Short Rotation Woody Crop Biomass Energy Feedstock Production Systems.

Bioenergy feedstocks can be produced through a variety of agricultural and forestry applications.  Woody feedstocks from forestry can be harvested year round and the resulting solid chips are easily handled, stored and converted to energy using well developed operations.  Short rotation woody crops (SRWC) refer to intensive forest management practices that grow woody feedstock in short harvest rotations using fast growing varieties, herbicides, fertilizer and possibly irrigation.  These approaches result in harvest cycles of three to twelve years at production rates up to 20 dry Mg/ha/yr.  Such SRWC approaches are appropriate for producing biomass for energy feedstocks as well as for pulp, paper, engineered and solid wood products.  Bioenergy feedstocks can be produced with a variety of SRWC systems using numerous species.  Dense plantings of willow, sycamore and eucalyptus that are capable of resprouting following cutting (i.e. coppice), will occupy the site rapidly, and have vigorous regrowth without replanting for multiple 3- to 5-year rotations.  Specialized planting and harvesting equipment is available for coppice systems.  Larger trees can also be produced in low-density plantings using the SRWC approach, which allows efficient use of conventional forest harvesting equipment.  Numerous hardwood tree species have been used for low-density SRWC including poplar, sycamore, sweetgum and eucalyptus.  Hardwood trees are selected for high productivity rates and converted to energy with thermochemical and biochemical approaches.  Conifers, such as loblolly pine, are also considered opportune bioenergy feedstock species for theomochemical conversion.  Economics favor rapid growth, but the most favorable trees for SRWC will have robust site requirements such as willow, pine and sweetgum that can be planted on a range of marginal sites.  Other tree species will be favored only if they can be bred or modified for water and/or nutrient use efficiency.  SRWC plantations near bioenergy facilities provides consistent feedstock supply and quality standards.