Bioinvasion - the spread of alien, "exotic" organisms - is gnawing away at ecosystems all over the world, largely unnoticed and unopposed. The continuing increase in travel and trade around the globe is fostering the spread of more and more invaders of almost every conceivable description, from highly flammable weeds to human pathogens and forest diseases.

Chris Bright tracks the extent and explains the dangers of bioinvasion - an environmental threat that may now be surpassed only by habitat loss in its potential to irreparably damage our planet. Bright explores the counterintuitive mechanisms of invasion, in which the addition of a non-native species to an area tends to reduce that area's biodiversity.

He shows that bioinvasions are not only destroying ecosystems, but also endangering public health, disrupting the cultures of traditional forest and fishing peoples, and costing our economies billions of dollars a year.

The current rates of invasion, Bright argues, are no more sustainable over the long term than are current rates of deforestation or greenhouse gas emissions. Yet according to Bright, we already have the knowledge and tools necessary to resist or roll back bioinvasions. He outlines a counter-invasion strategy that stretches from international legal reform to on-the-ground control techniques.

And, recognizing that the principal challenge may not be so much technical as cultural, he calls for a higher degree of ecological literacy - an appreciation of the value of native plants and animals, and an ability to "read" landscapes well enough to see the invaders within them.