The Southeastern U.S. Prescribed Fire Permit Database: Hot Spots and Hot Moments in Prescribed Fire across the Southeastern U.S.A.

Abstract

Prescribed fire is an important land conservation tool to meet ecological, cultural, and public safety objectives across terrestrial ecosystems. While estimates of prescribed burning in the U.S.A. exceed 4.5 million hectares annually, tracking the extent of prescribed fire is problematic for several reasons and prevents an understanding of spatial and temporal trends in landscape patterns of prescribed fires. We developed a regional prescribed fire database from 12 state forestry agencies in the southeastern U.S. using records of burn location, size, and calendar days and evaluated spatial and temporal patterns in burning from 2010 to 2020. Over half of all prescribed fires in the U.S. occur in the Southeast, with five states (Florida, Georgia, Alabama, South Carolina, and Mississippi) comprising over ninety percent of the burned area over a decade. We identified hot spots of concentrated prescribed fire activity on both public and private forestlands across the region, as well as regions of less burning, which often occurred in close proximity to hot spots. Temporally, most prescribed fires occurred in March and February across the region; the least activity was recorded between May and November. Our database reveals that burning is highly concentrated within the region, presumably reflecting local land ownership categories and associated land management objectives. This database and these analyses provide the first region-wide summary of fine-scale patterns of prescribed fire in the U.S. and demonstrate the potential for various analyses beyond this work for air quality modeling and remote sensing, as well as the potential impacts of demographic and land use changes.

1. Introduction

In terrestrial ecosystems around the world, prescribed fire is an essential management tool used to reduce wildfire hazards, maintain fire-dependent ecosystems, and improve habitat for wildlife, including threatened and endangered species [1]. In the U.S., pre-colonial use of fire by Indigenous peoples was integral to food harvesting, provision of basketry materials, managing game herds, vegetation clearing for travel efficiency, and farming [2]. Lightning was and remains a common source of fire, especially in the Southeastern U.S. Coastal Plain [3,4]. Increasing regulations, changes in land uses that do not require fire, and fire suppression have greatly reduced fires on the regional landscape, and prescribed fire is limited to locations with the authority, resources, and social license for burning [5,6].

In the U.S. and many other countries, increasing the pace and scale of prescribed burning is a central priority for containing and limiting the severity of wildfires that threaten communities and degrade ecosystem services [7]. In the southeastern U.S., prescribed fire is a primary management tool to meet a variety of conservation objectives [8,9,10].

Tracking prescribed fire extent and temporal patterns in the U.S. is surprisingly difficult. Federal prescribed fire data nationally show that the area burned is concentrated in the southeastern U.S. despite larger Federal ownership occurring in the West and Alaska [11]. Since private land ownership dominates the southeast region, federal data alone fail to represent a comprehensive accounting of prescribed fire activity. The best nationwide estimates of prescribed fire to date are those of Melvin (2012, 2018, 2020), who conducted periodic surveys of state forestry agencies for prescribed fire summaries. However, these state-level summaries represent broad estimates and lack finer-scale spatial details and temporal patterns.

Remote sensing analyses using the Landsat Burned Area product from the United States Geological Survey (USGS) [12,13] or the Moderate Resolution Imaging Spectroradiometer (MODIS) Burned Area product from the National Aeronautics and Space Administration (NASA) [14] reveal spatial and temporal patterns of fire [15]. Unfortunately, remote sensing methods (1) fail to differentiate between prescribed fires, wildfires, and agricultural burning and (2) have a coarse (seasonal) temporal resolution [16]. Remote sensing approaches are also limited by the availability of cloud-free days, rapid vegetation recovery (obscuring color change), and a coarse spatial scale that misses small burns or low-intensity prescribed burns beneath forest canopies [17,18,19,20]. Recent analyses have used burn permit data to evaluate spatial and temporal patterns of burning in Georgia and Florida [16,21,22,23] and Washington [24]. These analyses demonstrate the potential to use permit data to map prescribed fires across space and at finer temporal scales, but they are limited to the state level for only these three states.

To fill the gap in spatial and temporal patterns of prescribed fire in the southeastern U.S., we developed the Southeastern U.S. Prescribed Fire Permit Database. The database spans eleven years (2010–2020) of data recording burn locations and extent for the 12 southeastern U.S. states (Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, and Virginia). Here, we use the database to describe patterns in prescribed fire use across the region, focusing on the following research questions:

• What are the “hot spots” of prescribed fire activity in the Southeast on private and public lands?
• When are the “hot moments” on both public and private lands?

Additionally, we sought to examine the relationships between prescribed burned areas and landscape characteristics such as ownership, management, and location. These analyses are a first step toward evaluating region-wide patterns of prescribed fire that allow policymakers, regulators, and land managers to understand local or state fire activities within the context of regional spatial and ecological scales.

2. Data

We requested permit data from state forestry agencies in the region. Official letters were submitted to all the southeastern states to request burn data for the last eleven years (2010–2020). Since there is no regional standard for data records, the data were delivered in a variety of formats, usually either Excel tables or shapefiles. An interim geodatabase was created to evaluate individual state data for quality control and to consistently format the individual state datasets for aggregation into a regional geodatabase. We then developed a file-based geodatabase with a primary burn permit feature class with minimum attribution that was specific to prescribed fire, which included the following fields: State, Burn Type, Date, Year, Acres, Hectares, Latitude, Longitude, and Source. We created metadata to include how the permit location is tracked, which attributes are collected, spatial characteristics, period of record, and data stewardship. We also documented a formal updating process for each state.

