The Cilan region is in the northern part of the Xueshan Range, surrounded by the Dabajian Mountain, Tao Mountain, Meiyuyen Mountain (2,328 meters above sea level), Tangsui Mountain (2,090 meters), Cilan Mountain (1,918 meters), Cuantoumu Mountain (1,551 meters) and Daguan Mountain. The mountains of this range have an average elevation of 2,000 meters, and the region is the main water source for the Lanyan River and Dahan River that supply northern Taiwan. 

There are only seven species of cypress (Chamaecyparis) remaining in the world,  and they can be found on the east and west coasts of North America, as well as in Japan and Taiwan.

There are two species of cypress native to Taiwan: Taiwan red cypress (Chamaecyparis formosensis Mats.) and Taiwan cypress (Chamaecyparis taiwanensis Mas. et Suzuki). According to research on the current distribution of cypress trees in the world, the cypress is rare for producing gymnosperms, and its distribution and limited amount of species are unique among conifers.

Cypress habitats s are found in humid and foggy mountainous areas. While cypress forests in North America and Japan belong to the coniferous forest zone, Taiwan’s cypress forests are the only ones thatare found in the subtropical region.

The Cilan region is home to the remaining primal giant cypress trees in Taiwan. Such primal specimens are rare in the world because they contain a unique ecosystem and comprehensive gene pool. They provide crucial information in understanding the great migration of creatures on Earth during the ice ages, as well as comprehensive data for studying natural evolution and ecological restoration. 

Taiwan’s cypress trees grow in medium- and high-elevation mountainous areas, where high peaks, deep valleys, and abundant rainfall and fog have created an isolated island ecosystem.

Gymnosperms that grow in the region of cypress forests include Chinese yew (Taxus chinensis), Taiwan cedar (Taiwania cryptomerioides), China-fir (Cunninghamia lanceolata var. konishii), and Taiwan plum yew (Cephalotaxus wilsoniana), which are surviving Arcto-Tertiary species.. After isolated evolution, they became endemic to Taiwan. Having experienced long-term evolution of tens to hundreds of millions of years, they are considered “living fossils.”

In addition to coniferous forests, Formosan black bears (Ursus thibetanus formosanus) and odd-toed ungulates such as Taiwan serows (Capricornis swinhoei) and Reeves's muntjacs (Muntiacus reevesi) are also found in the Cilan region, making the region a perfect habitat for rare wild animals in northern Taiwan.

There are 31 mammal species, 100 bird species, 42 reptile species, 18 amphibians, and 417 insect species in the region. Some of these wildlife species are endemic and listed as protected species, including 10 endemic and 8 protected mammal species, as well as 13 endemic and 40 protected bird species.  In fact, 40 percent of the bird species here are protected species.

The area also has 13 endemic and 21 protected reptile species and the highest serpentine diversity in Taiwan at 32 snake species, which make up nearly 70 percent of all terrestrial snake species in Taiwan. As for butterflies and other insects, there are 94 endemic species and 10 protected species in Cilan. Over half of Taiwan’s 18 protected insect species are found here.

According to field research, there are 100 vascular plant species in this area. Among the species that grow mainly in the cloud forest, 38.5 percent are endemic species, which is significantly higher than the average distribution of the endemic vascular plant species in Taiwan (27 percent). This stands testament to the uniqueness of cloud forest species.

In addition, there are 62 species of rare plants, of which theRhododendron chilanshanense  and Asarum crassusepalum are endemic to the area. Moreover, the vegetation in this area is made up of cypress, Taiwan hemlock, and pine communities. Cypress is the dominant type of the region and Cilan’s Taiwan cypress forestsare the biggest remaining stretch of pure cypress forest in the world.
 
The Cilan Mountain Cypress Forest is comparable to the Sequoia National Park in the United States. Cypress trees are found in coniferous forests growing in the area between warm and temperate zones. Such forests in Taiwan are located at an elevation of 1,600 to2,400 meters where precipitation is the most abundant. Because the climate is warm, humid, and rainy, the composition of the vegetation community is very diverse, and the degree of divergence in terms of species is the most dense and stable among coniferous forests.

A history of long-term isolated evolution has given rise to rare gymnosperms that are endemic to Taiwan. They are widely called “living fossils” to commemorate tens to hundreds of millions of years of evolution.

In 1980, the Sequoia National Park in California was listed as a World Heritage Site by UNESCO. An elevation difference from sea level to 950 meters above sea level, an annual precipitation of more than 2,500 mm, and a maritime climate that is humid all year round have given the national park a variegated and diversified ecological landscape. A total of 856 vegetation species have been recorded, in which 699 are native species and redwoods (Sequoioideae) are the dominant tree species.

