Must be the money...

A study that caught my eye this week is from PNAS...

Population density and abundance of wealth are the driving forces for introduction of invasive species. This is especially true among trade routes. While trade has been a long known factor of invasive species into an ecosystem--bilge water from Asia introducing invasive oysters or Cargo boxes with insects infecting islands have been long studied, the panel of 26 researchers will likely impact policy of trade. Invasive species--animals or plants not native to an area-- place added pressure onto an ecosystem by competing and often winning against local flora and fauna. As international trade has increased, so have the numbers of invasive species.

While the exact mechanisms to the introductions maybe unknown, the scientists concluded that changes in climate, geography or land cover, were not as important as population density and wealth capital--in fact they have likely been over estimated in the past.

Petr Pysek et al. Disentangling the role of environmental and human pressures on biological invasions across Europe. PNAS, June 7, 2010 DOI: 10.1073/pnas.1002314107

Information has been provided through a press release from University of Oregon.