2-1. Geology of Datun Volcano Group

The Datun Volcano Group consists of more than 20 volcanoes, including the mountains of Qixing, Datun, Zhuzi, Huangzui, Miantian, Xiangtian, Dajianhou, and Shamao, most of which belong to the geological composition of andesite.

The first eruptions began 2.8 million years ago, and the landscapes that can be seen today were reshaped by tectonic and crust movements, eruptions, and weathering by wind, sun, and rain. Formations such as cone- and bell-shaped volcanos, craters, fumaroles, crater and barrier lakes, fault lines, and waterfalls were all created by volcanic eruptions.

Years after eruptions ceased, vivid traces of volcanic activity can still be found in the park. Post- eruption geological characteristics such hot springs and fumaroles, as well as sulfuric gas and steam from underground thermal water that snake their way through fault fissures and cracks in the Earth’s crust, serve to further highlight the vitality of the Datun Volcano Group.

2-2. Ecology of Datun Volcano Group

Steep terrain and high levels of human activity render the Datun Volcano Group unsuitable for large mammals, but the national park’s composite forests still provide ideal feeding and nesting habitats for many medium-sized and small wild animals such as the Formosan rock macaque, Formosan wild boar, Formosan gem-faced civet, and Coxing’s White-bellied Rat, which are frequently spotted in the park’s conservation zone.

Yangmingshan National Park is also home to about 123 species of birds, including the Chinese bamboo partridge, Japanese white-eye mejiro, and red-headed babbler that live among the woods; the vinous-throated parrot and wren-warblers in the grasslands and shrubs; and the Formosan whistling thrush and little egret in streams and ponds.

The most iconic birds of the national park are considered to be the Taiwan barbet and Formosan blue magpie, the latter of which is an endemic species known as the “Long-tailed Lady of the Mountain” for its extravagant plumage.

May to August at the park is considered butterfly season, in which thousands of Blue Tiger butterflies flutter in groups, buoyed by air flows to form a unique and graceful sight. The Pink-spotted Windmill, an endemic species, is another spectacular butterfly that can be found fluttering about the Datun Volcano Group.

When summer arrives, the cicadas stage a music symphony, with species such as Pomponia linearis, Tanna sozanensis, Mogannia hebes, and Platypleura kaempferi singing without a break.

There are also 53 reptilian species in this area, the most common of which are the red-banded snake and big-eyed rat-snake, as well as the venomous brown-spotted pit viper and cobra. Of the 23 amphibian species present, the Asian grass frog, Taipei tree frog, and Central Formosan toad have the widest distribution and the greatest numbers. Other species include the ornate pygmy frog and LaTouchte’s frog.

The Datun Volcano Group is located in the subtropical climate zone, but its vegetation differs from those in other areas of the same latitude because of two factors. First, the soil is unusually warm, lacking in calcium, and strongly acidic owing to post- eruption features, which allow for unique geothermal vegetation and aquatic plants to thrive.

Secondly, this region bears the blunt of the northeasterly monsoon during winter. The monsoon brings precipitation and lower temperatures, making Yangmingshan a much wetter and colder place than the land below it. This creates a phenomenon known as “north drop,” in which vegetation belonging to higher altitudes can be found at a lower elevation.

Therefore, the Datun Volcano Group region is inhabited by vegetation from different plant zones, including those found in subtropical rainforests, warm temperate evergreen broadleaf forests, and mountain-ridge grassy plains. Several alpine plants from the Central Range, an area of 2,000 meters above sea level, can also be found here.

Temperatures are high and laced with sulfur gas in regions that contain hot springs and fumaroles, and only a few species of lichen, moss, and algae have adapted to the harsh conditions of geothermal habitats. Datun is dotted with liverworts, mosses of the Microcampylopus genus, and as well as sulfuric bacteria and Synechocystis aquatilis Sauvageau, which is a type of cyanobacteria that were among the first-known organisms to photosynthesize.

Aquatic plants such as the bog bulrush, water chestnut, and rush can also be found among the region’s crater wetlands. Also of note is the Formosan quillwort, or Isoetes taiwanensis, which is an aquatic plant that is endemic to Taiwan and only grows in Yangmingshan’s Menghuan Lake.

Usawa cane, a type of arrow bamboo, and silvergrass make up the predominant vegetation of Datun’s grasslands. The underground stem vines of the arrow bamboo are tightly intertwined and wide reaching, leaving little room for other plants to root and grow.

