国产激情大臿免费视频,无码专区无码一区,超鹏在线视频97

1. Ecological Character of the Qinghai-Tibet Railway

Significance of the Qinghai-Tibet Plateau

Often referred to as "the Roof of the World" and "the Third Pole of the World," the Qinghai-Tibet Plateau is China's "climate adjuster" and may in fact influence weather patterns throughout many other parts of the world. From the plateau water flows to form rivers in what is a powerful ecological resource for both China and south Asia. With this quite unique ecological system it's an important starting point for many mountainous biological species of the world. The primitive ecological conditions have remained almost untouched, including the deeply frozen earth, lakes, wetlands, gentle-sloping hills and rare fauna and flora. It has significant ecological and scientific research value and holds special importance to the global environment.

Five ecological sections and their characteristics

The Qinghai-Tibet Railway travels through the hinterland of the Qinghai-Tibet Plateau for a distance of 1,110 kilometers. The various areas along the railway line are divided into five sections where the geomorphology, climate and vegetation are varied and ecological protection measures have been put in place accordingly.

(1) Golmud-Nanshankou section is relatively flat in terms of terrain, sloping northwards with an altitude of 2,800-3,000 meters. It's part of the arid climate zone of the Qaidam Basin. This district is scorching in summer and freezing in winter. The annual average temperature is 6.7?C with the highest being 35.5?C and lowest being 33.6?C below zero. The annual average precipitation is 40 mm with a relative humidity of 32 percent. This section is part of the Gobi ecosystem. The landscape is desert where vegetation, mainly the xerophyte bush, is sparse and covers only 2 percent of the land area.

(2) Nanshankou-Kunlun Mountains section is in the river valley of the Kunlun Mountains with an altitude of 3,000-4,770 meters. The railway line in this district stretches upwards along the Golmud, Kunlun and Xiaonanchuan rivers. In the dry climate zone to the north of Kunlun Mountains, this section has an annual average temperature of 3.6?C below zero. The annual average precipitation is 250-300 mm and relative humidity is 47 percent. The area under 3,500 meters has a hilly desert ecosystem which transforms gradually into prairie when the land stretches upwards beyond 3,500 meters. The vegetation coverage is 15-25 percent.

(3) Kunlun-Tanggula Mountains section sits at an altitude of 4,500 to 5,200 meters. This section is arid and cold featuring changeable weather, thin air and low pressure. The annual average temperature is between 2?C below zero and 6.9?C with the highest at 24.2?C and lowest at 45.2?C below zero. The annual average precipitation is 250-300 mm. The main part is frigid prairie except for a few areas of grassy marshland and meadow. The high and frigid prairie environment is a typical natural ecosystem of central Asia.

(4) Tanggula Mountains to Damxung section is in the North Tibet Plateau with an altitude between 4,300 and 5,200 meters. Affected by the maritime climate, it has a sub-dry climate. The annual average temperature is between 1.3?C below zero and 2.9?C with the highest at 24.2?C and lowest at 41?C below zero. The annual average precipitation is 293-430 mm. A high and frigid meadow ecological system dominates the main areas and wormwood and grassy marshland cover 60-90 percent of the ground. The wormwood meadow covers the largest region growing on the vast plateau in Nagqu and Amdo. The North Tibet Wormwood meadow and grassy marshland have a small and separate distribution normally in low-lying areas alongside rivers.

(5) Damxung-Lhasa section has an elevation of 3,640-4,300 meters. The Damxung-Yangbajing part is in the valley at the southern foot of the Nyainqêntanglha Mountains where the land is open and flat. The Yangbajing-Lhasa section is located in the steeply sloped Zangbo River canyon and the valley basin of Lhasa River. This section has a sub-dry climate zone with a shrubbery and grassland ecosystem. The annual average temperature is 1.6-7.8?C with the high of 29.6?C and low of 35.9?C below zero. The annual average precipitation is 407-468 mm. About 40 percent of the land is covered by brush and 10-30 percent by grassland vegetation.

A wealth of rare species

The unique natural conditions and abundant natural resources in the Qinghai-Tibet Plateau are home to a wide variety of animals and plants. The plateau is on the list of areas with priority in the World Wildlife Fund's global bio-diversity conservation program as well as being part of a similar initiative being undertaken by the Chinese government.

