Soil seed bank diversity and richness following cessation of cultivation in shrubland and grassland in semi-steppic rangelands of Chaharmahal and Bakhtiari province

Soil seed bank has an important role in vegetation restoration following cessation of disturbance. In this study, the soil seed bank richness and diversity were investigated in semi-steppic rangeland with a history of land conversion into cultivation in Charmahal-Bakhtiari province. Land-use changes were identified in grassland and shrubland and then were classified into four groups according to the time since abandonment including < 5, 5-15, 15-25 and > 25 years. Aspect was considered in each group. Soil was sampled and seed bank was identified using seedling germination method in glasshouse. Then, seed bank richness and diversity indices were calculated. Results showed that in seed bank the number of perrenilas was greater than annuals. In both grassland and shrubland time since abandonment significantly influenced the soil seed bank richness and diversity. In grassland soil seed bank richness and diversity decreased with time of abandonment but in area with more than 25 yrs of abandonment seed abnk richness and diversity significantly increased. Aspect significantly affected both seed bank richness and diversity in shrubland. North slpoe showed fluctuation in seed bank richness and diversity during abandonment while an increase was found in west slope and a reduction in south and east slopes. In both sites the soil seed bank indices significantly increased shortly after abandonment (<5 yrs) but seed bank richness and diversity showed resilient in >25 yrs in grassland and >15 yrs in shrubland.