Written by Almero Bosch - Timbavati PNR Ecologist

Background

The Wiggill and de Vos properties were incorporated on 2 March 2024.  Elephants as a species were not present in the area before the incorporation, thus no Elephant impact existed on the properties.

Thoughts were that Elephants would gradually populate the area as it was an unknown area for them, usually, bulls will first move into the area and there after breeding herds will occupy the area, almost as if the bulls will scout in the area and relay a message to the cows that the area is safe.  This sequence of events did not happen. Bulls moved into the area and immediately started to utilise the woody layer of the area. Breeding herds were also found in the area almost immediately with no time lag between bulls entering and breeding herds.

This short report, using graphs gives an overview of what the elephant impact was after 2 months.

Findings

The following four species were highly impacted on with impact contribution to the total data set in brackets; Common False-thorn (Albizia harveyi) (29.72%), Red Bushwillow (Combretum apiculatum) (10.83%), Marula (Sclerocarya birrea) (11.88%) and Knob Thorn (Senegalia nigrescens) (9.44%).

The average severity of impact on each of these species, given as a percentage is depicted in Figure 1.  Common False-thorn and Knob Thorn have the highest average percentage impact, the specific impact types are detrimental to individuals (Uproot and Pushed-over).  Impact types on each of the selected species are depicted in Figure 2.

Figure 1: Average % severity of impact on selected tree species.

Figure 2:  Impact type/ species.

It is interesting to see that all impact types except for bark-stripping are found within this group of highly impacted species.  This might be because the influx of Elephants was during the late growing season, with active nutrient transport within the bark of specific trees which is known to be heavily bark-stripped like Marula being low or already inactive.

Common False-thorn, which are still to be found in the TPNR but as small to medium sized dwarf shrubs and shrubs are almost exclusively uprooted and pushed over, making the survival of these individuals highly unlikely.  Marula received unusually low impact in terms of impact type with only branch breaking considered to be high, this might be as a result of the season.  Red Bushwillow has branch breaking as the highest impact type with some uprooting.  Knob Thorn has an almost equally distributed impact within all categories.

Conclusion

Elephant impact is high within large parts of the incorporated area.  Short-term impact findings as given here compared to findings in the Timbavati Private Nature Reserve which has been subjected to Elephant impact for more than 30 years are as follows:

• Elephants alter the structure of the vegetation, lower and more open structure
• Species growth form alteration, tall trees might become dwarf shrubs as elephants and other herbivores continuously utilize a species (in the TPNR Squat Star-Chestnut (Sterculia rogersii) can not be found as a tree anymore but as a shrub or dwarf shrub). In the incorporated area there are beautiful tall tree specimens of the Star-Chestnut
• Species-specific impact type might result in the loss of a species' propagation potential and survival in the long term. A good example of this is Elephants that pollard Marula (Sclerocarya birrea) and as a result, these impacted individuals do not flower or fruit, thus reducing the propagation potential of the species in the area.