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| Titel |
Effects of soil warming, rainfall reduction and changing water table level on CH4, CO2 emission and pore water DOC concentration of Zoige peatland in China |
| VerfasserIn |
Huai Chen, Gang Yang, Ning Wu |
| 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 |
250142170
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| Publikation (Nr.) |
 EGU/EGU2017-5751.pdf |
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| Zusammenfassung |
| The Zoige Plateau features approximately 4605 km2 of peatlands, making it the largest
peatland area in China. This area stored 2.9 Pg peat during the Holocene, yet little is known
about carbon (CH4, CO2) emissions and pore water DOC concentration from this region. We
designed a mesocosm experiment to measure CH4, CO2 emissions and DOC concentration
during the growing seasons under different scenarios involving soil warming, 20% reduction
in rainfall and changeing water table level. This research aimed to understand how climate
change affect CH4 and CO2 emissions and whether the trends of changes in CH4 and CO2
emission are consistent with those of DOC concentration. Our results showed soil warming
treatment increased average CH4 emissions by 28%, while rainfall reduction increased it by
30%; however, neither increase was statistically significant. In contrast, the combined effect
of soil warming and rainfall reduction significantly decreased CH4 emissions by an average
of 58%. Extending this result across the entire peatland area in the Zoige Plateau
translates into approximately 5.3 Gg of CH4 uptake per year. For CO2 emission,
we found temperature at 5 cm depth have positive linear relationship with CO2
emission. The combined effect of soil warming and rainfall reduction increased
CO2 emission by 96.8%. Extending this result to the entire peatland area in Zoige
Plateau translates into 0.45 Tg CO2 emission per year over a growing season. These
results suggest that a drier and warmer Zoige Plateau will become a CH4 sink and an
increasing CO2 source. We also found a positive relationship between water table
level and CH4 emissions. Average CH4 emissions decreased by approximately
82% as water drawdown varied from 0 to -50 cm. However, there is no significant
relationship between water table and CO2 emission or DOC concentration. When we
simultaneously examined the effect of all three factors of water table level, soil
warming and rainfall reduction on CH4 emissions, we found soil warming and
rainfall effect on CH4 emissions varied with water table levels. However, none of the
three factors significantly affected CH4 emissions at a water table depth of 30 cm
below peat depth. We also found the contribution rate of DOC concentration to CO2
emission was increased by 12.1% in the surface layer and decreased by 13.8% in the
subsurface layer with combined treatment of soil warming and rainfall reduction, which
indicated that the warmer and dryer environmental conditions stimulate surface
peat decomposition process and the subsurface peat layer is insensitive to climate
change.
Keywords: Qinghai-Tibetan Plateau; Peatlands; Climate change; GHG; DOC |
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