Native grasses in California under threat

July 29, 2011 at 7:25 PM
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BERKELEY, Calif., July 29 (UPI) -- Native grasses in California, already threatened by invasive exotic varieties, are likely to be pushed aside even more as the climate warms, researchers say.

Researchers at the University of California, Berkeley, have mapped the ranges of all 258 native grasses and 177 exotic grasses in the state and estimated how they would be affected by increased temperatures and decreased rainfall expected with climate change.

Many of the characteristics that make exotic grasses more successful than many natives would allow them to adapt better to increased temperature and likely expand their ranges, they said.

"When we looked at current patterns, we found that warmer temperatures favor certain traits, and these are the traits possessed by exotic species," study coauthor Emily Dangremond, a graduate student of biology, said. "This led us to predict that, if the mean temperature increases in all zones in California, there is an increased likelihood of finding exotic species, and an increase in the proportion of species in a zone that are exotic."

One consequence of an increase in exotic species could be a rise in the number and severity of wildfires, the researchers said, since invasive grasses dry out more in the summer than native grasses do.

Also, some exotic grasses serve as reservoirs for viruses and other pathogens that can attack food crops, while others are more efficient at taking up water that would normally be used by other grasses and plants, they said.

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