Plantes invasives en région méditerranéenne : quelles restrictions d’utilisation préconiser pour les jardins et les espaces verts ?

Abstract

Gardens and other amenity plantings are expanding rapidly throughout the Mediterranean region and may have a significant ecological impact due to fresh water consumption and use of fertilizers and pesticides. The choice of non-native plants with high horticultural value – for example attractive ground-cover species that are more resistant to dry conditions than conventional lawns – can help reduce this impact. However, some non-native plants may have a negative impact on natural or semi-natural ecosystems if they escape from planting areas and become naturalized. Here we provide an overview of the advantages and potential risks of using potentially invasive, non-native species in an horticultural setting and discuss assessment criteria to consider when framing recommendations or legislation aimed at restricting the spread and negative impact of invasive plants. We propose a simple decisionmaking protocol to help determine which types of restriction to prescribe for any given species. A sampler of 20 species is presented to illustrate the concept and utility of this approach. We also propose a model for a data base which assembles all the available information – both positive and negative – concerning a useful species of concern, Lippia canescens Kunth. This holistic approach could help reconcile objectives of an environmentally ‘friendly’ and sustainability-oriented horticulture, on the one hand, and of conservation of biodiversity and natural ecosystems on the other.