Forest soils could help offset climate changeFriday 17 May 2013  Surface appearances can be so misleading: In most forests, the amount of carbon held in soils is substantially greater than the amount contained in the trees themselves. If you’re a land manager trying to assess the potential of forests to offset carbon emissions and climate change by soaking up atmospheric carbon and storing it, what’s going on beneath the surface is critical. But while scientists can precisely measure and predict the amount of above-ground carbon accumulating in a forest, the details of soil-carbon accounting have been a bit fuzzy. Two University of Michigan researchers and their colleagues helped to plug that knowledge gap by analysing changes in soil carbon that occurred when trees became established on different types of non-forested soils across the United States. In a paper published online on 1 April in the ”Soil Science Society of America Journal”, they looked at lands previously used for surface mining and other industrial processes, former agricultural lands and native grasslands where forests have encroached. U-M ecologist Luke Nave and his colleagues found that, in general, growing trees on formerly non-forested land increases soil carbon. Previous studies have been equivocal about the effects of so-called afforestation on soil carbon levels. “Collectively, these results demonstrate that planting trees or allowing them to establish naturally on non-forested lands has a significant, positive effect on the amount of carbon held in soils,” said Nave, an assistant research scientist at the U-M Biological Station and in the Department of Ecology and Evolutionary Biology. “These forest soils represent a significant carbon reservoir that is helping to offset carbon emissions that lead to climate change,” said Nave, lead author of the paper. Large and rapid increases in soil carbon were observed on forested land that had previously been used for surface mining and related industrial processes. On a post-mining landscape, the amount of soil carbon generally doubled within 20 years of mining termination and continued to double every decade or so after that. The changes after cultivated farm fields were abandoned and trees became established are much subtler, though still significant. This type of tree establishment—which has been widespread in recent decades in the north eastern United States and portions of the Midwest—takes about 40 years to cause a detectable increase in soil carbon. But at the end of a century’s time, the amount of soil carbon averages 15 percent higher than when the land was under cultivation, with the biggest increases (up to 32 percent) in the upper two inches of the soil. Source: Scienceblog.com |
Copyright 2004-2026 © Innovatek Ltd. All rights reserved. |