Ecologist Daisy Dent shows fruit-eating animals replant forests better than planting does

On Barro Colorado, the forested islands flooded when the Panama Canal was built in 1914, forest ecologist Daisy Dent oversees plots spanning a century of regrowth — not one tree planted by human hands. Her dataset can say which animals built each patch: fruit-eaters like spider monkeys, bats and parrots plant more than 70% of trees in tropical forests. A 70-year-old patch approaching old-growth richness was planted by many species together; a similar-age patch dominated by one long-lived species traces to agoutis alone.

The evidence chain argues monocrop planting is often the wrong tool. A 2016 Nature paper using the Barro Colorado data showed a hectare of naturally regenerated secondary forest captures 11 times as much carbon each year as an old-growth one; a 2022 Royal Society study showed clearings surrounded by remnant habitat can regain old-growth richness within decades without planting a seed; 2024 work showed plots with as little as 35% tree cover can regenerate as forest. A 2024 estimate in Nature found some 215 million hectares worldwide — an area larger than Mexico — could regenerate naturally.

The research is now being applied. Dent and Yale ecologist Liza Comita work with nonprofits and carbon-crediting schemes in Panama, mapping corridors to reconnect fragments, planning animal reintroductions in silent forests, and replanting acceleration species — assisted natural regeneration. With London carbon-credit startup Ponterra they are developing solutions for southern Panama; Ponterra clients including Microsoft pay more than 10 times the roughly $5-per-tonne floor for high-quality removals, and the science helps credits avoid the failures of fresh plantations.

Don't plant trees — rebuild the animal networks that plant them: fruit-eating monkeys, bats and birds sow over 70% of tropical trees for free.

The dataset ties each patch of forest to the animals that planted it — cause, not just correlation.

It quantifies the alternative: 11x annual carbon capture from natural regeneration versus plantation schemes.

The playbook says where to intervene (corridors, reintroductions, enrichment planting) and where to leave plots alone.

A carbon-credit startup and its clients are paying premia built on the resulting quality bar.

Find the free labor in a system before hiring replacements. Natural regeneration captures 11x more carbon a year than old-growth — if the seed dispersers are there to plant it.

Dent suspects the coming year's 'mega El Niño' and its droughts could force policymakers and carbon creditors to face the weak resilience of cookie-cutter plantations: 'I think there's an increasing recognition that we can't just plant trees. We have to rebuild a system.' Millions of hectares are already regenerating naturally in Brazil, according to the Brazilian Restoration and Reforestation Observatory.