The need to reduce the Nation’s dependence on foreign oil as a source of energy has been elevated in recent years as a national priority. To achieve this vision, efforts have focused on developing a broader portfolio of energy sources for domestic use. Renewable energy will play an important role in diversification, and considerable investment has been directed to advancing the commercial feasibility of these technologies. Current legislation, The 2007 Energy Independence and Security Act (EISA), provides direct guidance for alternative liquid transportation fuels by mandating production of 36 billion gallons per year of biofuels by 2022. This goal includes 21 billion gallons of advance fuels derived from cellulosic biomass such as perennial grasses and woody resources, as well as residue from current industrial operations. The 2010 United States Department of Agriculture Biofuels Strategic Production Report estimates that the southern region will produce almost fifty percent of the supply of advanced biofuels, reflecting the suitability of this region for cellulosic biomass production.
The deployment of a cellulosic biofuels industry in the South requires the reliable supply of large volumes of lignocellulosic biomass at competitive prices that are produced using sustainable management practices. As noted, the region offers many potential options for feedstock including annual and perennial herbaceous crops and short rotation woody crops. One unique solution, however, is loblolly pine (Pinus taeda L.). Today there are approximately 45 million acres, or 22 percent of the timberland (Smith et al. 2009), of planted pine stands in the South. Of these stands, 30 million acres are loblolly-shortleaf pine. The photos on the right show representative loblolly pine plantations with different stand densities (top and middle), and a stand after thinning (bottom). Grown primarily for pulpwood and other conventional forest products, the current resource is the result of decades of research and leading-edge innovations in pine planting stock development and plantation management. Because of its general cultural acceptance and extensive management knowledge, high yields, and favorable production economics, loblolly pine is also a key candidate feedstock for renewable fuels and energy.
The Sun Grant Initiative and the Department of Energy’s Bioenergy Technologies Office formed the Regional Biomass Feedstock Partnership in 2009 to define the current state of the science of biomass feedstock production, and establish the baseline for yield potential of major biomass sources. Short rotation hardwood crops are an important component of that work, involving a national network of trials to accurately assess productivity of improved varieties of hybrid poplar and willow. The data generated by the partnership are the foundation of interactive yield maps that provide insight into future yield potential for these two woody crop species (see report on poplar by Berguson et al. 2013; on willow by Volk et al. 2013). Although loblolly pine is not a trial species within the scope of the Partnership, a yield map was developed as part of this project because of its anticipated contribution as a biomass feedstock in the southern region.
Extensive studies on the impact of planting density and management practices on growth and yield of loblolly pine have been conducted; however, information is still needed to more completely understand the factors impacting biomass yield across the entire management range. As part of the Regional Feedstock Partnership’s program, interactive maps based on current best management practices and regional climatic, soil and land use conditions have been created. This report provides a background for loblolly pine yield summarizes the assumptions made in producing the map, and discusses the data used for calibration and validation of pine yield.