The dispersal vectors for the plants are for their part manifold. There are of course natural factors. The seeds can be dispersed by the wind, birds and water courses; that is also true for fragments of rhizome, of which a few grams are sufficient for an individual to be regenerated. Certain species reproduce vegetatively, without sexual reproduction. That is without mentioning dispersals directly attributable to human activity – planting in parks and gardens, dumping of green waste, transporting soil and excavation and filling in work in the urban environment – which also contribute to occurrences of invasion. ‘With the flow of vehicles, the roadsides – as is true for the railways – are also transformed into dispersal corridors,’ adds Mathieu Halford. In such conditions, repelling these species back out of our regions is almost tantamount to an impossible undertaking.

Betting on prevention

In addition, if scientists know the risks connected to invasive plants, it is unfortunately not the case for the horticultural sector or the general public, ‘who are faced with a cruel lack of information.’ That is where the usefulness of AlterIAS lies, as through an information campaign it aims at reducing the deliberate introduction of invasive plants in gardens, parks, ornamental ponds, green areas and roadsides. Submitted in 2008 and accepted in 2010 for a duration of four years, the programme is structured into three campaigns: a general information campaign about invasive plants; a second campaign, ‘currently underway,’ based on solutions; and finally an awareness raising campaign designed specifically at horticultural teaching. The target audience mixes horticulture professionals, garden amateurs and the horticultural teaching sector. ‘In terms of solutions to reduce the spread of invasive plants, there are two major strategies. On the one hand, management: we are going out into the field and try to slow the development of populations established in nature, or even at times to eliminate them, which presumes significant and costly technical means, without for all that assuring a conclusive result; and on the other hand, prevention; we are setting up tools aiming to limit the introduction (planting, marketing) of invasive species.’ It is at this stage that the information available to the different publics is essential. The Code of Conduct drawn up within the context of the project follows the second pathway. This document – a first in Belgium – developed in a participative approach, on the basis of a dozen or so round tables which brought together the main horticultural federations and associations active within the country, recommends a whole series of good practices to be implemented in order to avoid the introduction and dispersal of invasive plants. The professionals of the horticultural sector, including the associations and the federations, are invited to adopt it. Five measures are highlighted within it.

1.    Keep informed of the list of invasive plants in Belgium (available on the Belgian platform for biodiversity)
2.    Stop the sale and/or planting of certain invasive plants in Belgium
3.    Spread information on invasive plants to clients and citizens
4.    Promote the use of alternative non invasive plants
5.    Participate in early detection of invasive plants

Based on free commitment, the code privileges self regulation over restriction and sanction. Because it is not a question of blaming the horticultural sector for bad practices. On the contrary. ‘The latter is in addition proving open to this type of arrangement’, insists Mathieu Halford, ‘as is witnessed by the country’s main horticultural federations support for it. Up until now the use of invasive species, whether by professionals or ordinary citizens, is the result of gaps in information on the issue. This public is generally not aware of the environmental risks connected to these species.’ AlterIAS well and truly hopes to remedy this.