Forests are the greatest potential source of energy of any terrestrial biome because of the organic carbon in their biomass, and soils are major sinks for atmospheric carbon. Carbon storage could be enhanced either by increasing forest area (impractical), or by reducing catastrophic losses from wildfire and insects through thinning and other means of fuel reduction. The high energy value and renewability of forest biomass makes it an attractive energy alternative to fossil fuel consumption—particularly if energy harvests can reduce wildfire risk and be sustained without impairing fundamental productivity. Gaining public ac- ceptance for increased biomass removal demands that forest productivity is not degraded, but many of the scientific challenges to increased removal rates rest on simplistic concepts lacking long-term field validation. This paper presents the author’s con- cept of sustained productivity, issues and problems in assessing it, and the value of coordinated efforts to address the question directly. The International Long-Term Soil Productivity program is described as such an effort, and recommendations are made for sustaining similar long-term studies.