Exotic plant invasions can alter the stocks and flux rates of carbon, nutrients, and water within a wide range of ecosystems. In addition to direct changes in the distribution and amounts of biomass, these changes can be associated with known and suspected mechanistic pathways by which plants affect the structure and function of the soil biota. A variety of both aboveground and belowground plant traits can be identified that effect changes in nutrient stocks and fluxes. From a review of cases in which such traits have been compared between exotic species and co-occurring native species, several traits emerge as potentially useful for predicting the ecosystem-level effects and for screening the species for potential effects. These traits include overall size (biomass, height growth, and horizontal cover) much larger than any native; high growth rate (measured as relative growth rate or photosynthetic rate); the capacity to form dominating ground cover; high live tissue and litter nutrient contents, especially nitrogen; the presence of nitrogen-fixing symbioses; and root system size or morphology that contrasts strongly with native species. Although the usefulness of plant traits for assessing and predicting the effects of exotic species invasions on ecosystem processes requires further research on basic aspects of plant–soil interactions, these results suggest that such an approach may prove useful for managing invasions.

Additional index words: Ecosystems, exotic species, nitrogen, plant–soil interactions, plant traits.