Effects of enclosure management on the structure of soil seed bank and standing vegetation in degraded sandy grasslands of eastern Inner Mongolia

This paper examined the effects of enclosure management on the structure of soil seed bank and standing vegetation in degraded sandy grasslands and the interactions between soil seed bank, early seedling community and final established vegetation. Several conclusions were drawn from this study. (1) Adoption of enclosure management practice significantly increased density and species richness (number of species per square meter) in both the seed bank and standing vegetation, compared with grazed grassland. (2) Grazing disturbance had the differential influence on the structure of the seed bank and standing vegetation. Grazing exerted a stronger impact on species richness in the standing vegetation than in the seed bank, reducing standing vegetation richness by as much as 43% and seed bank richness by 19%. In contrast, grazing showed a greater influence on density of the seed bank compared with the standing vegetation, reducing seed bank density by 88% and standing vegetation density by 5%. (3) Grazing reduced compositional similarity between the seed bank and the standing vegetation because of a significant decrease in the number of cooccurring species present both in the seed bank and in the standing vegetation. There was a higher compositional similarity in the seed bank species than in the standing vegetation species between the enclosed and grazed grasslands, providing evidence of a stronger effects of grazing on the standing vegetation composition than the seed bank composition. (4) Regressions using the data for densities of individual species in both sites showed significant positive linear relationships between soil seed bank density and seedling community density and established plant density as well as between seedling community density and established plant density. Differences in the seed bank density accounted for 56% of the variance of the seedling community density, and differences in the seedling community density accounted for 77% of the variance of the established plant density.