Down Woody Forest Materials: Estimating Forest Floor Fuels for the Eastern United States

This data set provides regional-scale estimates of down woody materials (DWM) that contribute to prescribed and wild land fire fuels. DWM is classified into three successive layers: (1) branches and logs (fine and coarse woody material), (2) litter, and (3) duff. Additionally, live and dead understory shrubs and herbs are included with forest floor measurements. Duff includes the dark, partly decomposed organic material (where plant forms are unrecognizable) above mineral soil. On top of duff is litter, which includes recognizable plant parts such as leaves and flowers but not branches. Branches are separated into three size classes of fine woody material (FWM): <6, 6 to 25, and 26 to 76 mm in diameter. These classes correspond to 1-hour, 10-hour, and 100-hour fire fuel classes, respectively. The U.S. Department of Agriculture Forest Inventory and Analysis (FIA) program currently measures variables related to DWM on a Phase 3 (P3) subsample of its Phase 2 (P2) plots. Investigators have used P3 and P2 FIA data to estimate DWM for all plots in the eastern half of the FIA database. Residuals for the separate DWM class estimates are available with the data set, as described in Chojnacky, D.C., Mickler, R.A., Heath, L.S., Woodall, C.W. 2004. Estimates of down woody materials in eastern US forests. Environmental Management 33(Supplement 1): S44-S55. Also see Woodall, C.W.; Heath, L.S.; Smith, J.E. 2008. National inventories of down and dead woody material forest carbon stocks in the United States: Challenges and opportunities. Forest Ecology and Management. 256: 221-228. DWM data are available online. After developing accurate models of down woody materials by fuel class, location, and other forest attributes, investigators will next link the models to PEcon, a species-level forest growth and economics model, to predict down woody materials and fuel loads in response to changes in climate, land use, species composition, and timber markets.