Soil Seed Bank Characteristics in Relation to Distance from Watering-Points in Arid Ecosystems (Case Study: Kahnuj, Kerman Province)

Epizoochory and endozoochory are well-known mechanisms by which seeds are dispersed by animals. Since, livestock gather around the watering-points to rest and drink, we expected to find that seeds would be frequently moved to the areas surrounding watering-points, resulting a higher soil seed density (and diversity) closest to the water. We investigated this issue by assessing soil seed bank density and composition along a distance gradient from the water and compared them with an ungrazed-control area in 2010. Therefore, three watering-points were selected in a dry rangeland of Kahnuj, Kerman Province, Iran. Soil seed bank characteristics were measured at eight distances with different intervals from the watering-points (totally 80 sampling points) and in an ungrazed area (30 sampling points) after seed dispersion in autumn. The results showed that in spite of the assumption, soil seed density and similarity between the soil seed bank and above ground vegetation increased with distance from the watering-points. A clear trend was not detected for the diversity of soil seed bank with distance from water source. Our findings suggested that the restoration of degraded sites could not rely on soil seed bank. Areas surrounding watering-points, where soil seed losses are potentially higher than those at greater distances from water source, should be given more attention for conservation by the rangeland managers.