A Study On The Grassland Flora From Maqu In Gannan Tibet Autonomous

Maqu in Gannan Tibet Autonomous lies in the northeast of Qinghai-Tibet Plateau and southwest of Gansu province. It's the area where more floras are convergent, and the floral composition is complex. It connects nearby floristic areas extensively. The seed plants from the Maqu, investigated and counted in view of taxonomy and floristic geography. On the basis of the modern geographic distribution patterns of all species, genera and family in this region, the geographic distributiontypes at the three toxonomic levels were identified and taken into statistical analysis. By three methods of Similarity Analysis, Clustering Analysis and Principle Component Analysis (PCA), the flora of maqu were compared with 13 adjacent regions to identify the relationships of floristic similarity among them. Also issue on the basic features, floristic properties and the principal origin of the floristic components in the Maqu were discussed. The results were showed as follows:1. The flora of the Maqu was consisted of 94 families , 352 genera and 827 species of vascular plants. The resource plants were rich.2. The seed plants of Maqu were complex geographical components, mainly consisting of temperate distribution, typical North temperate in nature.3. The flora was most of the plants are perennial herbs and poorest on trees, short of the ancient type and primitive species, and some endemic elements of China were few. Because the relative young geology age, the time of speciation was shorter and the differentiation later in Maqu.4. The Maqu was the intersection of Southwest element, North China element and the Tangute Region, and the region was short of endemic species, which showed the features of transitional flora. The species analysis showed that the distribution pattern of the region was the adaptable radiation from Southwest to Northeast as the major way, which was originated from Southwest regions and the East border district of Qinghai-Tibet Plateau. It kept the floristic nature of plateau and alpine.5. The flora of Maqu had the closest relationship with the adjunctive flora of the Datonghe Drainage Area. The relationship between the flora of Maqu and the one of Maxian Mountains, Taohe Drainage Area, Taizi Mountains, Lianhua Mountains, Bayankala Mountains, Qilian Mountains, Helan Mountains, Bailong River, Xiaolong Mountains and Taibai Mountains took the second place. The relationship between the flora of Maqu and the Hengduan Mountains and Baishui River was the farest.6. The flora belonged to the subregion of Northwest sichuan, South Gansu and Southeast Qinghai of Hengduan mountain region, Sino-Himalayan forest subkingdon, Holarctic Kingdom. And meanwhile it is the floras of the transition zone from the Qinghai-Tibetan Plateau to Longxi Loess Plateau , Hengduan mountain region of China.