Dead and downed wood in any forest serves an important ecological function with regards to decomposition and nutrient cycling in forest ecosystems. It also provides critical habitat for many reptile and amphibian species, such as the red-backed salamander (Plethodon cinereus), in addition to providing an important food source for insects and detritivores upon which many other species in the system depend. The GCPO LCC Integrated Science Agenda (ISA) targets density of down wood around one 6’ dead/down log of ≥8” dbh per acre, essentially saying that on every acre there needs to be at least one sizable down log. The U.S. Forest Service (USFS) Forest Inventory and Analysis program does not collect plot-level data directly quantifying down wood, but does have a calculated class for carbon in down dead, which is provided as tons of carbon per acre of down dead woody matter >3” dbh and/or stumps and roots >3” dbh. This metric is derived from U.S. Environmental Protection Agency Greenhouse Gas Inventory models, which include geographic area, forest type, and live tree carbon density, and can be imputed across the landscape using similar methods as other metrics above. However, the ISA presents down wood in terms of logs/acre and there presently is no direct algorithm that allows for the recalculation of the ISA endpoint in tons carbon/acre. We therefore made a broad assumption that areas with >0.05 tons carbon/acre would suffice for this endpoint, though we recognize this assumption is in need of testing and revision. The USFS-imputed dead-down wood layer was created in the target resolution for this assessment (250 m). Note estimates of dead-down wood were calculated on a per-acre-of-land basis, though forested lands were the primary sampling frame. We used an extract by mask function in ArcGIS to delineate dead-down wood in upland hardwood woodland and forest, using the USFS imputed dead-down wood layer as input data and the woodland and forest data as masks. We then reclassified the product to pull out pixels with dead-down wood with at least 0.05 tons carbon/acre. We assessed acreage by summing the count of pixels within each geographic construct and multiplying by pixel resolution (250 x 250 m = 62,500 m2) and converting to acres. For display we calculated the proportional area (acres upland hardwood (>0.05 tons carbon/ac dead-down wood/acres HUC 12) within each HUC 12 watershed using zonal statistics in ArcGIS.
