Fig. 1

The map of Shaanxi province, China (made through Microsoft PowerPoint, source of map: http://www.geodata.gov.cn/web/geo/index.html, under license without need for permission). *This figure was made by ourselves through Microsoft PowerPoint (Version 2013, Microsoft Crop, Redmond, WA, USA). The source of map was a public database, National Nature Resources and Geospatial basic information database of PRC (http://www.geodata.gov.cn/web/geo/index.html). This maps were under license without need for permission