Spatial datasets of wildfire risk to forest carbon for the conterminous United States (30m) circa 2014 landscapes

Wildfire Risk to Forest Carbon provides information on two carbon risk metrics: 1) wildfire risk to total forest carbon, which includes the sum of the following pools: aboveground standing live and dead trees; litter and duff; coarse and fine woody debris; and shrub/herb pools, and 2) wildfire risk to market carbon, which includes the sum of aboveground and belowground carbon in standing live and dead trees. Each carbon risk metric has four components: 1) initial carbon, 2) carbon retained following fire, 3) carbon emissions or carbon loss by fire intensity, and 4) the expected annual carbon retained, emitted, or lost. Emissions are defined here as the total loss of carbon from all forest pools as a result of wildfire, while loss is defined as the reduction in standing live and dead tree carbon as a result of wildfire. Each carbon risk metric component is provided as an individual georeferenced TIFF file (30 meter resolution) for the conterminous United States. Three national-level datasets were used to create products related to wildfire risk to total forest carbon and market carbon: 1) TreeMap, a CONUS-wide dataset of Forest Inventory and Analysis forest plot measurements that are imputed to spatially explicit LANDFIRE and biophysical datasets; 2) FuelMap, a dataset that complements TreeMap through the imputation of fuels data to the FIA plots in TreeMap for the subset of stands where fuels data are not collected; and 3) the annual burn probability and conditional fire intensity datasets produced using the Large Fire Simulator. FSim estimates were produced using LANDFIRE spatial data to model wildfire spread and intensity, resulting in fire probability datasets that are compatible for analysis with TreeMap and FuelMap. All three of these national-level datasets reflect landscape conditions circa 2014. To estimate initial carbon, carbon retained post-fire, and carbon emitted and lost, TreeMap and FuelMap stand data were used in conjunction with the FIA database to create stand and tree list inputs for simulations in the Fire and Fuels Extension to the Forest Vegetation Simulator (FFE-FVS). Simulations included a no-fire and wildfire scenarios for six flame lengths, corresponding to the midpoint of 5 conditional fire intensity levels (FILs) and a 20-foot flame length for the final “greater-than” conditional FIL category summarized by FSim. The six flame lengths are 1 foot (ft); 3 ft; 5 ft; 7 ft; 10 ft; and 20 ft. When fires are simulated in FFE-FVS, the program reports total fire emissions and carbon retained by pool for each stand. These outputs were linked back to the unique TreeMap IDs and mapped for the initial and conditional values. The expected annual values were then computed in conjunction with the FSim annual burn probability and conditional fire intensity probability layers.Geospatial quantification of wildfire risk to forest carbon can provide public and private land managers with information about how best to allocate limited budgets to mitigate risks to a valuable resource. Carbon market managers may use this information to inform risk tolerance for projects.For more details on how the expected annual values were computed, reference the Comparative Risk Assessment Framework for Wildland Fire Management (Calkin et al. 2011). For more details on wildfire risk to carbon and for access to an interactive web application to visualize and extract small project areas from the datasets produced here, see the Wildfire Risk to Carbon website at https://www.wildfireriskcarbon.org/.