Seeing the Forest and the Trees

Taiwan's Tree Researchers and Forestry Surveyors

2020 / May

Cathy Teng /photos courtesy of Lin Min-hsuan /tr. by Jonathan Barnard

How tall is a tree? How many leaves does it have? And how many trees are there in a forest? Almost all children ask such questions in their stage of inquisitive wonder.

After growing up, you aren’t likely to encounter these questions in daily life unless you’re a forestry professional. But when you do get a chance to go into a forest, do questions like these still prick at your curiosity: How do you go about measuring the forest? And what do the resulting figures really mean?


Forestry measurements can help to answer such questions, and they also offer a way of becoming acquainted with the forest. Researchers make use of all available means—including measuring tools, scientific instruments, mathematical formulas and statistical sampling—to under­stand the forest. Numbers are a language that can describe nature, and survey data provide basic information about a forest. People can draw from this well of knowledge both to manage forests and to learn how to coexist with nature.    

Looking for the tallest tree

How does one know or describe how tall a tree is? For instance, Taiwania (Taiwania cryptomerioides) is the tallest tree species in East Asia, and Taiwan’s indigenous Rukai people describe it as the tree that “knocks the moon.” Rebecca C.C. Hsu of the Taiwan Forestry Research Institute takes a different approach, measuring the height of these trees by climbing them.

Hsu is a forest ecology researcher with a special interest in the epiphytic plants that grow in the forest canopy, so getting up into trees is essential for her work. At first, she adopted her predecessors’ methods of collecting plants and seeds, driving L-shaped spikes into trees to ascend them. Later she adapted rock-climbing techniques to climbing trees.

Apart from her work on epiphytes, Hsu also has an interest in finding giant trees. Since she was always hanging out in treetops, she began to wonder how tall the trees could grow, and what factors influenced their growth.

Early in her quest to find Taiwan’s tallest trees, she mostly worked on word of mouth from forestry professionals or used a clinometer and trigonometric calculations to make ­estimates. Nowadays she is using more advanced devices and techniques. She works with Wang Chi-kuei, a professor in the Department of Geomatics at National Cheng Kung University, and his team, applying an algorithm to data gathered by an islandwide airborne LiDAR (light detection and ranging) survey program commissioned by the Ministry of the Inter­ior following Typhoon Morakot in 2009. The technique takes advantage of the ability of laser beams to penetrate the forest canopy to chart out a model of the height of the treetops and the topography of the ground beneath. After using the ­LiDAR data to pinpoint areas with old trees, Hsu then goes with an exploration team to check out the sites in person. In 2019, they discovered the tallest Taiwania tree yet found in Taiwan. Measuring 72.9 meters, the tree is loc­ated on the upper reaches of Nankeng Creek on Mt. Daxue.

Hsu and her team also successfully scaled a 46.4-­meter giant camphor (Cinnamomum camphora) in Nantou ­County’s Shenmu Village, and got it listed on the Monumental Trees website as the world’s tallest known camphor tree.

Once you’ve measured the tallest trees, then what? “Actually, a lot of scientific research emerges from researchers’ curi­osity,” says Hsu. But curiosity can elicit great resonance. In 2017 she launched a project to make isometric photos of Taiwania specimens. She invited a photographic team from Tasmania-­based The Tree Projects to come to Taiwan and take isometric photos of three large trees known as the “Three Sisters,” located along Forest Route 170 in the Mt. Qilan Forest Area. The Three Sisters are at least 800 years old. One of them rises to 69.5 meters, about the height of a 23-story building. Seeing the trees fully revealed in photographs, many observers remarked on how few people even know that Taiwan has trees this beautiful, recalls Hsu. “It fosters a sense of pride and identity.” The project is spotlighting the beauty of Taiwan’s forests and raising awareness of forest conservation. It’s one more fruit of the search for big trees.

Forest resources survey

Cut to Hsinchu County, where we’re following the motor­cycles of Lee Shenming and Luo Shih-fan of the Forestry Bureau’s Zhudong Work Station as they wind their way through the mountains to the woodlands of Mt. Wuzhi. According to GPS data, we are approaching the sample plot, and Lee and Luo look everywhere for trail markers left by the previous surveyors. With much effort, they finally locate the center of the plot, where there is a planted stand of Taiwan fir (Cunninghamia konishii). Lee and Luo need to sample 50 trees for the survey. Using maps made by earlier teams, they find the sample trees and take new measurements of their dia­meters and heights. They then store the new information in the trees’ RFID tags. If any of the trees has fallen, this is recorded too.

