Arid and semi-arid regions have increasingly become the subject of much research
and debate by scientists. By their very nature, these regions characteristically
exhibit extremes which complicate the implementation of effective management
strategies that ensure sustainable productivity and economic output. Namibia is
one such region where low and highly variable rainfall conditions and fluctuating
productivity pose a challenge to managers of commercial livestock enterprises,
/
who seek to optimise economic benefits while controlling the negative effect on
herd production and income of unpredictable and unfavourable climatic events.
Various management approaches are proposed as a means of exploiting periods
of abundant productivity and so optimising income from herd production, while
controlling for the effects of drought conditions. To analyse the effects of these
various offtake strategies, a rainfall-driven plant-herbivore simulation model is
used. The model comprises components simul~tihg vegetation and herbivore
dynamics. The vegetation component incorporates soil moisture and nutrient
allocation to plant parts. The herbivore dynamics sub-model comprises age and
sex classes, population dynamics and animal energy requirements which govern
accumulated fat reserves. The model is adapted to account for climatic and
vegetation attributes specific to Namibia. An economic component including a
seasonal monthly price structure is developed, and a dynamic feedback governing
management decisions is incorporated.
The much debated issue of whether to maintain a constant stocking rate or to track
climatic variation by employing a variable stocking level is investigated, with the
performance of management strategies incorporating these approaches ranked
according to various factors, including annual returns, associated risk and annual
stock mortality. The economic consequences of the timing of offtake are
investigated, with the simulation of management strategies that implement destocking
in the face of anticipated drought conditions. A dynamic projection of
expected income allows the impact of forecasting potential economic gains on
decision-making to be analysed.
Results indicate that the performance of management strategies is not as
dependent on climatic and seasonal price variability as was originally expected,
with the application of a constant stocking level proving to be the most favourable
strategy in terms of economic gain and variability of income. Tracking climatic
variation by adapting stocking levels does not provide the improvement in
economic returns from a livestock production system that was anticipated,
although this approach is successful in effecting a significant reduction in annual
stock mortality. Further results show the sensitivity of income to the long-term
average stocking level characterising the management strategies investigated, as
well as to the elasticity of the underlying price structure.
The results of this study indicate that the implementation of management
strategies designed to track climatic variation does not offer significant economic
advantages over the application of a constant stocking approach. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/3253 |
| Date | January 2001 |
| Creators | Tarr, Heather Lucy. |
| Contributors | Hearne, John W. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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