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Draft:The Tree Seekers (找樹的人) Search for Taiwan Champion Trees

Introduction

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The Tree Seekers (找樹的人), formed in August of 2014.[1][2], aim to search for the tallest trees in Taiwan[3]. This environmental group mainly comprises forest canopy scientists and tree climbers who use their climbing skills to search for champion trees[4] in Taiwan. The group has grown through adding members who bring new expertise to further the mission.

Taiwan (formerly known as Formosa) is an island in the southwest Pacific with an area of 36,000 km2. Active orogenesis has built up an extensive mountain system on the island, including 258 peaks over 3000 m in elevation, with the highest reaching 3952 m[5]. The dramatic topography hosts a wide range of vegetation, from alpine tundra to tropical rainforests. Approximately 60% of the island is forested with over 950 million trees[6]. Extensive logging from 1912 through 1991 significantly reduced the island’s primary forests[7], but it is Taiwan’s rugged mountainous terrain which has preserved significant tracts of old-growth forest[8]. Since 2014, The Tree Seekers organised field expeditions to explore unknown forests in the remote mountain areas of Taiwan. The group located some significant giant trees ever since. With the assistance of LiDAR[9] data from 2018, The Tree Seekers found the tallest tree of Taiwan Daan River Heaven’s Sword in 2023[10].

Early expeditions

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Three Chilan sisters (棲蘭三姊妹)

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During the expedition in July of 2014, the team climbed a 68 m tall Cunninghamia lanceolata var. konishii

The Tree Seekers’ first expedition to find tall trees was inspired by information shared long ago by a retired forester. The logging road leading to the area had been abandoned decades previously. It took two expeditions, first in July then in August of 2014 to locate the giant Taiwania (Taiwania cryptomerioides)[11]. The team successfully climbed the second tallest tree, and measured its height at 67 m. The tallest tree was later measured in 2017 at 69 m. These trees are named the Chilan Three Sisters[12]. This expedition was featured in the fall 2015 issue of What’s Up magazine[13].

 
August 2014 expedition to climb and measure the Three Chilan Sisters (24.5227 N, 121.3649 E)

Mt. Benya (本野山、平野山)

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The second expedition was in March of 2016. The team went to a remote region known for having the largest population of Taiwania firs. It took four days of hiking to reach the area, Mt. Benya (22.8882 N, 120.9013 E), located near a well-known aboriginal sacred site, Great Ghost Lake (22.869 N, 120.8616 E)[14]. However, the expedition team could not identify the tallest tree from the forest floor due to the great number of giant Taiwanias, making it difficult to compare the height of the trees from below. The team selected and climbed two trees based on experience. The second tree climbed was 71.7 m high. The tree was named Twin Towers since the tree has two leading trunks.

 
Giant Taiwania Twin Towers (雙子星) discovered in March of 2016 (22.8891 N, 120.8953 E)
 
The mysterious Great Ghost lake

DanDa area

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The team then went to the central Taiwan, DanDa[15], the traditional territory of Bunun[16] people in 2017 March. This time they found so far the tallest Taiwan spruce (SongYunYun, 62.4 m, Picea morrisonicola) on the island. And The team climbed a Taiwania fir (Ironman, 65.4 m) near the tallest spruce. Because there are abundant population of Taiwania fir in DanDa, the team came back in 2018 Jan to search giant trees. They climbed a Taiwania fir (DanSi) of height 72 m in this trip.

 
Team member Hunter (Bunun) standing in front of Songyunyun, the tallest Taiwan spruce.
 
Taiwania Ironman with a cable wire on the trunk, a remnant from the logging era
 
Danshi Giant 丹詩神木, 72m (23.798 N, 121.1799 E)

LiDAR data added to the search for Tall Trees

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The Tree Seekers realized that it was not possible to find the tallest tree on the island using the previous methods of interviews and ground searches on foot. So, they consulted LiDAR data from the government. However, they discovered LiDAR tends to overestimate tree heights in Taiwan’s extremely mountainous terrain. In 2018, LiDAR experts prof. Wang from National Cheng Kung University[17] joined the team, and the team began using airborne LiDAR data to search for tall trees on the island.

