A new study suggests that, despite the fact that trees grow larger or faster with increased levels of carbon dioxide, they are not necessarily going to be able to store an equally growing amount of the carbon dioxide.
The report, to be published in the journal Proceedings of the National Academy of Sciences, points to the fact that the availability of soil nutrients will not support the larger or faster growing tree.
A deciduous forest stand in Tennessee has been exposed to elevated carbon dioxide levels about 25% higher than those currently in the atmosphere today, effectively sending the trees forty years into the future.
It had been previously thought and proven out by the study that the trees would benefit from the increase in carbon dioxide levels, stimulating plant growth and increasing their ability to store the greenhouse gas. Over the first six years of the experiment this was exhibited, as productivity of the forest increased significantly.
However the latest report shows that the subsequent five years has seen a downturn in the productivity of the forest, due to, according to the researchers, the availability of nitrogen in the soil.
“We’re going to have to learn not to trust in trees to remove as much carbon from theatmosphere as we had hoped,” says Professor Ross McMurtrie of the UNSW School of Biological, Earth and Environmental Sciences.