Wire Warriors: Protecting South Africa's Savannah Trees From Elephant Encounters

In the Associated Private Nature Reserves (APNR), part of the Greater Kruger National Park, large tree densities decline due to the impact of browsing elephants (Loxodonta africana). Wire netting around the trunk of knobthorn (Senegalia nigrescens) and marula (Sclerocarya birrea) trees is used to protect individual trees. The success of the wire netting will depend on the species, the size of the tree, and variables that describe the tree's location in terms of its suitability for elephants. The objective of this study was therefore to quantify the impact of wire netting on tree survival, and to test whether tree, elephant and landscape variables were associated with tree survival. Data were collected from a nine-year survey of elephant impacts on tree species by Elephants Alive. Elephants Alive is a non-profit organisation whose mission is to ensure the survival of Africa's elephants through protection and research. A Cox proportional hazards model, that is, a survival analysis, was fitted for tree mortality and elephant impact over time. Wire netting significantly increased tree survival (p < 0.001), particularly for trees with a large diameter at breast height (DBH: 39–106 cm), and had a greater protective effect on large marula trees compared to knobthorn trees (p = 0.045). Landscape factors also influenced tree survival, with trees closer to the Kruger National Park (p < 0.001), at lower elevations (p = 0.001), and within 500–1500 m of water points (p = 0.074) having a higher risk of mortality. Trees further from roads (251–335 m) had higher survival (p = 0.073). These results suggest that wire netting is an effective mitigation tool for large trees in elephant-impacted landscapes, but its implementation should consider site-specific environmental factors and elephant movement patterns.