Sustainability of Biodiversity Under Global Changes, with Particular Reference to Biological Invasions

Five major interacting global forces heavily influence changed ­distribution and abundance of biodiversity: (1) biological invasions, (2) overharvest, (3) changes in climate, (4) biogeochemical cycles, and (5) habitat. Modified land use, overharvest, and climate change have already affected distributions over large areas, regionally eliminating or substantially reducing natural resources such as fishing stocks, forestry trees, and traditional food plants. Further, habitat and climate change indirectly affect biodiversity patterns by their effects on invasions, biogeochemical cycles, and overharvest. Species-level biodiversity—the number of species on the planet—is unsustainable unless these impacts are ameliorated. Insufficient attention has been paid to how invasions and changed biogeochemical cycles directly affect distribution and abundance of biodiversity, as opposed to indirectly affecting biodiversity by modifying land use. Several direct, large-scale impacts of invasions and altered biogeochemical cycles on distributions and abundances of important species have been documented. These suggest that these global phenomena warrant much more research. Forestalling these global changes, or simply retarding them, has proven difficult, perhaps because of the immense scale of the enterprises causing them. However, great improvements in preventing or minimizing impacts of invasions are attainable, though we have been slow to develop effective policies and management strategies. Risk assessment procedures for planned introductions and invasion pathways are improving and can be modified to account for predicted climate and biogeochemical changes. Early warning systems, an underused tool in invasive species management, can be expanded and tied to effective rapid response procedures. Many approaches to managing established nonnative populations have produced successful control, but these successes result from projects highly tailored to particular species rather than from “silver bullets” that target multiple invaders simultaneously. Such successes will be possible even as other global changes proceed, so long as we remain committed to the effort.