青海省大柴旦盆地植被

THE VEGETATION OF DA QAIDAM BASIN IN QINGHAI PROVINCE

大柴旦盆地属于茺漠植被区域。在盆地中,从洪积平原到湖积平原依次发育着矮半灌木、灌木砾漠,矮半灌木沙漠,禾草、杂类草盐生草甸,芦苇(Phragmites communis)盐沼泽。周围山地自低而高依次发育着矮半灌木,灌木低山石漠,小叶金露梅(Dasiphora parvifolia)亚高山灌丛,紫花针茅(Stipa purpurea)高寒草原和矮嵩草(Kobresia humilis)高寒草甸,高山稀疏植被。由于地形封闭,这里残存了在柴达木盆地其它地区已消失的一些植被类型,有些植物种远离其主分布区达500km以上。盆地海拔基准高达海拔3500m,加上山地的屏蔽作用向上逐渐减弱,致使气温的垂直递减率较大,在垂直带谱中缺失山地草原和针叶林等中山带植被。此外,盆地中湖积平原富积硼酸盐,使盐生草甸中的优势种之一盐角草(Salicornia herbacea)发生变态,这是本区植被中出现的一个有重要科学意义的指示植物现象。

The Da Qaidam Basin belongs to the desert vegetation region in China. In the basin, from flood plain to lacustrine plain, there are dwarf semi-shrubby, shrubby gravel desert;semi-shrubby sandy desert;holophtic grass and forb meadow; phragmites communis salt swamp, respectively. On the mountains around the basin, from low to high, we can find semi-shrubby, shrubby hilly-land rocky desert;Dasiphora parvifolia subalpine shrubby; Stipa purpurea alpine steppe and Kobresia humilis alpine meadow; and alpine sparse vegeta- tion. Since the topography is closed, the Da Qaidam Basin has some vegetation types that cannot be found in other areas of Qaidam. Some plant species are even 500—800 km away from their main-growed area. Because of the high elevation (3 500 m) of the mountain foot, and the Basin's protective screen effect descreases with the elevation, the vertical lapse rate of the air temperature is larger. So the vertical belt spectrum of the mountains vegetation lacks mid-mountain vegetation(e.g, mountain steppe and needle-leaf forest), and forms a special vegetation vertical belt spectrum which is unique in the high-elevational temperate desert in the north part of the Qinghai-Xizang Plateau. Besides, the lacustrine plain has a great deal of boron, and that makes Salicornia herbacea, one of the dominant species of holophytic meadow, metamorphosis. It is an interesting phenomenon in this area.