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Accueil du site → Master → Etats Unis → 2009 → Preliminary assessment of the effect of high elephant density on ecosystem components (grass, trees, and large mammals) on the Chobe riverfront in northern Botswana

University of Florida (2009)

Preliminary assessment of the effect of high elephant density on ecosystem components (grass, trees, and large mammals) on the Chobe riverfront in northern Botswana

Wolf Andrea

Titre : Preliminary assessment of the effect of high elephant density on ecosystem components (grass, trees, and large mammals) on the Chobe riverfront in northern Botswana

Auteur : Andrea Wolf

Université de soutenance : University of Florida

Grade : Master of Science 2009

Résumé
Elephants are well-known to affect landscapes by converting woodland into shrub or grassland. This is obviously the case along the Chobe riverfront in Chobe National Park, northern Botswana, where dead trees tower over the world’s largest elephant herd while tourists watch transfixed as they move through vast stretches of shrubland on their way to the riverfront. Two types of ecological transects developed specifically for the semi-arid savannas of southern Africa and historical accounts were used to assess change in riverfront ecosystem components over time and space from the herbaceous layer to the woody layer, and the large mammal component. A temporal comparison was made between Chobe National Park in 2007 and 1965, and time was substituted for space to make a spatial comparison between Chobe National Park 1965, 2007, and Bwabwata National Park in Namibia, a physiognomically similar environment, with lower elephant densities. Results demonstrate that the herbaceous layer in Chobe was already degrading by the 1960s because of past land use. The shrub layer has expanded and simplified, and is now dominated by two species (Combretum mossambicense and Capparis tomentosa), and animal composition and densities have changed dramatically. Selective grazers have decreased significantly with the loss of the grass sward, and non-selective browsers such as elephant, impala and kudu now dominate each site analyzed. Results show a simplification in the woody and animal layers, and degradation in the herbaceous layer, leading to questions about sustainability on the system, and whether this park is meeting its goals and objectives as a National Park.

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Page publiée le 3 janvier 2012, mise à jour le 23 octobre 2019