Lee and Luo are taking follow-­­up measurements for Taiwan’s fourth national survey of forest resources. By documenting basic informa­tion such as the land area of existing forests, the stock of growing timber, and trees’ periodic growth increments, these surveys allow national forestry policy to be based on more reliable information.

There have been four islandwide surveys of forest resources, explains Huang Chyun-shiou, director of the Forestry Bureau’s Forest Planning Division. The goals of each survey have varied according to society’s needs. Forest resources were first surveyed in 1956, when postwar Taiwan desperately needed economic revival. With US assistance, an inventory was made of forest areas, wood volumes, and usable resources. The second survey was carried out in 1977, when Taiwan was transitioning from an agricultural to an industrial society. Its focus was on determining what land was still available for development. The third survey took place in 1993, when the island’s economy was already largely based on manufacturing and services. With universal edu­cation and rising incomes, an ethos of forest conservation was taking hold. Along with newly cataloging the forests’ animals and plants, that survey put more emphasis on the varied uses of forests, including their recreational value.

The fourth survey began in 2008, more than a decade after the previous one. By that time the available data no longer truly reflected Taiwan’s forest resources and land use. Also, growing international concern about shrinking forests and atmo­spheric warming—as expressed, for example, in the Kyoto Protocol, which affirms forests’ role in reducing greenhouse gases—highlighted the import­ance of both forest resource monitor­ing systems and the sharing of forestry data as a responsibility for every nation. Although Taiwan is not a member of the United Nations, it is still a part of the global community. Thus the Forestry Bureau launched its fourth survey of Taiwan’s forest resources, with a new focus on evalu­ating woodlands’ capacity as a carbon sink (their ability to absorb carbon dioxide) and establishing a long-term monitoring system for forest resources. 

The need for forest management

Islandwide surveys of forest resources require enorm­ous inputs of time and money, and grueling effort by surveyors. But what can be done with the huge amount of data that such surveys yield? What do the numbers show?

The fourth survey found that forests covered 60.7% of Taiwan’s land, an increase of 2.2 percentage points over the 58.5% recorded in the previous survey. Landslides caused by Typhoon Morakot in 2009 destroyed large areas of forest, reducing the size of nationally owned forests, Huang explains, but total forest area still grew by more than 80,000 hectares thanks to reforestation in the foothills. As a consequence of Taiwan’s aging population and labor shortages, much farmland there has been abandoned to nature, becoming second-growth forest. What’s more, when Taiwan joined the World Trade Organization, govern­ment agri­cultural agencies promoted the reforest­ation of lowland areas. Both were important factors behind the increase in Taiwan’s forest coverage.

Globally, forests are disappearing at a rapid rate. And although the forest survey shows that Taiwan’s forest cover­age has grown and its forest resources have increased, that growth obscures some harsh realities. “As much as 60% of the island is covered by forests, but much of that wooded land can’t be managed productively,” Huang explains, breaking down some of the myths regarding forests in Taiwan. “For instance, the accessibility of forest land deep in the Central Mountain Range is low and the costs of logging there are high. Taiwan’s forest area per capita stands at only 0.092 hectares. The figure shows that Taiwan is far from self-sufficient in forest resources.”

Carbon sequestration

The forest coverage rate of each nation has different implications for action depending on the situation. “In Taiwan, the focus of forestry management should be on bolstering the health of existing forests and raising their capacity as carbon sinks,” says Huang Chyun-shiou.

Carbon sink capacity is a measure of how forest plants absorb carbon dioxide (CO2) through photosynthesis and fix it in vegetation and the soil, thus reducing the concentration of CO2 in the atmosphere. It may sound academic, but Huang quickly brings the subject down to earth: “It may be hard to connect life in Taiwan to carbon sinks, but globally 20% of growth in CO2 emissions comes not from the burning of fuel by factories and automobiles, but from the loss of forests.” In 2019, major forest fires in Australia and California put alarming amounts of CO2 into the atmosphere. 

