Abstract:The soil seed bank is important for vegetation regeneration and natural succession, and it may change as a result of over-grazing. In August 2004, we investigated the community of four sites with different degraded ranks of S. krylovii steppe in the Xilin River Basin, Inner Mongolia. The species present in the vegetation was assessed using five 1m×1m quadrats distributed randomly in each area. In spring 2005, in the same sites, fifteen soil cores (15 cm×15 cm×3 cm) were collected from three depth layers (0-3 cm, 3-6 cm and 6-9 cm) for each degraded ranks. The composition and density of the soil germinable seed bank was evaluated by monitoring seedling emergence. The similarity of soil seed bank and the standing vegetation was assessed using the Sorensen index. The results indicated that the composition and density of both total soil seed bank and persistent soil seed bank all decreased with the increase of degradation degree, the soil seed density of heavily degraded and extremely degraded steppe dropped to only 46.8% and 11.1% of slightly degraded steppe. The total soil seed banks (0-9 cm depth) of slightly degraded, moderately degraded, heavily degraded and extremely degraded steppe in April 2005 had 2800,1278,1311 and 311 seeds? m-2 respectively. In June results were lower but showed the same pattern (i.e. 1667,967,334 and 167 seeds? m-2). Most soil seeds were found in the top 0-6 cm, and there was a decrease with depth. The soil seed density (0-6 cm depth) of slightly degraded, moderately degraded, heavily degraded and extremely degraded steppe in April was 98.4,96.5,95.8 and 85.7% of the soil seed density (0-9 cm depth). Sorensen similarity index of seed bank composition and standing vegetation was 0.24-0.48.