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Three million hectares compared: saving forest beats replanting it

Qurexa Editorial Team22 September 20267 min read 0 0
Three million hectares compared: saving forest beats replanting it

What happened

A large study of the Amazon has compared the main ways of protecting tropical forest, and found that the most effective one is not the one that gets the most attention. The research was led by Lancaster University, with an international team. It was published in the journal Science on 17 September 2026. The team looked at more than three million hectares across two regions of Pará state in Brazil, over the decade from 2010 to 2020. That is a huge area. Three million hectares is larger than Wales. The scale of the fieldwork was unusual. They used 381 survey transects, studied 38 river catchments and 499 individual properties, and modelled where 426 tree species and 160 bird species live. That was combined with satellite imagery. They then compared three approaches. The first is stopping deforestation: preventing forest being cleared in the first place. The second is preventing disturbance: protecting forest that is still standing from wildfires and from selective logging. This is forest that stays on the map as forest, but is quietly degraded. The third is restoration: replanting and regrowing forest that has already gone. Protecting existing forest from fire and logging delivered the biggest benefits for wildlife. It also came close to matching the benefits of stopping deforestation when it came to protecting stored carbon. Restoration on its own came out worst. It was the least effective and the most expensive. And only combining all three approaches produced a net gain in both biodiversity and carbon storage. Dr Leonardo Miranda said: "Protection must go beyond avoiding deforestation. Avoiding forest disturbances from wildfires or logging delivered the greatest benefits." Dr Joice Ferreira added a warning: "Restoring forests while existing forests continue to be damaged can undermine overall benefits."

Why this matters

Tree planting is the conservation idea everyone understands. It is easy to picture, easy to photograph, and easy to sell. Companies offset flights with it. Schools do it. Governments announce targets in millions of trees. This study suggests that if you are choosing where to put limited money, planting is the least efficient option of the three. The reason is not complicated. A mature tropical forest is not just a collection of trees. It is a structure built over centuries, with species that depend on old trees, deep shade, particular soils and undisturbed conditions. A replanted area takes a very long time to become that, and some of it never does. Protecting what already exists keeps all of that intact, and costs less. The finding about degraded forest is the genuinely new part. Satellite maps tend to record forest as present or absent. A forest that has been burnt through or selectively logged still shows up as forest. But it holds less carbon, supports fewer species, and burns more easily next time. This study puts numbers on that hidden loss, and says it matters nearly as much as outright clearance. For anyone reading this in the UK, there is a practical connection. Much of the pressure on the Amazon is driven by demand, for beef, soy, timber and minerals, a good deal of which is exported. The policies that affect it are trade and supply chain policies as much as forestry ones.

What the evidence actually says

This is an unusually strong piece of work for this kind of question, and it is worth understanding why. Most conservation comparisons are done either by modelling or by studying one intervention at a time. This study combined a decade of satellite data with an enormous amount of actual fieldwork: hundreds of survey transects, bird and tree species recorded on the ground, and hundreds of individual properties assessed. The researchers describe it as the first systematic comparison of these strategies. Ground data matters because satellites cannot see what lives under a canopy. A forest can look healthy from space and be missing most of its birds. The limits are mainly about where and when. The study covers two regions of Pará state. The Amazon is vast and varies enormously. What holds in eastern Pará, where deforestation pressure is high and much forest is already fragmented, may not hold in intact western Amazonia or in other tropical forests in Africa or Southeast Asia. The ten-year window, 2010 to 2020, is short in forest terms. Restoration is slow. A replanted area assessed after ten years is still at the beginning of its life. The study's finding that restoration is less cost-effective is fair over that period, but part of the gap may narrow over fifty or a hundred years. The cost comparisons depend on local prices for land, labour and enforcement, which differ between countries. The central message, though, is hard to argue with, and the researchers are careful about it. They do not say stop restoring. They say restoration alone, while existing forest keeps being damaged, does not get you where you need to go.

Practical advice

If you want what you do to line up with what this study found, here are the honest versions. Be sceptical of tree-planting offsets. If a company offers to offset your flight or delivery by planting trees, that is the least effective of the three options studied here. It is not worthless, but it is often sold as more than it is. Look for schemes that fund protection of existing forest rather than only planting. Several established conservation charities work this way. The wording to look for is protection and land rights, not just planting targets. Supporting Indigenous and local land rights is one of the better-evidenced routes. Forests under Indigenous stewardship consistently show lower deforestation rates. On shopping, the biggest single lever for most UK households is beef and soy, since cattle ranching and soy production drive much Amazon clearance. Eating less beef, or choosing sources with traceable supply chains, has more effect than most other consumer choices. Certification labels for timber and paper are imperfect but better than nothing. And if you plant trees in the UK, do it because UK woodland is worth having, not as an offset for something happening 5,000 miles away.

What to know

A Lancaster University-led team compared conservation strategies across more than three million hectares in two regions of Pará state, Brazil, from 2010 to 2020, using 381 survey transects, 38 catchments, 499 properties, satellite imagery and models of 426 tree and 160 bird species. The results were published in Science. Protecting standing forest from wildfire and logging gave the greatest benefit for wildlife, and came close to matching the carbon benefit of preventing deforestation outright. Restoration alone was the least effective and the most expensive approach. Only combining all three, preventing deforestation, preventing disturbance and restoring, produced net gains in both biodiversity and carbon. The study covers two regions over ten years, which is short for forest recovery, so the restoration finding may look different over much longer timescales. Costs vary by country. The practical message: protecting forest that already exists is better value than replacing forest that has gone. Sources: ScienceDaily, "Amazon study reveals the best strategies for protecting biodiversity and carbon", 21 September 2026, https://www.sciencedaily.com/releases/2026/09/260920222356.htm; Miranda, L.S. et al., "Protecting tropical forests is more cost-effective for biodiversity and climate than restoration", Science, 2026; 393(6817):1221, https://doi.org/10.1126/science.adx9928; Lancaster University, https://www.lancaster.ac.uk/news/ This article is for general information about science and the environment, and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.

#Amazon#rainforest#conservation#climate#biodiversity#environment

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