Perspective article:The evolving use of stocking rate indices currently based on animal number and type in semi-arid heterogeneous landscapes and complex land-use systems

Abstract

Methods of determining stocking rate based on metabolic mass, animal type and biomass are reviewed in the context of equilibrial/disequilibrial paradigms. In South Africa, the calculation of 'carrying capacity' is based on conversion of animal species to metabolic mass equivalents. This assumes homogenous systems that tend to some point of equilibrium. It is applied widely in commercial livestock systems involving one or two species. Examination of a case study in the Lowveld of the Northern Province, South Africa, showed that the determination of 'stocking rate' in this multi-herbivore and heterogenous system, overestimated the 'carrying capacity' of the reserve over 20 years. The actual animal numbers in the system dropped by approximately 4 000kg km^-2 after a drought in the early period of the study into the bounds as determined by a model incorporating rainfall and animal biomass. An approach to determine stocking density using animal type, biomass, rainfall and vegetation parameters is suggested. The development of this as a coarse-scale (regional) and ranch-specific model to cover a range of scales and heterogeneity in key resources is advocated.

Keywords: animal biomass; animal type; botany; carrying capacity; feeding class; land-use; landscapes; large stock units; Northern Province; semi-arid; South Africa; stocking density; stocking rate; units; biomass; drought; livestock; lowveld; metabolic mass; method; model; rainfall; vegetation

African Journal of Range & Forage Science, Vol. 15(3), pp.117–127