Elephant impact on dragonflies
Journal of Insect Conservation
Department of Conservation Ecology and Entomology, Centre for Agricultural Biodiversity, University of Stellenbosch, Post Bag X1, Matieland 7602, South Africa
African elephants and other indigenous megaherbivores have a major impact on local vegetation structure, including aquatic communities, as their big feet and large mass pound the fringes of water bodies. This disturbance is likely to have a profound influence on the structure and composition of insect assemblages in these habitats. We investigated which dragonfly (Odonata) species were tolerant of trampling by elephants and other game. Assemblage composition differed according to extremely high, very high or high disturbance levels. Dragonfly abundance was greatest where impact was high, and decreasing when disturbance became very high or extremely high. Several odonate species are well-adapted to fairly high levels of disturbance, although too much is impoverishing. Medium and low impact sites were geographically separated, and this, combined with much lower disturbance levels, had a considerable influence on promoting regional dragonfly diversity. Several regional specialist species only occurred in the geographically separated, low-impact sites. The full complement of dragonflies is present only when there is a combination of various disturbance levels combined with spatial variation. Elephant impact is similar to that of humans, with too much of either or both, leading to a species-poor, habitat-generalist dragonfly assemblage. © Springer Science+Business Media B.V. 2007.
abundance; anthropogenic effect; biodiversity; community composition; community structure; dragonfly; spatial variation; species diversity; vegetation structure; Africa; Anisoptera (dragonflies); Elephantidae; Hexapoda; Loxodonta; Odonata