At a research station in central Panama, the forest tells time. Step from one plot to the next and the vegetation shifts from low, scrappy stands of young trees to towering canopies that resemble the vaulted ceiling of a cathedral. Forest ecologist Daisy Dent, now a senior scientist at ETH Zurich, helps oversee this living timeline across the Barro Colorado Nature Monument—an array of research plots that in some cases stretches back to the late 19th century.
What makes the site especially valuable is what hasn’t happened there: no one planted the trees Dent tracks. Instead, she and colleagues map, measure and monitor each trunk that appears, building a detailed record of how tropical forests can reassemble themselves from bare ground. That matters for climate policy because tropical forests are the world’s largest terrestrial carbon sink, holding roughly 40% of the carbon stored on land.
Dent’s work, carried out as part of an international community of forest researchers, focuses on the hidden web of relationships that determines whether a damaged forest rebounds—or stalls. Her findings point toward a potential alternative to common carbon-credit approaches that restore landscapes by planting vast areas with a single species. Over more than a decade, she has helped assemble evidence suggesting that large-scale monoculture plantings can become costly missteps, while naturally regenerating forests can return within a few decades and rebuild carbon-rich ecosystems.
Barro Colorado offers a rare opportunity to test those ideas. The reserve spans peninsulas and islands created when the Panama Canal was built and the region was flooded in 1914. Managed by the Smithsonian Tropical Research Institute, it has attracted generations of ecologists, producing more than a century of observations. That historical depth allows Dent to compare plots that once were cleared for farming and timber and then left to recover—revealing why some bounce back strongly while others develop into simplified forests.
A major driver of recovery, her data show, is animal life. In tropical forests, fruit-eating species such as spider monkeys, bats and parrots disperse the seeds that establish the next generation of trees, and they are responsible for planting more than 70% of tropical forest trees. By linking forest composition to the animals that delivered seeds—often through nutrient-rich droppings—Dent can infer which dispersers shaped particular patches.
The contrasts can be striking. One diverse stand, about 70 years into regrowth, appears to have been “built” by multiple animal partners and is developing the complexity and richness typical of much older rainforest. Nearby, another plot of similar age is dominated by a single long-lived species, Gustavia superba, forming a more uniform forest of slender trunks. That pattern suggests a different set of architects: tropical rodents called agoutis, which may have done much of the dispersal work in that area.
The broader aim is to develop a practical guide for restoration decisions—when it is best to allow nature to do the heavy lifting and when interventions are needed to restart key processes. A 2024 estimate published in Nature concluded that around 215 million hectares of forest worldwide—an area larger than Mexico—could potentially regenerate on its own.
Dent argues that such regeneration depends on an often-invisible network of biological partnerships: fungi that help trees acquire nutrients, pollinators that enable reproduction, and seed dispersers that repopulate cleared ground. Protecting those relationships, she says, is central to restoring forests that store carbon while supporting wildlife and local livelihoods.
Interest in forest recovery surged as the Paris Agreement took shape in 2015, and global leaders embraced initiatives to regrow a trillion trees after ecologist Thomas Crowther drew attention to forests’ potential to absorb a decade of human carbon emissions. Yet the core challenge has remained: what is the most reliable way to bring back forests at that scale? While companies have pitched drone-based seed dispersal and nutrient-coated “seed bombs,” Dent has spent two decades documenting what can happen when forests are allowed to rebuild themselves.
Her commitment began in the early 2000s during doctoral research in northern Borneo, where widespread clearing for palm oil left her searching for solutions beyond simply recording loss. She shifted toward restoration, and in 2005 joined Prorena in Panama—a partnership between the Smithsonian Tropical Research Institute and Yale’s forestry program—bringing her into a long-running effort to understand how tropical forests recover and how to help them do it better.
Why it matters
Governments, investors and communities are betting on forests to help meet climate targets, but the wrong restoration strategy can waste money and produce fragile ecosystems. Dent’s work suggests that protecting wildlife and ecological interactions may be as important as planting trees—especially where forests can regrow naturally. The next test is whether restoration programs and carbon markets will reward biodiversity-rich recovery rather than simple, single-species plantations.