Most seedlings and saplings remain in the forest understorey for decades before becoming adults or dying, and thus may be exposed to various sources of physical disturbance (Clark & Clark 1991, 2001). Because tree species vary in their ability to recover after physical damage (Gillman et al. 2003, Guariguata 1998), this damage can act as an ecological filter and influence the juvenile community structure and species composition (Peters et al. 2004). Studies have demonstrated the occurrence and magnitude of stem breakage in juveniles caused by falling branches and other canopy debris (Clark & Clark 1989, 1991; Gillman & Ogden 2001, Scariot 2000). Surprisingly, little is known about the magnitude and ecological consequences of physical damage to juvenile plants by mammals, particularly large ungulates, including herbivory, trampling and uprooting (Gillman & Ogden 2003, Roldán & Simonetti 2001).
