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| Titel |
Subsidence and carbon loss in drained tropical peatlands |
| VerfasserIn |
A. Hooijer, S. Page, J. Jauhiainen, W. A. Lee, X. X. Lu, A. Idris, G. Anshari |
| 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. 3 ; Nr. 9, no. 3 (2012-03-20), S.1053-1071 |
| Datensatznummer |
250006844
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| Publikation (Nr.) |
 copernicus.org/bg-9-1053-2012.pdf |
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| Zusammenfassung |
| Conversion of tropical peatlands to agriculture leads to a release of carbon
from previously stable, long-term storage, resulting in land subsidence that
can be a surrogate measure of CO2 emissions to the atmosphere. We
present an analysis of recent large-scale subsidence monitoring studies in
Acacia and oil palm plantations on peatland in SE Asia, and compare the findings
with previous studies. Subsidence in the first 5 yr after drainage was
found to be 142 cm, of which 75 cm occurred in the first year. After 5 yr, the subsidence rate in both plantation types, at average water table
depths of 0.7 m, remained constant at around 5 cm yr−1. The results
confirm that primary consolidation contributed substantially to total
subsidence only in the first year after drainage, that secondary
consolidation was negligible, and that the amount of compaction was also
much reduced within 5 yr. Over 5 yr after drainage, 75 % of
cumulative subsidence was caused by peat oxidation, and after 18 yr this
was 92 %. The average rate of carbon loss over the first 5 yr was 178 t CO2eq ha−1 yr−1,
which reduced to 73 t CO2eq ha−1 yr−1 over subsequent years, potentially resulting in an average loss of
100 t CO2eq ha−1 yr−1 over 25 yr. Part of the observed
range in subsidence and carbon loss values is explained by differences in
water table depth, but vegetation cover and other factors such as addition
of fertilizers also influence peat oxidation. A relationship with
groundwater table depth shows that subsidence and carbon loss are still
considerable even at the highest water levels theoretically possible in
plantations. This implies that improved plantation water management will
reduce these impacts by 20 % at most, relative to current conditions, and
that high rates of carbon loss and land subsidence are inevitable
consequences of conversion of forested tropical peatlands to other land
uses. |
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