Dr. Yvonne Buckley has recently been awarded funding by the Rural Industries Research & Development Corporation (RIRDC) National Weeds and Productivity Research Program for the project – “How do decisions by stakeholders affect weed distribution at a landscape scale?”.
This two year project is jointly funded by RIRDC in the first year and the Australian Research Council Centre for Excellence in Environmental Decisions (CEED) in the following year. Dr. Buckley will lead this investigation with other project members from the University of Queensland (Dr. Jonathan Rhodes, Shaun Coutts & Katrina Cousins) and University of Western Australia (Prof. David Parnell).
The background to this project stems from previous research undertaken by Shaun Coutts, Dr. Hiroyuki Yokomizo & Dr. Yvonne Buckley.
How do we achieve landscape scale control of weeds where multiple managers act independently? (Coutts et al. Unpublished).
Most damaging weeds infest many properties within a landscape, with each manager being able to control only a small part of the whole weeds population. Therefore, to achieve good landscape scale control of weeds manager behaviour needs to be taken into account along with weed ecology and available management strategies. Management behaviour is expected to have important consequences for the spread and persistence of weeds. For example, even if everyone in an area can eradicate the weed, the weed may still persist and spread due to mismatches in the timing of control or because a few land managers have little motivation to control the weed (e.g. non-commercial farms or those with very different production systems). In both cases the problem is the same, that at any one time some part of the weed’s population is left uncontrolled, which can lead to the infestation of new areas and/or reinfestation of recently controlled properties.
We tested to what extent this might affect weed invasions by modelling the spread of two pasture weeds, serrated tussock and African lovegrass, in landscapes where they are controlled. In this model, control was carried out by a large number (4096) of simulated land managers who each decide whether to control or not on their own piece of the land. Our simulated land managers made this decision based on different aspects of human behaviour: attitude to profit, conformity to social norms, response to pressure from neighbours and individuals’ level of motivation. Land managers’ ability to recognise and act on expected benefits also influenced how consistently economic and social motivations resulted in action.
We found that factors which synchronised weed control among land managers greatly reduced the extent of weed invasions. These factors include a high cost for leaving the weed uncontrolled and land managers’ ability to perceive and act on the benefits of weed control. If most managers in a landscape believe that weed control is a good idea, and consistently act on it, then weed control efforts tend to occur at the same time and the weed’s extent can be greatly reduced. In some cases a few managers will have less motivation to control due to different economic goals. One or two unmotivated managers did not make a difference to the spread of either serrated tussock or African lovegrass. However, if long distance dispersal was possible (e.g. transported by road), a small minority (ca. 10%) of land managers who were reluctant to control could lead to the whole landscape being infested.
As serrated tussock is both economically damaging and has effective control strategies in place, most simulated managers chose to control it on economic grounds and social norms were less important. In contrast, for African lovegrass the economic grounds for control were less clear, as a result strong social norms to control were very important.