This data publication provides plot-based measurements of: stem diameter for each stem > 0.4 centimeters on every sampled shrub, shrub status at time of sampling (live/dead/charred), and estimated shrub height obtained from 5 plots sampled in 2012-2013 on each of three sites (15 total plots) in the Cleveland National Forest. The sites are located near Kitchen Creek Road on southern Laguna Mountain in San Diego County, CA and were characterized by time since last burn -- 7 years, 28 years, or 68 years prior to the study. These data also include stem diameter, biomass, and representative percent moisture values from shrubs harvested outside of the study plots at 18 locations across the three sites. Locations were outside, but near to, the study plots to avoid destructive sampling within the study plots. These data were collected between 2011 and 2013.

Post-fire vegetation structure and fuels data are essential for understanding the recovery process after major disturbances. To meet this need, 40 plots within and around the perimeter of the 2021 KNP Complex Fire were surveyed between July 12 and July 28, 2024. Data was collected on sites previously established by the U.S. Geological Survey Kings Canyon and Sequoia Field Station, as well as new plots selected for their accessibility and burn severity. These plots were visited to assess fuel status and vegetation recovery after the KNP Complex Fire. Newly established plots were situated at least 50 meters from roads or trails, with a randomly designated center point. Each plot had a diameter of 20 meters and was surveyed at the transect and entire plot level. A terrestrial lidar scanner was also used to collect point cloud data of each site. This data release includes the manual fuel metrics in comma-separated values format (CSV), point clouds in the lidar data exchange file format (LAS), and a shapefile (SHP) of the plot locations.

These data were compiled so that annual wildfire could be modelled across the sagebrush region in the western United States. Our goal was to understand how wildfire probability relates to climate and fuel conditions across the entire sagebrush region. To do this we developed a statistical model that represents the relationship between annual wildfire probability and a small number of climate and fuel variables. Specifically, created predictions of wildfire probability using a biologically plausible logistic regression model that related wildfire probability to mean temperature, annual precipitation, the proportion summer precipitation (PSP), and aboveground biomass of annual herbaceous plants and perennial herbaceous plants. The biomass variables were used as proxies for fine fuel availability. These data represent annual fire occurrence in 1 km pixels (i.e. did a given pixel burn that year), predicted wildfire probability, as well as the three year running average (i.e. average across the current and previous two years) of climate and vegetation variables. These data were collected across the sagebrush region (the extent of the study area is provided by the cell_number_ids.tif file). The climate and vegetation data were compiled using a existing gridded dataset (Daymet) of daily precipitation and temperature, and vegetation data were summaries of annual estimates of aboveground biomass of annual and perennial herbaceous plants from the Rangeland Analysis Platform (https://rangelands.app/). These data can be used to understand spatial and temporal variability in wildfire occurrence and modelled wildfire probability between 1988 and 2019 and how that variability relates to spatial and temporal variability in climate and vegetation.

These data were compiled so that annual wildfire could be modelled across the sagebrush region in the western United States. Our goal was to understand how wildfire probability relates to climate and fuel conditions across the entire sagebrush region. To do this we developed a statistical model that represents the relationship between annual wildfire probability and a small number of climate and fuel variables. Specifically, created predictions of wildfire probability using a biologically plausible logistic regression model that related wildfire probability to mean temperature, annual precipitation, the proportion summer precipitation (PSP), and aboveground biomass of annual herbaceous plants and perennial herbaceous plants. The biomass variables were used as proxies for fine fuel availability. These data represent annual fire occurrence in 1 km pixels (i.e. did a given pixel burn that year), predicted wildfire probability, as well as the three year running average (i.e. average across the current and previous two years) of climate and vegetation variables. These data were collected across the sagebrush region (the extent of the study area is provided by the cell_number_ids.tif file). The climate and vegetation data were compiled using a existing gridded dataset (Daymet) of daily precipitation and temperature, and vegetation data were summaries of annual estimates of aboveground biomass of annual and perennial herbaceous plants from the Rangeland Analysis Platform (https://rangelands.app/). These data can be used to understand spatial and temporal variability in wildfire occurrence and modelled wildfire probability between 1988 and 2019 and how that variability relates to spatial and temporal variability in climate and vegetation.

