Tropical study maps 7.49 million square kilometres where natural forest regeneration pays off
A Nature Ecology and Evolution study maps costs and benefits of natural forest regeneration across 7.49 million square kilometres of the tropics, plus a free map.
Photo by Diego Girón on Pexels
Researchers led by the University of Queensland have mapped the costs and the carbon and biodiversity gains of natural forest regeneration across 7.49 million square kilometres of the tropics, and published a free interactive map of the results. The study, “Variation in the costs and ecological benefits of tropical natural forest regeneration”, appeared in Nature Ecology and Evolution on 20 August 2026. It finds that if all of that area regrew, it would accumulate about 9.57 gigatonnes of carbon over 30 years and cut the overall extinction risk of forest-dependent species by roughly 31 per cent against a baseline.
The paper’s central point is that those gains are not evenly distributed. Areas delivering high carbon storage, high biodiversity benefit and low cost at the same time, which the authors call holistic hotspots, cover only 9.67 per cent of the study region. The five countries holding the largest areas of them are Indonesia, Madagascar, the Philippines, Mexico and Malaysia.
What the study measured
The team worked at roughly one-kilometre resolution and sorted every eligible pixel into 12 cost-benefit categories, combining three cost levels with four benefit combinations. Costs covered both the opportunity cost of the land and the implementation cost of restoration. Benefits covered carbon accumulation and biodiversity, the latter expressed as a reduction in extinction risk using a species-area relationship with an exponent of 0.25. Analysis ran in R 4.3.3, with maps produced in ArcGIS Pro.
Water regulation, soil stabilisation and livelihood benefits were not quantified. The authors list them as work still to be done.
| Study result | Value |
|---|---|
| Area with biophysical potential for natural regeneration | 7.49 million km2 |
| Carbon accumulated if fully regenerated, over 30 years | About 9.57 Gt C |
| Reduction in extinction risk, forest-dependent species | About 31 per cent versus baseline |
| Holistic hotspots as a share of the study region | 9.67 per cent |
| Spatial resolution | About 1 km |
| Cost-benefit categories | 12 |
Source: Li, Luskin, Chazdon and Williams, “Variation in the costs and ecological benefits of tropical natural forest regeneration”, Nature Ecology and Evolution, 20 August 2026, abstract.
The abstract also reports that the most cost-effective areas for carbon alone and for biodiversity alone fall in different places from the holistic hotspots. Lead author Jiaqi Li said carbon benefits were strongest in the Neotropics and the Indomalayan tropics, and biodiversity benefits strongest in the Afrotropics, including Madagascar.
Where the cost comparison comes from
Coverage of the study has led on a figure stating natural regeneration can be up to 96 per cent cheaper than active restoration. That number is not a result of this paper. It is a citation the authors carry from Busch and colleagues in Nature Climate Change, published on 24 July 2024, and it compares implementation costs only.
Busch and co-authors put the median implementation cost of passive natural regeneration at US$140 per hectare, against US$3,729 per hectare for plantations, across 138 low- and middle-income countries. The gap of 96.2 per cent is where the headline comes from. Their median opportunity cost, US$4,807 per hectare, is the same for both methods and larger than either implementation cost, so on total cost the two approaches sit far closer together.
Their median abatement costs were close: US$23.80 per tonne of CO2 for natural regeneration against US$23.00 per tonne for plantations. Cheaper to start does not mean better value everywhere, which is the point the new mapping study builds on.
Why the location matters
Tropical forests cover about 18 per cent of the Earth’s land area and hold 62 per cent of terrestrial vertebrate species, according to Pillay and colleagues in Frontiers in Ecology and the Environment, the first reference cited in the paper. Baccini and co-authors measured gross tropical forest carbon losses of 861.7 plus or minus 80.2 teragrammes of carbon a year over 2003 to 2014, against gains of 436.5 teragrammes, leaving a net source of 425.2 teragrammes.
Global forest loss over 2000 to 2012 totalled 2.3 million square kilometres against 0.8 million square kilometres of gain, in the Hansen et al. mapping published in Science in 2013. The tropics were the only domain where the rate of loss was rising.
The study frames its map against restoration targets already agreed. Target 2 of the Kunming-Montreal Global Biodiversity Framework, adopted in Montreal in December 2022, calls for at least 30 per cent of degraded terrestrial, inland water, coastal and marine ecosystems to be under effective restoration by 2030. The Bonn Challenge, launched by Germany and the IUCN on 2 September 2011, set 150 million hectares under restoration by 2020 and 350 million hectares by 2030, and has drawn pledges of more than 210 million hectares from over 60 countries and partners.
The interactive map, hosted at costbenefitpnr.netlify.app, lets users inspect the cost and benefit categories by location. Code is on GitHub and the underlying data are deposited on Zenodo. Winss Solutions has reported on how satellite biodiversity monitoring has advanced while gaps remain, and on research finding that China’s solar expansion has hampered bird diversity.
Background
The paper was received on 19 April 2025 and accepted on 17 July 2026. Jiaqi Li, a PhD candidate at the University of Queensland’s School of the Environment and its Centre for Biodiversity and Conservation Science, is the corresponding author. Co-authors are Matthew S. Luskin, an associate professor at the same school; Robin L. Chazdon of the Tropical Forests and People Research Centre at the University of the Sunshine Coast and the University of Connecticut; and Brooke A. Williams of the Centre for Conservation Science at the University of Newcastle and the UQ centre. Williams is supported by an Australian Research Council Discovery Early Career Researcher Award, grant DE260100352. The authors declare no competing interests.
The University of Queensland established its School of the Environment in June 2023, combining environmental science, ecology, conservation, marine biology, earth sciences, geography, zoology, biodiversity, genetics and evolution. The United Nations General Assembly declared 2021 to 2030 the UN Decade on Ecosystem Restoration, and the interactive map released alongside this paper is aimed at the planners now deciding where the second half of that decade’s restoration money goes.
Sources: Nature Ecology and Evolution; University of Queensland; Cost and benefit of natural regeneration interactive map; Nature Climate Change; EurekAlert; Bonn Challenge; Convention on Biological Diversity
Featured image: photo by Diego Girón on Pexels (free Pexels license).
Become a Sponsor
Our website is the heart of the mission of WINSS – it’s where we share updates, publish research, highlight community impact, and connect with supporters around the world. To keep this essential platform running, updated, and accessible, we rely on the generosity of you, who believe in our work.
We offer the option to sponsor monthly, or just once choosing the amount of your choice. If you run a company, please contact us via info@winssolutions.org.
I specialize in sustainability education, curriculum co-creation, and early-stage project strategy. At WINSS, I craft articles on sustainability, transformative AI, and related topics. When I’m not writing, you’ll find me chasing the perfect sushi roll, exploring cities around the globe, or unwinding with my dog Puffy — the world’s most loyal sidekick.
