Institute for Sustainability

Shirley

Modelling the expansion and control of invasive species

Key Words: invasive species; simulation modelling; statistical analysis; management; control; eradication

Summary

Lead Supervisor: Dr Mark Shirley

Project Studentship Code: IFS012

Programme Code: 8020F

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The worldwide cost of invasive species is more than $1.4 trillion, 5% of the global economy (Pimentel, 2001) and are a major threat to biodiversity; they have contributed to 40% of the animal extinctions in the last 400 years (CBD 2006). Sustainable Development Goal 15 calls for the management of priority Invasive Alien Species (IAS). Prioritising management of IAS is a key challenge as the scale of the problem far outstrips the available resources. Policy tools for species prioritisation are being developed that balance the risk posed (Risk Assessment) with the feasibility of control (Risk Management). Interdisciplinary cooperation between scientists and decision makers is required to overcome the mismatch between knowledge production and knowledge needs for solving societal problems such as IAS. Modelling efficacy and effectiveness of management strategy has the opportunity to provide a common currency between the underlying science and the decision makers and provide an objective assessment of the priorities of both disciplines to facilitate successful cooperation.

A key component of risk management is to understand the speed and pattern by which a novel species may spread in a new environment; and failure to predict spread is a key factor limiting the success of intervention.

This project will investigate the underlying principles which determine the speed and pattern by which IAS establish and spread in order to support prioritisation of control paradigms. The success of any management attempt will be dependent on qualitative and quantitative aspects of the organism's invasive strategy; specifically: the length of the establishment phase; the rate of edge expansion; the rate of propagule formation; the mechanisms and frequency of long-distance dispersal; and the role of anthropogenic movement. For the biological variables, different organisms employ varied strategies and while the end result might be the same - ubiquitous colonisation of suitable habitat - the means by which that end point was reached can determine the nature and feasibility of any intervention.

This project will involve statistical analysis of historical data of IAS range expansion and mathematical modelling of a variety of invasion paradigms to uncover characteristics of successful and unsuccessful invasions. Successful strategies will be implemented into a process-based model to quantify the impact of management strategies. Key outcomes of the analysis and modelling will be development of a framework by which invasive alien species can be prioritised for the likely speed and pattern of their spread while they are still in the lag or early exponential phase of their expansion, at a time when management activities are likely to be most effective. Modelling a range of simulation models will support the assessment of the feasibility of different management regimes and subsequent societal costs.

Pimentel, D., et al. 2001. Economic and environmental threats of alien plant, animal, and microbe invasions. Agriculture, Ecosystems and Environment 84: 1-20

CBD: Secretariat of the Convention on Biological Diversity (2006) Global Biodiversity Outlook 2. Montreal, 81 + vii pages