TREE CLEARING AND DRYLAND SALINITY HAZARD IN THE UPPER BURDEKIN CATCHMENT OF NORTH QUEENSLAND

This paper provides experimental data on the effect of tree clearing, introduction of perennial Stylosanthes based pastures, and the use of native grasses on the water balance of a red earth soil in the Upper B urdekin Catchment near Charters Towers. The water balance simulation m odels SWIM and PERFECT are used to extend the results and estimate dee p drainage for this and other soils in this tropical environment. The analysis illustrates that the soil/climate interaction in the wet/dry tropics has a similarity with the winter-dominant rainfall zone where vegetation change can substantially increase deep drainage beyond the root-zone. Salt distribution in the soil/landscapes of the Upper Burde kin suggests that there is a salinity hazard, should a significant shi ft in the water balance occur as a result of tree clearing. Therefore, in the Upper Burdekin Catchment of North Queensland, indiscriminate t ree clearing is a hazardous form of land management and should only pr oceed after the risks of dryland salinity have been evaluated and show n to be negligible.