Ecology, Environment and Conservation Paper

AFRICAN ELEPHANT (LOXODONTA AFRICANA) IMPACT ONSELECTED TREE SPECIES AND ASSESSMENT OF PIOSPHEREGRADIENTS IN VENETIA-LIMPOPO NATURE RESERVE

S.E. Nkosi1, E. Adam, A.S. Barrett and L.R.

Abstract

Trees utilised by elephants often undergo a significant amount of damage compared to trees utilised byother browsers. Woody plants play a crucial role in plant community dynamics, species composition, andthe savannah system’s functioning. As drivers ofecosystems, elephants are capable of transforming habitatsin terms of structure and species composition. In this paper, the damage caused by elephants on differentselected tree species in Venetia-Limpopo Nature Reserve was studied following a field-based approach.Field data collected for trees included the species name, GPS location, tree height class, extent, and type ofdamage resulting from elephant foraging. The Normalized Difference Vegetation Index (NDVI) was usedto evaluate vegetation’s vigour using Landsat-5 imagery. A Multiple Ring Buffer Tool was used to extractmean NDVI values of buffer rings spread around waterholes at 400-metre intervals. The impact on woodyvegetation along the vegetation gradient, ‘Piosphere’, was evaluated. NDVI values extracted for the differentyears indicate that the impact on woody vegetationdegradation along the Piosphere gradient is negligible.There was no statistically significant relationship (Pearson correlation r3= –0.500, P = 0.391), trend or patternbetween the number of damaged trees and the type of damage. Different trees at different height classeswere utilised inconsistently by elephants. The dominant (45%) type of damage was for Broken Main Stem(BMS), with the lowest (1%) damage being for BarkStripping (BS). Overall, there was a statistically significantdifference (Pearson correlation r3= 0.973, P = 0.146) between the number of trees selected by elephants inthe various height classes. Trees between 3 m and 4 mwere the most selected and the impact seemed to bestabilising at these tree heights. Additional studies need to be focused on the recruitment rates of elephantforaged trees in the reserve to prevent local extirpation of these species in the future.