User:Slashem/env
From Wikipedia, the free encyclopedia
Contents |
[edit] Habitats
The world's third largest country, China rises from sea level in the east to peak of Mount Everest on the border with Nepal. The south shares tropical rainforests with Laos, Vietnam and Burma, while the Da Hinggan Mountains in Inner Monglia have tundra vegetation on top of permafrost. China is also home to East Asia's most important wetlands and Asia's longest river (Yangtze), and is the source of two rivers of inestimable importance to hundreds of millions of people in South and Southeast Asia - the Ganges and the Mekong. Deserts make up one-fifth of China's total territory, largely in the northwest. Arid steppes cover additional areas in the Altai, Tian, and Kunlun Mountains in the far west, a region blocked from the southwestern monsoon by the Tibetan plateau and from the southeastern monsoon by its distance from the sea. This massive diversity of geography and habitats has resulted in an extraordinary range of plant and animal life.
[edit] Forests
China contains a variety of forest types. Both northeast and northwest reaches contain mountains and cold coniferous forests, supporting animal species which include moose and Asiatic black bear, along with some 120 types of birds. Moist conifer forests can have thickets of bamboo as an understorey, replaced by rhododendrons in higher montane stands of juniper and yew. Subtropical forests, which dominate central and southern China, support an astounding 146,000 species of flora, as well as the famous giant panda, golden monkey and South China tiger. Tropical rainforest and seasonal rainforests, though confined to Yunnan and Hainan Island, actually contain a quarter of all the plant and animal species found in China.
[edit] Grasslands
Grasslands make up about a third of China's total land area. The immense and productive grasslands are largely concentrated in Inner Mongolia, Ningxia, parts of Qinghai and Tibet. The natural wildlife they support includes three species on the verge of extinction: Przewalski's horse, the Asiatic wild ass and the Bactrian camel (the ancestor of domesticated camels). There is often direct competition between domestic animals and wild fauna, and herdsmen poison or trap carnivores, and sometimes set fires to increase pasture area. The government has recently stepped up efforts to control the conversion of grasslands to pasture, but lacks the manpower to enforce policy.
[edit] Freshwater ecosystems
Freshwater habitats are of massive importance to China, and a huge percentage of the population is directly dependent on wetlands — marshes, rivers, and lakes — for economic activity, flood control and drinking water. Seven of the most important rivers in the world begin in the highlands of western China. The Yellow River (Huang He), Yangtze River (Chang Jiang), Lancang Jiang (Mekong) and the Salween rise in the east of the Qinghai-Tibet Plateau. The Indus, Ganges, and Brahmaputra rise in the south. Downstream these rivers serve as sources of irrigation and drinking water, modes of transportation, and centers of cultural and religious importance for some two billion people in China, India, Pakistan, Bangladesh and throughout Southeast Asia. These rivers rise and gather strength from many of the thousands of freshwater lakes of the region.
China's northeast is the focus for much of the country's freshwater marshes. Two million hectares on the Sanjiang Plain of Heilongjiang are essentially a collection of shallow freshwater lakes and reed-beds where the Heilongjiang, Sungari, and Wusuli rivers come together. Jilin, Liaoning and Inner Mongolia all share these ecosystems. One of the most well-known wildlife areas in this ecosystem is Zhalong Nature Reserve, a 2,000-square-kilometer area which was created in 1979 to protect breeding areas for the red-crowned crane, and other wintering migrants. These marshes are also of great value for reed production, the bulk of which is turned into pulp for paper. Waterfowl and reed production can usually co-exist, at least at present levels, so this is a useful confluence of conservation and economic uses. In western Sichuan, marshland provides breeding grounds for the black-necked crane and bar-headed goose.
China's freshwater lakes include the country's best-known wetlands: Jiangxi's Poyang Hu and Hunan's Dongting Hu. Dongting Hu, China's second largest freshwater lake, is vitally important for wildlife, including the highly endangered Yangtze river dolphin and Chinese sturgeon, as well as more wintering wildfowl. Poyang Hu is a similar complex of small lakes and marsh areas which fluctuates seasonally; summer floods give way in autumn to fertile agricultural land, attractive both to farmers and visiting birds. The importance of the area is hard to overstate, as the lakes provide a wintering habitat for almost the entire world population of two hundred Siberian Cranes, and as many as five hundred thousand birds may be on Poyang Hu at any one time during the winter months. In recent years, however, some of Poyang's larger lakes have been drained at the end of autumn, leaving waterfowl with inadequate shallow land on which to feed.
[edit] Saltwater lakes
About half of China's lakes are saline and, once again, are important breeding grounds for waterfowl. Most are concentrated in northwest China on the inland drainage systems of the North Tibetan Plain and in the Zaidan basin. The largest is Qinghai Lake, a 4,426-square-kilometer reserve which attracts thousands of birds each summer, including cormorants, great black-headed gulls, bar-headed geese and pied avocets. Similarly, the Tarim River basin in Xinjiang supports one of the largest breeding populations of black stork in China. The Ordos plateau area of Inner Mongolia as well as the Xinjiang's Taolimiao-Alashan Nur (lake) support breeding sites for the endangered relict gull. Most of these lakes and marshes fluctuate seasonally and are threatened by increased diversion of water for human use.
[edit] Coastal wetlands
China's coastline is approximately 18,000 km long, extending from the Bohai Gulf, which freezes in the winter, to the tropical waters of the South China Sea. Coastal wetlands are important as fuel stops for waterfowl on the migratory route between Siberia and Australia. Chongming Island in the Yangtze River delta near Shanghai - China's largest city and one of its fastest growing regions - is vital for these migrants.
