That is the prime task of the ecology of the future. With respect to the current mandate to scientists to unravel the complexity of terrestrial ecosystem responses to global change, the future is now. Changes in the production and turnover of roots in forests and grasslands in response to rising atmospheric CO 2 concentrations, elevated temperatures, altered precipitation, or nitrogen deposition could be a key link between plant responses and longer-term changes in soil organic matter and ecosystem C balance. While Tansley's call for integrated studies of all ecosystem components have long been embraced, ecosystem-level observations of root production and mortality in response to global change variables are just starting to emerge. These questions are considerably easier to ask than they are to answer.
Results are often ambiguous, contradictory, and confounded by methodological problems.
Although the body of knowledge may be immature for a definitive synthesis, we have an opportunity to highlight the critical uncertainties, generate new hypotheses, and improve our techniques in current and future research programs.