Figure 1

Map showing the location of the study area in Xifeng District, Qingyang city, Gansu province, including the watersheds of forestland and grassland (Chinese map in the figure was created by ArcGIS 9.3 software, http://www.arcgis.com/features/; satellite image in the figure derives from Google Earth and copyright of the satellite image belongs to Google Earth and CNES/Astrium).