8 Conclusions

Policy on the transportation of alien plants between and around countries is outside the scope of this section (see Anon. 1993 for discussion) but there are steps that protected areas managers can take to minimise new inputs of alien plants. Some of the ways in which this could be achieved are listed:

· The costs and benefits of new alien plant species introductions for whatever purpose should be carefully appraised. The deliberate introduction of alien woody plants for forestry purposes is discussed in greater detail in the next sections of this report.

· Populations of a weed outside a park or protected area need to be controlled. Otherwise continued re-invasion of the controlled areas is most likely resulting in further control measures. Landowners outside these protected areas need to be made aware of the problem and some form of assistance may be necessary to help them eradicate the invader from their land.

· Promote environmental education and initiate awareness programmes relating to biological invasions. Special attention must be paid to the problem of transferring human value judgment to plants. The current tendency in the British media to link the control of introduced/alien/exotic species to racist attitudes (e.g. Moore 1992, Evans 1995 and see Binggeli 1994 for critique of some of these views) is a good example of the some of difficulties to be overcomed by educational programmes.

· Regulate or reduce the introduction of new alien plant species into gardens in or near protected areas.

· Regulate tourism and the movement of vehicles into and within protected areas. Humans and vehicles can be important carriers of alien propagules.

· Regulate the movement of plant materials and soil into the protected areas. Both can carry seeds, especially those of herbaceous weeds.

· Control all developments that may facilitate the spread of weeds, such as new roads or tourism development projects.

Every invasive event is unique and is affected by the species distinctive set of attributes, and the specific local environmental factors and biological communities. Thus it is important to investigate these specific factors in detail in order to devise a strategy to successfully tackle an invasion. If the knowledge about the invasion and the species is extensive this should allow some flexibility in the management response but this requires long term commitments of resources and management time. Management must set specific targets for areas or species to control and collect and maintain full records. It is only with a better basis of information from past control programmes that future ones can be planned more effectively and at a lower cost.