The strategic landscape investment model: a tool for mapping optimal environmental expenditure

This paper presents the strategic landscape investment model (SLIM). This tool can be used to map optimal landscape treatment patterns at regional scales. Developed for New South Wales (NSW) in Australia, SLIM aims to maximise an indexed measure of environmental benefit within a budget constraint. The attributes considered include salinity, water yield, nitrogen run-off, phosphorus run-off, stream sediment concentrations, soil erosion and carbon sequestration. The modelling is undertaken spatially with a roughly 1 km2 grid covering NSW. With estimates of costs and benefits, maps of marginal environmental benefit per dollar expended can be constructed. These maps are used to define an optimal treatment pattern within the confines of a program budget. SLIM is demonstrated through an analysis of perennial pasture establishment on NSW grazing lands. It was found that the optimal treatment area is around 4% of the total treatable area, demonstrating the importance of careful investment targeting. Through sensitivity analysis it is found that the location of optimal landscape treatment patterns is relatively robust under numerous attribute weighting scenarios. The paper explores the strengths and weaknesses of SLIM considering how improved analytic capabilities could be added to future revisions.