Monday, January 26, 2009

Climate change enhances grassland productivity

Red Orbit: More frequent freeze-thaw cycles in winter can increase biomass production according to the results of a recent study conducted by the Helmholtz Center for Environmental Research (UFZ), the University of Bayreuth and the Helmholtz Center in Munich. For their experiment at the Ecological-Botanical Garden of the University of Bayreuth the researchers installed underground heating on their plots, thereby enabling five additional thawing periods to take place in the winter of 2005/2006.

They found that on the manipulated plots ten percent more biomass grew compared to on the control plots. Such increased plant productivity can be explained by several factors, like for example an increase in nitrogen supply in the spring, according to the researchers account in the scientific journal New Phytologist.

…Due to global warming and a greater absence of an insulating snow cover, these cyclic processes are likely to increase. In spite of this and apart from a study from the North of Sweden there are hitherto practically no investigations that have conducted research on the significance of these cyclic processes for plants. Scientists working together with J├╝rgen Kreyling therefore set up an experimental site on the outskirts of Bayreuth to investigate the effects of extreme weather events such as droughts, torrential rain and freeze-thaw processes.

…In the following summer the plants were harvested twice, dried and then weighed. Here it was found that the manipulated plots produced 10 percent more above-ground biomass than the control plots on which in the previous winter less freeze-thaw cycles had occurred. In comparison it was also found that root length up to five centimeters soil depth was reduced.

Image by Katy Prairie Conservancy, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License

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