“…Studies have been conducted on the definition and classification (Yang, 2001;Chen et al, 2008a), formation and development processes (Wang et al, 2009(Wang et al, , 2010b, spatial distribution patterns at various scales (Wang et al, 2010a(Wang et al, , 2011a(Wang et al, , 2012a and sustainable recovery (Fan et al, 2004;Wang et al, 2011bWang et al, , 2012b of DSL.…”