Abstract
We used body weight ratio to determine the degree of
species-packing of the Okavango Delta (22,000 km2)
grazers and compared it to that of four conservation areas
of similar sizes but varying in the diversity of habitat types.
They are Etosha National Park (23,175 km2) in Namibia,
Hwange National Park (14,621 km2) in Zimbabwe, Kafue
National Park (24,000 km2) in Zambia and Kruger
National Park (19,633 km2) in South Africa. We considered
possible ecological explanations for existing gaps
within the assemblage. The weight ratio (measure of the
degree of species-packing) of the grazers of the Okavango
Delta was 1.25, with a total of 27 species which was far less
than the theoretically expected 2.0. One-way analysis of
covariance (ANCOVA) showed that there were significant
differences in the degree of species-packing between the
Okavango Delta and other conservation areas of similar size
in southern Africa (F1,5 ¼ 166, P <0.001). Regressing
habitat heterogeneity (expressed as number of different
habitat types) on species-packing of the five conservation
areas yielded a positive linear relationship with R2 ¼ 0.76
implying that 76% of the variation in the degree of speciespacking
in the five conservation areas is explained by
variation in habitat heterogeneity. We conclude that size
ratios are useful descriptors of animal communities and it is
a useful measure of species diversity, which can be used for
monitoring purposes. Imbalances in weight ratios provide a
measure of identifying perturbations due to species loss or
arrival of new species within a natural ecosystem.
Translated title of the contribution | Grazers species-packing in the Okavango Delta, Botswana |
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Original language | English |
Pages (from-to) | 527 - 534 |
Number of pages | 8 |
Journal | African Journal of Ecology |
Volume | 45 |
DOIs | |
Publication status | Published - Dec 2007 |