O'Kane C.A.J., Duffy K.J., Page B.R., MacDonald D.W.
Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Abingdon Road, Tubney, Oxon OX13 5QL, United Kingdom; Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa; School of Biological and Conservation Sciences, Westville Campus, University of KwaZulu Natal, Private Bag X 54001, Durban 4000, South Africa
O'Kane, C.A.J., Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Abingdon Road, Tubney, Oxon OX13 5QL, United Kingdom, Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa, School of Biological and Conservation Sciences, Westville Campus, University of KwaZulu Natal, Private Bag X 54001, Durban 4000, South Africa; Duffy, K.J., Institute of Systems Science, Durban University of Technology, P.O. Box 1334, Durban 4000, South Africa; Page, B.R., School of Biological and Conservation Sciences, Westville Campus, University of KwaZulu Natal, Private Bag X 54001, Durban 4000, South Africa; MacDonald, D.W., Wildlife Conservation Research Unit, Department of Zoology, University of Oxford, Abingdon Road, Tubney, Oxon OX13 5QL, United Kingdom
Research has increasingly established that mesoherbivores influence the regeneration of woody plants. However the relationship between mesoherbivore density and degree of impact, and the spatial component of this impact, has not been well established. Using a novel sampling design, we assessed in iMfolozi Park, South Africa, the impact of impala (Aepyceros melampus) across the full complement of woody species within the home range, evaluating its spatial component and relationship to impala density. We used four GPS collars, in separate breeding herds, and a GIS to detect zones of different density of impala in the landscape, thus defining a fine-grain browsing gradient. We assessed impact on woody recruits (≤ 0.5 m height) across this gradient by means of 1600 random 1 × 1-m quadrats. Densities of woody seedlings, and mean percentage of remaining canopy, were significantly less in areas of high impala density versus low-density areas. There was a significant correlation between increasing impala density and decreasing density of favoured woody recruits. We propose a hypothesis of impala-induced patch dynamics. It seems likely that the ubiquitous impala may create and sustain a shifting mosaic of patches, and thus function as a key determinant of landscape heterogeneity. © 2012 Cambridge University Press.