- The richest part of a tropical rainforest is often the hardest to study: the canopy, where much of its biodiversity lives beyond reach from the ground. Francis Hallé helped change that by finding ways to observe the treetops without cutting them down.
- A French botanist, biologist, and illustrator, he became known for the “canopy raft,” a platform set onto the crowns of trees by a balloon. It turned the upper forest from a place described in theory into one examined up close.
- Hallé was an expert in tropical forest ecology and “the architecture of trees,” a way of identifying trees by how they grow and branch. He paired field science with drawing and plain speech, and he was unsparing about the forces driving deforestation.
- In his later years he pursued a long-term plan to restore a “primeval forest” in Western Europe, left to evolve with minimal human interference over centuries. It was, in his view, a test of whether societies could think beyond the political moment.
In most forests, a visitor’s eye is trained on what can be reached. The trunk can be measured. The leaves can be plucked. A specimen can be pressed, labeled, and filed away. Yet the largest share of life in a tropical rainforest is suspended overhead, in a zone of light, wind, and constant exchange. For much of the 20th century, that upper world remained a blank on the map of biology, less from lack of curiosity than from a practical problem: it was hard to work where you could not stand.
Science often advances when someone treats a logistical obstacle as an intellectual one. In the 1980s, a group of researchers and engineers devised a way to bring a laboratory to the canopy itself. A balloon could lift a platform, set it down on the crowns of trees, and allow botanists to move and observe without felling what they came to study. The method was unglamorous in its intent, even if the image was memorable: a raft perched in the treetops. It opened a layer of forest that had been described more than it had been examined.
The botanist at the center of this project had little taste for grand titles. Asked if he was an explorer, he waved it away. “No, no, no, botanist is more than enough for me.” he said. “Life is too short for a botanist,” he added, as if the subject could never be finished. The remark was not a pose. It reflected a view of plants as a vast, largely uncharted subject, and of human attention as a scarce resource too easily spent elsewhere.
Francis Hallé, who died on December 31st, 2025 in Montpellier, spent decades urging people to look up, and then to look harder. He was a French botanist, biologist, and illustrator, a former professor at the Institute of Botany at the University of Montpellier, and an expert in tropical forest ecology and what he called “the architecture of trees.” That specialty, shaped by field experience, addressed an old frustration in tropical botany: the difficulty of identifying giants when their flowers were out of reach. It let him identify trees by the way they grew and branched.
His sense of vocation took time to arrive. As a student in Paris, he noticed a small plant growing on his balcony whose “total autonomy” and “fundamental otherness” fascinated him. In the 1960s he lived in Côte d’Ivoire (Ivory Coast), where he encountered a primary tropical forest near Abidjan, and began to understand how much of the forest’s reality was invisible from the ground. At that time, he recalled, these forests “seemed invincible.” Later he would admit, “I never imagined these forests would disappear before my very eyes.” The threat, as he framed it, was not an abstraction but a belated recognition, accompanied by fear and then resolve: “we had to act.”
Hallé’s fieldwork ranged across Africa, America, Asia, and Oceania. He drew as he worked, in part to slow himself down. The aim was “to take the time to get to know the trees, complex three-dimensional objects, which are sometimes hundreds of years old.” The habit also suited his dislike of scientific jargon and his instinct for explanation. He became a popular figure beyond academia, able to make living systems clearer with sketches and plain speech, sometimes softened by humor. When the subject demanded it, he could also be blunt. Of officials, he said that “politicians don’t give a damn.” Of the economic forces behind deforestation he spoke of an “addiction to money,” and of tropical forests treated as “mere reservoirs of goods.” He was not shy, either, about the habits of mind that place plants below animals. “We are interested in our navels, it’s not complicated,” he said, laughing at his own species even as he granted it “a little tenderness.”
The canopy raft, launched in 1986 in French Guiana with collaborators including a balloon pilot and a young architect, became the best-known expression of his approach: curiosity joined to restraint. He wanted access to the canopy, but not at the cost of destroying it. Expeditions continued for years, bringing months of observations and drawings. They helped show that the canopy was not a decorative roof but a crowded, intricate habitat, and that ignorance of it was no longer defensible.
In later life he turned to a project that matched his patience and his impatience at once: the creation, in Western Europe, of a large “primeval forest” left to evolve without human intervention over centuries. He knew the timeline was politically absurd. “It’s utopian because what will happen in seven centuries? Will Europe still exist? Will France still exist? Nobody knows. But in my opinion, that’s no reason not to try.” For him it was also a test. “I’ve often felt that our project was a test of human nature.”
He could sound severe about human limits, but he did not argue for despair. He argued for attention, for research, and for education early enough to become reflex. He also argued, with a botanist’s stubborn literalism, that life is not preserved by slogans. “Loving trees doesn’t mean speaking in platitudes,” he liked to say.
A forest canopy is not a metaphor. It is a place where light falls, leaves trade gases, insects and epiphytes crowd the branches, and time is measured in new shoots and slow thickening wood. Hallé devoted himself to that reality. He insisted that the highest parts of a forest are not above politics or economics, only above the reach of those who do not bother to climb.
Header image: Francis Hallé. Photo by Thomas Samson / AFP
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