Sa mạc Gobi, châu Á

Khí hậu

Khí hậu là lục địa và khô hạn: mùa đông khắc nghiệt, mùa xuân khô và lạnh và mùa hè ấm áp. Phạm vi nhiệt độ hàng năm là đáng kể, với mức thấp trung bình trong tháng 1 đạt −40 ° F (−40 ° C) và mức cao trung bình trong tháng 7 leo lên 113 ° F (45 ° C); phạm vi nhiệt độ hàng ngày cũng có thể khá lớn. Tổng lượng mưa hàng năm thay đổi từ dưới 2 inch (50 mm) ở phía tây đến hơn 8 inch (200 mm) ở phía đông bắc. Điều kiện gió mùa tồn tại ở các khu vực phía đông, nơi nhận được phần lớn lượng mưa của chúng vào mùa hè. Gió bắc và gió bắc chiếm ưu thế trên Gobi vào mùa thu, mùa đông và mùa xuân.

Thoát nước và đất

Thoát nước của sa mạc phần lớn dưới lòng đất; sông mặt có dòng chảy không đổi. Suối núi bị giới hạn ở rìa của lũ yêu tinh và thậm chí sau đó nhanh chóng khô đi khi chúng biến mất vào vùng đất lỏng lẻo hoặc những vùng trũng mặn, kèm theo. Nhiều dòng sông chỉ chảy vào mùa hè. Mặt khác, nước ngầm là phổ biến và có chất lượng đủ để cho phép chăn nuôi gia súc.

Trong thời đại Holocene (tức là khoảng 11.700 năm qua), các hồ của người Anh đã bị thu hẹp kích thước, để lại một loạt các sân thượng xa hơn và cao hơn so với các bờ biển hiện tại. Thật vậy, Hồ Orog và Bööntsagaan, ở phía đông Mông Cổ Altai và Hồ Ulaan, ở phía tây bắc Gobi Altai, nhưng chỉ là bóng tối của bản thân trước đây.

Đất của Gobi chủ yếu là màu nâu xám và nâu carbon (giàu carbon), thạch cao (chứa thạch cao), sỏi thô, thường kết hợp với đầm lầy muối cát và takyr.

Đời sống thực vật

Vegetation, as mentioned above, is sparse and rare. On the plateau and on the plains beneath the mountains, small bushlike vegetation occurs: Echinochloa (a type of succulent grass found in warm regions), yellowwood bean caper, winter fat (a shrub covered with densely matted hairs), nitre bush, and bushlike halophytic vegetation. In the salt marshes, too, halophilous groups prevail: potash bush, Siberian nitre bush, tamarisk, and annual halophytes; in the sands grow saxaul, the sandy wormwood, and sparse perennial and annual herbs such as the annual Gobi kumarchik (Agriophylum gobicum) and the perennial timuriya (Timouria villosa). In semidesert tracts vegetation is richer, belonging to the herbaceous and wormwood groups: Gobi feather grass, Gobi kumarchik, timuriya, snakeweed (Cleistogenes species; another perennial), and cold wormwood. There are herb meadows with rhizome Mongolian onions and herb salt marshes with sparse beds of bushlike Caragana. In the Gobi Altai and other high mountains, desert-grass steppes completely cover the lower slopes, and, on the upper parts, mountain versions of the feather-grass steppes appear.

Animal life

The Gobi’s fauna is varied, with such large mammals as wild camels, kulan (Equus hemionus), dzheiran gazelles, and dzeren (an antelope). Przewalski’s horse, which once ranged in the western region of the desert, is probably extinct in the wild. Rodents include marmots and gophers, and there are reptiles.

People and economy

The population density is small—fewer than three persons per square mile (one per square km)—mostly Mongols with Han Chinese in Inner Mongolia. In Inner Mongolia the Chinese population has increased greatly since 1950. The main occupation of the inhabitants is nomadic cattle raising, though agriculture is predominant in regions where the Chinese are concentrated. The traditional living quarters of the Mongol nomads are felt yurts and orgers (types of tent), while the Chinese farmers live in clay homes built from crude brick.

