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| Titel |
Carbon dioxide emissions from an Acacia plantation on peatland in Sumatra, Indonesia |
| VerfasserIn |
J. Jauhiainen, A. Hooijer, S. E. Page |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 2 ; Nr. 9, no. 2 (2012-02-01), S.617-630 |
| Datensatznummer |
250006756
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| Publikation (Nr.) |
 copernicus.org/bg-9-617-2012.pdf |
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| Zusammenfassung |
| Peat surface CO2 emission, groundwater table depth and peat temperature
were monitored for two years along transects in an Acacia plantation on thick
tropical peat (>4 m) in Sumatra, Indonesia. A total of 2300 emission
measurements were taken at 144 locations, over a 2 year period. The
autotrophic root respiration component of CO2 emission was separated
from heterotrophic emission caused by peat oxidation in three ways: (i) by
comparing CO2 emissions within and beyond the tree rooting zone, (ii)
by comparing CO2 emissions with and without peat trenching (i.e.
cutting any roots remaining in the peat beyond the tree rooting zone), and
(iii) by comparing CO2 emissions before and after Acacia tree harvesting. On
average, the contribution of autotrophic respiration to daytime CO2
emission was 21% along transects in mature tree stands. At locations 0.5
m from trees this was up to 80% of the total emissions, but it was
negligible at locations more than 1.3 m away. This means that CO2
emission measurements well away from trees were free of any autotrophic
respiration contribution and thus represent only heterotrophic emissions. We
found daytime mean annual CO2 emission from peat oxidation alone of 94 t ha−1 y−1
at a mean water table depth of 0.8 m, and a minimum
emission value of 80 t ha−1 y−1 after correction for the effect of
diurnal temperature fluctuations, which may result in a 14.5% reduction
of the daytime emission. There is a positive correlation between mean
long-term water table depth and peat oxidation CO2 emission. However,
no such relation is found for instantaneous emission/water table depth
within transects and it is clear that factors other than water table depth
also affect peat oxidation and total CO2 emissions. The increase in the
temperature of the surface peat due to plantation establishment may explain
over 50% of peat oxidation emissions. Our study sets a standard for
greenhouse gas flux studies from tropical peatlands under different forms of
agricultural land management. It is the first to purposefully quantify
heterotrophic CO2 emissions resulting from tropical peat decomposition
by separating these from autotrophic emissions. It also provides the most
scientifically- and statistically-rigorous study to date of CO2
emissions resulting from anthropogenic modification of this globally
significant carbon rich ecosystem. Our findings indicate that past studies
have underestimated emissions from peatland plantations, with important
implications for the scale of greenhouse gas emissions arising from land use
change, particularly in the light of current, rapid agricultural conversion
of peatlands in the Southeast Asian region. |
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