AsianScientist (Jul. 18, 2013) – Increased levels of carbon dioxide (CO2) have helped boost green foliage across the world’s arid regions over the past 30 years through a process called CO2 fertilization, reports a new study.
In findings based on satellite observations, CSIRO, in collaboration with the Australian National University (ANU), found that this CO2 fertilization correlated with an 11 percent increase in foliage cover from 1982-2010 across parts of the arid areas studied in Australia, North America, the Middle East and Africa.
“In Australia, our native vegetation is superbly adapted to surviving in arid environments and it consequently uses water very efficiently,” said CSIRO research scientist, Dr Randall Donohue. “Australian vegetation seems quite sensitive to CO2 fertilization. The fertilization effect occurs where elevated CO2 enables a leaf during photosynthesis, the process by which green plants convert sunlight into sugar, to extract more carbon from the air or lose less water to the air, or both. This, along with the vast extents of arid landscapes, means Australia featured prominently in our results.”
Using mathematical modeling together with satellite data adjusted to take out the observed effects of other influences such as precipitation, air temperature, the amount of light, and land-use changes, the team was able to tease out the CO2 fertilization effect, explained Donohue.
The fertilization effect occurs where elevated CO2 enables a leaf during photosynthesis, the process by which green plants convert sunlight into sugar, to extract more carbon from the air or lose less water to the air, or both.
If elevated CO2 causes the water use of individual leaves to drop, plants in arid environments will respond by increasing their total numbers of leaves. These changes in leaf cover can be detected by satellite, particularly in deserts and savannas where the cover is less complete than in wet locations, according to Donohue.
“On the face of it, elevated CO2 boosting the foliage in dry country is good news and could assist forestry and agriculture in such areas; however there will be secondary effects that are likely to influence water availability, the carbon cycle, fire regimes and biodiversity, for example,” Donohue said. “Ongoing research is required if we are to fully comprehend the potential extent and severity of such secondary effects.”
The article can be found at: Donohue RJ et al. (2013) Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments.
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