Woody energy crops in the southeastern United States: Two centuries of practitioner experience

Forest industry experts were consulted on the potential for hardwood tree species to serve as feedstock for bioenergy in the southeastern United States. Hardwoods are of interest for bioenergy because of desirable physical qualities, genetic research advances, and growth potential. Yet little data is available regarding potential productivity and costs. This paper describes required operations and provides a realistic estimate of the costs of producing bioenergy feedstock based on commercial experiences. Forestry practitioners reported that high productivity rates in southeastern hardwood plantations are confined to narrow site conditions or require costly inputs. Eastern cottonwood and American sycamore grow quickly on rich bottomlands, but are also prone to pests and disease. Sweetgum is frost hardy, has few pest or disease problems, and grows across a broad range of sites, yet growth rates are relatively low. Eucalypts require fewer inputs than do other species and offer high potential productivity but are limited by frost to the lower Coastal Plain and Florida. Further research is required to study naturally regenerated hardwood biomass resources. Loblolly pine has robust site requirements, growth rates rivaling hardwoods, and lower costs of production. More time and investment in silviculture, selection, and breeding will be needed to develop hardwoods as competitive biofuel feedstock species. Because of existing stands and fully developed operations, the forestry community considers loblolly pine to be a prime candidate for plantation bioenergy in the Southeast.