Effect of exclosure on soil seed bank density, species richness and similarity to the above-ground vegetation in sub-alpine rangeland of Plour

Using of the soil seed bank is one of the most important methods for plant conservation particularly in natural ecosystems. Different factors can affect the soil seed bank. In the present study، we investigated the effect of exclosure on soil seed bank richness and diversity to use the results in plant conservation projects. Therefore، 10 2*2 plots were established in each grazed and non-grazed areas. In each plot، about 1kg soil was taken from each depth i. e. 0-5 and 5-10 cm. Soil samples were transported to the greenhouse after cold stratification. All seeds germinated during the first four months were identified. The number of seeds per m2 and the number of species per plot were then calculated. Soil seed bank characteristics were compared between grazed and non-grazed areas using unpaired t-test. Paired t-test was performed to compare soil seed bank characteristics between the two depths in each area. The results showed that soil seed bank diversity، richness and similarity with aboveground vegetation were higher in grazed than non-grazed plots. We concluded although that exclosure has important role in plants conservation while it may lead to the extinction of some plant species through decreasing soil seed bank density and species richness.