The ecologist revealing the invisible networks that revive rainforests

Forest ecologist Daisy Dent studies how tropical rainforests regenerate naturally in Panama’s Barro Colorado Nature Monument, a research site covering forested peninsulas and islands formed after the Panama Canal’s construction flooded the area in 1914. Dent tracks trees across plots dating back to the 19th century, none planted by humans, to observe how forests recover from bare earth to mature canopies. Tropical forests act as Earth’s largest land-based carbon sink, storing about 40% of carbon on land. Dent’s work, part of an international research network, challenges common reforestation methods like planting single-species forests, which can be costly and less effective. Instead, her research shows that diverse, naturally regenerating forests can recover in decades, absorbing vast amounts of carbon dioxide while supporting wildlife and local communities.

Dent’s research highlights the critical role of animals in forest regeneration. Fruit-eating animals such as spider monkeys, bats, and parrots plant over 70% of trees in tropical forests by spreading seeds in their droppings. For example, a 70-year-old patch of forest in Barro Colorado, regenerated by these animals, closely resembles the structure and richness of ancient jungles. In contrast, patches dominated by a single tree species like Gustavia superba suggest that agoutis, small rodents, are the primary seed dispersers, leading to less diverse forests. Dent’s data helps determine which animal-planted forests thrive and which struggle, providing insights into when ecosystems can regenerate without human intervention.

Dent’s findings challenge the idea that planting trees is the best way to restore forests. In 2016, her research showed that a hectare of naturally regenerated secondary forest can capture 11 times more carbon annually than an old-growth forest, as young trees absorb carbon quickly while competing for sunlight. A 2024 study further revealed that plots with as little as 35% tree cover can regenerate into forests without planting. However, some degraded sites, like those once used for cattle ranching, may need human help, such as replanting native species or reintroducing wildlife. Dent works with organizations like Ponterra, a carbon-crediting startup, to develop strategies for restoring forests in southern Panama, balancing natural regeneration with targeted interventions.

Dent’s approach builds on decades of ecological research. In 2005, she joined Prorena, a project studying how to restore diverse native forests on clear-cut land in Panama. Initially, the project focused on transplanting nursery-grown trees, but Dent’s 2009 research showed that animal populations rebound quickly as forests regrow naturally. In 2010, she began working in Barro Colorado, adding younger plots to a sequence established by ecologist Julie Denslow in 1994. This long-term data helps scientists understand the processes behind forest recovery, such as how fast-growing pioneer trees are eventually overtaken by larger, carbon-storing species. Dent’s work provides a playbook for deciding when to let forests regenerate on their own and when to assist the process.

The idea of regrowing forests gained global attention in 2015 with the Paris Agreement, when ecologist Thomas Crowther proposed plans to regrow a trillion trees to capture a decade’s worth of global carbon emissions. However, the challenge lies in how to achieve this effectively. While some reforestation projects use drones to spray seeds or nutrient-coated seed bombs, Dent’s research emphasizes the importance of natural regeneration. She notes that monoculture plantations, often used in carbon-crediting schemes, can be less resilient to extreme events like droughts, floods, or heatwaves. Dent argues that rebuilding entire ecosystems, rather than planting single species, is key to long-term success. Her work with Ponterra and other organizations aims to create high-quality carbon credits by restoring forests in ways that support biodiversity and local communities.