Qing Trail Giants Forest 清八巨木森林

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In February of 2019, the Tree Seekers embarked on a 9-day expedition to visit a legendary forest found by Bunun elders 11 years previously. The trip, over a decade earlier, had not left many clues to follow. The team used LiDAR imagery to search for the giant tree forest rumored to be near the abandoned historical Qing trail built in 1875[18]. LiDAR data successfully lead the team to the majestic forest, where they measured four giant trees using a drone, including a tree that Bunun elders had found 11 years previously[19].

 
LiDAR image that lead the team to the Qing trail giant forest
 
The tree seekers measured the same tree found in 2008

Nankeng Stream Giant 南坑溪巨木

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In September of 2019, the Tree Seekers found another Taiwania that broke the previous height record. The tree was located from a forester interview and LiDAR data. The tree is near logging road No. 230, in the watershed of the major Daan[20] River in central Taiwan. The tree lies along the Xueshan Range and is 72.9 m tall[21], named after nearby upstream Nankeng Stream.

 
Nankeng Stream Giant, 72.9 m (24.3147 N, 121.0237 E)

The Tao Tree (桃山神木)

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Building on their experience with each successive giant tree search expedition, the Tree Seekers team found that LiDAR measurement accuracy is related to the steepness of the slope where the trees grow. The flatter the slope, the higher the accuracy of the tree height predicted from LiDAR. Based on a preliminary report from the Taiwan Giant Tree Map[22], the team focused on a tree with height measured by LiDAR of 76.38 m, growing on a relatively flat 10% slope in a mountainous area.

It took three expeditions, from  March to June of 2020 to locate the giant tree. The tree was finally climbed and measured in August of 2020. Tape measurement of the tree height was 79.1 m[23]. It remained the tallest tree on the island until 2022. The tree was named after a nearby peak, Mount Tao[24].

 
The Tao Tree, 79.1m (24.4583 N, 121.3002 E)

Shihtzu Giant (西施神木)

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Shitzu[25] Giant was named after an ancient beauty from Chinese history, as the forester who discovered the tree was struck by its grace at first sight. The tree’s location is very close to Nankeng Stream Giant. The team climbed this tree in August of 2021, measuring the height with a tape at 73.7 m.

 
Shihtzu Giant 73.7 m (24.3124 N, 121.0367E)

Kaalang Giant (卡阿郎巨木)

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Kaalang Giant is located in the upstream reaches of Taiwan’s longest river, the Zhuoshui River. The Tree Seekers found this tree in March of 2022, in Bunun traditional territory. In the Bunun language “kaalang” means “crabs.” [26]The tree is located near sacred Qicaihu Lake (七彩湖) of the Bunun. Since the top of the tree top includes a section of dead branches, the team measured the final section using a 3 m fishing pole and drone photography[27].

 
Qicaihu Lake in snow
 
Kaalang Giant, 82m (121.2151 E, 23.7085 N)
 
Height measurement of the top section of the tree

Behuy Giant (風之巨木)

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Behuy Giant is also a Taiwania fir, like other giant trees that exceed 70 m in height. The name “Behuy” comes from the language of the Atayal people meaning “winds.”[28] On the day the Tree Seekers followed the river Tqzing (Atayal language) to its source, they enjoyed the winds in the river valley[29]. The tree is located in Atayal traditional territory and was measured using the same method as Kaalang Giant.

 
Using a fishing pole to measure the top section of Behuy Giant
 
Behuy Giant 75.9 m (121.3319 E, 24.5044 N)

Daan River Heaven’s Sword (大安溪倚天劍)

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In 2023 January, during the Lunar new year, the Tree Seekers set off an expedition to find the tallest tree candidate from the Taiwan Giant Tree Map. The first day was a 20 km river trace along the Daan river, followed by two days of hiking to reach the tree[30][31]. LiDAR measurement was 79.9 m, while tape drop measurement from climbing the tree was 84.1 m. So far, Heaven’s Sword remains the tallest tree in Taiwan[32]

 
Heaven’s Sword, the tallest tree in Taiwan
 
Team member, Bird, at the top of Heaven’s Sword to release the measuring tape
 
LiDAR image of Heaven’s Sword
 
Heaven’s Sword, 84.1 m (121.1142 E, 24.4164 N)

Tree portraits

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In 2017 and 2022, The Tree Projects members[33], Jennifer Sanger and Steven Pearce from Australia visited Taiwan to shoot giant tree portraits. Jen and Steve are from Tasmania, a place known for big trees and are highly experienced in climbing and photographing big trees. The first trip took them three weeks to complete the portrait of the Three Sisters, which became very popular after being published in Taiwan. In 2022 the team spent a week making a portrait of Tao tree including two days of tough hiking. Tao tree is the 11th tallest tree of the tree project’s collection of portraits[34].

