Climate change can enhance grassland productivity

January 27th, 2009 - 2:34 pm ICT by ANI  

Berlin, Jan 27 (ANI): The results of a recently conducted study by scientists have indicated that climate change can lead to enhanced grass productivity.

The study, by researchers at the Helmholtz Center for Environmental Research (UFZ), the University of Bayreuth and the Helmholtz Center in Munich, Germany, has found that more frequent freeze-thaw cycles in winter can increase biomass production.

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.

The change between freeze-thaw cycles is considered to be one of the major factors for the release of nitrogen into the soil and consequently for an increase in microbial activity.

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 Jurgen 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.

The site is located at the transition between oceanic and continental climates, where the average air temperature in January is 1 degree Celsius. On 30 of the 4m2 plots, one hundred common plants (grasses and herbs) were planted.

As soon as the temperature had remained continuously below 0 degree C for 48 hours, the soil was heated until the temperature remained above 0 degree C for 48 hours.

In the cold winter of 2005/06, which was 2 degree C colder than the long-term average, there were a total of 62 days with ground frost.

The researchers added 5 artificial freeze-thaw cycles to the three natural ones and compared the results from the different plots.

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. (ANI)

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