Integrated control of invasive alien plants in terrestrial ecosystems

Effective management of invading alien plants in natural and semi-natural systems is imperative if weare to prevent enormous impacts. An integrated approach involving the combined use of a range ofmethods is usually necessary to control invasive alien plants effectively. The various methods that areavailable are usually classified as: mechanical methods (felling, removing of invading alien plants,often in conjunction with burning); chemical methods (using environmentally safe herbicides); andbiological control (using species-specific insects and diseases from the alien plant's country of origin).Approaches available for integrated control depend on the species under consideration (features ofindividual species and the number and identity of species that occur together), features of the invadedsystems, the availability of resources and other factors. Mechanical and chemical control are short-termactivities, whereas rigorous and disciplined follow-up and rehabilitation are necessary in the mediumterm. Biological control can provide effective control in the short and medium term in some cases, andit is often the only really sustainable solution in the longer term. We suggest that the biological attributesof plants represent a stable set of attributes, which enable managers to devise control approaches, butthat such approaches are likely to be upset by stochastic events such as fires, floods or budget cuts. Whilean approach of adaptive management, based on trial, error and continual improvement is a logical wayin which to progress, the advent of powerful computer simulation modelling technologies will allowmanagers to do hundreds of 'trial and error' runs in order to explore the consequences of certain coursesof action. This should represent an improvement on the current state of affairs, and should allow forbetter decision-making. We present a series of simulations to illustrate this point.