Comparing levels of invasion in North American and in European habitats
In the last decades, several quantitative studies have revealed that habitats differ in their levels of invasion. To consider whether invasion patterns observed at regional scale are also valid at larger scales, levels of invasion in different habitats were compared between temperate parts of North America and Europe. Native and alien vascular plant species were identified within 4165 vegetation plots randomly selected from vegetation-plot databases. Levels of invasion were calculated as the proportion of alien species in vegetation plots assigned to a specific habitat.
The comparison revealed that on both continents, the most invaded habitats were alluvial forests, riverine fringes and freshwater marshes whereas the least invaded habitats were mires, waterlogged and coniferous woodlands. A consistent pattern of invasion of different habitats between the two continents indicates similar mechanisms influencing the invasion in habitats despite differences in biogeographical and socio-economic features between the regions. Habitats with high levels of invasion have high resource availability, frequent disturbances, strong human impact and a large alien species pool. In contrast, habitats in sparsely populated areas with low nutrient availability, low disturbance and a limited pool of alien species show low proportions of aliens.
Kalusova V (2014) Intercontinental comparison of habitat levels of invasion between North-America and Europe. Abstract of the 4th International Symposium on Environmental Weeds and Invasive Plants, Montpellier (FR), 2014-06-19/23.