Disentangling the role of environmental and human pressures on biological invasions across Europe

Abstract

The accelerating rates of international trade, travel, and transport in the latter half of the twentieth century have led to the progressive mixing of biota from across the world and the number of species introduced to new regions continues to increase. The importance of biogeographic, climatic, economic, and demographic factors as drivers of this trend is increasingly being realized but as yet there is no consensus regarding their relative importance. Whereas little may be done to mitigate the effects of geography and climate on invasions, a wider range of options may exist to moderate the impacts of economic and demographic drivers. Here we use the most recent data available from Europe to partition between macroecological, economic, and demographic variables the variation in alien species richness of bryophytes, fungi, vascular plants, terrestrial insects, aquatic invertebrates, fish, amphibians, reptiles, birds, and mammals. Only national wealth and human population density were statistically significant predictors in the majority of models when analyzed jointly with climate, geography, and land cover. The economic and demographic variables reflect the intensity of human activities and integrate the effect of factors that directly determine the outcome of invasion such as propagule pressure, pathways of introduction, eutrophication, and the intensity of anthropogenic disturbance. The strong influence of economic and demographic variables on the levels of invasion by alien species demonstrates that future solutions to the problem of biological invasions at a national scale lie in mitigating the negative environmental consequences of human activities that generate wealth and by promoting more sustainable population growth.climate | economy | exotic plants and animals | geography | prediction

Annual monitoring reveals rapid upward movement of exotic plants in a montane ecosystem

“…Indeed, the role of propagule pressure in biological invasions is considered the least contentious aspect responsible for the successful establishment and spread of non-native plants and animals (Richardson et al 2000;Pyšek et al 2010). We did not interpret dynamic elevational range limits-where the upper range limit increases in one year and then decreases the next-as an indication that species had reached their range limit.…”

“…For exotic species, however, this assumption does not hold since many are still in the process of colonizing their potential niche (Wilson et al 2007). In addition, the rate at which a potential niche becomes occupied depends on a range of indirectly measured or reconstructed variables, such as residence time and propagule pressure (Becker et al 2005;Pyšek et al 2010;Pyšek et al 2011;le Roux et al 2013). Species distribution data therefore need to be sufficiently detailed to detect spatio-temporal trends (Pauchard et al 2009;Walther et al 2009).…”

Origin Matters: Diversity Affects the Performance of Alien Invasive Species but Not of Native Species

“…The number of established alien species and measures of the local dominance of alien invasive species are response variables of invasibility that address different aspects of the invasion process (Blackburn et al 2011) and that are likely to be influenced by different processes. Although the establishment of alien species is considerably influenced by human activities and their effect on disturbance and propagule availability (e.g., Pyšek et al 2010), the local dominance of established alien species, which ultimately affects their environmental impact (Parker et al 1999), is predominately affected by their competitive abilities under the local biotic and abiotic conditions. Separating studies assessing the establishment phase from those assessing the build-up of local dominance of alien invasive plant species may at least partly explain the variation in the effect of native species richness on invasibility as revealed by observational studies.…”

The Human Release Hypothesis for biological invasions: human activity as a determinant of the abundance of invasive plant species

“…Presumably, this reflects that biological invasions are aided by human transport and that species establishment is facilitated by human disturbance 7 . Nevertheless, at the global scale, the proportion of widely distributed alien plant species (relative to all species) is far lower in Europe than in North America – despite Europe’s long history of trade and therefore a longer residence time of alien plants 8 .…”