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Southeastern Asia: Taiwan

Taiwan, the largest island off the coast of China, is comprised of steep, granite mountains that rise on the eastern slope from a deep oceanic trench to nearly 4,000 m in elevation at the summit of Mt. Yushan. Because of the north-south alignment and the large vertical relief, Taiwan possesses a wide range of habitats and a correspondingly high biodiversity. A range of subtropical to subalpine forests still remain on mountain slopes while the coastal plains have been largely converted to agriculture. Taiwan’s system of national parks and nature reserves offers a good measure of protection to the montane forests, while lowland and coastal areas would benefit from increased conservation measures.

  • Scientific Code
    (IM0172)
  • Ecoregion Category
    Indo-Malayan
  • Size
    12,900 square miles
  • Status
    Vulnerable
  • Habitats

Description
Location and General Description
The island of Taiwan is located about 200 km off the east coast of China. Most of the island is mountainous. Several ranges trend from northeast to southwest, and the highest peaks approach 4,000 m. The east side of the island rises steeply from the Pacific, while the west side includes some coastal plains that lie adjacent to the East China Sea. The mountains are high enough so that summits higher than 3,000 m receive some winter snow.

Taiwan includes two ecoregions. Taiwan subtropical evergreen forests occupy most of the island while South Taiwan monsoon rainforests cover the southern tip. Of course, with 20 million people and a vigorous economy based on agriculture and industry, Taiwan’s natural environments have been severely affected by people. Most of the natural habitat occurs in mountain areas where several nature reserves and national parks have been established. Today, forest cover is estimated to be about 52 percent of the total land area, although much of this consists of non-native tree plantations.

Taiwan lies at the edge of the tropics and is washed by ocean currents that move north from the equator, creating a tropical monsoon climate with a mean annual temperature of 22oC and only about 10oC seasonal variation in temperature. Precipitation patterns vary across the length of Taiwan. The southern portion of the island receives most of its precipitation (about 2,900 mm a year) during the summer southwest monsoon from the South China Sea. The northern portion of the island, however, is affected by the northeast "winter monsoon," and it receives most of its precipitation during winter. In general, the eastern slopes of the island receive the most rain (up to 6,000 mm annually) while the western plains receive only about 1,500 mm. Because Taiwan faces a great expanse of the tropical Pacific to the east, it is subject to intense typhoons.

The Taiwan subtropical evergreen forests are dominated by broadleaved species. But the island’s topographic complexity means that many different forest types occur at different elevations on slopes of different aspect. MacKinnon et al. (1996) observed that these forests tend to form concentric rings around the island, like the lines on a topographic map, as elevation increases toward the interior. Despite this complexity, the overall forest zonation sequence seems to follow a pattern that re-occurs in mountain ranges throughout subtropical East Asia. As elevation increases, evergreen broadleaved forests are gradually replaced by deciduous hardwoods and conifers.

Here, low elevation plains areas support monsoon evergreen broadleaved forests that are dominated by the chestnut, Castanopsis hystrix, and the laurel, Cryptocarya chinensis. Laurel-Castanopsis spp. forests are widely distributed across subtropical South Asia, forming climax forest associations throughout southern China and into the southern foothills of the Eastern Himalaya. The species, C. hystrix, itself is widely distributed; it extends clear across subtropical Asia as far west as Nepal. Some stands of the subtropical pine species Pinus massoniana also occur in this zone. Higher-elevation forests are dominated by the oak-like tree Cyclobalanopsis glauca.

Upper temperate and subalpine forests occur at about 3,000 m. Here, deciduous hardwoods like alder (Alnus cremastogyne) and maple (Acer spp.). co-occur with hemlock (Tsuga chinensis). In the Eastern Himalaya as well, hemlock is a coniferous species transitional to the subalpine forest zone. At the highest elevations are stands of cold temperate (subalpine) coniferous forest dominated by Tsuga spp., Picea spp., and Abies spp.

Biodiversity Features
Taiwan has an extensive protected area network that includes both coastal and mountain habitats. However, as in many places throughout the world, the protected area network protects a higher proportion of habitat in montane areas than in the coastal lowlands, which have been densely settled and intensely farmed for many centuries. Both national parks and nature reserves are better demarcated and described here than they are in most of China. MacKinnon et al. (1996) provide a comprehensive account. A summary is provided here.

Some of the larger protected areas include Yushan National Park (1,055 km2), Shei-Pa National Park (769 km2), and Taroko National Park (920 km2). Yunshan includes high mountains, mostly over 2,000 m. It supports rare mammals such as Taiwan muntjac (Muntiacus reevesi micrurus), Taiwan serow (Naemorhedus swinhoei), and Taiwan black bear (Selenarctos thibetanus formosanus) as well as the two pheasants endemic to Taiwan, the Mikado pheasant (Syrmaticus mikado) and Swinhoe’s pheasant (Lophura swinhoei). Shei-Pa is a relatively new national park, much of which is set aside for ecological protection rather than mountain tourism. It supports the endemic landlocked salmon (Oncorhynchus masou formosanum) and the Taiwan salamander (Hynobius formosanus). Tsenwen Estuary (3 km2) is a small nature reserve on Taiwan’s Southwest Coast. It provides critical habitat for black-faced spoonbills (Platalea minor) and important wintering habitat for other waterbird species.

