A short-term mechanistic model of forage and livestock in the semi-arid Succulent Karoo: 2. Evaluation and application

In this paper, we present the results of an evaluation and report on an application of a short-term (one to two years) mechanistic model of plant and livestock production in the semi-arid Succulent Karoo of Namaqualand in South Africa. The model has been evaluated by comparisons of model predictions with empirical observations. An operational evaluation shows that simulations of kid growth agree well with recorded data from Paulshoek in Namaqualand. Realistic predictions of reproductive and survival rates depend on assumptions in respect of stocking rates and date of onset of the breeding season. Technical evaluation shows that model responses to changes in litter size in the present and previous years, doe liveweight after parturition and season of kidding are reasonable. The model is used to study the effects of amount of rainfall and its distribution during the year and stocking rate on the productivity of vegetation and livestock. An important application of the model is the production of a comprehensive data set required for the generation of equations for a long-term (100 years) model of the system.