‘The Heaven Sword’ crowned as East Asia’s tallest tree after a nearly decade-long search

Taiwan, historically known as Formosa, holds a secret deep within its rugged interior: it is one of the rare locations on Earth capable of supporting “giant” trees—specimens that tower over 80 meters in height. Since 2014, a dedicated group, the “Taiwan tree seekers,” has been on a mission to locate and document these sky-piercing giants. The multidisciplinary team is a unique blend of professional tree climbers, ecologists, geologists, and remote sensing specialists.

In 2023, this persistence paid off: the team located the reigning champion of the island’s forests: an 84.1-meter-tall Taiwania fir (Taiwania cryptomerioides). This massive tree currently holds the title of the tallest tree in all of East Asia. To the Indigenous Rukai people, these gargantuan firs are known by a much more poetic name, “The tree that hits the moon.”

The landscape of the island

To understand how these trees grow so large, one must look at the unique geography of Taiwan. The island covers an area of 36,000 square kilometers—roughly the same size as Switzerland. Taiwan is defined by its dramatic mountain systems. The island boasts a staggering 258 peaks that exceed 3,000 meters in elevation, with the highest point, Mt. Jade, reaching 3,952 meters.

It hosts an incredibly rich variety of plant life. It is estimated that 5,000 different species thrive there, creating a spectrum of ecosystems that range from steamy tropical rainforests at sea level to frigid alpine tundra at the highest peaks.

Approximately 60% of the island remains forested and is home to an estimated 950 million trees. While extensive industrial logging between 1912 and 1991 significantly depleted the island’s original primary forests, the incredibly steep terrain served as a natural fortress, preserving significant pockets of old-growth forest that were simply too difficult for loggers to reach.

The search for the hidden giants

The formal quest began in August 2014. Researchers from the Taiwan Forestry Research Institute (TFRI), launched their first major expedition into the Cilan conservation area. Their specific target was a legendary group of trees known as the “Chilan Three Sisters.” These three giant Taiwania firs had been known to locals for years, but had never been scientifically measured or thoroughly documented.

The team found the tallest of these giants reached 69.3 meters with a trunk diameter of nearly three meters. International attention followed in 2017 when professional climbers from “The Tree Projects” in Australia traveled to Taiwan to fully photograph the Three Sisters, sharing the majesty of Taiwan’s forests with the world.

Spurred by this success, the team set sight on a more remote region near Mt. Benya, rumored to hold the largest population of Taiwania firs. This area is located near Great Ghost Lake, a site considered sacred by Indigenous peoples. The journey was grueling, requiring four days of heavy hiking just to reach the site.

This expedition proved to be a turning point; the team realized that identifying the tallest trees from the ground was nearly impossible. Within the dense, multi-layered canopy of an old-growth forest, the eyes can easily be deceived. While they managed to climb a 71.7-meter tree during that trip, they knew they needed a more scientific way to scan the horizon.

The work has been published in Frontiers in Forests and Global Change.

A high-tech solution: LiDAR

With 9.5 million trees spread across deep, inaccessible valleys, the team were essentially looking for a needle in a haystack. To modernize the search, they collaborated with remote sensing experts from National Cheng Kung University to utilize LiDAR (Light Detection and Ranging).

LiDAR is a sophisticated 3D scanning technique that transmits laser pulses from an aircraft toward the ground. By measuring how long it takes for the light to bounce back, the system generates a highly detailed 3D map of the landscape, revealing the height of the trees.

A community effort

Due to Taiwan’s rugged, uneven terrain, the automatic algorithm often estimates trees to be much higher than they are, for example, when the tree is right next to a steep cliff. Human eyes are much better at recognizing these geological “tricks” than the automatic algorithm, so in 2020 the project became a community effort.

By having hundreds of Taiwanese citizens examine the LiDAR profile images, the team could filter out tens of thousands of false leads. As it turned out, 93% of trees had been mismeasured by the automatic algorithm.

Without the help of citizen scientists to sort through the mountain of data and identify the most likely candidates, the researchers could have wasted years hiking to trees that were far shorter than they appeared on the map. By the end of 2022, this collaborative effort led to the publication of the “Taiwan Giant Tree Map,” which officially identified 941 individual trees that exceeded 65 meters in height.

Finding the champion

In January 2023, during the Lunar New Year holiday, they utilized the new map to target the most promising candidate for the title of “tallest tree.” This expedition was an endurance test, which involved a 20-kilometer river tracing and two days of steep uphill hiking.

Once the climbers reached the crown and dropped a measuring tape from the very top to the ground, the height was revealed to be 84.1 meters. This tree, christened the “Heaven Sword of the Da’an River,” was officially recorded as the tallest specimen in Taiwan and East Asia.

By early 2026, the team’s ongoing efforts led to the discovery and climbing of ten different Taiwania trees over 70 meters tall, two of which have broken the 80-meter barrier.

A legacy for the world

The data from the Giant Tree Map also pointed the way to the exceptional “temples of giants.” Near Mt. Benya, they found a single hectare of forest containing 11 trees that each exceeded 65 meters. Returning to the Great Ghost Lake area 10 years after the initial expedition, the team were left speechless by a “pure forest” of approximately 30 giant Taiwania firs growing in a dense, ancient cluster.

These trees are vital for the planet’s health. In 2024, the researchers and 15 citizen scientists conducted a detailed study of the “Tao Tree” valley, which is home to the island’s third-tallest tree, to learn how much carbon dioxide the forest scrubs from the atmosphere and stores in its wood.

The results were staggering: the total carbon density of the forest (even without counting the massive root systems) was 1,384.5 Mg/ha. This makes Taiwan’s giant forests some of the most carbon-dense environments in the entire world, comparable to the most famous old-growth forests on Earth. These “trees that hit the moon” are not just natural wonders; they are essential guardians of the environment.

Who’s behind this story?

Sadie Harley

BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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