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Pasture Responses to Elevated CO2 in the Swiss Alps
Riedo, M., Gyalistras, D. and Fuhrer, J. 2001. Pasture responses to elevated temperature and doubled CO2 concentration: assessing the spatial pattern across an alpine landscape. Climate Research 17: 19-31.

What was done
The authors used a mechanistic pasture simulation model (PaSim) in combination with a stochastic weather generator (WeathGen) to predict pasture responses to changes in climate and atmospheric CO2 concentration. The pasture modeled in this study is located in the eastern part of the Swiss Alps. It covers an area of roughly 250 km2 and spans an altitudinal gradient of approximately 1700 m.

What was learned
Increasing the air temperature by 2C increased ecosystem evapotranspiration; but the imposition of twice-ambient atmospheric CO2 concentrations reduced this impact of the temperature increase while simultaneously enhancing ecosystem net primary production. Thus, ecosystem water-use efficiency rose under conditions of simultaneously-elevated air temperature and CO2 concentration. In addition, the air temperature increase had little effect on soil organic carbon content, boosting it by only 1%. Doubling the atmospheric CO2 concentration, on the other hand, increased soil carbon storage by 5%; and when both air temperature and CO2 concentration were increased together, the simulated increase in soil carbon content was a full 10%.

What it means
As the air's CO2 content continues to rise, pastures in the Swiss Alps will likely exhibit increases in net primary productivity and water-use efficiency. In addition, they should display an increased ability to sequester carbon within their soils. Consequently, carbon sequestration in such pastures should increase with future increases in the air's CO2 concentration, even if air temperature rises by as much as 2C.

Reviewed 7 August 2002