FuelMap 2014: Imputed map of carbon stored in litter, duff, fine woody debris, and coarse woody debris for CONUS forests circa 2014

FuelMap 2014 is an imputed map of litter, duff, fine woody debris, and coarse woody debris loadings for the forests of the conterminous United States (CONUS) circa 2014. In fire science, these strata are often referred to as “fuel” for a wildland fire. FuelMap 2014 is largely derived from the TreeMap 2014, which provides a tree-level model of CONUS forests. To create TreeMap, we assigned forest plot data measured by Forest Inventory and Analysis (FIA) to a 30x30 meter (m) grid. Specifically, we used a random forests machine-learning algorithm to impute the forest plot data to a set of target rasters provided by Landscape Fire and Resource Management Planning Tools (LANDFIRE: https://landfire.gov). Predictor variables for both the forest plots (reference data) and LANDFIRE rasters (target data) consisted of percent forest cover, forest height, and vegetation type, as well as topography (slope, elevation, and aspect), location (latitude and longitude), biophysical variables (photosynthetically active radiation, precipitation, maximum temperature, minimum temperature, relative humidity, and vapor pressure deficit), and disturbance history (time since disturbance and disturbance type) for the landscape circa 2014. FIA records down woody material (DWM) at some but not all of their forest plots. Thus, many of the FIA plots imputed (assigned) in the TreeMap carried DWM information with them. For pixels in TreeMap 2014 where the assigned FIA plot recorded DWM, we used the FIA plot assigned in TreeMap 2014 in the FuelMap 2014. For pixels where FIA plots were assigned that did not have DWM measured, we identified the most similar plot that had DWM measured from the list of FIA plots available for imputation in TreeMap 2014, and then we assigned that plot in the FuelMap 2014. The main outputs of this project are rasters at 30x30 m spatial resolution for the imputed FIA plot identifier. The plot identifier corresponds to a unique visit to a plot by FIA’s field crew, and is also referred to as the plot control number [CN]. Using the CN, we looked up the loading in each of the carbon pools (in pounds per acre) and include a raster for each: 1) litter, 2) duff, 3) fine woody debris in the 1-hour (hr) size class, 4) fine woody debris in the 10-hr size class, 5) fine woody debris in the 100-hr size class, 6) coarse woody debris in the 1000-hr size class, and 7) “total carbon” in the DWM strata produced by adding these six strata together. We present these data in geodatabase and GeoTIFF formats. The spatial extent is CONUS for landscape conditions circa 2014. The carbon loadings for DWM are drawn from the FIA COND_DWM_CALC tables for the assigned plot CN for litter, duff, fine woody debris and coarse woody debris.
The FuelMap provides spatial estimates of forest floor carbon at fine resolution (30x30 m). These spatially contiguous estimates are needed for landscape-level analyses of forest biomass and carbon, as well as estimates of emissions from wildland fire. The FuelMap can be used in combination with the TreeMap to provide estimates of forest carbon that include both the trees and forest floor. The FuelMap is the first imputed dataset to partition forest floor carbon into different strata of which we are aware. FuelMap does not provide estimates of soil carbon or carbon stored in roots of trees, nor of carbon stored in understory shrubs or grasses.
See the Entity and Attributes section for details regarding the relationship between the data files included in this publication and the FIA DataMart (https://doi.org/10.2737/RDS-2001-FIADB). For additional information regarding TreeMap 2014, see Riley et al. (2019, https://doi.org/10.2737/RDS-2019-0026). These data were published on 07/26/2023. On 02/07/2024, a lookup table containing the predicted FIA plot CN was added to the package and a few minor metadata updates were made. On 08/12/2024, a corrected lookup table was added to the package and a few publication URLs were updated. On 08/30/2024, FIA documentation URLs were updated.