This is the VOA Special English Agriculture Report.

California has more than two thousand kinds of plants that are not found anywhere else. A new study says climate change could severely affect these plants by the end of the century.

Many could move northward and toward the Pacific coast in reaction to rising temperatures and changes in rainfall. Others might climb up mountains to find the cooler climates they like.But David Ackerly at the University of California, Berkeley, says the speed of climate change is greater than during ice ages in the past. He says plants that cannot move fast enough are in danger of getting killed off before they can relocate. Changes in plants could also affect animals that depend on the plants for food.

About forty percent of all native plants in California are endemic, meaning they are found only in that state. The new study says that for two out of three endemic plants, the areas where they are found could shrink by more than eighty percent. That, they say, is the worst possible case.

The researchers point out that there are many things they cannot be sure about. That includes how much warming to expect in the future from releases of heat-trapping greenhouse gases. Also, they cannot be sure what will happen to individual species of plants.

Scientists say California's coastal redwoods are among plant species that could be affected by climate changeStill, they say California's coastal redwood trees, for example, could move farther north. California oak trees could disappear from the central part of the state. Professor Ackerly says established trees could survive, but seedlings would not grow. Oaks could move to cooler weather in the Klamath Mountains along the border with Oregon.The Central Valley of California could become the new home for plants now found in the Sonoran desert of Mexico.The study says people who protect or manage natural areas will need to plan for the possible movement of so-called refugee plants. The researchers identified places around California where large numbers of plants hit hardest by climate change are expected to relocate.

But they say many of these areas are already under increasing pressure from development. They say it is not too early to prepare for helping plants re-establish themselves in new areas.

The Berkeley study also involved researchers from Duke University and other schools. The findings can be read online in PLoS One, a journal published by the Public Library of Science.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. I'm Bob Doughty.