Randall E. Jones

An economic decision model of wild rabbit Oryctolagus cuniculus control to conserve Australian native vegetation

Context Economic decision models are seldom used in developing policies for the cost-effective control of invasive species that threaten natural ecosystems. However, their potential value is shown using an example of European rabbits damaging native vegetation in Australia. Aims To better define the problem of rabbit damage, provide a sound theoretical basis for implementing cost-efficient strategies for rabbit control and show how resources available for ecosystem protection can be most effectively applied. Methods A dynamic economic decision model was developed, incorporating the costs and effectiveness of three methods for controlling rabbits among native vegetation to consider alternative management strategies. A monetary value on native vegetation was set using the ‘avoided’ cost of replanting trees on roadsides and from field data we described how capacity of plant communities to regenerate improves if rabbit numbers are reduced. Key results Model outputs indicated the best combinations of methods for cost-effective rabbit control and showed how the highest benefits could be gained in protecting natural vegetation. Conclusions The model provided a framework for deciding how limited resources might be used to greatest benefit for protecting native vegetation. Implications This methodology could apply to other invasive species, provided that natural assets can be given a justifiable monetary value, control costs and effectiveness can be determined and the impact of the pests on assets can be modelled as dynamic population processes.

Dynamic General Equilibrium Analysis of Improved Weed Management in Australia's Winter Cropping Systems

A recent analysis indicated that the direct financial cost of weeds to Australias winter grain sector was approximately

Representing climatic uncertainty in agricultural models- an application of state contingent theory

A1.2bn in 1998-1999. Costs of this magnitude represent a large recurring productivity loss in an agricultural sector that is sufficient to impact significantly on regional economies. Using a multi-regional dynamic computable general equilibrium model, we simulate the general equilibrium effects of a hypothetical successful campaign to reduce the economic costs of weeds. We assume that an additional

Redesigning Livestock Systems to Improve Household Income and Reduce Stocking Rates in China’s Western Grasslands

50m of R&D spread over five years is targeted at reducing the additional costs and reduced yields arising from weeds in various broadacre crops. Following this R&D effort, one-tenth of the losses arising from weeds is temporarily eliminated, with a diminishing benefit in succeeding years. At the national level, there is a welfare increase of

Significance of supply response for estimating agricultural costs of soil salinity

700m in discounted net present value terms. The regions with relatively high concentrations of winter crops experience small temporary macroeconomic gains. Copyright 2005 Australian Agricultural and Resource Economics Society Inc. and Blackwell Publishing Asia Pty Ltd..

Economic cost of environmental flows in an unregulated river system

The state-contingent approach to production uncertainty presents a more general model than the conventional stochastic production approach. Here we investigate whether the state-contingent approach offers a tractable framework for representing climatic uncertainty at a farm level. We developed a discrete stochastic programming (DSP) model of a representative wheat–sheep (mixed) farm in the Central West of NSW. More explicit recognition of climatic states, and associated state-contingent responses, led to optimal farm plans that were more profitable on average and less prone to the effects of variations in climate than comparable farm plans based on the expected value framework. The solutions from the DSP model also appeared to more closely resemble farm land use than the equivalent expected value model using the same data. We conclude that there are benefits of adopting a state-contingent view of uncertainty, giving support to its more widespread application to other problems.

An Economic Evaluation of Research into the Improved Management of the Annual Grass Weed Vulpia in Temperate Pastures in South-Eastern Australia

Synopsis Results and implications of a study of rangeland/livestock systems in four counties in western China are discussed. Two key questions were posed: (1) Can changing the current livestock production system to an alternative enterprise, or (2) can changing key management practices in current enterprises increase household profit at same stocking rate (SR) or maintain profit at lower SR? The answers to these questions and their implications in terms of structural adjustment and attitudinal change for the long term sustainability of NW China are helpful in planning new livestock systems.

Tactical Opportunities, Risk Attitude and Choice of Farming Strategy: an Application of the Distribution Method

Abstract An economic analysis of the agricultural cost of soil salinity in the Murrumbidgee Irrigation Area in southeast inland Australia is reported. The analysis involved use of a single-year regional linear programming model to predict on-farm supply response to changed salinity conditions. The sensitivity of the estimated cost to assumed length of the delay in responding was tested. The present value of the cost under an assumption of immediate response was found to be 63% of that under the preferred assumption of a 10-year average delay in response. The estimate under an assumption of no farmer response was 4·5 times greater than under the preferred assumption. This confirms that accounting for on-farm response is required if the economic impact of soil salinity is to be accurately estimated.

An Economic Evaluation of a Pest Management Control Program: "Outfox the Fox"

This paper applies a stochastic dynamic programming framework, incorporating links to hydrological and biophysical models, to assess the economic costs of environmental flows in an unregulated river system in the Namoi Valley of northern New South Wales, Australia. Structural adjustment decisions are included in the model to account for farmer responses to changes in environmental flows through the introduction of a water sharing plan. The results of the analysis indicate that the proposed level of environmental flows reduces water extractions by around 6 per cent, and imposes an opportunity cost of less than 1 per cent in terms of reduced net income over a 20-year period.