African elephants: Influence on the environ­ment

The search for food as well as the feeding behaviour of elephants leave traces in nature. Thus, elephants allogenicly change the landscape. Anthropogenic influences, such as the construction of settlements and fences, lead to the habitat of elephants becoming smaller and they inhabit a certain area for an unnaturally long time. The population density of elephants is higher in smaller areas. However, the elephants still need the same amount of food, so that the vegetation in the reduced area is continuously stressed. This has consequences for both flora and fauna.

During the search for food and intake of food, elephants detach the bark from the tree, break branches, damage the trunk or even uproot entire trees. This damage of the trees leads to an increased occurrence of insects. Trees may die due to insect infestation. Furthermore, the damaged bark is less resistant to fire and, thus, offers the tree less protection. These injuries to the tree can lead to the fact that it is no longer possible for vultures and birds of prey to build their nests on it.

Kruger National Park has long been researching how to protect tree populations from elephants. Due to their size and mass, elephants are one of the few animal species capable of damaging large tree species. Unfortunately, the power of the elephants is a problem for the national park. The trees are an important component of the biogeochemical cycle of the savannah and are used by other animals for shade, food, as nesting sites or as retreats.
Wire-mesh fencing is intended to be a solution to this problem. The wrapping technique of the wire-mesh fence around the trees comes from Kenya. If these fences are successful in the long term, the method will cost-effective and environmentally significant solution for continued elephant activity in limited areas.

Derham, K., Heneley, M. and Schulte, B. have investigated the impact of the wire-mesh fence on elephant damages in the Associated Private Nature Reserve (APNR), a 1,800 km² region adjacent to Kruger National Park. The investigations showed that the presence of the wire-mesh fence had no influence on whether the trees were used by elephants. This means that trees with and without wire-mesh fences were used by elephants. However, it was found that the frequency and extent of damage were less pronounced in trees with wire-mesh fences. It could not be prevented that branches broke off or trees were damaged on a larger scale, but the trunk bark was largely spared. In order to preserve the large tree species and mitigate the effects of elephants, wire-mesh fences would be a good first approach.