ATTRIBUTES OF DOWN WOODy MATERIALS IN HARDWOOD FORESTS OF THE EASTERN UNITED STATES

The Forest Inventory and nalysis Program (FI ) of the USD Forest Service conducts a national inventory of down woody materials (DWM) on forestland in the United States. Estimates of DWM for inventory plots occurring in eastern U.S. hardwood forests facilitate largescale assessment of hardwood forest fuel loadings and wildlife habitat. Therefore, the objectives of this study were (1) to quantify fuel loadings by National Fire Danger Rating System (NFDRS) hour-class for common hardwood forest types of the eastern U.S., (2) to quantify coarse woody debris (CWD) size distributions for common hardwood forest types of the eastern U.S., (3) and to compare the means of CWD and fine woody debris (FWD) by classes of stand live-tree basal area and stand age for hardwood forests of the eastern U.S. using currently available data from FI . Results indicate appreciable amounts of forest fuels in eastern hardwood forests, particularly in pure and mixed species forests with oak components. Furthermore, size-class distributions of coarse woody pieces indicate a dearth of large-sized coarse woody debris in eastern hardwood forests. Overall, a large-scale assessment of down woody attributes in hardwood forests of the eastern U.S. contributes to understanding this resource’s role in the management of fuels and wildlife habitat of the United States. INTRODUCTION Down Woody Materials (DWM) are dead organic materials that accumulate in forests as a result of plant mortality and leaf turnover (Woodall and Williams 2005). The Forest Inventory and nalysis Program (FI ) of the USD Forest Service conducts a national inventory of down woody materials (DWM) on forest land in the United States. FI inventories numerous DWM components including fine woody debris, coarse woody debris, litter, duff, slash, live/dead shrubs, and live/dead herbs. Fine woody debris (FWD) are small pieces of woody material typically made up of fallen twigs, branches, and upper tree boles. Coarse woody debris (CWD) is often defined as large pieces of woody material that meet minimum size and decay requirements. Coarse and fine woody debris are often the central focus of forest ecosystem analyses because they serve as important indicators of fire hazards, carbon stocks, and wildlife habitat. The size specifications of fine and coarse woody debris sampled by the FI program were selected to match the components defined by the National Fire Danger Rating System (NFDRS). This system divides fine and coarse woody debris into size classes that are equivalent to the fuel-hour class system (1-hour, 10-hour, and 100-hour) used by many fire scientists (Deeming and others 1977). In terms of wildlife habitat, coarse woody debris serves as critical habitat for numerous flora and fauna. CWD provides a diversity (stages of decay, size classes, and species) of habitat for fauna ranging from large mammals to invertebrates (Maser and others 1979, Harmon and others 1986, ull and others 1997, Carey and Harrington 2001, Moseley and others 2004). Flora utilize the microclimate of moisture, shade, and nutrients provided by CWD for regeneration establishment (Harmon and others 1986, Nordén and others 2004). ecause of CWD’s importance with regard to biodiversity, nutrient cycling, carbon stocks, and fire risk, wood debris is a leading concern for managed forest ecosystems. lthough coarse and fine woody debris serve as an important indicator of numerous forest ecosystem functions, they have been infrequently investigated in hardwood forests of the eastern U.S. Chojnacky and others (2004) presented the most recent efforts to estimate DWM in forests of the east. However, most 1 Christopher W. Woodall, Research Forester, USD Forest Service, North Central Research Station, St. Paul, MN, 55108; Sonja N. Oswalt, Research Forester, USD Forest Service, Southern Research Station, Knoxville, TN 37919; and Randall S. Morin, Research Forester, USD Forest Service, Northeastern Research Station, Newtown Square, P 19073.