Whilst non-spatial economic models can calculate the costs and benefits of different weed management strategies, they have to assume a uniform rate of weed spread, that is either under management or spreading without control. They do not take into consideration the heterogeneous nature of the landscape and the resultant differences in costs and benefits at specific locations. Program managers often report on the effectiveness of control programs in terms of the number of inspections and/or extent of area treated, but rarely is there the ability to:
- calculate the benefit-cost ratio of programs (the productive value of the area protected over time);
- optimise the strategy by balancing costs with future benefits; or
- allow for adaptive management scenarios.
To address these issues we developed an agent-based weed dispersal model in NetLogo with in-built economic evaluation and management strategies components. We modelled the spread of serrated tussock (Nassella trichotoma (Nees) Hack. ex Arechav.) under three management scenarios to compare their costs and benefits: a (hypothetical) baseline scenario where only self-motivated landholders treat infestations as there is no enforced control of the species; the current strategy of uniform intervention where the government intervenes on every property that is known to have (or have had) an infestation; and a proposed new containment line strategy where a buffer zone around the known infestations prescribes the properties that will be subject to government intervention.
The insights provided by the modelling suggest that in the study area improved targeting of enforcement via a containment line could produce an outcome at least as good as the current approach, but without the need for larger government expenditure every year as the weed spreads to more properties.
Cite this article as:
Steel, J., Weiss, J. and Morfe, T. (2014). To weed or not to weed? The application of an agent-based model to determine the costs and benefits of different management strategies. Plant Protection Quarterly 29(3), 101-110.