The areas which the railway runs through have fewer animal species but most of these are rare. There are about 16 mammal species of which 11 are peculiar to the Qinghai-Tibet Plateau and 30 species of bird with 7 peculiar to the plateau. Under the state first-level protection are the Tibetan antelope, Tibetan kiang, wild yak, white-lipped deer, snow leopard, Tibetan snow cock and black-necked crane. Among animals under state second-level protection are Mongolian gazelle, lynx, brown bear and bar-headed goose. There are approximately 202 varieties of plants in this region.

The areas on both sides of the railway are home to 14 rare wildlife species – mainly mammals and birds. Investigation shows that rare wild plants which are under state-level protection haven't been found around the route of the railway.

Fragile ecology

Due to the high altitude, thin air, very cold and dry climate, wildlife on the Qinghai-Tibet Plateau is relatively not abundant. The low biomass and simple bio-chain causes the process of matter circulation and energy transformation in the ecosystem to be slow leading to a fragile eco-environment. Because of the long-term low temperatures and short growing season it's difficult for vegetation to recover after being damaged. Moreover, vegetation which has been harmed can accelerate the melting of frozen earth which could result in further soil erosion and desertification. At present some regions along the railway are not populated and natural conditions remain completely intact. However, in general, scientific research shows the global warming has affected the Qinghai-Tibet Plateau adversely.

Diverse natural landscape

Natural landscapes along the Qinghai-Tibet Railway are diverse and unique. The high and frozen eco-landscape which is flat and composed of brush, meadow, prairie and desert and the vertical eco-landscape of meadow, prairie and snow and ice belt coexist. The landscape provides habitats and migration routes for both animals and birds. Other landscapes offer snow-capped mountains, glaciers, the frozen earth, rivers, canyons and extensive grasslands.

Vastly-distributed wetlands

Wetland along the railway line can be classified in three ways – marsh, lake and riverbed.

The wetland in the Kunlun and Tanggula Mountains section is marsh and riverbed wetland. This was formed by melting ice and river water overflows, the distribution of which is scattered and inconsistent. The railway passes through 50 such wetlands in this section which covers 15 kilometers.

The Tanggula Mountains-Lhasa section has many wetlands most of which are marsh and lake. The Nyainrong-Amdo and Nagqu wetlands which the railway line passes through are part of the Action Plan for the Protection of China's Wetlands. The Nyainrong-Amdo wetland is located in the area between the Tanggula Mountains and Co Nag Lake covering 3,879 square meters at an altitude of 4,500-5,200 meters. The earth here is peat, meadow and humus bog soil and the main vegetation is North Tibet Wormwood. The Nagqu Wetland is at an elevation of 4,300-4,800 meters and the railway will pass through 25 kilometers of it.

Nature reserves

There are five established nature reserves and six are planned along the Qinghai-Tibet Railway. The five completed are the Hoh Xil Nature Reserve and Sanjiangyuan Nature Reserve in Qinghai Province; Qiangtang Nature Reserve, Linzhou Pengbo Black-necked Cranes Nature Reserve and Lalu Wetland Nature Reserve in Tibet Autonomous Region. The six planned ones, all in Tibet, are the Yijiang Lianghe Nature Reserve (Yijiang refers to the Yarlung Zangbo River and Lianghe refers to the Lhasa and the Nyang-chu rivers); Namco Nature Reserve; Yangbajing-Geda Hot Spring Snakes Nature Reserve; Lhasa Ancient Cypress Forest Nature Reserve and the Dagze Yaiba Karst Landscape; and Maxiang Nature Reserve in Deqen County. The Qinghai-Tibet Railway runs across the Hoh Xil, Sanjiangyuan and the planned Yijiang Lianghe Nature Reserve.

(1) The Hoh Xil Nature Reserve

The nature reserve was established in October 1995 and was put under state-level protection in December 1997. It includes south Kunlun, north Tanggula and south Hoh Xil mountains. It covers an area of 45,000 square kilometers. Protected are rare wildlife and plants as well as the primeval natural environment, the frozen grassland ecosystem and natural landscape. All these things are of special significance. It is within the jurisdiction of the Yushu Prefecture of Qinghai Province. The railway runs across 100 kilometers of the nature reserve.

