Total Value Assessment of Tree Clearing for Developing Grazing Systems in Central Queensland

Tree clearing is widely practised in Queensland to develop exotic pastures to enhance pasture production and hence the financial gains. One of the major woodland community i.e. brigalow (Acacia harpop hylla) was targeted for clearing in the early 1950s due to its fertile soils. Recently, some marginal communities such as Poplar box (Eucalyptus populnea) and Iron bark (Eucalyptus melanophloia) are targeted for clearing. Net benefits from clearing woodlands to increase pasture production, hence cattle production, is questioned in this paper. Previous studies have emphasised the gains in pasture yield over <10-15 years of clearing, without considering any long term ecological effects. The questions are whether an increase in pasture production following clearing is sustainable over a long term (>15 yrs.) or whether such an increase is 'actually beneficial' and does not result in any adverse in-situ and ex-situ ecological effects on grazing systems? The study is based on detailed ecological data on pasture production, soil properties (biological and physicochemical), litter production and nutrient recycling, and pasture plant diversity and diet quality. For this, three tree communities i.e. A. harpophylla, E. melanophloia and E. populnea were selected in central Queensland. There were three different ages of clearing i.e. 5 yr, 11-13 yr and 33 yr for each of the tree community. Comparisons were made for paired plots between cleared and uncleared (intact) woodlands across 3 age groups of clearing. An economic analysis was conducted of tangible (pasture yield) and intangible parameters (soil properties, plant diversity and diet quality, and nutrients recycled through litter). The total assessment for pasture yield and various ecological parameters across 3 different age groups of clearing and their paired uncleared plots provides information for the land holders, policy makers and land managers to make decisions on tree clearing for pasture development considering the long term ecological effects.