Cushion plants can affect wind speed and sediment movement patterns that probably modify the water and sediment redistribution along slopes and increase the accumulation of seeds under and around their canopies. This study was carried out to assess the spatial variability of soil seed bank (SSB) and seed bank composition around cushion plants to estimate the SSB potential for restoration of degraded area. Twenty cushions of Onobrychis cornuta were selected in a mountainous rangelands in northern Alborz in Iran, measuring density, richness and composition of SSB at four locations of each cushion (upslope edge, downslope edge, centre and outside). SSB composition and density were determined by seedling emergence method. The results showed that the locations of cushions had significant effect on density and richness of the SSBs. The highest SSB density and richness were observed in the centre and upslope edge of the cushions, while there was no significant differences of density and richness between downslope edge and outside (bare grassland soil) of the cushions. In addition, the results showed that seed bank composition was highly correlated between the four locations in the same cushion. We concluded that cushion plants can act as seed traps specially trapping seeds dispersed by barochory and hydrochory and therefore play an important role in conservation and recovery of degraded areas.

No abstract

International audienc

Little information is available about the effects of different species of shrubs on the composition of the soil seed bank (SSB) in the semiarid regions. We determined the role of three dominant shrub species on SSB characteristics and evaluated their potential for their possible use in rangeland restoration projects. Fifteen sites, each containing three shrub species (Amygdalus scoparia, Daphne mezereum and Ebenus stellata) and a herbaceous patch (control) in close proximity, were sampled and their SSB density, species richness and diversity at 0–10 cm depth were determined. The results showed that the density of the SSB was highest under A. scoparia and lowest in the control. The highest SSB density of grasses was found under A. scoparia, while the highest SSB density of forbs was found under E. stellata. Species diversity of the SSB was significantly greater under E. stellata than under the other shrubs and control. This study revealed that the extent to which shrubs affected SSB characteristics did not only depend on the presence of shrubs, but also on the species of shrubs. These different roles of different species of shrubs on SSB are advised to be considered in the restoration of degraded areas through the SSB in the semiarid areas. In the case of changing management type from intensive grazing to extensive grazing or non‐grazing, the role of different shrub species in the conservation herbaceous species through their SSB can be different.