The regrowth of Amazonian forests following deforestation can happen much slower than previously thought, a new study shows.The findings could have significant impacts for climate change predictions as the ability of secondary forests to soak up carbon from the atmosphere may have been over-estimated.
The study, which monitored forest regrowth over two decades, shows that climate change, and the wider loss of forests, could be hampering regrowth in the Amazon. By taking large amounts of carbon from the atmosphere, forests regrowing after clear-felling - commonly called secondary forests - have been thought an important tool in combatting human-caused climate change.
However, the study by a group of Brazilian and British researchers shows that even after 60 years of regrowth, the studied secondary forests held only 40% of the carbon in forests that had not been disturbed by humans. If current trends continue, it will take well over a century for the forests to fully recover, meaning their ability to help fight climate change may have been vastly overestimated.
The study, published in the journal Ecology, also shows that secondary forests take less carbon from the atmosphere during droughts. Yet, climate change is increasing the number of drought-years in the Amazon.
First author Fernando Elias from the Federal University of Pará explained: "The region we studied in the Amazon has seen an increase in temperature of 0.1 C per decade, and tree growth was lower during periods of drought. With predictions of more drought in the future, we must be cautious about the ability of secondary forests to mitigate climate change. Our results underline the need for international agreements that minimise the impacts of climate change."