Development of a Downed Woody Debris Forecasting Tool Using Strategic-Scale Multiresource Forest Inventories

Abstract

The increasing interest in forest biomass for energy or carbon cycle purposes has raised the need for forest resource managers to refine their understanding of downed woody debris (DWD) dynamics. We developed a DWD forecasting tool using field measurements (mean size and stage of stage of decay) for three common forest types across the eastern United States using field observations of DWD from the US Department of Agriculture Forest Service's Forest Inventory and Analysis program. Residence times for DWD ranged from as short as 20.3 ± 9.7 years (mean ± SD) for loblolly pine biomass in the southeastern United States to as long as 41.7 ± 20.9 years for aspen biomass in the Lake States. Although we suggest numerous improvements through refined DWD measurements and models, our proposed tool can be considered a rapid assessment technique to assist natural resource managers in forecasting DWD populations. Beginning with using log size and decay stage to understand deadwood dynamics, future researchers should seek to refine DWD metrics through implementing enhanced forest inventory information and exploring the impacts of forest disturbances on inputs to the DWD pool. Management and Policy Implications Downed woody debris (DWD) is an integral component of forest health and is of interest to managers involved in forest management, wildlife habitat, and forest fuel assessment and fire risk. The presence and abundance of woody debris encourages biodiversity by serving as cover and habitat for deadwood-dependent plants and animals. To date, the majority of research has focused on how to accurately assess forest DWD attributes at a given time period. Our study highlights the ability to inform DWD dynamics through the development of a forecasting tool that allows managers to forecast woody debris populations. We estimated shorter residence times in southeastern US forests than in northern forest types. Through a rapid assessment of average deadwood diameter and stage of decay, trends in future deadwood stocks can be understood. Applying these results can aid natural resource managers in meeting management objectives and policy requirements that seek to maintain and/or promote the abundance of forest DWD. These results can enhance the value of using existing forest inventory information to provide insights into future forest composition and structure as a part of forest management plans.