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| Titel |
Effects of land-use change on the greenhouse gas exchange in Western Siberia |
| VerfasserIn |
Elisa Fleischer, Hanna Lokys, Bastian Paas, Degefie Tibebe, Tarek El-Madany, Otto Klemm |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082464
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| Zusammenfassung |
| The interface between the steppe and the northern forest zone in Western Siberia plays a
significant role in the global carbon cycle. Induced by changing climate and by changing
socio-economic conditions, agricultural expansion and other fundamental land-use changes
are expected in these regions. Such changes will exhibit a strong impact on the budgets of the
greenhouse gases (GHGs) carbon dioxide and methane, which are the most important
long-lived GHGs in the atmosphere. Nevertheless, hardly any research concerning this topic
has been done in these regions.
In the framework of the research project SASCHA (Sustainable land management and
adaptation strategies to climate change for the Western Siberian corn-belt), which is funded
by the BMBF, the turbulent exchange of water vapor, carbon dioxide and methane
between the surface and the atmospheric boundary layer, and the surface energy
balance were measured over a grassland near the city of Tyumen in the Tyumen
Oblast. Therefore, an eddy covariance station was operated from July to September
2012, which was equipped with a Gill R3-50 sonic anemometer (Gill Instruments,
UK), a LI-7200 enclosed CO2/H2O analyzer (LI-COR Biosciences, USA), and a
LI-7700 open-path methane analyzer (LI-COR Biosciences, USA). The grassland
around the station was ploughed in mid-September in order to prepare it for crop
production.
Before ploughing, the CO2 fluxes showed daily courses, mostly with negative fluxes
during daytime due to photosynthesis, and emissions during the night because of respiration.
However, after the ploughing process, positive CO2 fluxes throughout the days resulted
because photosynthesis was inhibited. During the whole measurement period a positive
CO2 balance was found, for the period before ploughing as well as for the period
after.
The fluxes of water vapor also showed clear diurnal courses with intense
evapotranspiration from the surface to the atmosphere during daytime, and a small
deposition flux during the nights. Despite the very low water content of the soil
due to the extreme dryness in 2012, the water vapor emissions did not increase
when the soil was wetted during rainy days. An effect of ploughing could not be
identified.
It was also possible to detect methane fluxes over the dry grassland, but they fluctuated
around zero so that the grassland could be neither identified as a clear source nor as a clear
sink of methane during the period of investigation.
In 2013, two eddy covariance stations will be operated in parallel from March to October
over a natural wetland and a neighbored oat field, respectively, which allows a direct
comparison of the impact of the two different land-use types. In addition, continuous
meteorological measurements will be performed nearby in order to obtain background
information about the climatic conditions. The chosen study areas are representative for the
region, so that the obtained data could be used for upscaling and developing future scenarios. |
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