Volume 27, 87

Tropical Grasslands (1993) Volume 27, 87–93

Dynamics of perennial grasses with sheep grazing in Acacia aneura woodlands in south-west Queensland

D.M. ORR¹, C.J. EVENSON², J.K. LEHANE³, P. S. BOWLY⁴ and D.C. COWAN⁵

¹Department of Primary Industries, Rockhampton;
²Arid Zone Institute, Charleville Pastoral Laboratory, Charleville;
³Toowoomba, Queensland, Australia;
⁴Maranoa Graziers’ Association, Roma, Queensland, Australia; and
⁵Brisbane, Queensland, Australia.

Abstract

The effects of grazing on the dynamics of perennial grasses in Acacia aneura woodland were monitored between 1978–1984. Sheep numbers were adjusted annually to utilise between 20–80% of the total forage available at the end of summer
Increasing pasture utilisation reduced the total basal area of perennial grasses and resulted in major shifts in the occurrence of individual grass species. Aristida spp. were the main species under very heavy grazing. Variation in rainfall between years resulted in large changes in total basal area and in the occurrence of individual grass species.
It is concluded that long-term wool production (data not presented) commensurate with maintenance of the vegetation may be maximised by 20% rather than higher levels of utilisation.