关键词: 生态恢复, 干旱荒漠, 物种多样性

Abstract: Soil seed banks in Alxa desert present horizontal zonality mainly affected by water and heat gradients. Soil seed banks concentrate in the 0~5 cm soil layer, with very less seed banks exist in deeper soil layer. Twenty-six seeds in Alax desert have been checked and belong to 9 families and 22 genera, in which Gramineae was dominant family. Annual plant seeds make up 51.36% of all life forms. No effective seed banks appear under the extremely arid environment. Biodiversity of seed banks is the most(0.546~0.917) in steppe-desert of eastern Alxa, less in desert regions of western Alxa(0.417~0.915), and 0.855 in Ejin oasis, showing decreasing trend form east to west. Because of high heterogeneity of habitat and vegetation, the differences of seed banks similarity are obvious among regions in Alxa desert, ranging from 0.17~0.67 in steppe-desert of eastern Alxa, 0~0.75 in typical desert of western Alxa, and 0~0.4 in gobi desert of Ejin. Besides, the difference between species compositions of seed banks and aboveground vegetation is significant. The dominant species of aboveground vegetation are xerophytic and mesophytic shrubs or subshrubs, but that of seed banks are annual and perennial grasses without shrub seeds, which indicate that soil seed banks have little contribution to regeneration and succession of shrub layers.

Key words: ecological restoration, arid desert, biodiversity