Effect of rainfall on biomass,growth and dieback of pastures in an arid grazing system

The influence of rainfall and initial pasture biomass on growth and dieback of pastures in temporary enclosures over quarterly periods was examined from 1980 to 1985 at Menindee in western New South Wales. Rainfall during the previous 12 months had the most influential effect on biomass of grazed pasture, and accounted for 69% of the variance. During quarterly periods, when the biomass of pasture protected from grazing increased, rainfall accounted for 93% of the variance. For all quarterly periods (whether pasture biomass increased or decreased) current rainfall accounted for 72% of the variance in biomass change (growth minus senescence) and initial biomass accounted for a further 14%. The growth response to rainfall was similar in pastures grazed by a combination of sheep and kangaroos and in those grazed by kangaroos alone.