Human expansion and poaching have forced elephants to alter their traditional ranges and migration patterns. As a result, elephants have been concentrated in protected areas. Elephants play a crucial role in forests by dispersing seeds and fertilizing the soil with their dung. They create light gaps by knocking down trees. They keep the undergrowth clear by trampling vegetation and speed decomposition by shattering rotting logs. In doing so, elephants influence the structure and composition of the forest. Nonetheless, the effects of elephants on Bwindi forest ecosystem remain only partially understood given that elephants in Bwindi are little studied.

The impact of elephants on trees in Bwindi Impenetrable National Park was investigated by documenting tree species, sizes and sites most affected by elephants. Elephant impacts recorded were bark stripping, tree toppling, breaking of branches and trampling. A series of plots of 20 x 4 m was laid out along fresh elephant trails in four sites, varying in vegetation type. In each plot, all damaged and undamaged trees were identified, counted and their stem sizes measured. Environmental variables, namely ground slope, aspect, altitude and tree cover were also recorded.

The study revealed that elephants are selective in where and how they feed. It also showed that the probability of a given stem being bark stripped increases with stem size but decreases with proximity to permanent water sources. In addition, the probability that tree toppling or branch breaking will occur on a given tree decreases with stem size. Species of small trees selected by elephants include Newtonia buchananii, Myrianthus holstii, Chrysophyllum albidum and Macaranga kilimandscharica. Studying the interactions of elephants and trees is important for understanding ecosystem changes in Bwindi. The study recommends further study of elephants to clarify their role as ecosystem modifiers.