Mechanical fuel treatments are a primary pre-fire strategy for potentially mitigating the threat of wildland fire, yet there is limited information on how they impact shrubland ecosystems. This publication contains data related to vegetation structure and composition in mechanically masticated chaparral communities used to assess the impact of these fuel treatments on shrubland vegetation and to determine the extent to which they emulate postfire succession. Data were collected from within chaparral dominated communities on the Angeles, Cleveland, Los Padres, and San Bernardino national forests of southern California. The climate of the region is Mediterranean with mild, wet winters and hot, dry summers and the topography is rugged and steep with elevations from near sea level to over 3500 m in the Transverse and Peninsular ranges. The rocky and shallow soils of the area are predominantly granitic and support a wide range of shrubland communities that include stands dominated by a single species (>50% cover) such as Adenostoma fasciculatum (chamise), Arctostaphylos spp. (manzanita), Ceanothus spp. (wild lilac) and Quercus spp. (oak) and mixed stands without a single dominant. The mechanically masticated fuel treatments utilized for this study were identified using the USGS Southern California Fuel Treatment Data Set (http://www.calfiresci.org) and were limited to single-entry mastication treatments with no follow-up treatment of burning or re-mastication. The size and shape of available treatments were highly variable and thus a random sampling design was used to maximize the number of study sites. This was accomplished by selecting sites from within treatment boundaries using the random-point generator in ArcGIS and a buffer of at least 400 m between points. The final sample size of accessible locations included 149 mechanically masticated study sites, each with a treatment plot and a control. All treatments were completed between 2004 and 2011 using a variety of masticating equipment and ranged in size from less than a hectare to large-scale treatments spanning thousands of hectares across entire ridgelines. The timing of mastication treatments extended across all seasons and ranged in completion time from several days to several years depending on their size. In order to evaluate the differences between mechanically masticated and early successional postfire vegetation two comparisons were made. The first was a single site case study on the Cleveland National Forest where a spark from a masticator ignited the 39 acre Long Canyon Wildfire on September 23rd, 2010 that burned next to the mechanical treatment being implemented and comprised similar pre-disturbance vegetation. This comparison consisted of four study plots in the masticated treatment and four study plots in the adjacent burned area that were monitored for the first two years following the disturbances. The second was a regionally broad comparison of two-year old mechanically masticated study plots from this fuel treatment study (n = 25) to a subset of two-year-old postfire plots (n = 56) from a regional study of early postfire succession in southern California chaparral published in an earlier paper (Keeley et al. 2008). This study investigated factors determining fire severity and ecosystem responses in 250 randomly selected study plots within the 2003 Cedar, Grand Prix, Old, and Paradise fire perimeters. The subset of 56 plots chosen from the original 250 plots were based on the criteria that the site was located within one of the four southern California national forests, was in chaparral vegetation, and had a pre-disturbance stand age and elevation within the same range as the two-year-old masticated sites used in the regional comparison. These data support the following publication: Brennan, Teresa J., Keeley, J.E. In Press. Response of chaparral shrubland vegetation to mechanical mastication fuel treatments. Regional postfire data were extracted from this

Mechanical fuel treatments are a primary pre-fire strategy for potentially mitigating the threat of wildland fire, yet there is limited information on how they impact shrubland ecosystems. This publication contains data related to vegetation structure and composition in mechanically masticated chaparral communities used to assess the impact of these fuel treatments on shrubland vegetation and to determine the extent to which they emulate postfire succession. Data were collected from within chaparral dominated communities on the Angeles, Cleveland, Los Padres, and San Bernardino national forests of southern California. The climate of the region is Mediterranean with mild, wet winters and hot, dry summers and the topography is rugged and steep with elevations from near sea level to over 3500 m in the Transverse and Peninsular ranges. The rocky and shallow soils of the area are predominantly granitic and support a wide range of shrubland communities that include stands dominated by a single species (>50% cover) such as Adenostoma fasciculatum (chamise), Arctostaphylos spp. (manzanita), Ceanothus spp. (wild lilac) and Quercus spp. (oak) and mixed stands without a single dominant. The mechanically masticated fuel treatments utilized for this study were identified using the USGS Southern California Fuel Treatment Data Set (http://www.calfiresci.org) and were limited to single-entry mastication treatments with no follow-up treatment of burning or re-mastication. The size and shape of available treatments were highly variable and thus a random sampling design was used to maximize the number of study sites. This was accomplished by selecting sites from within treatment boundaries using the random-point generator in ArcGIS and a buffer of at least 400 m between points. The final sample size of accessible locations included 149 mechanically masticated study sites, each with a treatment plot and a control. All treatments were completed between 2004 and 2011 using a variety of masticating equipment and ranged in size from less than a hectare to large-scale treatments spanning thousands of hectares across entire ridgelines. The timing of mastication treatments extended across all seasons and ranged in completion time from several days to several years depending on their size. In order to evaluate the differences between mechanically masticated and early successional postfire vegetation two comparisons were made. The first was a single site case study on the Cleveland National Forest where a spark from a masticator ignited the 39 acre Long Canyon Wildfire on September 23rd, 2010 that burned next to the mechanical treatment being implemented and comprised similar pre-disturbance vegetation. This comparison consisted of four study plots in the masticated treatment and four study plots in the adjacent burned area that were monitored for the first two years following the disturbances. The second was a regionally broad comparison of two-year old mechanically masticated study plots from this fuel treatment study (n = 25) to a subset of two-year-old postfire plots (n = 56) from a regional study of early postfire succession in southern California chaparral published in an earlier paper (Keeley et al. 2008). This study investigated factors determining fire severity and ecosystem responses in 250 randomly selected study plots within the 2003 Cedar, Grand Prix, Old, and Paradise fire perimeters. The subset of 56 plots chosen from the original 250 plots were based on the criteria that the site was located within one of the four southern California national forests, was in chaparral vegetation, and had a pre-disturbance stand age and elevation within the same range as the two-year-old masticated sites used in the regional comparison. These data support the following publication: Brennan, Teresa J., Keeley, J.E. In Press. Response of chaparral shrubland vegetation to mechanical mastication fuel treatments. Regional postfire data were extracted from this

