Dynamic monitoring on land cover in loess hilly and gully area by the methods of RS and GIS Types of Natural Grassland and Their Sustainable Utilization on Hilly and Gully Area of the Loess Plateau The character and dynamics with season of soil seed banks in abandoned croplands of loess gully region Selection of Microhabitat of Carabid Beetles (Coleoptera:Carabidae) in Different Ecological Restored Habitats in the Hilly and Gully Area of Loess Plateau, Ningxia, China