After ten years of fieldwork in Taiwan’s remote mountain regions, researchers have identified an 84.1-meter (276-foot) Taiwania fir, now recognized as the tallest tree documented in East Asia. The team also found dense forests containing dozens of giant Taiwania firs, suggesting that other giant trees may remain hidden in Taiwan’s rugged interior.
The study, published in Frontiers in Forests and Global Change, was conducted by a team led by Rebecca Chia-Chun Hsu of the Institute of Taiwan Forestry Research, in collaboration with researchers Chi-Kuei Wang and Chung-Cheng Lee of National Cheng Kung University. Starting in 2014, the group, known as the Taiwan tree seekers, located and measured trees that had previously gone unrecorded by combining traditional field surveys with laser-based mapping and the help of citizen scientists.
The researchers found that the giant trees generally grow at elevations of about 2,087 meters and on slopes with an average inclination of 40 degrees. This combination of elevation and rugged terrain makes conventional tree surveys extremely difficult.
A Decade of Ground-Truthing
In August 2014, a systematic search began when scientists from the Taiwan Forestry Research Institute visited the Cilan conservation area to measure the ‘Chilan Three Sisters’, a group of Taiwania firs known locally but not formally recorded. The tallest tree was 69.3 meters high and had a trunk almost three meters wide. The Tree Project, a group of professional climbers from Australia, photographed the trees in 2017 and helped draw greater attention to Taiwan’s giant forests.
During a subsequent expedition near Mt. Benya and Great Ghost Lake, the team hiked for four days with their equipment to reach the study area. This experience showed how difficult it is to estimate the height of giant trees from the ground, since visual estimates can be unreliable in densely wooded, multi-layered old-growth forests. Although the team measured one tree at 71.7 meters, they concluded that ground-based surveys alone would not be sufficient for such a large and complex landscape.
LiDAR and a Problem With the Landscape
To improve their search, Hsu’s team collaborated with Wang and Lee’s remote sensing group at National Cheng Kung University and adopted LiDAR technology. LiDAR uses laser pulses from aircraft to create three-dimensional models of the forest, including estimates of tree height. However, Taiwan’s rugged topography caused the automated software to misinterpret cliffs and abrupt elevation changes as extremely tall trees.
Human reviewers proved more effective than the automated software at identifying these geological false positives. In 2020, hundreds of citizen scientists began examining the LiDAR profile images manually to distinguish real cases from artifacts. By the end of 2022, the Taiwan Giant Tree Map had identified 941 trees taller than 65 meters.
The researchers concluded that combining airborne laser scanning with crowdsourced image reviews and expert analysis can greatly reduce terrain-related errors in estimating tree heights.
Finding the “Heaven Sword”
In 2023, the mapping project led the team to a candidate for Taiwan’s tallest tree, which could be reached after traveling 20 kilometers down a river and then spending two days climbing. A direct measurement established the tree’s height at 84.1 meters, making it the tallest tree ever documented in Taiwan and East Asia. The team called it the ‘Heaven Sword of the Da’an River’. The Indigenous Rukai people have a name for trees of this kind and describe them as ones that ‘hit the moon’. By early 2026, researchers had documented 10 Taiwania firs taller than 70 meters, including two that exceeded 80 meters.
The mapping effort also brought the team back to the Great Ghost Lake region, nearly ten years after their initial visit. There, they identified about 30 large Taiwania firs growing together in an ancient stand, which the team began calling ‘temples of giants.’ In a hectare of forest near Mt. Benya, they recorded 11 individual trees exceeding 65 meters in height.
What the Giants Are Storing
The importance of these forests goes beyond their height. In 2024, Hsu’s team, in collaboration with 15 citizen scientists, surveyed Tao Tree Valley, home to Taiwan’s third-tallest tree, to determine how much carbon the forest stores. They found a carbon density of 1,384.5 megagrams per hectare, without including the root systems. The estimate is comparable to carbon-storage densities reported for some of the world’s most carbon-rich forests, including giant eucalypt forests in Tasmania. The researchers noted that their estimate did not include root systems and may have underestimated the forest’s true carbon storage.
The researchers still do not know how many other giant trees remain hidden in Taiwan’s mountains. However, the combination of LiDAR mapping, citizen science, and field verification gives them a way to search terrain that would otherwise be nearly impossible to survey systematically.
Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.