The effects of artificially supplied perennial water on soil properties, vegetation dynamics and the
distribution of large herbivores was investigated in southeastern Zimbabwe. Data collection took
place between March 1997 and July 1998. Water points were situated primarily on three different
soil types (clay-loam, sandy-clay-loam and sand), and in four different vegetation types (Hill
communities, Colophospermum mopane veld, Acacia nigrescens woodland and Albizia petersiana
woodland). One water point in C. mopane veld (Bandama) had been closed two years prior to data
collection, while another, in the Hill community (Manyoka), had been introduced, two years prior to data collection.
Changes in physical (infiltration) and chemical (organic carbon and nutrients) properties of
soils around water points were largely restricted to within 100 m of water. Chemical enrichment of
the soil occurred only at water points that had been in place for more than two years. Soil surface
conditions were altered to distances beyond 100 m from water. Manyoka (the new water point) was
an exception, with extreme changes limited to within 100 m of water.
Herbaceous and woody species composition changed in response to distance from water
with changes best described by asymptotic equations. Changes in species composition of the woody
component appeared to be longer lasting than changes to the herbaceous component. Most perennial
grass species declined close to water, but Urochloa mosambicensis increased close to water in areas
outside of the Hills. Herbaceous species diversity was adversely affected by distance from water on
sandy soils (Hill communities and A. petersiana woodland), but was largely unaffected on clay-loam
(A. nigrescens woodland) and sandy-clay-loam soils (C. mopane veld). Woody species
composition and density was altered out to 500 m from perennial water in Acacia nigrescens
woodland on clay-loam soils. Results suggest that this vegetation type may be susceptible to bush
encroachment close to water. Trends in woody canopy utilisation were generally similar to trends in
woody species composition, and it is proposed that the former may be used to indicate future
changes in the latter. Conversion of trees to shrubs was highest at Manyoka (the new water point)
indicating that woody destruction by elephants is extreme during the initial years following water introduction.
Large herbivore biomass was greatest close to water (< 1 km) during the dry season but not
during the wet season. Herbivore species distributions appeared to be influenced by the position of
perennial water, but since all range was within easy access of water, it is unlikely that animal
distributions were constrained directly by the position of surface water. It is more likely that
herbivores were spatially separated on the basis of habitat type. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1999.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10273 |
| Date | 19 December 2013 |
| Creators | Clegg, Sarah. |
| Contributors | Goodman, Pete., O' Connor, Tim G. |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
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