Scientists Have Found “The Heaven Sword” After Years of Looking

Taiwan's giant forests are among the most carbon-rich places on Earth. For years, the tallest trees remained hidden in remote valleys.

Since 2014, a group called "Taiwan Tree Seekers" has been exploring these forests. This team includes tree climbers, scientists, and mapping experts. They spent nearly 10 years looking for the island's biggest trees.

In 2023, they found an 84.1-meter-tall Taiwania fir (Taiwania cryptomerioides). This tree is now the tallest known in East Asia. The local Rukai people call these huge trees "the tree that hits the moon."

Taiwan's unique landscape helps these giants grow. The island is about the size of Switzerland, but it has 258 peaks over 3,000 meters high. This creates deep valleys, steep slopes, and many different climates.

This rugged land supports many different plants and animals. About 5,000 plant species grow there, from tropical rainforests to high mountain tundras.

About 60% of Taiwan is still forested, with an estimated 950 million trees. While logging happened from 1912 to 1991, the steepest and hardest-to-reach areas kept their old-growth forests safe.

The Search for Giants

The search began in August 2014. Researchers from the Taiwan Forestry Research Institute (TFRI) went to the Cilan Conservation Area. They wanted to study the "Chilan Three Sisters," a group of giant Taiwania firs.

The tallest of these was 69.3 meters high, with a trunk almost three meters wide. In 2017, climbers from Australia helped show these amazing forests to the world.

After this, the team looked at a more remote area near Mt. Benya. They thought it had many Taiwania firs. This spot was near the sacred Great Ghost Lake and took four days of hard hiking to reach.

This trip changed their approach. They realized it was almost impossible to find the tallest trees from the forest floor. It was hard to guess tree heights in the dense, old-growth canopy. Even after climbing a 71.7-meter tree, they knew they needed a better way.

Technology Helps the Hunt

Finding a few giant trees among 950 million was like finding a needle in a haystack. The team partnered with National Cheng Kung University and started using LiDAR technology.

LiDAR uses lasers from the air to create detailed 3D maps. It measures how long it takes for laser pulses to bounce back from the ground and trees. This helps estimate tree heights over large areas.

However, Taiwan's steep mountains caused problems. The automated system often made trees seem taller than they were, especially near cliffs. People were much better at spotting these errors. In 2020, the project became a citizen science effort. Hundreds of volunteers reviewed LiDAR images to find false readings.

Their work showed that 93% of the automated measurements were wrong. Without this help, the team would have wasted years visiting trees that were not as tall as expected. By the end of 2022, this effort created the "Taiwan Giant Tree Map." It showed 941 trees taller than 65 meters.

Discovering East Asia's Tallest Tree

In January 2023, the team used the new map to find Taiwan's tallest tree. The trip was tough, involving a 20-kilometer river trek and two days of climbing.

Once climbers reached the top, they dropped a measuring tape to the ground. The tree was 84.1 meters tall. They named it the "Heaven Sword of the Da’an River." It is now officially the tallest known tree in Taiwan and East Asia.

By early 2026, the project had found and climbed 10 Taiwania trees over 70 meters tall. Two of these were even taller than 80 meters.

(a) Point cloud data of the ‘Temples of Giants’ near Mt. Benya, collected using a handheld laser scanner. (b) Zoomed view of the point cloud showing three individuals within the giant forest; the persons serve as a scale reference to convey tree height and canopy size. Credit: Hsu et al., 2026

Carbon-Rich Forests

The Giant Tree Map also led researchers to areas with many giant trees. Near Mt. Benya, they found a one-hectare forest with 11 trees taller than 65 meters. They also returned to the Great Ghost Lake region and found a dense, ancient stand with about 30 giant Taiwania firs.

These forests are very important for the environment. In 2024, researchers and 15 citizen scientists studied the "Tao Tree" valley, home to Taiwan's third-tallest tree. They wanted to see how much carbon dioxide the forest stores.

The results were amazing. The forest's carbon density was 1,384.5 Mg/ha, even without counting its roots. This means Taiwan's giant forests are among the most carbon-dense places on Earth. These "trees that hit the moon" are not just natural wonders; they also help protect the environment.

Deep Dive & References

The journey of finding the tallest tree in Formosa Taiwan - Frontiers in Forests and Global Change, 2026