Volume 40, 14-23

Tropical Grasslands (2006) Volume 40, 14–23

Pasture management in semi-arid tropical woodlands: effects on tree regrowth

JOHN G. McIVOR

CSIRO Sustainable Ecosystems, St Lucia, Queensland, Australia

Abstract

The impact of pasture management on tree regrowth (from seedlings and/or root suckers) was measured from 1982 to 1992 at 'Hillgrove' and 'Cardigan', near Charters Towers, north-east Queensland. Oversowing introduced legumes and grasses, applying superphosphate and cultivating the soil before sowing had little impact. In contrast, on plots where the trees were killed, the number of stems, height and leaf area indices of regrowth were much greater than on plots with live trees. Heavy stocking rates (1 steer/ha) also greatly reduced stem number and leaf area index of regrowth but these stocking rates were not sustainable. Clearing and killing trees can give large herbage growth responses but the regrowth problems reported here, and other potential negative impacts, necessitate a cautious approach to clearing and careful post-clearing management.