Taiwan is an important endemic bird area (Stattersfield et. al. 1998) with 15 restricted-range species, the majority of which are forest birds that might have once inhabited lowland forests but are now restricted to upland mountain slopes. These include Mikado pheasant (Syrmaticus mikado), collared bush-robin (Tarsiger johnstoniae), white-whiskered laughingthrush (Garrulax morrisonianus), and flamecrest (Regulus goodfellowi). Fairy pitta (Pitta nympha) is a widespread but threatened species (status: vulnerable), that occurs in Taiwan’s subtropical forests.

Species richness for plants and mammals is rather poor on Taiwan, although rates of endemism are higher than on the mainland. This follows the general pattern for an island. On Taiwan, 24 endangered plants occur, including the tree fern (Cyathea spinulosa) which has fibrous stems that are an ideal substrate for cultivating orchids. Taiwan supports a total of 48 mammal species, of which 7 are endemic. Two of these endemics, the Taiwan macaque (Macaca cyclopis) and Taiwan serow (Naemorhedus swinhoei), are first-class protected species.

Bird species richness is quite high. Fully 338 species have been recorded, 55 of which have protected status (9 first-class, 46 second-class), and 10 of which are endemic to the island. Of the first-class protected birds, two are endemic. Mikado pheasant (Syrmaticus mikado) occur in middle-elevation montane forests at 2,000 to 3,000 m, and Swinhoe’s pheasant (Lophura swinhoei) occur at lower elevation (900 to 2,100 m or higher). Both of these species are severely threatened because they are both ornamental and large enough to provide a good meal.

Other threatened birds in Taiwan are coastal migratory species. Tsen Wen Estuary is the main wintering site of black-faced spoonbills (Platalea minor) and holds about 60 percent of the world’s population. Short-tailed albatross (Diomedea albatrus) sometimes visit offshore islands like Diaoyu. Waders like Chinese egrets (Egretta eulophotes), Nordmann’s greenshanks (Tringa guttifer), and Saunder’s gulls (Larus saundersi) also winter here.

This high bird species richness likely results from several factors: high amounts of forest cover, diverse landscapes, near-tropical latitude, and Taiwan’s position along the western Pacific coastal migratory routes.

Additional biodiversity includes an estimated 76 reptiles, 30 amphibians and 130 freshwater fish species. About 400 butterfly species have been recorded. Many of the larger, more colorful species are believed threatened by habitat destruction and commercial exploitation.

Current Status
Taiwan has been peopled for thousands of years. In recent centuries, the indigenous population has been augmented by waves of settlement from other areas of China so that the native Taiwanese are now greatly outnumbered by Chinese, mostly from the coastal provinces of Fujian and Guangdong. Because of the long history of human habitation, many Taiwanese are familiar with the useful resources found in their forests. These forests contain more than 300 economically important species, including figs, laurels and bamboo. Conifers such as Keteleeria fortunei, Chamaecyparis obtusa, and C. formosensis are used for timber. The camphor tree (Cinnamomum camphora) is another abundant, commercially valuable tree.

Types and Severity of Threats
Altogether, Taiwan has a considerable number of coniferous taxa of conservation concern at the level of species and subspecies. There are 3 subspecies and 14 species placed in this category on the preliminary list of Fajon et al. (1993). The coniferous genera that occur in the mountains of Taiwan that include at least one threatened species are Cephalotaxus spp., Calocedrus spp., Chamaecyparis spp., Abies spp., Keteleeria spp., Picea spp., Pinus spp., Nageia spp., Podocarpus spp., Amentotaxus spp., Cunninghamia spp., and Taiwania spp.

Justification of Ecoregion Delineation
This ecoregion was derived from broadleaf evergreen forests that dominate Taiwan (classes 21a, 22a, 20a) according to the CVMCC (1979) Vegetation Map of China. It also includes conifers (classes 8c, 4a) and double crop agriculture (74a,b) from the same source. These classes form a subset of Mackinnon’s (1996) tropical Taiwan biogeographic region subunit (27).

References
Chinese Vegetation Map Compilation Committee. 1979. Vegetation map of China. Map (1:10,000,000). Science Press, Beijing, China.

Farjon, A., C.N. Page, and N. Schellevis. 1993. A preliminary world list of threatened conifer taxa. Biodiversity and Conservation 2: 304-326.

MacKinnon, J. 1996. Wild China. The MIT Press, Cambridge MA.

Mackinnon, J., M. Sha, C. Cheung, G. Carey, Z. Xiang, and D. Melville. 1996. A biodiversity review of China. World Wide Fund for Nature, Hong Kong.

Stattersfield, A. J., M.J. Crosby, A.J. Long and Devid C. Wege 1998 Endemic Bird Areas of the World: Priorities for Biodiverstiy Conservation. Birldlife International, Cambridge, UK

Zhao, J. editor. Zheng Guangmei, Wang Huadong, Xu Jialin. 1990. The Natural History of China. McGraw Hill Publishing Company, New York.

Prepared by: Chris Carpenter
Reviewed by: In progress

 

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