عنوان مقاله [English]
Background and objectives: Assessment and evaluation of soil seed resources in an ecosystem provide valuable information about the status of plant composition in this ecosystem. The information obtained from these studies will lead to better understanding and recognition of vegetation conditions in that area. In this study, for the first time soil seed potential in the Baghe-shadi protected area in Yazd province was studied.
Materials and methods: at first, two grazing and exclosure areas were selected from in the Baghe-shadi forest site of Yazd province with similar type. Then, in each area 20 circular plots were measured in a radius of 12 meter. Samples were taken from the soil seed bank, up to 10 cm soil depth in tow depth (0-5 cm and 5-10 cm) beneath the canopy and also outside the canopy in two growing seasons (spring and autumn). Density, composition and species richness of soil seed bank samples were estimated by combined method (extraction of large seeds and germination of small seeds).
Results: soil depth showed significant effects on soil seed bank. The effects of spring and autumn vegetative seasons were different on soil seed bank and autumn season showed a higher rate than the spring in terms of number, density and numerical values of biodiversity indices. Also, according to the results, the number and density of seed bank under crown cover was higher than outside and the exclosure had no significant effect on soil seed bank. The results of independent t-test showed that there is no significant difference between grazing and exclosure areas, but grazing area had higher seed numbers than the exclosure area. The results of analysis of variance showed that vegetative season and crown cover had significant effects on all studied parameters of soil seed bank. Also comparison of numerical biodiversity index of soil seed bank between grazing and exclosure areas showed that species richness, Simpson, Shannon-Wiener and Pielou evenness were higher in autumn season than spring season and below the crown cover was significantly higher than outside.
Conclusion: The area under grazing produces enough seed of different species, but is likely destroyed by livestock after emergence. In fact, due to seed density and diversity of seed soil bank, it can be concluded that in this forests, exclosure alone can guarantee forest regeneration. But, it seems that it should be thought about fix the problems of Amygdalus scoparia droughts and pests, especially timber beetles.