Shrinking Plant Leaves Linked to Climate Change
The leaves of the Narrow-leaf Hopbush are getting narrower, and scientists say the cause is climate change.
Researchers at the University of Adelaide in Australia discovered that the plant species (Dodonaea viscosa angustissima) found in South Australia's Flinders Ranges have responded to raising temperatures with a 2mm decrease in leaf width over 127 years.
"Climate change is often discussed in terms of future impacts, but changes in temperature over recent decades have already been ecologically significant," said lead author Greg Guerin.
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Analyzing the leaf shape of 255 specimens of the same subspecies from the 1880s to the present, the researchers found that the leaves had become narrower over time. And measurements of hopbush plant from the region showed that the closer the plants were growing to the equator - leaving them in warmer and drier climates - the narrower their leaves had become.
Such changes would be expected as a result of warming and attendant drought: plants in dry areas often bear long, slender leaves, to reduce the amount of water lost from them owing to evaporation and gas exchange, reports Nature. Still, the extent of the changes was surprising to the researchers. "Before I did the analysis I suspected there hadn't quite been enough time for that kind of shift to happen," said Guerin.
According to New Scientist, there are a few reasons that could be behind the visible changes in the hopbush. The changes to the leaf size could be due to "plasticity", where individual plants shrink their leaves in response to warm weather. Alternatively, it could be due to migration, where plants that used to grow further north are moving south. There is a third possibility, however: the change in leaf size could be an evolutionary adaptation to climate change, said Guerin.
Though it may be good news that the plants are adapting to their changing environments, not every plant may be so lucky.
"Other species in the region have less potential to adapt. These species may rely more heavily on migration - moving from location to location where the climate is favourable - but this can be problematic in a landscape fragmented by human activity," said Guerin.
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