Unexpected benefit of rising carbon dioxide more likely driven by water

One of the unexpected benefit from increasing carbon dioxide levels in the atmosphere is that plants might use less water as well as avoiding the damaging effects of drought. By closing the pores of the stomata on their leaves, plants take less water from the soil out through the plant and into the air. Taking in more carbon dioxide, plants can then close their stomata earlier, losing less water than they would otherwise. The process has been tested in cold temperate ecosystems, such as the grasslands of the Northern United States, but little research has been conducted in warm, dry ecosystems that cover much of the world in the tropical, subtropical and dry temperate regions including most of Australia. Researchers from Australia and the UK tested the theory on Australian grass species, finding that it is the presence of water that controls whether plants open their stomata more and not because of the extra carbon dioxide in the air. The results are the opposite of what scientists expected to find based on experiments from international research and is another example of the importance of tailored experiments specific to Australia’s unique ecosystems. To find out more go to Water availability affects seasonal CO2-induced photosynthetic enhancement in herbaceous species in a periodically dry woodland.