Climate change threatens native plant diversity in California grassland ecosystems

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Global warming is likely to cut native plant diversity in California, with cascading ecosystem effects, a new UC Davis study suggests. @bberwyn photo.

UC Davis study documents ‘direct loss’ of native wildflowers

Staff Report

FRISCO — California scientists say they’ve documented a loss in native wildflower diversity after with a string of dry winters, showing how climate change will affect the state’s grassland ecosystems.

The study is based on 15 years of monitoring on about 80 sampling plots at McLaughlin Reserve, part of the natural reserve system at the University of California at Davis.

“Our study shows that 15 years of warmer and drier winters are creating a direct loss of native wildflowers in some of California’s grasslands,” lead author Susan Harrison said in a press release. “Such diversity losses may foreshadow larger-scale extinctions, especially in regions that are becoming increasingly dry,” said Harrison, a professor in the Department of Environmental Science and Policy at UC Davis.

The study was publisehd this week in the Proceedings of the National Academy of Sciences. It conforms that drought-intolerant species suffered the worst declines and suggests that climate change will make California’s grasslands less productive and more vulnerable to invasive species.

Similar trends have been found in other Mediterranean environments, such as those of southern Europe, bolstering the case for increased climate change awareness in the world’s semi-arid regions.

The researchers expect these negative effects to cascade up through the food web–affecting insects, seed-eating rodents, birds, deer and domesticated species like cattle, all of which rely on grasslands for food.

Some species may be able to withstand dry spells through extensive seed banks, which can lie dormant for decades waiting for the right conditions to germinate. But since California droughts are expected to intensify in the coming decades, some plant species probably won’t survive, the researchers concluded.

 

The study’s co-authors include Elise Gornish, a UC Cooperative Extension specialist in the UC Davis Department of Plant Sciences, and Stella Copeland, a doctoral student in the Department of Environmental Science and Policy.The research was supported by the National Science Foundation.

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