Elephants – effects from ecosystem engineers on arthropods

When foraging and moving, elephants change their environment by pulling down trees, braking off branches or trampling wood vegetation. This creates gaps in the forest canopy and high amounts of dead wood. Dead wood is the habitat of many organisms such as fungi, insects, birds and mammals. A positive effect of high elephant activity on the diversity of dead-wood inhabiting species can thus be assumed, but has not been studied. Elephants in the Arabuko Sokoke forest depend on water holes and thus, a natural gradient of habitat disturbance from elephant activity exists with regard to distance to water holes. Strongest disturbance can be assumed around the water hole (see aerial picture taken with a UAV DJI Phantom 3), while other areas more distant from the water hole are only marginally affected from elephant distrubances. And, luckily, the elephant population of Arabuko Sokoke became restricted to some areas, while other areas can not be reached due to the existence of an elephant fence (exclosure situation).

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The impact of elephants on the diversity mainly of dead-wood inhabiting insects was studied by the master student Allison Hall-Mullen using flight-interception traps and light traps along this gradient of elephant activity, between July and August 2017. Allison found that …