(2) The Sanjiangyuan Nature Reserve

The nature reserve was established in May 2000 and is applying for state-level protection. It includes Qinghai's Yushu and Golog Tibetan autonomous prefectures; Zekog and Henan counties in the Huangnan Tibetan Autonomous Prefecture; Xinghai and Tongde counties in the Hainan Tibet Autonomous Prefecture; and Tanggulashan Township of Golmud City. It has a total area of 318,000 square kilometers, accounting for 44.1 percent of the total area of Qinghai Province. Things protected include the entire natural water resource environment, bio-diversity and plateau ecosystem. According to natural resource distribution, protected species and goals, the nature reserve is divided into three key areas – 25 core zones, 25 buffer zones and 1 experimental zone. The railway runs across 193.4 kilometers of the experimental zone in the section from north Tangulashan Township to the Tanggula Mountain; through 119.75 kilometers of the experimental zone of the Qumar River Wildlife Core Protection Area in the section from the Kunlun Mountains to the northern border of Tanggulashan Township; and 14.91 kilometers of the border of the Suojia Wildlife Core Protection Area's experimental zone.

(3) The planned Yijiang Lianghe Nature Reserve

This nature reserve is a planned area aiming to protect Tibetan black-necked cranes' breeding habitats. With Xainza at the center it includes the other six areas of Nagqu, Ngari, Shannan, Nyingchi, Qamdo and Xigaze and 41 counties in Lhasa. It will be divided into a number of zones – center protection, satellite protection and seasonal protection. The satellite area is composed of four large lakes and many scattered wetland protection areas. Plans for these areas have yet to be drawn up. The railway runs across 61 kilometers of scattered wetland protection areas near Amdo and Nagqu. Seasonal protection areas are divided into core areas including the habitats of black-necked cranes and seasonal buffer zones where the birds look for food. The railway runs across 17.1 kilometers of the seasonal buffer zone in the lower reaches of the Lhasa River.

The railway runs across 78.2 kilometers of the planned Yijiang Lianghe Nature Reserve.

2. Principles and solutions for ecological protection

The ecological environment along the route of the railway is extremely fragile. If damaged recovery would be extremely difficult. The engineering design concept recognizes the principle, "with prevention as the main point and with protection as the top priority".

Designers and builders must have high environmental protection awareness to protect wild plants, animals, wetlands, the frozen earth environment, water resources and water quality along the railway.

When the line passes through the Hoh Xil Nature Reserve, the Qumar River and the Suojia Wildlife Protection Area, designers must ma ke plans to reduce any loss of protection areas and the impact on the environment.

When passing environmentally sensitive belts like lakes and wetlands, designers must make a series of selective plans to deal with it or simply make a detour.

According to wild species' distribution, habitat and breeding characteristics, special passageways must be built for them to move across the railway.

Plans must be made to strengthen the mixing intensity of earth and rock and reduce the number of earth-collecting sites and the volume of earth abandoned.

To protect the ecological environment and natural landscape along the railway, earth-collecting projects must be conducted by collecting earth in sections. Earth-collection site should be built in hillocks, flood lands or icy areas which are at least 200 meters away from the railway.

Marsh, lake, riverbed wetlands along the railway have not only special ecological functions of conserving soil fertility but also are habitats for wildlife. Earth sites resulting from the project must avoid this type of wetland to protect its special ecological functions.

When encountering flowing water and wetland areas, measures such as building bridges and increasing their culvert intensity must be taken to avoid cutting or blocking surface and underground water runoff.

Engineering buildings must be planned and built according to their topographic conditions and hydrological characteristics. No one can force any decisions which would change surface runoff directions, ditches or rivers.

Temporary projects are forbidden to be placed in, or near, the passageways installed for wild animals.

Meadow vegetation must be removed by being cut into pieces and taken to locations suitable for their replanting. Keep surface soil at the earth-collecting sites together so as to recover the growing capabilities soon as the earth removal work is complete. Prepare effective and feasible vegetation recovery proposals for areas around roadbed projects. Strictly forbid the digging out of meadow areas for the protection of roadbed projects.

Strengthen the management of slag-tipping and reduce the number of slag sites. Choose low-lying, non-surface runoff and sparse vegetation areas to keep unusable slag. Forbid the occupation of rivers, lakes, wetlands and nature reserve's buffer and core zones, and the grassland areas where frigid vegetation is growing.

(China.org.cn June 26, 2006)

亚洲精品无播放在线播放,精品国精品自拍自在线,免费国产污网站在线观看不要卡,97色欧美视频在线观看,久久精品本无码一本,国产精品高清视亚洲一区二区,全部无码特级毛片免费播放