The Mountains of Southwest China Hotspot stretches over 262,400 km² of temperate to alpine mountains between the easternmost edge of the Tibetan Plateau and the Central Chinese Plain. It lies to the north of the Indo-Burma Hotspot, and to the immediate east of the Himalaya Hotspot, and is bounded in the northwest by the dry Tibetan Plateau, in the north by the Tao River of southern Gansu, and in the east by the Sichuan Basin and the plateau of eastern Yunnan.
The Mountains of Southwest China are characterized by extremely complex topography, ranging from less than 2,000 meters in some valley floors to 7,558 meters at the summit of Gongga Shan (Mountain). The mountain ridges are oriented in a generally north-south direction, perpendicular to the main Himalayan chain. The region includes the Hengduan, Gaoligong, and Nu Shan of western Yunnan; the Nyainqentanglha, Ningjing, Taniantaweng Shan, and others at the southeastern edge of the Tibetan Plateau; the Shaluli, Daxue (including Gongga Shan), Chola, and Qionglai Shan systems of Sichuan; and the Min Shan on the Sichuan-Gansu border. The Ailao Shan and Wuliang Shan of central Yunnan are not part of this hotspot (both are included in the Indo-Burma Hotspot).
The Mountains of Southwest China feed the most species-rich temperate and tropical river systems in Asia. Major river systems that traverse or originate in the hotspot include the Jingshajiang, Yalongjiang, Daduhe, and Minjiang, all branches of the Yangtze River, which empties in the East China Sea. The Lancangjiang (Mekong River), passes through Yunnan Province, Laos, Cambodia, and Vietnam on its way to the South China Sea. The Nujiang reaches the Indian Ocean through Yunnan Province and Burma.
The complex topography results in a wide range of climatic conditions. Temperatures range from frost-free throughout the year in parts of Yunnan and short, frost-free periods at the northern boundary of the region, to permanent glaciers on the high mountain peaks of Sichuan, Yunnan, and Xizang. Annual average rainfall in the region exceeds 1,000 millimeters on southwestern slopes at higher altitudes in Yunnan, while areas of the northwestern part of the region, in the rainshadow of the Tibetan Plateau, rarely receive more than 400 millimeters annually.
Climatic and topographic conditions result in a wide variety of vegetation types across the hotspot, including broad-leaved and coniferous forests, bamboo groves, scrub communities, savanna, meadow, prairie, freshwater wetlands, and alpine. |