This data publication contains a geospatial file in raster format of wildfires and fuels treatments that occurred between 1995 and 2013 on Stanislaus National Forest and Yosemite National Park in California within the area burned by the 2013 Rim Fire, excluding the outer 500 meters of the fire perimeter. Tabular data are provided for three sets of circular sample windows of size 500 acres (ac), 2500 ac and 5000 ac within the same geospatial extent. Variables included for the sample windows are proportion burned at high severity in the Rim Fire; proportion treated/burned prior to the Rim Fire; mean values for actual evapotranspiration, water deficit, energy release component, and burning index; and proportion in shrubland, riparian, hardwood, conifer, and grassland LandFire vegetation classes. Tabular data are also provided for a set of transects within the same geographic extent that are placed along radial lines centered on the Rim Fire's origin point.

Populations of the chaparral shrub were sampled in southern California and further north in Monterey and Santa Clara counties and it was discovered that postfire regeneration modes were different. The southern California populations had substantial resprouting with some seedling recruitment. The Monterey populations had no resprouting ability and recovery was entirely by seedlings. However, there is an age effect in that when young these northern California populations fail to recruit seedlings due to lack of a seed bank buildup in the short interval since the last fire. These populations likely will be extirpated. I hypothesize that this obligate seeding mode has been selected for because seed reproduction is more reliable when intervals between fires are very long, longer that resprouting shrubs would survive. Support for this is provided by demonstrating substantially higher lightning fire frequencies in southern California than in the Monterey and Santa Clara area.

Populations of the chaparral shrub were sampled in southern California and further north in Monterey and Santa Clara counties and it was discovered that postfire regeneration modes were different. The southern California populations had substantial resprouting with some seedling recruitment. The Monterey populations had no resprouting ability and recovery was entirely by seedlings. However, there is an age effect in that when young these northern California populations fail to recruit seedlings due to lack of a seed bank buildup in the short interval since the last fire. These populations likely will be extirpated. I hypothesize that this obligate seeding mode has been selected for because seed reproduction is more reliable when intervals between fires are very long, longer that resprouting shrubs would survive. Support for this is provided by demonstrating substantially higher lightning fire frequencies in southern California than in the Monterey and Santa Clara area.

Physical site characteristics including aspect, elevation, and slope were recorded for each study plot and spatial coordinates were obtained from a global positioning system. Stand height was determined by averaging the heights of the first live woody individual encountered along each 10 m subplot in mechanically masticated plots as well as in the adjacent controls. Unfortunately height data was not collected from postfire plots in the prior study. The age of the stand prior to each mechanical disturbance was obtained from stem samples collected from the first two obligate seeding individuals encountered within controls and ranged from seven to sixty-four years across all mechanically masticated fuel treatments. The stand ages of postfire plots, on the other hand, were obtained from stem samples collected from nearby unburned vegetation or estimated from burned skeletons of obligate seeding species collected within the burn area. These sites ranged in age from twenty-four to fifty-one years old at the time of the 2003 wildfires. All data from mechanically treated study sites, including both treatment and control, were collected in the spring and summer of 2011 and 2012. The postfire data from the local case study were also collected in the spring and summer of 2011 and 2012 whereas the postfire data used in the regional comparison were collected in the spring and summer of 2005. The age of each plot at the time of sampling was determined by subtracting the year of the disturbance from the year of data collection.