Rainforest regrowth boosts carbon capture

Newly grown rainforests can absorb 11 times as much carbon from the atmosphere as old-growth forests, a study has shown.

The researchers have produced a map showing regions in Latin America where regrowing rainforests would deliver the greatest benefits.

However, they added that old-growth forests still needed to be protected as they locked away vast amount of carbon. Details of the study have been published in the journal Nature.

The international team of scientists compiled data from almost 1,500 plots at 45 sites across the Neotropics, which covers southern and central America, allowing them to produce map highlighting the carbon sequestration potential of areas across the Neotropics.

New growth, or secondary, forests grow as a result of a major clearing of old-growth vegetation. The clearing could be the result of a natural event, such as a fire, or as a result of human activity, such as logging or farming.

In order to maximise access to sunlight, nutrients and water, new trees grow quickly. This means the plants sequester a much greater amount of carbon from the atmosphere, which it uses as part of the photosynthesis process that uses sunlight to produce the sugars the plant needs to grow.

The team found that in optimum conditions, new-growth vegetation could sequester up to 11 times as much carbon as old-growth forests.

Co-author Lourens Poorter from Wageningen University, The Netherlands, told the Nature podcast that while it was important to halt deforestation, it was also important to recognise the role of secondary forests in a climate mitigation context.

"There is a potential for forests to regrow," he said. "You can either do that actively by planting but it can also be done passively (via natural regrowth).

"What we have tried to do in this study is to get a comprehensive picture of how fast this recovery is in terms of biomass. If you have abandoned areas that have been used for agriculture , how fast do the forests regrow naturally and how much biomass has been taken up - we call that the recovery or resilience of biomass."