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| Titel |
Soil-atmosphere exchange of carbon dioxide, methane and nitrous oxide from a typical karst region under different land use in southwest China |
| VerfasserIn |
J. Z. Cheng, X. Q. Lee, H. Zhou |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250071536
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| Zusammenfassung |
| In recent years, the eco-environmental problems characterized with the lost of soil nutrition
elements in the southwest karst area of China are severe due to the increasing conflict
between land and population. The changes of land use would have a great impact on the
pools of soil carbon and nitrogen and change the exchanges of greenhouse gas
(GHG) between soil and atmosphere. Fluxes of GHG from different land use patterns
(matured forest, secondary forest, grassland and cropland) were measured directly
with a vented enclosed chamber technique and gas chromatography method in a
subtropical karst region of Guizhou province, southwest China. Soils under different land
use in karst region acted as the sources of CO2, N2O and the sinks of CH4. The
average fluxes of soil CO2 ranged from 35.5±91.4 to 134.1±78.8 (mean ± SD)
mgC-
m-2-
h-1, ranking order: matured forest, secondary forest, cropland, grassland. The
average uptakes of soil CH4 ranged from 51.5±74.7 to 93.0±32.5 ugC-
m-2-
h-1, the
order of soil CH4 absorption was in accord with that of CO2 release. The average
emissions of soil N2O ranged from 16.0±13.0 to 21.8±8.5 ugN-
m-2-
h-1, and soil
N2O emission was highest in the cropland, but no significant differences (p>0.05)
were observed between different land use. Converting from the matured forest to
secondary forest tended to increase annual emissions of N2O (from 1.40 to 1.65 kg
N ha-1 yr-1), while changing land use from the secondary forest to grassland
tended to decrease slightly (from 1.65 to 1.45 kg N ha-1 yr-1). Moreover, the
seasonal variations of soil CO2 fluxes under different land use were very distinct, they
increased from spring to summer and decreased from autumn to winter in response to
changes of temperature and precipitation in this region. In contrast, seasonal patterns
of CH4 and N2O fluxes were not clear, although higher CH4 uptake rates were
often observed in autumn and higher N2O emission rates were often observed in
spring. In the matured forest, there was a significant correlation between CH4 flux
and NH4+-N (r2 = 0.39, p |
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