Investigating the Soil Seed Bank and Its Relation with the Aboveground Vegetation along an Elevation Gradient in Kashan, Iran

A part of plant species composition in natural ecosystems is live seeds that are hidden in the soil and known as soil seed bank. Detecting this species resource has a key role in protecting and restoring the vegetation. The present study aims to investigate the soil seed bank and its relationship with the aboveground vegetation along an elevation gradient in Kashan, Iran. For sampling from the soil seed bank, three transects with 200 m length were established in June 2017. The soil samples were taken from two depths ranging 0-5 and 5-10 cm out of 1 m2 plots with 20 m intervals. The soil samples were transferred to the greenhouse. Moreover, the cover percent of plant species within each plot was recorded in the vegetation season in spring 2018. The features of soil seed bank in different elevations were compared by F-test. The results of one-way analysis of variance showed that the effect of altitude from sea level on the Shannon's diversity and soil depth on the density, Menhinik and Margalef richness was significant. The higher value of Shannon diversity in upper altitude (2800-3000 m above sea level) and higher value of Dnensity, Margalof and Menhinik in upper soil depth (0-5 cm) was obtained. The results of greenhouse experiments showed that most of the germinated seeds belong to annual grass species. While the surface cover of most species is related to perennial plants. The highest coverage of Artemisia aucheri was from 2600-2800 m and the lowest percentage of cover belonged to Alyssum linifolium in the elevations of 2800-3000 m. It can be concluded that in the study area, seeds of perennial plants do not have a readiness for germination in soil depths or they should remain in soil for a long time and should be described as stable seed banks.