The Mysterious World of Chilai


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Its Geological Make-up

　Chilai Mountain Area is within the northern section of the Central Mountain Range's main ridge. It begins at the north from Chilai North Peak passing the Main Peak, Carloro Mountain, Chilai Koashan and ends at the Chilai South Peak. Its main ridge at the north is connected to the Huhuanshan Mountain Area. The crest lines' interchange is a depression with steep drop. This is the watershed for the Liwu and Zhosui Rivers. The main ridge at the south is connected to Lenkao Mountain and Antonzin Group of Mountains. The intersection consists of level Yishan Arrow Bamboo Grassland. Chilai's main ridge is the watershed for both the Zhosui River and Mukua (Papaya) Rivers. The Central Mountain Range's crest line stretches initially at the southwest direction. But as it reaches the Hohuanshan East Peak, the crest line turns towards the southeast direction into Chilai Mountain Area. It then continues in its initial southwest direction. The entire contour is in an "S" shape. Such undulating contours and mixed directions have resulted in complex wind flow direction as the cloud and mist enters the mountain areas. Frequently, the areas are covered with thick mist with visibility less than 5 meters, making it difficult for climbers to tell the directions.

Its Weather Conditions

　The spring weather in the mountain areas is often unstable. The vapor from the river valley at the eastern flank of the Central Mountain Range rises and then converges with the dense vapor from the river valley at the western flank. Consequently, even when the mist at Hohuanshan has already dispersed, the Chilai mountain area is still heavily blanketed in mist. Only on rare occasion can we see the edge of the cloud over Chilai North Peak. Only when the weather is clear for a few fine days continuously, then only the clear blue sky would appear at the mountain area.

　In mid summer, the dense moisture from the Pacific Ocean enters and moves along the Liwu and Mukua Rivers into the mountain areas. At the beginning, these two air currents do not converge, maybe segregated by the high terrain of the Chilai North Peak's east branch crest line. However, they finally converge as they enter the Hohuanshan area. Consequently, the entire mountain areas are blanketed in clouds and mist.

　In summer, it is possible to tell from the grayish white start clouds appearing at dawn, if the sky would rain on that day. This is because as temperature rises in the morning, the start clouds gradually condense and turn into cumuli, drifting actively over the mountain areas. The more grayish the starts clouds' color is, the higher is their moisture content, and naturally, more cumuli would form, which ultimately increases the chance of rainfall. If such condition coincides with the mist and clouds from the east flank of the river valley, dense cumuli would transform quickly into nimbocumuli (rain clouds). Soon, torrential rainfall mixed with hailstones would befall. When the sky is clear, the mist disperses from east of the Chilai Mountain areas. At this time, the wind is usually very strong, resulting in some spectacular changes in the shapes of the cumulus clouds.

　The change in wind direction during fall is very obvious. The wind pressure from the west flank of Chilai Main Ridge intensifies. This causes the clouds and mist that have entered into the mountain areas from the Liwu and Mukua River Valleys, unable to rise further. They accumulate at around the 2,500 meters high altitude, creating spectacular seas of cloud. As the landscape at the Carloro Broken Ridge is lower, the clouds could only rise along the main ridges, but unable to cross over to the west flank of the main ridge. They could only tuck dive towards the eastern river valley direction, and as they do, majestic patches of flag-liked clouds are formed.

　On a fine day at dawn, we can see waves of clouds pass rapidly from the Tachia River Basin at the eastern flank of the main ridge, northwards into the Shiashan Mountain Range. Occasionally, the clouds would cross the Zhousui River Valley into the Chilai Mountain Areas. When waves of cold front pass through Taiwan in fall, there are three ways to predict the weather condition:

　At Chilai South Peak at dawn, if cirrocumuli or altocumuli appear over the mountain area, the weather condition would turn adverse towards mid night. Also, the amount of clouds has direct bearing on the duration of the bad weather on the following day, usually from 6 days to 7 days. At dawn the next day, the ground is often covered by frost and the whole day is affected by strong wind.

　During daytime, the cloud layers are at the mid or high cloud's height and gradually expand and extend onward, yielding a highly pressurizing atmosphere over the entire mountain areas. Then, gloomy weather blankets the entire region. Such adverse condition usually lasts for more than 4 days. Whether the sky would start snowing or not depends largely on the temperature.

　At dawn, the clouds and mist rise quickly from the river valley at the East Side of the main ridge and enter the mountain areas. Subsequently, they converge with the thick cumuli rising from the west flank of the river valley. Suddenly the entire mountain area starts to rain continuously for at least 3 days. This pattern of rain formation would yield to snowfall when the temperature is low enough. Up to now, during mid winter, very few climbing teams made it to the summit. They are often hindered by the tall and densely grown Yishan Bamboo Grasslands, scattering at the recessed areas from Hohuanshan East Peak to Chilai's North Peak, as well as at the Kuoshan areas.

Vegetation around the Main Ridge Area

　Although Chilai mountain areas are blanketed by fog all year round making passage strenuous for climbers, the moist atmosphere actually favors the growth of alpine plants in their entire splendor. The slopes are dotted with densely grown vegetation, even on steep slopes or bare rock surface on hanging cliff walls. The type of vegetation and forestland varies according to the height and locality of the mountain.

