With the escalation of extreme weather conditions, rapidly melting polar icecaps and rising sea levels, combating climate change and reducing greenhouse gas emissions are matters of urgent and global concern.

A large international team of 65 forest ecologists from 49 institutions across 15 countries, including Yale-NUS College, has embarked on a collaborative research to show that secondary tropical forests which are re-growing after forest clearance or agricultural abandonment can sequester large amounts of carbon. Forests are carbon sinks that are critical in the efforts to absorb greenhouse gas emissions.

While efforts have largely concentrated on old-growth tropical forests, this research shows that attention should also be given to secondary forests. The research has been published in the online edition of Nature, a leading weekly, international scientific journal on 3 February 2016.

Assistant Professor of Science at Yale-NUS College, Michiel van Breugel was one of the researchers involved in this large-scale collaboration, in which he was directly involved in the set-up of and research in sites in Panama and Mexico.

Dr van Breugel worked with his colleagues to analyse the recovery of aboveground biomass using 1500 forest plots and 45 sites across Latin America. Biomass is the total quantity or weight of organisms in a given area or volume, and its growth is a measure of forest re-growth, which is important for the mitigation of climate change.

Combining their findings, the researchers found that carbon uptake is surprisingly fast in these young forests. After 20 years, these forests have recovered 122 tons of biomass per ha. This corresponds to an uptake of 3.05 ton carbon per ha per year, which is 11 times the uptake rate of old-growth forests.

Through online conferences, Dr van Breugel and his fellow researchers could easily communicate and collaborate on this study across multiple sites in Latin America.

Commenting on the collaborative nature of the research, Dr van Breugel said, "This allows the research to be more consolidated and enables us look at data from a much larger scale, across different research sites around Latin America."

The study also found that second-growth forests differ dramatically in their resilience; in 20 years, between 20 and 225 ton biomass has recovered. Biomass recovery, or the regrowth of vegetation, is high in areas with high rainfall and water availability throughout the year, whereas soil fertility or the amount of forest cover in the surrounding landscape were less important.

These findings were used to produce a potential biomass recovery map for Latin America that can be used to support the development of regional and national policies aimed at reducing carbon emissions and increase carbon uptake.

Moving forward, Dr van Breugel also hopes that the research will lend more attention to natural forest re-growth by international and national policy makers, as a cheap and nature-based solution with tremendous carbon mitigation potential.