Areas of low natural regeneration potential post-fire in shrublands of southern California (selected years between 2008 and 2020)

Identifying locations where shrubland vegetation will not recover naturally post-fire is a challenge given the vast areas that are regularly burned in southern California. When shrublands are within the historic fire return interval, e.g., 55 years for low-elevation shrubland (Keeley and Safford 2016, Van de Water and Safford 2011), biomass accumulates and shrub cover recovers after 10–14 years (Black et al. 1987, Bohlman et al. 2018). However, in many parts of southern California, the fire return interval has decreased, often in conjunction with an increase in non-native plant species, drought, and nitrogen deposition (Pratt et al. 2014, Allen et al. 2018, Syphard et al. 2019, Safford et al. 2022). Under these conditions, post-fire biomass recovery can be impeded and, in some cases, may result in type conversion from native shrubland to non-native grassland (Syphard et al. 2019). We developed a repeatable method to identify areas of low regeneration potential in southern California usi..., We obtained the historical wildfire perimeter database from the California Department of Forestry and Fire Protection (FRAP 2021). We then generated from this database a set of binary rasters indicating the occurrence of fire in a pixel for a given year across the southern California study area. The years for this input data stack range from 1967 to 2020. We have included this input data stack in this collection in the file L4fires.zip.
We implemented a script to calculate the low natural regeneration potential rasters in the Julia language using the Rasters library (https://github.com/rafaqz/Rasters.jl), opting to use Julia for performance reasons. This script uses a collection of binary rasters, one for each year, that indicate whether a pixel was burned in a given year, across the entire study region. The code is structured as follows. It has two functions (last40yrs and last10yrs) that construct year-by-year raster stacks of all fires in the past 40 and 10 years. A subsequent functi..., The file archive here is named lowregenfiles.zip and is composed of three files: prepregenrasters.zip, which is the archive of the shrubland low regeneration rasters, L4firerasters.zip, which is the archive of the binary input rasters, and L4files.jl, which is the Julia script for processing the input rasters.
The shrubland low regeneration raster layers are available for 9 years using the following naming structure:
prepregen20XX.tif
Where 20XX is the year of the estimate and reflects that the fire perimeter data from that year. The years that are included in the data stack are 2008, 2009, 2010, 2015, 2016, 2017, 2018, 2019 and 2020.
The dimensions of the geotiff raster files is 20,632 rows by 15,603 columns at a 30-meter pixel resolution. The rasters are in a California Albers Equal Area projection (EPSG 3310). These rasters are encoded as bytes with a NoData value of 255. Intended users of this dataset include resource managers and researchers who are assessing post-fire shrubland re...