Deep in Taiwan's misty mountains, researchers have confirmed the tallest tree in the country: an 84.1-meter Taiwania fir that towers higher than a 20-story building, which they've named "the Heaven Sword of the Da'an River." The discovery caps a decade-long quest by a team of ecologists, geologists, remote-sensing specialists, professional climbers, and Indigenous guides who call themselves the "Taiwan tree seekers"—and it reveals something remarkable about how science works when communities come together.
Taiwan is one of the few places on Earth where trees can grow this tall. The island sits where the tropics meet the subtropics, and its mountains host several giant conifer species. The Taiwania cryptomerioides, known to the Indigenous Rukai people as "the tree that hits the moon," is particularly suited to this misty terrain. Nearly 60 percent of Taiwan is covered in forest, though loggers cleared much of the island's old-growth forest between 1912 and 1991. Pockets of ancient forest survived in the steepest, most inaccessible mountain ranges—places too dangerous for loggers to reach. Still, with 258 peaks above 3,000 meters and an estimated 950 million trees, finding the tallest individual tree felt nearly impossible.
The team's early expeditions were painstaking. In 2014, they hiked into the Cilan area to document three famous giant trees called the "Chilan Three Sisters," with the tallest measuring 69.3 meters. Later trips near Mt. Benya, in an area sacred to Indigenous peoples, required four days of hiking to reach a 71.7-meter specimen. As the researchers noted, "Within the dense, multi-layered canopy of an old-growth forest, your eyes can easily deceive you." So the team pivoted to technology: they partnered with remote-sensing experts at National Cheng Kung University to deploy airborne lidar—laser pulses fired from aircraft that build precise 3D maps of the forest below.
The technology was powerful but imperfect. Taiwan's steep cliffs confused the computer algorithms; a short tree perched on a cliff edge could appear much taller in the data. In fact, 93 percent of the trees the algorithm flagged turned out to be incorrect candidates. This is where the project transformed. Beginning in 2020, nearly 400 citizen scientists logged onto a website and clicked on the apparent top and base of each candidate tree in sliced-up profile images. Their collective effort narrowed down more than 57,000 candidates to fewer than 5,000, which expert researchers then reviewed. By late 2022, the team had published the Taiwan Giant Tree Map, cataloging 941 confirmed trees taller than 65 meters across the island.
Armed with this map, the team selected their most promising candidate: a tree in the Sheshan range of northern Taiwan, near the Da'an River. In January 2023, professional climbers scaled the tree and dropped a measuring tape from the summit to the forest floor, confirming the height of 84.1 meters. The findings have been published in Frontiers in Forests and Global Change.
These giant trees store enormous amounts of carbon, making them crucial for climate resilience. Yet they face growing threats from drought, lifting clouds, stronger typhoons, and illegal logging. As Rebecca Chia-Chun Hsu, lead author from the Institute of Taiwan Forestry Research, told CNN: "The common characteristics [of our team] are probably that we are all tree lovers and like adventures." That spirit of collaboration—combining Indigenous knowledge, expert science, and citizen participation—may be what the world's remaining ancient forests need most.