Spatial Variation of Soil Seed Bank under Cushion Plants in a Subalpine Degraded Grassland

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. Copyright (c) 2017 John Wiley & Sons, Ltd.