Which factors determine plant invasions in man-made habitats in the Czech Republic?

Factors determining the invasibility of different types of anthropogenic vegetation were studied in the Czech Republic. A data set of 3420 vegetation plots recorded between 1945 and 2005, containing 913 species, was used. A set of climatic variables (mean annual temperature and precipitation, together with elevation), propagule pressure (substituted by human population density) and local habitat conditions (substituted by values of CSR life strategies and Ellenberg indicator values of native species) was obtained for each plot. All species were classified as native, archaeophytes (i.e. alien species introduced before 1500), and neophytes (i.e. aliens introduced after 1500) and their relative proportion was calculated for each plot. Regression tree models were used to determine the ecological characteristics of the most invasible man-made habitats in the Czech Republic. The plots contained on average 31.9% archaeophytes and 7.3% neophytes. Correlation between the proportions of archaeophytes and neophytes was positive and significant. Both archaeophytes and neophytes were found predominantly in strongly disturbed habitats with a high nutrient supply located at low elevations in warmer climatic areas of the Czech Republic. Archaeophytes are more influenced by local habitat conditions and preferentially colonize sunny and dry man-made habitats with higher soil reaction. Neophytes have no special preferences for local habitat conditions and their highest proportion was found mainly in disturbed habitats at low elevations. Our results show that for anthropogenic vegetation in the Czech Republic, ecological and habitat characteristics are more important factors for plant invasions than different land use in the surrounding area.