 
The Tao Tree Portrait team in 2022

Taiwan Giant Tree Map

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Since Taiwan is very mountainous, most tree height measurements using LiDAR are over estimated. This is because many trees grow on cliff edges, and their heights are estimated vertically to the cliff base by LiDAR. In January of 2021, the Tree Seekers uploaded 71,751 records of trees over 65 m high and engaged the public to help identify the locations of giant trees[35]. Over 220 thousand crowd sourced tasks were completed within one month, resulting in the identification of 4,736 giant tree candidates. LiDAR experts then worked on these results, publishing data for 941 giant trees exceeding a height of 65 m at the end of 2022[36]. Among these 941 giant trees, 202 trees over 70 m high and only 27 trees are over 75 m high.[37]

 
Distribution of giant trees, red indicates trees taller than 75 m

Other Projects

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Removal of Cables from Trees

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Beginning in 2021, the Tree Seekers began removing cables left on giant tree trunks during the logging era[38]. The team uses an electric grinder to cut off steel cables from the tree trunks. So far more than ten trees have been released from theses potentially lethal logging cables.

 
Cable scars on the tree
 
The Tree Seekers hold a removed steel cable under the rescued tree
 
Tree Seekers climb a red cypress to cut off cables from the trunk.

Quantifying illegal logging using airborne LiDAR data 

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In 2000, there was a surge in poaching medicinal mushrooms from cypress trees (Cunninghamia lanceolata var. konishii), as people believe these mushrooms can cure cancer. The mushrooms grow inside hollow trunks of giant cypresses, leading to the cutting down of many big trees in remote mountain areas. The Tree Seekers inspected forests affected by illegal logging over several expeditions. The team used LiDAR imagery along with field observations to identify areas of illegal logging in mountain areas.[39]

 
A cypress tree cut down and hole cut to harvest medicinal mushrooms

Carbon Density Inventory

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To determine the carbon density of Taiwan’s primary forests, the Tree Seekers along with 15 citizen scientists returned to the Tao Tree valley for a 4-hectare forest inventory in August of 2024. During a one-week workshop, volunteers measured the diameter of 180 giant trees, 80 fallen logs, surveyed 50 sample lines, and collected soil samples for analysis.[40]

 
LiDAR image of the Tao tree valley
 
Volunteers measuring the diameter of a tree during the carbon density workshop

Extreme Weather Events and Disappearing Giant Trees

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By comparing LiDAR images of giant trees in Taiwan from 2010 and 2021, the Tree Seekers found that approximately 4% of the giant trees had disappeared. Considering that most giant trees are nearly one thousand years old, the recent mortality rate is surprisingly high. This may be due to an increase in extreme weather events. The research team is working to understand the reasons behind the disappearance of these giant trees.

 
LiDAR image of a giant tree 2010 (left) and its disappearance by 2023 (right)

 

