Effective management of rangelands requires the development of landscape-scale models for predicting spatial and temporal variability of forage. In the Magellanic tussock steppes, as in other cold-temperate regions, grazing capacity is dependent on the winter season. To develop a management tool for the region, we analysed links between winter forage availability, weather, stocking rate and vegetation structure. We studied four paddocks over five years with a range of stocking rates from 0 to 1.53 sheep.ha–1. We sampled forb and non-tussock graminoid biomass, vegetation structure and faecal pellet abundance at the end of each summer. Daily temperature and rainfall data were also recorded. A regression model explained the amount of winter forage as a positive function of graminoid cover, spring minimum temperature, annual precipitation and a negative function of dwarf shrub canopy, bare soil and stocking rate (R2 = 0.59). Interactions of structural variables with precipitation and stocking rate were detected, indicating strong fluctuations of forage availability in lawn communities dominated by short graminoids. The most probable causes of this response would be higher utilisation and lack of canopy structure. Our results illustrate how maps of vegetation structure, obtainable from satellite images, with weather and stocking rate data could be used for predicting optimal stocking rates in large, heterogeneous sheep paddocks.
Nomenclature: Correa (1969–1984); Moore (1983).
Abbreviation: EE = Ewe equivalent.