From the backyard to the backcountry: how ecological and biological traits explain the escape of garden plants into Mediterranean old fields

• Published in: Biological invasions 2010-04, Vol.12 (4), p.761-779
• Main Authors: Marco, Audrey, Lavergne, Sébastien, Dutoit, Thierry, Bertaudiere-Montes, Valérie
• Format: Article
• Language: English
• Subjects: adaptation; Agricultural land; Asexual reproduction; Biomedical and Life Sciences; climatic factors; Cultivation; Developmental Biology; ecological invasion; ecological traits; Ecology; escape from cultivation; fields; Freshwater & Marine Ecology; gardens; Gardens & gardening; Introduced species; Invasions; Invasive plants; Invasive species; Landscape; Landscape ecology; Life Sciences; Nonnative species; Old fields; Original Paper; Ornamental plants; phylogenetic regression; Phylogeny; Physical training; Plant biology; plant characteristics; plant cultural practices; Plant ecology; Plant reproduction; Plant Sciences; pre-adaptation; Pressure; propagule pressure; Propagules; Regression analysis; risk factors; Rural areas; seed dispersal; Soil; zoochorous species
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-009-9479-3

To explain current ornamental plant invasions, or predict future ones, it is necessary to determine which factors increase the probability of an alien species becoming invasive. Here, we focused on the early phases of ornamental plant invasion in order to identify which plant features and cultivation practices may favor the escape of ornamental plants from domestic gardens to abandoned agricultural land sites in the Mediterranean Region. We used an original approach which consisted in visiting 120 private gardens in an urbanizing rural area of the French Mediterranean backcountry, and then visited surrounding old fields to determine which planted species had escaped out of the gardens. We built a database of 407 perennial ornamental alien species (most of which were animal-dispersed), and determined nineteen features that depicted the strength of species' propagule pressure within gardens, the match between species requirements and local physical environment, and each species' reproductive characteristics. Using standard and phylogenetic logistic regression, we found that ornamental alien plants were more likely to have escaped if they were planted in gardens' margins, if they had a preference for dry soil, were tolerant to high-pH or pH-indifferent, and if they showed a capacity for clonal growth. Focusing only on animal-dispersed plants, we found that alien plants were more likely to have escaped if they were abundant in gardens and showed preference for dry soil. This suggests that gardening practices have a primary impact on the probability of a species to escape from cultivation, along with species pre-adaptation to local soil conditions, and capacity of asexual reproduction. Our results may have important implications for the implementation of management practices and awareness campaigns in order to limit ornamental plants to becoming invasive species in Mediterranean landscapes.