Range management on the basis of a model which does not seek to establish equilibrium

M. Westoby, B. Walker, I. Noy-Meir

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

Discussion of the choice of models for managing rangelands is couched in terms of a contrast between the "range succession model' and the "state-and-transition model'. The range succession model supposes a given rangeland has a single persistent state (the climax) in the absence of grazing. Succession towards this climax is a steady process. Grazing pressure produces changes which are also progressive and are in the opposite direction to the successional tendency. Therefore the grazing pressure can be made equal and opposite to the successional tendency, producing an equilibrium in the vegetation at a set stocking rate. A sustainable yield of livestock products can be harvested from such an equilibrium. All possible states of the vegetation can be arrayed on a single continuum, from heavily-grazed, early successional, poor condition, to ungrazed, climax, excellent condition. Condition is the technical term for the vegetation's position on this continuum. Under the range succession model the object of management is to choose a stocking rate which establishes a long-term balance between the pressure of grazing and the successional tendency. The model deals with varying rainfall by supposing that drought affects vegetation in a similar way to grazing, and conversely that above-average years have effects which can be understood as accelerating the successional tendency. Therefore management should respond to drought by reducing grazing pressure, so that the combined pressure of drought and grazing varies as little as possible, the balance of these combined pressures with the successional tendency is maintained, and the position of the vegetation on the condition scale is stabilized. -from Authors

Original languageEnglish
Pages (from-to)235-239
Number of pages5
JournalJournal of Arid Environments
Volume17
Issue number2
Publication statusPublished - 1989

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