Bamboo forests ensure continuity of their species by mass flowering before they die. In 1999, the Usawa cane forest in National Yangmingshan Park blossomed on a massive scale before collapsing, paving the way for better-evolved new seedlings to grow.

The silvergrass of this region are of the white-backed cultivar, which grow on shorter stems and produce red flowers. Fields of bright red silvergrass tassel on slopes swathed in warm volcanic mist are a unique sight that can only be seen in this area every September and October.

Broadleaf evergreen forests are situated about 500 to 900 meters above sea level and are usually populated by trees of the Lauraceae family, including the red nanmu and large-leafed nanmu. Other traditional mid-elevation plants such as the Formosan gentian, Taiwan fetterbush, and wheel stamen tree are also found in this area.

Accompanied by plants and vines, such forests form an ecosystem with considerable vertical variation in Yangmingshan Park, providing an excellent habitat for birds, insects, mammals, and amphibians to nest and foray for food. 

There are many species of rare plants in this area, including the endemic Formosan quillwort, the Rhododendron varieties longiperulatum and nakaharai, Bretschneidera sinensis, Dysosma pleiantha, and flowering dogwood. Within the Yangmingshan National Park, upstream of Shanghuang Creek and Datun Mountain are the only areas that produce Maackia taiwanensis, a small tree of the legume family endemic to Taiwan. 

The Datun Volcano Group enjoys an abundance of geothermal resources, hot springs, and sulfur. Sulfur was once a highly sought-for commodity for its use in explosives. As early as Ming dynasty, Ketegalan plains aborigines ventured into the mountains to mine sulfur. When Qing dynasty came to power, the Manchu court sent explorer Yu Yong-ho to search for sulfur in Taiwan following the loss of over half a million catties of gunpowder during an explosion at the Fuzhou gunpowder depot in winter 1969.

The Zhejiang native wrote a book titled “Small Sea Travel Diaries” after returning to Xiamen in the following year. The book preserved his experiences from the seven-month foray in Taiwan, in which he bartered with Taiwanese aborigines and traded textiles for sulfur. “Small Sea Travel Diaries” is now considered one of the first and most valuable first-handed records on the early history and culture of the Datun region. 

Today, visitors to Datun’s Dayou Pit can see the sulfur mining equipment once used by a special administration established by Qing authorities. The plant was responsible for mining sulfur and harvesting camphor to help ease the empire’s financial difficulties under the rule of Guangxu Emperor.

Yangmingshan was also the largest cultivation area for Assam indigo (Strobilanthes flaccidifolius) in the 1880s. As the main source of blue dye in Taiwan, the Acanthaceae plant was introduced to northern Taiwan and widely planted in Yangmingshan ravines in the early 19th century to meet dye demand. Although the introduction of synthetic dyes led to the decline of Taiwan’s dye industry in the last century, the hardy plant survived without human care and can be found today in the vicinity of Yangmingshan creeks and streams.

The legacy of the Assam indigo plant, which is known as “Jing” in Chinese, is also preserved in road and region names such as “Jing Mountain Road,” “Upper Jing Mountain,” “Middle Jing Mountain,” and “Lower Jing Mountain.”

Criterion VIII:

The unique landscapes of the Datun Volcano Group were created by an upheaval of volcanic eruptions and large structural deformations of the Earth’s crust from more than two million years ago. The 25-million-year-old stratum, volcanic terrain, and post- eruption geological landscape are records of the ever-changing crust movement and geological evolution of planet Earth, meeting the eighth selection criterion of the UNESCO’s world heritage register.

Criterion IX:

Other regions of the same latitude are mainly arid deserts with homogenous ecology. In comparison, the humid and wet island of Taiwan offers a wide range of geological landscapes and rich ecological resources that have been augmented by the influence of tectonic movements, volcanic eruptions, thermohaline circulation of ocean currents, and annual northeasterly monsoons.

Moreover, the Datun Volcano Group enjoys four distinct seasons, serving as a microcosm of Taiwan’s diverse landscapes and ecology. The region is home to plants and animals from volcanic, geothermal, grassland, and forest habitats, and the “north-drop” environmental effect of the northeasterly monsoon give rise to rare species that survived the Ice Age. As an outstanding example representing significant ecological and biological development, the Datun Volcano Group meets the ninth selection criterion.

Selection X:

Lush vegetation and considerable variety of terrains have nurtured 34 species of mammals, 123 species of birds, 23 species of amphibians, 53 species of reptiles, and 191 species of butterflies. As home to an additional 1,600 species of plants, the Datun Volcano Group holds invaluable research and conservation value, thereby meeting the tenth selection criterion.