Woody plant damage by African elephants in relation to leaf nutrients in western Zimbabwe

Abstract

The relationship between elephant damage and leaf nutrient concentration across tree species was investigated in a semi-arid savanna in western Zimbabwe with the purpose of investigating possible nutritional factors influencing elephant feeding preferences in Kalahari sand woodlands. The presence of elephant damage was recorded in all trees above 1 m in height, and leaf samples were collected from all tree species encountered in 12 vegetation plots during the late dry season. Elephant damage was positively correlated with leaf calcium, magnesium, potassium and protein concentration, but not with sodium, phosphorus or fibre. Tree species associated with sandy soils appeared to be less preferred by elephants and to have lower nutrient concentrations than species occurring on more fertile soils, such as species associated with termite mounds. Elephant damage may suppress recruitment in preferred tree species in these woodlands. This notion was supported by (1) the fact that 44% of all trees surveyed had had their main stems broken by elephants, a situation that leads to a multi-stemmed growth form with limited vertical growth; and (2) the negative correlation between the height of damaged trees and elephant damage across species.