　Formosa Fir Woodland between the Huhuanshan's East Peak to Chilai North Peak, one side of the recessed slope is exposed to sunlight where as the other side is against sunlight. As strong valley current from the Liwu River valley affects the recessed slope on the northeast side, no forest vegetation is grown there. As a result, the entire landscape becomes a highland meadow, dotted by dense Yishan Arrow Bamboo grassland. The remaining slopes are covered with dense Formosa Fir woodland. The eastern section of the slope is exposed to sunlight. At higher altitude, the fir woodland overlaps with the Yishan Arrow Bamboo scrubs.

　On the western section of the recessed slope where it is sheltered from sunlight, a mixture of fir woodland and Yishan cypress scrubs is seen at higher ground. Whereas, at the lower ground, there is a mixture of fir woodland and the hemlock spruces. The best venue to observe the mountain fir woodland is either at the edge of the fir woodland or within the forestland. At the exposed side of the mountain, there are more mixed woody plants at the edge of the fir woodland than at the unexposed side. Some examples of these plants are the Yishan Rhododendron, Chinese Juniper, Brown Hair Willow, Alpine Rosa, Yishan pod plant, grandiflora, and horse mulberry and yarn wine. Vegetation on the sunny side of the slope is mainly dominated by Formosan Deer Herb, Gentiana Flower, Borneo Winter Green Tree, Yishan thorny plant, Glandular Fern (Swertia Randaiensis), Formosan Wild Mint and Yishan Southernwood Grass (Pedicularis Verticillata). Within the dim fir woodland and at the slope against sunlight, vegetation consists mainly of herbaceous plants such as Creeping Pine, ferns, conch chrysanthemum, Yishan Kuitoyu, Biting Cat and alpine oxalis Grass.

　The fir woodland at the mountain areas is the source of the Zhosui and Mukua Rivers. The moist atmosphere resulted from these river flows, has given rise to a variety of fir communities. The woody plants growing within the woodland itself do not differ much. However, the herbaceous plants consist of a large variety namely plum grass, Japanese knotweed, scene morrisonensis, Fine leave randaiensis, Hohuanshan palladium, Formosan Mountain Leaf Mustard and Yishan Knotweed. By the riverside at the Chilai South Peak, there is a small amount of the very rare green flower orchid.

　Although the Chilai mountain areas are blanketed in mist all year round, making passage difficult for most climbers, the moisture, however, has provided a perfect environment for growth of various vegetation's; even at steep slopes or bare rocky surface on cliff wall. The type of vegetation and forestland varies according to the altitude of the areas. Alpine Meadow and Yishan Cypress scrubs WoodlandThe east flank of the Chilai Main Peak is often exposed to strong air current from the Mukua River. As a result, except for Carloro Mountain, densely grown Yishan Arrow Bamboo Grasslands often cover slopes on the east flank above altitude 3,000 meters. They are very picturesque sights when viewed from far area. The fir woodland could only scatter at the recessed areas of the slopes where it is sheltered from wind. The meadow is mixed with many shrubs and herbaceous plant of the same height as the Yishan Arrow Bamboo scrubs. The species are mainly Yishan barberry, single stalk Yellow Flower, Alishan Gentiana, Yishan cork Tree (Raspberry) and Thick Lip Butterfly Orchid (phalaenopsis aphrodite). At the upper sheltered section of the meadow, there is a small amount of Yishan Cypress scrub and Yishan rhododendron. On a whole, there are not many varying varieties of vegetation on the meadow.

　Vegetation growing on rock fragments is commonly found on the northeast flank of the Main Peak, where there are several small pieces of rocky surface. They are also found on the southeast bare rock surface stretching from the Carloro Mountain to Kuoshan main ridge. Here, the vegetation is exposed to scattering light rather than direct sunlight. At noon, the area is often blanketed in mist and clouds, providing a conducive growing environment for the plants. The vegetation consists mainly of buttercup, Yishan Mountain Radish, Flaming Grass, 5-bud Plum, Nepalese anaphalis and Yishan Ground Centipede. However, on the rock faces at the northeast flank of the Main Peak, there are many varieties of Nanhu epilodiums and other rare species of alpine willow. At the same time, on the rock face at the southeast flank of Kuoshan Main Ridge, we can find the rare species of the Forest alpine willow chrysanthemum scattering all over the area.

　The west flank of the Chilai Peak is made up of undulating landscape and steep walls. The slopes are densely covered with Yishan Cypress woodland and Fir woodland. The slopes at the boundary intersection of these two forestlands serve as the dividing line between the strong and weak air currents from the Zhousui and Tachia River Valleys. Nurtured by the rich moist contents from the river valleys, the Yishan Cypress woodland here is dotted with tremendous amount of Yishan rhododendron (azalea). At the same time, on the rock face at the upper reaches of the forest boundary, there are several communities of rare Alpine Willow species. Other woody plants growing inside the forestland consist mainly of Yishan barberry, Yishan Wild glandular Rosa and kawakami barberry. The Yishan Chinese angelica, single-flower geraniaceae, Yishan Chinese mugwort, Chilai Red Orchid, Alpine Fragrance and Yishan aniseed celery mainly dominate the herbaceous plants. At the North Peak area, there is a small amount of twin-stalk Yellow Flora Violets and At the Main Peak area, you can find the very rare Green flora Orchid plants.