Abstract

In this study, the effect of cushion plants on spatial distribution of soil seed bank was studied in mountainous and hilly rangelands in Vaz watershed, Mazandaran province. Therefore, we selected randomly 20 Onobrychis cornuta individuals and sampled from soil at four positions around each individual (upslope, downslope, center and, outside as control). Soil samples spread out under natural conditions in greenhouse to germinate the seeds. Germinated seeds were identified then, the seed density per square meter and species richness were calculated and both of them were compared between the four sampling positions. Two and one-way ANOVA, T-test and Duncan test were used to compare the effect of location, depth and their interaction on soil seed bank characteristics. The results showed that the effect of the location and depth of the density and species richness at level of 0.01% were significant. The results of Duncan test showed that seed density in the upslope and center positions (average 5473 and 4099.5 seed/m2, respectively) was significantly higher than seed density in the downslope and outside positions (average 2685.5 and 2413.8 seed/m2, respectively). Similarly, species richness in the upslope and center positions (the average 9.7 and 9.5, respectively) was significantly higher than species richness in the downslope and outside positions (average 7 and 6.4, respectively). Density and species richness of soil seed bank at depth of 0-5cm was significantly greater than the depth of 5-10cm. This study clarified the positive significant effect of canopy of cushion plants on seed density and richness.