Resumen de Site `dumpability': Where is illegal dumping in forests, and does signage help reduce it?

Cameron Williams, Tobias Probst, Vicki Hall, Samantha Low-Choy, Daniela Vasco

• Previous research had identi ed factors a ecting people's decisions to dump household waste, illegally, in forests. This information helped redesign signage aiming to deter dumping. The main question was: Where should signage be placed? From the perspective of state forest managers: What kinds of locations in the state forest are more `dumpable' and tend to attract more illegal dumping than others? This study was one of the rst to address the environmental context of dumping within a forest, which aggregates the psychological context of motivations of many individuals. Due to this novelty, we used expert elicitation techniques to formulate a conceptual model, which guided design of eld data collection, both before and after introducing signage into the forest. Importantly, this also engaged a range of stakeholders with the project aims. Signage locations were pre-determined by regulators and forresters. Information from three phases of surveillance in the forest was analysed using a `multimethod' statistical approach, starting with models more familiar to stakeholders: examining main e ects via regression with smoothing splines; and high-order interactions via regression trees. Model-based clustering via Bayesian mixture models permitted insight directly relevant to the research questions, and found that: highly dumpable sites occurred both in close or far proximity to waste collection sites with varying pro les describing seclusion. Overall ndings across model kinds con rmed that the `nudging' sign motifs were most e ective whilst evidence was con icting regarding e ectiveness of didactic signage.