Abstract:

Elephants in systems: Additive and substitutive effects of browser guild members on woody vegetation.

Christopher A J O’Kane¹²³, Kevin J Duffy², Bruce R Page², David W Macdonald¹

¹Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, The Recanati-Kaplan Centre, Tubney House, Abingdon Road, Tubney, Oxon OX13 5QL, UK
² Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa
³School of Life Sciences, Westville Campus, University of KwaZulu-Natal, Private Bag X 54001, Durban 4000, South Africa

The impact that elephants have on woody vegetation in savannas has been investigated in many studies over several decades. However, despite the extended focus, precisely how vegetation changes in response to browsing by elephants is not clearly established. In addition, the effect of other members of the browser guild on the ultimate plant community species mix is not known. We present the results of an extensive literature review of plant use by browsers, and the impacts that they have, which suggests that the influence of is both additive and substitutive. The review also shows that there are very few studies where impacts by more than one member of the browser guild has been investigated in the same locality, and that the predictive value of current knowledge is weak. We present data from Hluhluwe-iMfolozi Park that show the extent of overlap and exclusive use in diet and habitat use by different members of the browser guild. Using an experimental approach in which we collared impala and then examined impacts on woody vegetation in different parts of home range we showed how mosaics of vegetation patches with different physiognomy and species composition are established. We explored the additive and substitutive impacts on woody vegetation by elephants and impala in the longer-term, using a modeling approach, and showed how different functional groups of woody plants are likely to change in both relative and absolute abundance in response to browsing. The results show that woody species mixes in the presence of large browsers are substantially different to those that occur when browsers are absent.

Presentation Topic

Elephants in systems: Additive and substitutive effects of browser guild members on woody vegetation.

 

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Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa

 

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