Compared with the Sequoia National Park, the Cilan Mountain Cypress Forest is located in mountains at medium elevation that are equipped with high peaks, deep valleys, and abundant rainfall and fog, which have created a closed ecological environment.  Favorable factors such as warm temperatures and high humidity have created an environment where many plants compete for survival. Therefore, cypress trees in Taiwan often share the same habitat with Taiwan hemlocks, China-firs, Taiwan cedars, and Chinese white pines, resulting in a region rich in plant species. 

Statistics reveal that there are 1,009 species of vascular plants in the area, including 14 species of gymnosperms descending from the ice ages. Compared with the Sequoia National Park, the Cilan Mountain Cypress Forest contains more abundant and rare plant species and offers a more spectacular forest landscape.

The earliest written records about cypress trees in the Cilan Mountain are found in the Kavalan Office Records of the Qing Dynasty. Two entries for important trees in the area are listed in the “Genus of Tree” chapter, with one saying “There are no pines and fir trees in the Kavalan area, but there are such hardwoods as camphor and Phoebe zhennan … Camphor trees have a fine and intricate texture, and it takes several people to encircle the big ones, which provide shade covering several acres. They are suitable for carving and have a strong aroma; the wood and leaves of the camphor laurel are distilled by steam for their essential oils, which can be made into medicine. Big trunks are used as pillars while small ones are made into camphor.”  

The second entry reads: “Local cypress – big ones take 10 people to encircle and cover a circle of five kilometers in circumference. However, the trees are in the mountainous aboriginal territory of Balishanan [today’s Sanshing Township in Yilan County], therefore no one dares to cut them.”

In comparison to the contemporary humanitarian and environmental development of Yilan, the wild forest conditions of Yilan about a century ago are clearly captured by the two brief historic entries.

The most important human activities in the area’s early history were those carried out by Taiwan’s aboriginal Atayal tribe, including settlement, migration, and various production activities. The Atayal tribe has the second largest population distribution out of all the indigenous groups in Taiwan: research shows that old communities near the Cilan area once included the Atayal settlements of Manauyan, Taiyaho, Buyugan, and Tetahan.

Early Han Chinese immigrants to Taiwan mainly developed land in the plains region and did not enter the Cilan area to interact  with aboriginal communities. At the beginning of the Japanese colonial era, the immigration policy from year 28 on the Meiji calendar (1895) to the Taisho era (1912 to 1926) had forcibly relocated many Atayal people from their remote mountain homes to enclaves surrounded by “barrier defense lines” or garrison areas along “roads of barbarian subjugation,” leaving behind  today’s ruins of old communities.

Criterion VIII

The Cilan Mountain Cypress Forest is located in mountainous areas of medium to high elevations. The high peaks, deep valleys, and abundant rainfall and fog there have created an enclosed ecological environment, allowing rare Arcto-Tertiary gymnosperms such as the Chinese yew, Taiwan cedar, China-fir, and Taiwan plum yew to grow among cypress forests, evolve in isolation, and become endemic to Taiwan. After experiencing tens to hundreds of millions of years of evolution, these plants are considered “living fossils” that serve as an index in ecological evolution, thereby meeting the eighth selection criterion for World Heritage Sites.

Criterion X

Rainfall records show that the average annual rainfall in the Cilan Mountain area reaches 5,000 mm. The area is foggy and rainy for nearly 250 days a year, making the woodland a “cloud forest” as termed by the botanical world.

The natural ecosystem in the area is categorized as a “warm temperate mountain coniferous forest” by academia. In botanical studies, it is divided into two plant ecology categories – mixed coniferous forest and cypress forest. 

Cypress forests are distributed at an elevation of 1,600 to 2,600 meters above sea level, where the warm and humid climate allows diverse plants to grow in the forest. From the perspective of biodiversity, there is a wide variety of plant species, including many endangered and valuable ones.

These rare conifer forest conditions are suitable for such large ungulate mammals as Taiwan black bears, Formosan serows and Formosan muntjacs. The Cilan area has become a perfect habitat for rare and valuable wild animals in Taiwan, which meets the tenth selection criterion for inclusion.

5-1. Origins of Taiwan’s primal cypress forest

It is an incorrect impression that all four seasons in Taiwan are like spring, because there has long been a snowy environment on the towering backbone of Taiwan proper. When autumn comes, the weather gradually turns cool on high mountains in Taiwan, and cold air masses from northern China hit Taiwan’s high mountains one after another during winter. Cold currents from the north often bring snow to the Qixing Mountain and Taiping Mountain in northern Taiwan, Dayuling in central Taiwan, and Alishan in southern Taiwan.

Taiwan, where mountains cover three fourth of the island, was visited by northern continental glaciers during the ice ages, providing the perfect conditions for the southward migration of ancient gymnosperm coniferous trees.

