**1. Introduction**

The soil seed bank (SSB) comprises seeds that have survived at the soil surface and in the soil [1]. The SSB represents potential plant communities and is essential for rehabilitating degraded ecosystems via revegetation and restoration. Moreover, the SSB determines the progress and direction of the future vegetative composition of communities [2–4]. Consequently, understanding species composition, density, and diversity of SSB can provide a basis for understanding mechanisms of vegetation succession, and is a particularly important indicator for evaluating the effects from treating degraded desert steppe ecosystems [5]. Human disturbance always generate significant negative effects on the SSB in desertified regions in a semi-arid climate [6]. The research on seed banks in a degraded desert shrubland showed there were consistently positive relationships between ground cover of litter and viable seed density [7]. In degraded drylands, the re-establishment of post-disturbance native plant community was almost exclusively conducted using seeds [8]. The average seed density decreased from stabilized sand dune to interdune lowland of stabilized sand dune, to interdune lowland of active sand dune, and to active sand dune [9]. The latest researches indicated that vegetation cover and seed bank size were notably lower in the degraded grassland. And there were significant differences in understory vegetation and soil seed stocks among different vegetation types on the Loess Plateau [10]. The restoration effect of planted forest was obviously better than that of abandoned farmland [11]. Tree seed density and diversity increased with regeneration time and vegetation structure [12]. Spatially, the distribution of the seed density and species diversity of the SBB in the marginal zones were higher than those of seed banks in the hinterland of the desert [13, 14]. Although considerable research has investigated various aspects of SSB characteristics for different vegetation types, little research has been conducted to systematically evaluate SSB of planted shrubs, and how those treatments can affect dessert steppe ecosystems.

Beginning in the 1970s, plantation of *C. microphylla* in addition to fencing has been used in Yanchi County to restore degraded desert steppe. Currently, there are 600,000 hectares *C. microphylla* plantation. In this study, the SSB was investigated in semi-fixed dune, and *C. microphylla* plantation with different ages within fencing in a degraded desert steppe, while using a neighboring natural steppe without desertification as a control. Several important indicators of SSB were evaluated, including species composition, the number of germinations, and species diversity. The changes of plant species and seed density in SBB of *C. microphylla* plantation with different ages can provide scientific basis for the selection of plant species and the determination of seeding amount for aerial seeding [15].
