Natural recovery ability of the initial vegetation stage of earthquake landslide in the middle reaches of Bai Longjiang——A case study in Qingshuigou earthquake landslide of Wudu District, Longnan City, Gansu Province

• He MA, 
• Ji-qiang ZHANG, 
• Jian-jun KANG, 
• Rui XUE, 
• Ya-ping ZHAO, 
• Zhi-yong GONG, 
• Dong-hao LIU