What happens when you send a team of ecologists, geologists, remote-sensing specialists, and professional tree climbers on a field trip to Taiwan?
They discover the tallest tree in East Asia.
A group nicknamed the “Taiwan Tree Seekers” from institutions in Taiwan conducted an island-wide survey of vegetation for almost a decade. About the size of Maryland, Taiwan is around 60 percent forested, with an estimated 950 million trees clinging to its mountainous slopes and nestled in tropical valleys. After a grueling four-day journey to a site rumored to have giant trees, the Taiwan Tree Seekers realized they needed to harness technology to find the tallest ones.
Remote-sensing experts from National Cheng Kung University brought LiDAR (light detection and ranging) into the mix, transmitting laser pulses from optical sensors during flyovers of the forests. The LiDAR data yielded a 3-D map of the terrain, including tree heights. Still, with distortions in the data because of the steep topography, it took human eyes to ultimately uncover the highest trees. Volunteers were crowd-sourced to examine the 57,065 candidate images for “tallest tree” sorted by an algorithm, followed by visual inspections by LiDAR experts.
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In the Taiwan Giant Tree Map, 941 trees that ranked taller than the height of a 20-story building (or 213 feet) became targets for ground truthing. Given their association with montane cloud forest ecosystems, the tallest trees tended to be on steeply inclined slopes at high elevations. High humidity and stable climate are thought to benefit tree growth, such that “these mild, oceanic climates served as crucial forest refugia during post-glacial eras,” wrote the study authors. Most of the tallest-tree candidates were Taiwania fir (T. cryptomerioides), with just a handful of other species.
Additional fieldwork required following a river for 12 miles, hiking precipitously uphill, and then sending professional tree climbers up tree trunks. The winner was a T. cryptomerioides in the Sheshan range in northern Taiwan that boasted a height of 276 feet, or the equivalent of a 25-story building.
It’s no wonder that the Indigenous Rukai peoples of Taiwan consider these giant species to be “the trees that hit the moon.” 
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Lead image: Phatara Thitiwimol / Adobe Stock
