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Abstract:
Natural protected areas are critically important in the eff ort to prevent large-scale megafaunal extinctions caused by hunting
and habitat degradation. Yet such protection can lead to rapid increases in megafauna populations. Understanding
ecosystem-scale responses of vegetation to changing megafaunal populations, such as the case of the African elephant
Loxodonta africana in savannas, requires large-scale, high-resolution monitoring over time. From 2008 to 2014, we repeatedly
surveyed the fate of more than 10.4 million woody plant canopies throughout the Kruger National Park, South Africa
using airborne Light Detection and Ranging (LiDAR), to determine the relative importance of multiple environmental,
biotic and management factors aff ecting treefall rates and patterns. We report a mean biennial treefall rate of 8 trees or
12% ha 1 , but with heterogeneous patterns of loss in both space and time. Th roughout Kruger, the infl uence of elephant
density on treefall was matched only by spatial variation in soils and elevation, and all three factors co-dominated parkwide
treefall patterns. Elephant density was up to two times more infl uential than fi re frequency in determining treefall
rates, and this pattern was most pronounced for taller trees ( 2 m in height). Our results suggest that confi ning megafauna
populations to protected areas, or reintroducing them into former or new habitat, can greatly alter the structure and
functioning of the host ecosystem. Conservation strategies will need to accommodate and manage these massive ecological
changes in the eff ort to save megafauna from extinction, without compromising system functionality.
