Eriophyllum lanosum, one of the desert winter annuals that Larry Venable, an ecologist at the University of Arizona in Tucson, and his collaborators monitored for 26 years. The photo was taken in March 2008.
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Image Courtesy of Jonathon Horst

Even in the Desert, Plants Feel the Heat of Global Warming

Scientists who study plants in the Sonoran Desert are worried about global warming.

Desert winters have become warmer and drier over the years, and climate changes have pushed the arrival of winter rains later in the winter season. This forces some winter annual to come out when temperatures are colder.

Larry Venable, an ecologist at the University of Arizona (UA) in Tucson, has been studying something called "bet-hedging" in plants. Bet-hedging is an adaptation seeds make to help them survive when conditions in the environment aren't good. The seeds delay their germination until the conditions are better. This delay can be caused by lack of rainfall, lack of nutrients, temperatures that are too hot or too cold, or any other condition that would affect the survival of a seed.

Researchers measure carbon and nitrogen in the plants' leaves to learn how well the different species grow at winter's lower temperatures. The amount of carbon in a plant's leaves tells scientists how well a plant has adapted to water storage in cold weather. Higher amounts of nitrogen can mean that the plant is better at gathering light in cold weather and is better able to photosynthesize.

If plants are better at photosynthesis, they are more able to use energy from sunlight and convert it into food, which improves the plant's chances for survival. They also found that plants that are better at storing water do better in colder environments.

Last modified May 12, 2010 by Becca Hatheway.

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