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Environmental Processes Affecting the Greenhouse Gas Budget of Grasslands in an Elevational Transect in Switzerland

English title Environmental Processes Affecting the Greenhouse Gas Budget of Grasslands in an Elevational Transect in Switzerland
Applicant Eugster Werner
Number 105949
Funding scheme Project funding (Div. I-III)
Research institution Departement Umweltsystemwissenschaften ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Other disciplines of Environmental Sciences
Start/End 01.02.2005 - 31.05.2008
Approved amount 184'380.00
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Keywords (7)

NITROUS OXIDE EMISSIONS; METHANE EMISSIONS; METHANE OXIDATION; CARBON DIOXIDE EXCHANGE; ISOTOPIC DISCRIMINATION; EDDY COVARIANCE FLUX MEASUREMENTS; flux partitioning with stable isotopes

Lay Summary (English)

Lead
Lay summary
The most important greenhouse gases from agricultural areas are carbondioxide (CO2), methane (CH4), and nitrous oxide (N2O). The high share ofagricultural emissions that contribute 72% and 63% to the total Swissemissions of N2O and CH4, respectively, require a more detailedunderstanding of the processes governing those greenhouse gas fluxes.Particularly in grasslands, where N2O fluxes are known to be relevant, andwhere CH4 may be taken up via oxidation, or be released when soils arewater saturated. The motivation for the proposed research has emergedduring the record-breaking summer of 2003 which according to ourpreliminary understanding was not exceptional in many parts of thepre-Alps where grassland yields were rather good. This is in contrast tothe situation experienced in the low altitudes of the Swiss Plateau wherea significant drought affected agricultural yields dramatically, leadingto severe economic losses for lowland farmers.

Working Hypotheses
Our working hypothesis is thus that a changing climate of the typesuggested by the summer of 2003 could potentially revive the economicimportance of pre-Alpine and Alpine agriculture, namely in relation tolowland farming which revealed to be much more vulnerable to such extremesin climate. In order to understand the implications that suchmodifications of environmental conditions could have on the nationalgreenhouse gas budget we suggest to quantify the N2O and CH4 fluxes overgrassland in combination with continuous CO2 exchange measurements. Wealso hypothesize that if CH4 is oxidized by the grassland soils aroundcattle farms, then we should be able to find a close relation between themeasured CH4 emissions from cattle and the CH4 uptake that we propose tomeasure here.

Experimental Design and Methods
We take benefit of the unique opportunities given by the three ETHResearch Stations at 400, 1000, and >1900 m a.s.l., which provide arepresentative transect for the Swiss three-step system of Alpine summergrazing. We suggest to measure N2O and CH4 fluxes continuously with theeddy covariance method at the lowest elevation site. CO2 exchange andassociated energy fluxes will be continuously measured at the two lowerstations.
At all three sites we plan to carry out additional stable isotope (13C and18O) sampling campaigns to study the most relevant biogeochemicalprocesses that are active during the growing season, and at the lowestsite also in winter. These data will enable us to partition net CO2 fluxesobtained with eddy covariance into the process components assimilation andrespiration. This will allow us to assess the carbon turnover of thegrassland ecosystems.
Direct link to Lay Summary Last update: 21.02.2013

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