Concepts of carrying capacity and substitution ratios: a systems viewpoint

Abstract

Usefulness of the concepts of carrying capacity and species substitution ratios in natural resource management has been limited by single objectives and single management options implicit in their definitions. When applied to livestock, they have been further limited by poor conceptualisation of the animal-unit concept often used to quantify them. A systematic approach to the animal-unit concept logically leads to concepts of livestock carrying capacity and livestock substitution ratios compatible with the multiple objectives and multiple management options characteristic of range livestock systems. This paper develops simplified multi-objective concepts of carrying capacity and substitution ratios, and discusses their interpretation and application in agro-ecological systems. Also discussed is the applicability of these concepts to describe components other than livestock in managed and unmanaged systems. Some thoughts are presented on abstraction and simplification of concepts.