Provision of artificial surface water

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The amount, distribution and duration of surface water sources affects all components of savanna ecosystems. Increased trampling and defecation by animals alter soils close to water. The species composition and structure of the vegetation is also indirectly changed through the modified soil environment, and directly through the increased utilisation and trampling.

Changes in the vegetation, in turn, affect the availability of forage and cover for animals, birds, and insects. When permanent sources of water are closely spaced (less than five km apart), vegetation is homogenised because all areas are intensively utilised, and the grading from heavy to light utilisation with increasing distance from water is lost. Certain animal species flourish in the modified environment, while others decline or are eliminated because habitat essential for their survival is diminished.

 

 

The effects of artificially supplied water were first studied at Malilangwe in 1997 (Clegg 1999b). Results showed that mopane woodlands on basalt-derived soils (51% of the reserve) were least affected, while vegetation on sandy soils was most impacted. Consequently, it was recommended that artificial water be sited primarily in the mopane woodlands and, where possible, removed from areas with sandy soil.

In addition to that, to achieve a more distinct separation between the wet and dry season range of herbivores, it was recommended that areas greater than five km from permanent water be increased. This would improve resilience by creating forage reserves that could be utilised by animals during drought.

Following these recommendations, 11 artificially supplied water points were closed. This was a bold move because at the time it was a radical departure from conventional thinking. The decision paid off, however, because while neighbouring reserves frequently lose animals to drought, Malilangwe is yet to do so.

Waterholes are focal points for game viewing, and a common argument against their removal is that their closure will adversely affect the viewing spectacle for tourists. Contrary to popular belief, however, large numbers of water points do not necessarily improve game viewing because animals are dispersed over a wider area as opposed to being concentrated at a few predictable points.

This perception was tested at Malilangwe (Clegg 2008). A game drive route was repeatedly driven before and after the strategic closure of four waterholes, and the encounter rate with game recorded. It was found that the closure of the water points improved the game spectacle at the remaining ones, and that the encounter rate with game along the route also increased.