Food preferences and feeding interactions among browsers and the effect of an exotic invasive weed Chromolaena odorata on the endangered black rhino (Diceros bicornis), in an African savanna.
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Date
2009
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Abstract
Biodiversity changes, often resulting from climate change, land transformation, and the
transportation of organisms across geographical barriers are among the most important human
induced global changes. To optimize the spatial allocation of conservation efforts, and how to
best protect indigenous species, requires an understanding of the principal determinants that
structure ecological communities and ecosystems. We studied community-level interaction
among a diverse assemblage of specialist and generalist browsers in an African savanna.
Hluhluwe-iMfolozi Park (HiP), South Africa, hosts a complete assemblage of vertebrate species
across all trophic levels and contains a diverse guild of large browsers. Using species abundance
distributions (SADs) we graphically illustrate the diversity and abundance of woody species that
comprise six structural habitat types within HiP. We calculated the Shannon-Wiener index and
Pianka’s niche overlap to characterise the utilization of forage across habitat types among
different browser groups. By using individual plant traits we investigated mechanisms of
resource partitioning. We specifically investigated the effect of the temporal expansion of an
exotic invasive plant (Chromolaena odorata) on the critically endangered black rhino using GIS
and statistical analyses. We found that lower lying habitat types were important forage resources
for browser species and individual plant traits that are highly correlated with digestibility
strongly predicted browser preference. Black rhino used different strategic and metabolic
mechanisms to successfully compete within the same forage height range of other, smaller,
browsers. C. odorata has negatively impacted forage species utilization and has led to a spatial
reorganization of the population of black rhino. This may partly explain the recent decline in the
population. The principles within metapopulation management can be used to successfully
conserve endangered species. High diversity of browse across three dimensions (diversity,
abundance and maximum height) relative to area facilitates a high diversity and abundance of
different browsing herbivores. Therefore the spatial configurations of resources ranging from
topological attributes to the individual plant traits are essential to maintaining viable populations
of many co-occurring species within conservation areas of limited extent.
Description
Thesis (M.Sc.)-University of KwaZulu-Natal, 2009.
Keywords
Black rhinoceros., Chromolaena odorata., Theses--Zoology.