In the Gobi, particularly its semidesert sections, livestock raising is the main economic activity, sheep and goats constituting more than half of the total herds. Next in importance are the large-horned cattle. Horses make up only a small percentage of the total and, together with the large-horned cattle, are concentrated in the lusher semidesert of the southeast. A fair number of the livestock consists of two-humped Bactrian camels, still used for transportation in some areas. Pasturage for cattle is available throughout the year because of underground water supplies. Livestock raising is mainly nomadic, and herds move several times a year, migrating as much as 120 miles (190 km) between extreme points.

Useful mineral deposits are scant, but salt, coal, petroleum, copper and other ores are mined. Agriculture is developed only along the river valleys.

The Gobi is crossed by railroads in the east and west, notably the line from south-central Inner Mongolia to Ulaanbaatar, capital of Mongolia. There are several highways, including one from eastern China to Xinjiang across the Bei Mountains and the Gaxun Gobi; from the town of Kalgan (Zhangjiakou) in Inner Mongolia (northwest of Beijing) to Ulaanbaatar; and from Ulaanbaatar to Dalandzadgad in southern Mongolia, some 300 miles (500 km) south-southwest of Ulaanbaatar. In addition, various ancient caravan tracks crisscross the Gobi in all directions.

Since the 1950s, population increase and the overuse of marginal lands have decreased vegetation cover and increased soil erosion, resulting in an overall expansion of the desert area of the Gobi at the expense of semiarid grasslands on the fringes. In the 1980s industrialization in the Gobi intensified environmental pollution. A significant example is phosphate contamination of the groundwater caused by chemical fertilizer manufacture in the Hohhot area, which has adversely affected local herds. Contamination with arsenic has also become a major problem where water in wells has been depleted, and thousands of people have been affected. Processes used to mine certain ores in large quantities, notably copper, also have increased contamination of the groundwater at other sites. High radiation levels caused by fallout have been detected in the western Gobi in the area around China’s chief nuclear weapons test site near Lop Nur.

Study and exploration

The ancient Silk Road traversed the southern part of the Alxa Plateau and crossed the Gaxun Gobi as it skirted north and west around the Takla Makan Desert. Along this route, travelers from many Asian lands crossed the Gobi. The region first became known to Europeans through the vivid 13th-century descriptions of Marco Polo, but it otherwise remained for them virtually unknown and untraveled.

European interest in the region was rekindled in the late 19th and early 20th centuries. A number of geographic expeditions were launched by the Russians and British; and, though the main focus of these expeditions was the Takla Makan, most of them also went through the Gobi, where basic mapping and some study of the flora and fauna were conducted. Much of the geographic study of the Gobi since then was undertaken by Soviet investigators; the Chinese and Mongolians, however, have become increasingly active since the 1960s.

The area of greatest cultural interest in the Gobi has been the Mogao Caves complex, a series of Buddhist cave-temples near the city of Dunhuang in Gansu province, China; the complex was designated a UNESCO World Heritage site in 1987. Dating from the 4th to the 10th century ce, these temples have been well preserved in the arid desert air, and the quality and quantity of their fresco paintings and texts has remained unmatched. Scientific study of the complexes began with the discovery in 1907 of the caves by the Hungarian-British archaeologist and geographer Aurel Stein.

During the 1990s, joint Mongolian-Russian-American archaeological expeditions excavated Paleolithic and Neolithic caves in the Mongolian Gobi. During the same period, U.S. and European expeditions conducted paleontological research on exceptionally preserved dinosaur fossil assemblages in the desert dating to Late Cretaceous times (i.e., about 100 million to 66 million years ago). Since 1995, joint Mongolian-American and Mongolian-European expeditions have also investigated the tectonic history and landscape evolution of the Gobi.