Invasive alien species in an era of globalization

© The Ecological Society of America www.frontiersinecology.org F hundreds of years, humans have been introducing plants, animals, and other organisms around the world, in a relatively slow process of globalizing the Earth’s biota (DiCastri 1989). More recently, the pace of this process has increased with modern trade, travel, and technology, so that biological invasions have become a consequence of globalization. Globalization facilitates and intensifies the spread of invasive alien species (IAS) – defined here as “alien species whose introduction does, or is likely to, cause economic or environmental harm or harm to human health” (Executive Order 1999) – through intentional or accidental introductions. Researchers can approach critical questions surrounding IAS by focusing on global-scale phenomena such as international trade and regional scale patterns (Figure 1), or by focusing more specifically on particular species or an ecosystem that has been colonized by IAS. For example, global research may examine commerce and travel trends over time to inform predictions, risk analyses, and policy. Regional-scale analyses often focus on patterns of invasion such as rates of introduction or the presence of invaders because data on IAS impacts are rarely collected at large spatial scales. Local-scale experimental research frequently uses observation and manipulation to tease apart the complex ecological relationships that promote invasions and may seek to specify IAS impacts. However, research is rarely conducted at these three scales simultaneously. Invasive plants, animals, and pathogens are indelibly altering ecosystems and shaping how we live in them. Meeting the challenges associated with IAS requires the INVASIVE SPECIES INVASIVE SPECIES INVASIVE SPECIES