Short rotation, even-aged, monoculture, intensively managed bioenergy plantations, which offer the great environmental advantages of providing a renewable energy source and displacing fossil fuels, face a problem. They are increasingly at odds with the environmental movement＇s paradigm of what forests should be: late successional, long rotation, uneven-aged, partially harvested, with retention of much of the net primary production as soil carbon, snags and coarse woody debris. International pressure to certify forests as being sustainably managed is having a major and generally positive effect on forests managed for conventional forest products. But if this movement expands to encompass bioenergy forests, these alternative energy production systems will Face new challenges: how to maintain the efficiency of the systems while at the same time satisfying "criteria and indicators" that are being established to define "sustainability". Methods by which the sustainability of bioenergy systems can be predicted are discussed, and it is concluded that multi-value, ecologically-based ecosystem management models of the hybrid simulation type will be needed to design sustainable management systems that will satisfy the emerging set of criteria and indicators of sustainability. The second and third generation hybrid simulation models FORECAST and FORCEE, which had their origins in the FORCYTE models developed specifically to evaluate the sustainability of bioenergy plantations, are briefly reviewed. It is concluded that strategies that combine biological and technological approaches, which conserve soil organic matter and nutrients, and which utilize organic wastes will have the greatest chance of attaining sustainability.