To cope with a rise in atmospheric carbon, vegetation in Florida is changing the way it absorbs water, a study has found.
Through photosynthesis and transpiration, plants absorb carbon dioxide and release moisture through tiny pores called stomata. Comparing modern plants with samples from peat bogs and museums, ecologists have found that over time, the number of stomata found on leaves has decreased due to rising levels of carbon dioxide.
Water evaporates from the stomata, and the plant pulls up more water from the soil. Fewer stomata mean that less water is released. In the long term, increasing CO2 in the atmosphere will decrease the rate of evaporated water into the atmosphere by half, the researchers predict, with harsh consequences for rainfall and weather patterns.
"Our analysis of that structural change shows there's been a huge reduction in the release of water to the atmosphere," said David Dilcher, a researcher at the University of Florida. "The carbon cycle is important, but so is the water cycle."
Although this will lead to more soil moisture at first, less rainfall will eventually lead to less water in the ground, added Dilcher.
The study was published in Proceedings of the National Academy of Sciences (Discovery News/MSNBC.com, Mar. 8). -- TS