Traces of glacial striations, glacial cirques, and glacial valleys are left on Xueshan (3,884 meters above sea level) and Nanhu Mountain (3,740 meters) of Taiwan’s central mountain range. These traces indicate that ancient glaciers had visited Taiwan. Moreover, the global history of the influence of environmental changes on ancient gymnosperms shows that without the severe weather pressure brought by several ice ages, there would be no southward migration of coniferous trees that had originally grown in the north. The glacial abrasion found on high mountains in Taiwan today also provides strong evidence that the vast coniferous forests in Taiwan are closely related to the long-term migration and evolution of ancient gymnosperms around the world.

Gymnosperms originated in the Triassic period of the Mesozoic era more than 200 million years ago. Four ice ages were formed after the Earth’s climate dropped severely between 2 million and 10,000 years ago. During the ice ages, global temperatures were much lower than today, and the scope of icy tundras grew with each major drop in temperature, forcing creatures to migrate to warmer areas in the south. The region between the Himalayas and Taiwan was the largest shelter for these creatures at the time, and this was when coniferous forests began to develop in Taiwan.

The surviving gymnosperms in Taiwan today are called “living fossils” and the rare specimens are mostly hidden in cypress cloud forests located at medium to high elevations. The ancient cypress forest environment preserved on Taiwan’s mountains in the moist maritime climate represents a surviving century of rare forests after geographical and historical changes and the long-standing evolution of gymnosperms.. The Cilan area serves as a natural heritage representative of the world’s ancient cypress forests that currently exist only in North America and East Asia.

5-2. Cypress types and global distribution

There are only seven species of cypress remaining in the world today and they are distributed on the east and west coasts of North America, and in Japan and Taiwan. No cypress tree has ever been found in mainland China or the entire Eurasia continental block.

Since northern gymnosperms were widely distributed as a result of their large-scale southward migration in the ice ages, cypress trees also gradually migrated to the south at the time. According to academic research and scientific hypotheses, Japan was originally connected with central China, and Taiwan was connected with southern China at that time. Later on, Japan and Taiwan were separated from the continental block due to the collapse of the East China Sea continental block, forming the current terrain distribution. Among the seven existing types of cypress trees, three species are found in North America, two in Japan, and two in Taiwan.

5-3. The two cypress species of Taiwan:

1. Taiwan red cypress (Chamaecyparis formosensis Mats.) – The tree is tall and big; it can grow to 38 meters tall supported by a trunk up to 1.7 meters in diameter. They are distributed on the mountainside or in valleys at an elevation of 900 to 2,700 meters. They are often found below the areas where Taiwan cypress trees grow, and live among the Taiwan hemlock, Chinese white pine, Taiwan yew, and Taiwan cedar. Some of them are found in mixed broad­leaved  forests but there are also massive pure cypress forests. Taiwan red cypress wood is fragrant.

2. Taiwan cypress (Chamaecyparis taiwanensis Mas. et Suzuki) – The tree is tall and big; it can grow to 35 meters tall supported by a trunk up to 1 meter in diameter. They can be found in mountainous areas at an elevation of 1,300 to 2,900 meters. They are found among Taiwan hemlocks at a higher elevation, but they grow together with Taiwan red cypress trees in areas of a lower elevation. There are also pure Taiwan cypress forests. As a general rule of thumb, Taiwan cypress trees are distributed at an elevation of 200 to 500 meters higher than that of Taiwan red cypress trees.  Taiwan cypress wood is fragrant.

Judging from the global distribution of cypress trees, Chamaecyparis gymnosperms are very rare in the present genus of conifers, regardless of their species and distribution. In terms of habitat,  the remaining cypress species in the world are located in the moist mountainous environments on the east and west coastal areas of the Pacific Ocean. Among the existing Chamaecyparis coniferous forests in North America and East Asia, only Taiwan’s cypress forests are located in the subtropical zone.

5-4. Original distribution of Taiwan cypress species and the cloud forest ecosystem

The term “Taiwan cypress” refers to both Taiwan cypress and Taiwan red cypress. The two important Taiwan conifers got their scientific names when Japanese botanists published academic research reports in the early 20th century.

According to related records, the most northern and lowest distribution of Taiwan cypress forests are on the North Chatien Mountain at an elevation of 1,050 meters above sea level, which is near Fushan in Wulai of the Xueshan Range.The most southern Taiwan red cypress forest is found on the Wutou Mountain on the south side of Nandawu Mountain in Pingtung, at an elevation of some 2,000 meters above sea level.

Taiwan cypress forests are distributed in areas of 1,500 to 2,800 meters above sea level, particularly in elevated regions of 1,800 to 2,400 meters above sea level. Taiwan red cypress forests can generally be found  about 300 to 500 meters lower than  Taiwan cypress forests. Due to temperature differences, cypress forests in the north are located in areas at a lower elevation than in the south, and Taiwan cypress forests are dominant in mountains north of central Taiwan while Taiwan red cypress forests dominate mountains to the south.

