Application of bio-economic simulation models for addressing sustainable land management issues for northern Australia

Abstract

Commencing in 2009, Meat and Livestock Australia has funded the Northern Grazing Systems Project (NGS) which seeks to identify and extend sustainable herd and land management strategies for nine major bio-regions of northern Australia. Conduct of the NGS is built around a multistep framework of scientific reviews, regional industry workshops, bio-economic modelling of the impact of the most promising 'best-bet' options on landscape degradation and production, and regional testing and extension of those options. Bio-economic modelling is a central component of NGS and has been applied to exploring the production, resource condition and financial implications of northern beef enterprises adopting the more promising strategies that are revealed through the science review and workshop phases. The modelling process combines a pasture and animal production model (GRASP) and a dynamic beef herd economic model (ENTERPRISE) to mimic the performance of representative beef enterprises defined at each regional workshop. NGS is exploring four major herd and management strategies across the regions, including: (a) Stocking rates, (b) Wet season pasture spelling, (c) Prescribed fire, and (d) Infrastructure. The paper briefly describes the overall NGS framework and illustrates the application of the modelling process for one of the herd and management strategies, namely stocking rates, in one of the nine bioregions, the Fitzroy River Basin. The effect of employing variable versus fixed stocking rate strategies on a range of physical (carrying capacity, pasture condition, animal growth) and financial (total enterprise profit) measures is explored for a hypothetical 10,500 ha property located at Duaringa. The stocking rate strategies include set stocking rates and two variable stocking rates that involve either constrained or unlimited variation in response to pasture availability. The economic results favoured a set stocking strategy over either of the two variable stocking rate strategies. While the unlimited variation strategy did yield the highest profit in any one year of the simulation period, it also yielded the lowest profit in any year and for 50% of years this measure was negative. Nevertheless, the result is contingent on the actual climate sequence of the simulation period and did differ substantially to that observed in several of the other regions which experienced quite different seasonal sequence.