A study in the Tibetan plateau has shown that plants emit methane in the natural environment, shedding new light on their role in global warming.
A 2006 study in Germany suggested that although plants absorb carbon dioxide, they emit large amounts of methane, another greenhouse gas.
A team led by Zhao Xinquan, director of the Northwest Plateau Institute of Biology, Chinese Academy of Sciences, in Xining, China, conducted field trials on two grass types and one shrub.
They found that the grasses emit methane while the shrub absorbs it. Both were influenced by seasonal variations, with the grass emitting methane most in summer and the shrubs absorbing most in winter.
Zhao's team estimate that the Tibetan Plateau meadows emit about 130,000 tonnes of methane every year.
However, Zhao says it is premature to speculate on the role of plant methane in global climate change, with further research needed to understand the basic biology of the process.