PLANTS, it turns out, are showing signs of living recklessly. About 70 per cent of forest plant species seem to live within a slim safety margin of survival in the face of drought and changing rainfall patterns. What's more, trees and flowering plants in wetter forests not often considered to be at risk of drought are endangered by their profligacy with water.
Biologist Steven Jansen, at the University of Ulm, Germany, and colleagues analysed existing data on the water transportation systems of 226 plant species from 81 forests globally (Nature, DOI: 10.1038/nature11688).
Jansen says drought stress causes bubbles of gas to be brought into plants' water transport tubes, which blocks water from reaching leaves and in turn halts the food-creating process of photosynthesis.
In wetter forests, plants have a greater access to water so have wider water tubes. As well as increasing water intake, this also ups the intake of gas bubbles and hence the risk of blockages. Rainforests and drier forests are equally at risk, says Jansen.
The study shows that "all plants seem to be living on the edge", says Yadvinder Malhi, an ecosystems scientist at the University of Oxford.
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