Using dynamic ecological-economic modelling to facilitate Deliberative Multicriteria Evaluation (DMCE) in quantifying and communicating bio-invasion uncertainty

Abstract

Uncertainty is a ubiquitous feature of biosecurity and for this reason managing invasive species has long been a reactive business. In order to move towards proactive management it is critical to communicate uncertainties to the stakeholders. The uncertainty components exist not only in biological but also socio-economic processes during an invader's entry, establishment, spread and impact creation. A STELLA model was developed to capture the dynamics of this socio-ecological system and to estimate the expected economic costs of the apple maggot (Rhagoletis pomonella) over the next 30 years for the entire country of Australia. Like complex climate models, it cannot be meaningfully calibrated because it is simulating a never before experienced state of the system. Therefore it is inappropriate to apply generic techniques which utilize observations to calibrate models to forecast the economic cost of bio-invasion in the real world. Instead of forecasting, a more proper use is as a communication tool for uncertainty, which organizes our existing understanding and present "what if" scenarios in front of stakeholders in a DMCE environment. One of the major modelling outputs, the potential economic cost of the apple maggot, was used in DMCE as a criterion. The DMCE participants were asked to weigh the same criterion twice, before and after the modelling uncertainty was exposed and discussed. The effectiveness of the model as a communication tool was examined by comparing the average group weights and standard deviation of the individual weights before and after the uncertainty injection. Preliminary results showed that after the parameter uncertainty was exposed the mean weight did not change significantly yet the standard deviation of the weights did become smaller. We hypothesized that this could be because of the anchoring effect: economic cost was one of the most important criteria therefore the uncertainty exposure would not make much of a difference in weighting. The decreased dispersion of weights among DMCE participants, as reflected in a smaller standard deviation of the individual weights, indicated that uncertainty communication has a potential of building consensus. This is certainly an area for future research. This integrated modelling-DMCE approach seeks to combine the advantages of dynamic modelling in providing a systematic analysis with the benefits of DMCE. The ecological-economic modeling offers a systematic and more objective way of organizing data and synthesizing knowledge. The DMCE allows a participatory decision-making process with active involvement and commitment from the participants. The integrated approach is more effective in quantifying and communicating bioinvasion uncertainty to stakeholders.