, -1.4 (± 1.0), 0.4 (± 0.9), -1.7 (± 0.7), -0.2 (± 0.3) and 0.2 (±
0.7) kg C ha−1 y−1; and for carbon dioxide, 13 (± 1), 13 (± 1), 16 (± 2), 14 (±
1) and 17 (± 2) Mg C ha−1 y−1). The overall greenhouse gas balance in carbon
dioxide equivalents was significantly lower in the forest (-5 (± 5) Mg ha−1 y−1)
than in the oil palm plantation (40 (± 7) Mg ha−1 y−1). There was no significant
difference in the overall greenhouse gas balance of the disturbed forest, one year
rubber plantation and twenty-year rubber plantation (12 (± 17) Mg ha−1 y−1),
but this was also significantly lower than in the oil palm plantation. The overall
results support the assertion that the undisturbed forest conserves carbon dioxide
and has a negative greenhouse gas balance, while oil palm plantations lead to net
emissions.
Keywords: land-use change, global warming potential, carbon flux change, methane,
nitrous oxide, carbon dioxide |
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