Abstract:

Main aims of this study are to investigate effects of shrubs on vegetation restoration of grassland from previous farmland, and then to optimize management measures to build the grassland. The study site was in Siziwang Banner, central Inner Mongolia, where the local vegetation is temperate and arid grassland. The followings are our main findings. 1) Grassland restoration depends on width between neighboring shrub belts. If the width is within appropriate distance, land between the belts will be restored with grasses well, otherwise not. 2) If a distance from an abandoned farmland to its nearest shrub belt is moderate, the land will be restored with grasses effectively, with better coverage vegetation and rich grass species, and otherwise less effectively. 3) Gaussian mathematic model well fits the relationship between restoration degrees of grassland and the distances from abandoned farmland to shrub belts. 4) According to the fitted model, shrub belts can promote grassland restoration well if the distances between the belts are in a range of 16－28 m. This study is helpful to optimize the structure of shrub belts in dry abandoned farmland such as in Siziwang Banner. As for the genera of Caragana korshinskii,the optimal width of belt-gap is found being between 16－28 m.

Key words: farmland abandoning, grassland rehabilitation, primary succession, shrub, shelterbelt, Gaussian model