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