However, the two cypress species often overlap in vast forest areas. In mountainous areas of higher elevation, they are mixed mainly with such conifers as Taiwan hemlocks, China-firs, Taiwan cedars, and Chinese white pines. Cypress forests at lower altitudes are mixed with a large number of beech and oak tree species, forming large mixed forests of conifer and broad-leaved trees.
 

Today, Chamaecyparis are found in coniferous forests  growing between warm and temperate climate zones, and cypress forests in Taiwan are located in mountains at medium and high elevations. The high peaks, deep valleys, and abundant rainfall in these areas have created an enclosed ecological environment. Favorable factors such as warm temperatures and high humidity have also created an environment where many plants compete for survival.  Therefore, cypress forests in Taiwan are mostly mixed with other tree species, and pure cypress forests (or cypress-dominated forests) seldom appear. 

According to past forestry documents and old pictures of the cypress-harvesting industry, pure Taiwan cypress-dominated forests might have appeared in Alishan, Taipingshan, and the Mugua Mountain once. However, natural cypress forests in those areas were completely deforested, so a thorough analysis of the ecological environment of pure Taiwan cypress forests cannot be made.

The largest trees in Taiwan mainly grow in cypress forests located at a medium elevation. Rainfall data shows that these forests are also located in areas with the most abundant rainfall in Taiwan, with annual rainfall reaching 3,000 to 4,000 mm. Cilan Mountain and Taipingshan in northern Taiwan have even received a record-breaking 5,000 mm of annual rainfall. The area is foggy and rainy for nearly 250 days a year, making the woodland a “cloud forest” as termed by the botanical world.

The ecosystem of the area is categorized as a “warm temperate zone mountain coniferous forest.” Botanically, it is further divided into two ecological subgroups – mixed coniferous forest and cypress forest.

Mixed coniferous forests are distributed in areas at a relatively high elevation of 2,200 to 2,600 meters above sea level with a relatively simple plant composition. Cypress forests are in areas at a lower elevation (1,600 to 2,400 meters above sea level), where the warm and humid climate allows more species of trees to grow. In terms of biodiversity, there are complex plant species in cypress forests and its vegetation environment is the most stable among all coniferous forest types.

Cypress forests also have several layers. The top layer is usually  dominated by the Taiwan cypress and Taiwan red cypress, while the second layer comprises mainly trees from  the Falgaceae family such asCastanopsis and other oak tree species, as well as dozen of broadleaf tree species. Tree species in the north and the south are also different. In the third layer, there are small arbors and shrubs. The bottom layer is herbaceous vegetation dominated by fern and grass (Poaceae).

5-5. Cilan Mountain Cypress Forest

Cypress forests in Taiwan started to disappear after the Japanese authorities began to cut down cypress trees in large numbers in 1900. After the retrocession of Taiwan, the cypress-logging business was resumed to help alleviate the government’s financial difficulties at that time. Logging of the precious species was finally banned in 1989. According to present-day field research, natural cypress forests only exist in the Cilan Mountain in northern Taiwan and the Xiuguluanforest area in eastern Taiwan now.

Today, the Cilan Mountain Cypress Forest is a collective term that refers to the mountainous area stretching from the main ridge line of Karaheye Mountain of the Xueshan Range in northern Taiwancovering both sides of the ridge to encompass the Manao Mountain, Meiyuyen Mountain, Tangsui Mountain, Cilan Mountain, and Cuantoumu Mountain . In terms of administrative districts, the Cilan area is located in the catchment basin deep in the mountains at the junction of Yilan County, New Taipei City, Taoyuan County, and Hsinchu County.

The CilanMountainCypressForest occupies an area of about 45,000 hectares and contains some 4 million cubic meters of cypress lumber. The forest is mainly divided into two north and south sections, and the south section is where the main Cilan cypress forest is located. The total area of natural cypress forests in the two sections is about 15,000 hectares of mostly pristine environment unvisited by humans.

5-6. Cypress forests as large animal habitats

Formosan black bear: In the Cilan Mountain Cypress Forest, there are also such rare conifers as Taiwan cedars, Chinese yews, China-firs, and Taiwan plum yews. Formosan black bears and large ungulate mammals such as Formosan serows and Formosan muntjacs are also found in the area. The  Cilan area is a major habitat for rare and endangered wild animals in northern Taiwan.

The Cilan Mountain cloud forest is also a major incubation environment for 314 species of plants in 200 genus and 106 families, including 103 species that are  endemic to Taiwan. Many of these endemic species are also endangered, such as Lycopodium taiwanense, Monachosorum maximowiczii, Pentapanax castanopsidicola, Epigeneium fargesii, and Sparganium fallax. Precious species of large plants include Taiwan cedars, Taiwan cypresses, China-firs, Chinese yews, and Taiwan plum yews.