Restoration of Stipa kryloviisteppes in Inner Mongolia of China: Assesment of seed banks and vegetation composition

摘要

The landscapes of Inner Mongolia are widely known for the vast Stipa krylovii steppes. However, overgrazing and other improper land uses have extensively degraded the Stipa krylovii steppe ecosystem in recent decades. Knowledge about the soil seed banks and the remaining vegetation in these damaged ecosystems is crucial for guiding the restoration efforts. Using a germination method, this study examined the size, composition, and species richness of the soil seed banks in three field types: overgrazed steppe, enclosed steppe and abandoned crop field. The abandoned crop field had the largest soil seed bank with mostly annual and weedy plant species. Seeds of desirable perennial grass species were impoverished by the intensive cultivation in the abandoned crop field. The lack of desirable perennial species in the abandoned field was a critical limiting factor for restoration. Grazing decreased the size of the seed bank in the overgrazed steppe. But seeds of desirable grassland species were present in both the overgrazed and the enclosed steppes. As indicated by the Sorenson's indices of community similarity (50-67), plant species abundance and composition in the soil seed banks were closely related to the corresponding vegetation for each of the three sites.