“…Lateral preferential flow in soil pipe systems, which crucially determines hillslope scale subsurface runoff generation, is intermittent and is likely to be a threshold phenomenon as well (Adams and Parkin, 2002;Buttle and McDonald, 2002;Negishi et al, 2007;Weiler and McDonnell, 2007). Threshold behaviour is also discussed in the context of the long-term development of soil structures and landforms (Newson and Newson, 2000;Phillips, 2004Phillips, , 2006, fluvial morphology (Willgoose et al, 1991a(Willgoose et al, , 1991bGrant, 1997;Piégay et al, 2000;Fryirs et al, 2007;Harnischmacher, 2007), rill and gully erosion (Bull and Kirkby, 1997;Kirkby et al, 2003;Poesen et al, 2003;Shao et al, 2005;Parkner et al, 2006Parkner et al, , 2007, badlands formation (CalvoCases and Harvey, 1996;Howard, 1997;Faulkner et al, 2000Faulkner et al, , 2003Boardman et al, 2003;Faulkner, 2008), and formation and growth of channel networks (Willgoose et al, 1991a(Willgoose et al, , 1991bRinaldo et al, 1996;Rodriguez-Iturbe et al, 1998;Rodriguez-Iturbe and Rinaldo, 2001). Threshold behaviour and feedbacks between vegetation patterns and redistribution of abiotic resources determine the resilience of geoecosystems in semi-arid regions (Grant, 1997;Piégay et al, 2000;Wilcox et al, 2003a;Wilcox and Newman, 2005;Fryirs et al, 2007;…”