蒙古高原乌兰巴托—锡林浩特草地样带植物物种的空间分布

草原植物物种多样性分析是生物多样性研究及草原可持续发展研究的重要内容.基于2012 年野外实地调查数据,对蒙古高原乌兰巴托—锡林浩特草地样带上植物物种类型和数量的空间分布格局及变化规律行了分析,结果表明:①蒙古高原样带上共有33 科103 种植物,蒙古国有29 科87 种,中国内蒙古地区有22 科62 种.中国内蒙古境内植物物种数量的绝对数值低于蒙古国,但中国内蒙古境内的垂向百米物种数、百公里物种数及多年生物种占全部物种比例、可食性牧草物种占全部物种比例等指标均高于蒙古国境内的相应指标;②样带上植物物种总数呈现南北高、中间低的U字形;具体到不同物种,则其分布形态略有差异:禾本科物种数量由北向南逐渐增多,菊科植物物种数量由北向南逐渐减少,豆科植物及杂类草的物种数量呈现南北高、中间低的U字形;③多年生植物与可食性牧草数量呈现南北高、中间低的U字形;一年生植物则呈现不明显的倒U字形,非可食性植物在整个样带上则变化相对平稳,南北差异不明显.

Spatial Distribution and Variety of Grass Species on the Ulan Bator - Xilinhot Transect of Mongolian Plateau

Understanding the spatial distribution and variety of grass species in the Mongolian Plateau is very important for both the general biodiversity research and the region's sustainable development. However, due to many parctical difficulites, such as the vast territory, national border division, language barrier and hard field conditions, little studies have been done on the grass specie diversity in an expansive area in this plateau. In the summer of 2012, an ecological transect from Ulan Bator of Mongolia to Xilinhot of China was selected, and a series of grass sampling sites and sampling quadrats along this transect were investigated in detail. Based on the field survey, the spatial distributions and varieties of grass species along the transect were analyzed. The result turns out: 1) 103 grass species belonging to 33 families were identified. Specifically, 87 species belonging to 29 families are in Mongolia territory and 62 species belonging to 22 families are in Inner Mongolia territory of China. Although the absolute number of grass species, edible grass and perennial grass in Inner Mongolia are less than those in Mongolia, the relative indices, including the specie numbers per vertical hundred meters, specie numbers per horizontal hundred kilometers, the ratio of the edible grass specie in total species, and the ratio of the perennial grass specie in total species, are higher in Inner Mongolia than those in Mongolia. 2) The numbers of grass species along the transect present the "U" shape, i. e. number of species is higher in the northern and the southern parts, and lower in the middle part of the transect. 3) From the north to the south, the number of gramineal grass ascends, and the number of grass in composite family descends. The numbers of grass in leguminosae family and other forbs present the"U"shape. The numbers of perennial plants and edible grass also show as the "U" shape, while the number of therophtye grass appears the inverted "U" shape, and the number of non-edible grass changes smoothly along the transect.