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Project Description

The SAGS (Semi-Arid Grazing Systems) Project is a long-term research project at the University of Edinburgh, UK.

The primary objective of modelling semi-arid grazing systems was to find out how far the existing knowledge of the underlying processes could account for and replicate the dynamics of the system. Thus, subsidiary objectives included the prediction of animal performance in response to variation in rainfall and to stocking rate, and the effects of animal type and vegetation conditions on system performance. Modelling was used to assess the components and processes to which the system is most sensitive, and identified inadequacies in current knowledge which limit our understanding and ability to predict system performance. An important output was the evaluation of management policies and interventions as techniques for increasing economic output and coping with climatic variability.

The original scope for application and validation of the model ranged across a rainfall gradient running between Zimbabwe, South Africa and Botswana. It was confirmed that the model was capable of replicating the main features of semi-arid system dynamics. Its predictions of carrying capacity were found to be in broad agreement with carrying capacities reported in the literature. Subsequently, the model has also been successful predicting optimal strategies for responding to market fluctuations under variable climate in Namibia, and most recently has illustrated the benefits of a modelling approach in conservation efforts to protect the Mongolian Gazelle and towards an assessment of the damage being caused to the Great Barrier Reef through silt deposition resulting from the Queensland cattle industry.

The model will continue its usefulness in Africa, Mongolia and Australia while it is subsequently being considered for application to livestock and mixed livestock/wildlife systems in India.