A more common misconception is that most people believe that cutting down trees is inevitably bad for the environment. “Wood from forests being used for furniture or other items is a form of carbon sequestration,” Huang explains. “Where the old tree grew, a new seedling will be planted that will continue to absorb CO2. It’s an example of sustainable use. That's why we advocate that people use more sustainable materials like wood.”

In terms of lumber production, Taiwan is far from self-sufficient, but that doesn’t mean we should simply rely on imports. “Taiwan’s forestry policies ought to put a greater focus on forestry management, including the proper management of lumber plantations,” says Huang. “To revive national natural resources, we need to make more efficient use of the land.”

Forests are among Taiwan’s most important natural resources, and an ethos of forest conservation is already widely established among the island’s people. Looking ahead, says Huang, “Taiwan must make better use of re­cyclable lumber to help reduce our carbon footprint.”

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最も高い木を発見してどうするのだろう。「実は科学研究の多くは、最初は研究者の好奇心から始まったのです」と徐嘉君は言う。その好奇心が大きな反響を得ている。彼女は2017年に「タイワンスギ等身大写真撮影計画」を行ない、オーストラリアからThe Tree Projectの撮影隊を招き、棲蘭山のタイワンスギ三姉妹の等身大写真を撮影した。林道170号線沿いに立つタイワンスギ三姉妹は少なく見積もっても樹齢800年で、そのうち一本の高さは23階建てに匹敵する69.5メートルだ。撮影隊はカメラの軌道を垂直に立てて下から上へと撮っていき、それらをつなぎ合わせると三姉妹の全貌が明らかになった。「台湾にこんなに美しい木があったのかと多くの人が知り、人々は誇りに思い、アイデンティティも高まりました」こうして多くの人が台湾の山林の美に触れ、森林保全の意識が高まってきたのである。



















文‧鄧慧純 圖‧林旻萱








早期要找到最高的樹,多是林業人員口耳相傳,或是用測高儀、三角函數推估;如今可借助科技,如空載光達(airborne LiDAR),自上空向地面發射雷射光束,藉由回波訊號計算對地面的距離,以獲得精密的地表資訊。徐嘉君跟成功大學測量及空間資訊學系教授王驥魁團隊合作,利用內政部在莫拉克風災後,啟動全島光達探測計畫的資料,輔以演算法,善用雷射穿透森林樹冠層的特性,繪出樹冠高度及地面地形的模型,靠光達篩選出巨木的區域,再由人力實地探勘。2019年,成功找到迄今尋獲最高、位在大雪山區南坑溪上游的台灣杉,樹高72.9公尺。


利用量測,找到最高的樹,然後呢?徐嘉君說:「其實很多科學研究剛開始都起因於學者的好奇心」,但好奇心卻可能引起大迴響。她在2017年發起「台灣杉等身照片拍攝計畫」,邀請了澳洲「The Tree Projects」拍攝團隊來台,為位在棲蘭山區的台灣杉三姊妹拍攝等身照。這佇立在170號林道上的台灣杉三姐妹,少說已800歲高齡了,其中一株高達69.5公尺,約是一棟23樓高的建築。拍攝團隊架起垂直的相機軌道,由底而上拍攝,再一張張拼接起來。三姊妹的全貌一曝光,讓許多人驚嘆,「很多人都不知道台灣有這麼漂亮的樹,從而升起一股驕傲和自我認同感。」讓更多人認識台灣山林的美麗,提升森林保育意識,是尋找高樹外的另一個迴響。






第四次調查在2008年展開。距上次調查已逾十餘年,森林資源及土地利用資訊皆未能反映實際現況,再加上國際社會對於森林面積縮減、氣候暖化等議題的關注;如「京都議定書」中肯定森林對溫室氣體減量的重要性,進而倡議將森林動態監測與資訊共享列為各國應盡的責任。台灣雖非聯合國成員,但仍是地球的一份子,林務局啟動第四次森林資源調查,除了解台灣森林現況外,更著重在森林碳匯(carbon sink,森林吸收二氧化碳的能力)評估,建置森林資源的長期監測系統。











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