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Abstract
Effective management of invading alien plants in natural and semi-natural systems is imperative if we
are to prevent enormous impacts. An integrated approach involving the combined use of a range of
methods is usually necessary to control invasive alien plants effectively. The various methods that are
available are usually classified as: mechanical methods (felling, removing of invading alien plants,
often in conjunction with burning); chemical methods (using environmentally safe herbicides); and
biological 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 of
individual species and the number and identity of species that occur together), features of the invaded
systems, the availability of resources and other factors. Mechanical and chemical control are short-term
activities, whereas rigorous and disciplined follow-up and rehabilitation are necessary in the medium
term. Biological control can provide effective control in the short and medium term in some cases, and
it is often the only really sustainable solution in the longer term. We suggest that the biological attributes
of plants represent a stable set of attributes, which enable managers to devise control approaches, but
that such approaches are likely to be upset by stochastic events such as fires, floods or budget cuts. While
an approach of adaptive management, based on trial, error and continual improvement is a logical way
in which to progress, the advent of powerful computer simulation modelling technologies will allow
managers to do hundreds of 'trial and error' runs in order to explore the consequences of certain courses
of action. This should represent an improvement on the current state of affairs, and should allow for
better decision-making. We present a series of simulations to illustrate this point.