In a new publication, Kew scientists say that where new trees are needed, the focus should be on natural forest growth, provided site conditions such as soil quality and proximity to existing forests are appropriate.

Underestimated benefits

The promoters are calling for natural regeneration to be taken more seriously in national and international efforts to mitigate climate and biodiversity crises. Recent research has shown that natural regeneration can potentially absorb 40 times more carbon than plantations and provide a home for more species. It’s also much cheaper than planting trees, with different studies in Brazil showing costs reduced by 38%, or even up to 76%.

This could make a significant difference in the costs of international forest restoration ambitions, such as the Bonn Challenge, which targets 350 million hectares (1.4 million square miles). It could cost $ 12 trillion (£ 8.5 billion) if only active tree planting is used.

Not only that, but the ability of naturally regrown forests to absorb carbon has been underestimated by 32% by the Intergovernmental Panel on Climate Change (IPCC), according to research conducted by environmental organizations based in the United States. United States, the World Resources Institute and The Nature Conservancy, which was published in the journal Nature in September.

IPCC rates are used by many countries to estimate the capacity of forests to absorb carbon and to report on progress towards meeting climate change targets. This strengthens the case for a greater focus on forest regeneration as a climate change mitigation policy, alongside active tree planting, says Susan Cook-Patton of The Nature Conservancy and author of the report. .

The rate at which trees accumulate carbon varies up to 100 times, depending on factors such as climate and soil quality, so the researchers also produced a global map, down to a resolution of 1 km. (0.6 mile), highlighting areas with the greatest carbon returns allowing land to reforest naturally. They hope this will help policymakers see where regrowth of natural forests could have the greatest impact on climate change mitigation, thereby removing the guesswork involved in using the approach.

“There are many ways to bring trees back into the landscape, including actively planting them, establishing a wood plantation, or letting them grow naturally,” says Cook-Patton. “Our goal is to help people have the information they need to decide which makes the most sense.”

Potential not realized

Until now, the potential for natural regeneration of forests has been overlooked in national and international efforts to increase tree cover. The reasons include a lack of recognition that this is a viable restoration option; perverse incentives that favor the clearing of young trees for the development of plantations or other land uses; lack of support from government agencies and other organizations; lack of incentives for local communities; and uncertainty about processes and outcomes, according to the Food and Agriculture Organization of the United Nations.

Natural regeneration is sometimes criticized for being “messy,” Tree says. “Humans are such monsters of control. The more compelling the climate emergency becomes, the more we feel physically obligated to do something, and our instinct is often to tidy up, ”she says.

As more policymakers, conservation organizations and members of the public see the approach in action, the mindset will change, Tree believes. She agrees with Kew scientists that natural tree regeneration should be the default method, unless there is a specific reason for active planting.