Scientists Traced a River 20 Kilometers Into Taiwan's Mountains and Found the Tallest Tree in East Asia — 84 Meters of It

A Taiwania fir standing 84.1 meters tall — 276 feet — in the mountains of central Taiwan is the tallest tree ever measured in East Asia, and the survey that confirmed it turned up something larger than a single record: an entire population of giant trees that nobody had catalogued.

The tree is called the Heaven Sword of the Da'an River, and reaching it is not casual work. The route requires tracing a river 20 kilometers upstream, then two days of steep uphill hiking, into terrain near Mt. Benya and Great Ghost Lake that Indigenous communities regard as sacred. Its height was formally recognized in 2023 and the full survey behind it was published this year in Frontiers in Forests and Global Change.

The method was a three-way collaboration between machines, professionals and volunteers. Researchers at the Taiwan Forestry Research Institute and remote-sensing specialists at National Cheng Kung University flew LiDAR — laser scanning that builds a three-dimensional model of the canopy and the ground beneath it — over the island's forests. LiDAR is good at spotting tall objects and bad at telling a genuinely tall tree from a merely well-positioned one: the automated system mismeasured 93% of the trees it flagged, mistaking steep slopes and stacked canopy for height.

That is where the volunteers came in. Beginning in 2020, hundreds of Taiwanese citizens worked through the scan data manually, screening out false candidates so that climbing teams would not waste multi-day expeditions on trees that were not there. For the survivors, the only way to settle the question was direct measurement: professional climbers from The Tree Projects, an Australian outfit, ascended into the crowns and lowered measuring tapes to the ground.

The catalogue that resulted, the Taiwan Giant Tree Map completed in 2022, documents 941 individual trees taller than 65 meters. The trees also cluster in a way the researchers describe as "temples of giants." One site near Mt. Benya holds 11 trees over 65 meters within a single hectare. Another contains roughly 30 giant Taiwania firs.

The clustering has consequences beyond record-keeping. In the valley holding a specimen the team calls the Tao Tree, the forest stores 1,384.5 megagrams of carbon per hectare — a density that places it among the most carbon-dense ecosystems measured anywhere on Earth, in the same class as the old-growth eucalypt forests of Tasmania and the redwood stands of coastal California.

Taiwania cryptomerioides was heavily logged through the twentieth century and survives mainly where the terrain defeated the loggers. The paper, by Rebecca Chia-Chun Hsu, Chi-Kuei Wang and Chung-Cheng Lee, is published under DOI 10.3389/ffgc.2026.1746112.