Sustainable deployment of bioenergy production systems requires that we achieve the ability to predict the impact of intensive harvesting on forest site productivity. During the period 1992-94, collaborators in International Energy Agency Bioenergy Agreement (IEA/BA) Task IX Activity ''Environmental consequences of intensive harvesting'' have refined protocols for conducting field and laboratory research designed to reduce uncertainty associated. with predictive models; have published comprehensive reviews of the state of our knowledge related to long-term productivity in intensively managed forests; have sought to improve our understanding of recent research advances on theoretical and empirical levels in the areas of carbon cycling, sustainable forest management, and managing site fertility; and to direct this information to developing acceptable and efficient bioenergy production systems. This paper summarises the findings of these efforts, and indicates where future international collaboration is required to achieve the predictive ability required by the IEA/BA.