Population dynamics of the perennial rangeland shrubs Atriplex vesicaria, Maireana astrotricha and M. pyramidata under grazing, 1980-87.
Moderate grazing by Hereford cattle or by sheep on the Mundi Mundi Plain, New South Wales, in 1980-87 did not affect the population dynamics of the perennial shrubs A. vesicaria, M. astrotricha and M. pyramidata. Density of A. vesicaria declined on both grazed and ungrazed transects, but that of Maireana spp. remained almost constant. Turnover rates of A. vesicaria were quite high for both grazed and ungrazed populations, but were extremely low for Maireana spp. Shrub size was the only population parameter significantly affected by grazing. Heights and diameter for both grazed and ungrazed populations declined during dry periods, but this decline was greater for grazed shrubs. After rain, however, grazed shrubs quickly returned to sizes similar to ungrazed. The results suggest that current grazing strategies in this area are having no adverse effect on populations of these shrubs.