external link

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Taiwan giant tree map

The tree project

Facebook page of The tree seekers/ Taiwan champion trees

References

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  1. ^ 徐, 嘉君 (2021). 找樹的人：一個植物學者的東亞巨木追尋之旅 (in Traditional Chinese). 紅樹林. ISBN 9789869741897.
  2. ^ "找樹的人-Taiwan champion trees". Facebook page. 2018.
  3. ^ "Taiwan.gov.tw". Government Portal of the Republic of China (Taiwan).
  4. ^ "What are Champion Trees?". Vizcaya Museum and Gardens.
  5. ^ Rebecca Hsu and Jan HD Wolf (2009). "Diversity and phytogeography of vascular epiphytes in a tropical–subtropical transition island, Taiwan". Flora-Morphology, Distribution, Functional Ecology of Plants. 204 (8): 612–627.
  6. ^ 邱立文、黃群修、吳俊奇、謝小恬 (2015). "第4次全國森林資源調查成果概要". 台灣林業雙月刊. 41 (4): 3–13.
  7. ^ 李, 根政 (2018). 台灣山林百年紀. 天下雜誌. ISBN 9789863984009.
  8. ^ Lin SY, Shaner PJ, Lin TC. (2018). "Characteristics of old-growth and secondary forests in relation to age and typhoon disturbance". Ecosystems. 21 (8): 1521–1532.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ Andersen, Hans-Erik, Stephen E. Reutebuch, and Robert J. McGaughey. (2006). "A rigorous assessment of tree height measurements obtained using airborne lidar and conventional field methods". Canadian Journal of Remote Sensing. 32 (5): 355–366.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  10. ^ Yang, Yuan-ting (2023). "Taiwan's tallest tree found". pp. Taipei Times.
  11. ^ 臺灣植物紅皮書編輯委員會 (2017). 臺灣維管束植物紅皮書名錄. 行政院農業委員會特有生物研究保育中心. ISBN 9789860550214.
  12. ^ "The Trees That Reach the Moon: Journey to Taiwan's Giants – The Three Sisters in Qilan". Taiwan Hikes.
  13. ^ Hsu, Rebecca. "Exploring Treetops in Old-growth Cloud Forests of Taiwan". What's up. 21: 2–3.
  14. ^ "雙鬼湖野生動物重要棲息環境". 農業部自然保育署自然保育網.
  15. ^ "丹大野生動物重要棲息環境". 農業部自然保育署自然保育網.
  16. ^ "布農族". 原住民委員會.
  17. ^ "Department of Geomatics, NCKU". Faculty.
  18. ^ "清朝八通關古道全線". 健行筆記.
  19. ^ "找樹人的故事：清八通關古道 發現巨木森林探勘實錄". 環境資訊中心.
  20. ^ "大安溪水系". 經濟部水利署.
  21. ^ 曹, 婷婷 (2019). "暫居台灣第一高樹，南坑溪上游標高72.9公尺台灣杉巨木". 中時新聞網.
  22. ^ "台灣巨木地圖". 台灣巨木地圖.
  23. ^ 游, 昇俯 (2020). "桃山神木79.1M刷新紀錄，可能是臺灣第一高樹". 農傳媒.
  24. ^ "桃山". 健行筆記.
  25. ^ "西施". 百度百科.
  26. ^ "布農語單詞查詢". 族語E樂園.
  27. ^ "當台灣最長河遇見島上最高樹：記「卡阿郎巨木」與美麗島的原住民們". 環境資訊中心.
  28. ^ "泰雅語單詞查詢". 族語E樂園.
  29. ^ 徐, 嘉君 (2022). "找樹的人遇上取芝的人──行過巨木墳場，幸好「風」還在那裡". 農傳媒.
  30. ^ "倚天出鞘記（上）：找樹的人整裝出發". 環境資訊中心.
  31. ^ "倚天出鞘記（下）：目擊東亞第一高樹". 環境資訊中心.
  32. ^ 林靜梅、郭俊麟 (2023). "84.1公尺台灣杉「大安溪倚天劍」 創東亞最高樹紀錄". 公視新聞網.
  33. ^ "The tree projects".
  34. ^ "Photographing the giants". The tree projects.
  35. ^ 林, 燕如 (2021). "我們一起尋找全台最高的樹｜募求找樹的群眾力量". 我們的島.
  36. ^ 徐, 嘉君 (2022). "找尋百萬分之一的冠軍巨木". 環境資訊中心.
  37. ^ 謝有忠、孫武群、吳庭瑜、徐嘉君、王驥魁 (2023). "台灣巨木棲地分布之地形特性與地質環境". 中華民國地球物理學會與中華民國地質學會112年暨學術研討會.
  38. ^ 謝, 安安 (2021). "《新聞深呼吸》第170集-PART2索道木纏滿鋼索 「找樹的人」拯救台灣最高雲杉 ！". 壹電視.
  39. ^ 徐嘉君、王驥魁、李崇誠 (2023). "空載光達初探香杉盜伐跡地". 台灣林業雙月刊. 49 (6): 53–56.
  40. ^ "台灣的樹，我來護!". TNF自然保育與環境資訊基金會. 2024.
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