In many southeastern states, state forestry agencies have formal burn authorization systems to track prescribed fire occurrence by day and approximate location. Half of these states (Alabama, Georgia, Florida, North Carolina, Mississippi, and Tennessee) have a burn permit system. In contrast, the other states have burn ‘notifications’ (Oklahoma and South Carolina) or voluntary data submissions (Arkansas, Louisiana, Texas, and Virginia) provided by both public and private entities. Those states with a burn permit system track burns throughout the year, with the exception of Tennessee, which tracks prescribed burns only from 15 October to 15 May.

Given that these states’ systems are not all mandatory or depend on voluntary reporting by fire departments and other entities, they likely underrepresent total burn extent compared to state survey methods [25]. Legal requirements may vary depending on the time of year, burn type, size of burn, land ownership, and fuel type. Some state agencies do not cover all federal lands for burn data collection. Additionally, some agencies did not capture the extent of all burns, or included pile burns, as indicated through their spatial datasets. Prescribed fire records generally include geographic information regarding the location and extent of the burn, but the precision of such data varies. States variously map locations of authorized burns to the county centroid, an address, or a point in a GIS database according to the caller’s description. However, some online systems allow the requester to specify the point location (

Table 1. Prescribed burn permit data for southeastern states used in this analysis.

State or Federal Agency	Years	Locational Data	Type of Burn System
Alabama Forestry Commission	2011–2021	X,Y	permit (required)
Arkansas Forestry Commission	2011–2021	X,Y	voluntary
Florida Forest Service	2010–2020	X,Y	permit (required)
Georgia Forestry Commission	2010–2020	X,Y; geocoding; county centroid	permit (required)
Fort Moore Military Base (GA)	2010–2020	X,Y	collected internally
Louisiana Department of Agriculture and Forestry	2010–2020	X,Y	voluntary
Kisatchie National Forest (LA)	2010–2020	X,Y	collected internally
Mississippi Forestry Commission	2010–2020	X,Y	permit (required)
North Carolina Forest Service	2014–2021	X,Y	permit (required)
Oklahoma Forestry Services	2015–2021	X,Y	notification (required)
South Carolina Forestry Commission	2010–2020	X,Y	notification (required)
Tennessee Division of Forestry	2012–2020	geocoding	permit system (required October 15–May 15)
Texas A&M Forest Service	2017–2019	X,Y	voluntary
Virginia Department of Forestry	2010–2020	X,Y	voluntary

). Two missing locations (Fort Moore, GA, and Kisatchie National Forest, LA) were appended to the geodatabase since they were not included with the state permit datasets. Even with these limitations and variations in reporting systems, burn permitting systems often provide the most complete record of prescribed fire activity.

3. Methods

To examine the relative density of burn locations over 2010–2020, we used heat map symbology in ArcGIS Pro 2.8 to display the frequency of burn locations. This density is based on the number of prescribed burns (recorded as points), and we also used the ’Hectares’ field to weight the density for larger burns (Figure A2, Figure A3 and Figure A4). The density of burns is calculated using the kernel density method [26] with a search radius of 10 m with an output area in km${}^2$ [27].

For dist ${}_i$ < radius

$$\mathrm{Density}=\frac{1}{{\left(\mathrm{radius}\right)}^2}\sum _{i=1}^n\left[\frac{3}{\pi }·{pop}_i{\left(1-{\left(\frac{{\mathrm{dist}}_i}{{\mathrm{radius}}^2}\right)}^2\right)}^2\right]$$

where ${}_i$ = $1,\dots ,n$ are the input points, and points in the sum are only included if they are within the search radius distance of the (x,y) location. The population field value of point ${}_i$ is represented by pop${}_i$, which is an optional parameter, and dist ${}_i$ is the distance between point ${}_i$ and the (x,y) location [27].

The Hot Spot Analysis in ArcGIS Pro 2.8 was then used to calculate the Getis–Ord Gi* statistic (conceptualization of spatial relationships set at a fixed distance band and using the Euclidean distance method with a threshold of 2 km) for each burn point by analyzing all neighboring burn points, where the extent of the burn is the main feature in the analysis:

$$G_i^{*}=\frac{{\sum }_{j=1}^n{w}_{i,j}{x}_j-\overline{X}{\sum }_{j=1}^n{w}_{i,j}}{S\sqrt{\frac{\left[n{\sum }_{j=1}^n{w}_{i,j}^2-{\left({\sum }_{j=1}^n{w}_{i,j}\right)}^2\right]}{n-1}}}$$

where $x_j$ is the attribute value for the feature j; $w_i$, ${}_j$ is the spatial weight between feature ${}_i$ and ${}_j$; ${}_n$ is equal to the total number of features; $\overline{X}$ is the mean of all measurements; and S is the standard deviation of all measurements [28].

The Hot Spot Analysis displays statistically significant hot spot clusters that are not just spatially random but are statistically significant when weighted by burn acreage area values, in addition to statistics including the z-score, p-value, and confidence level. The p-value is the probability that the spatial pattern was created randomly, and z-scores are standard deviations [29].

To be a high-confidence hot spot, a burn area will have a high value and be surrounded by other features with high values, both in number and extent. These high-confidence hot spots were then aggregated into the U.S Department of Agriculture (USDA) firesheds’ ‘management containers’ of approximately 100,000 ha in size, without regard for administrative boundaries [30]. Once aggregated into named fireshed units, the firesheds were ranked into a table with the 17 top firesheds with the highest number of hot spot clusters (greater than or equal to 1000) with over 90 percent confidence (Appendix C 

Table A1. Table of firesheds with the top 17 locations with highest number (greater than or equal to 1000) of hot spots with over 90 percent confidence within each fireshed.

Fireshed Name	Hot Spot Count	Location Description of Hot Spots
Camilla, Georgia	6243	Private lands (Albany, Ichauway section); 2% public lands.
Hinesville, Georgia	3379	Fort Stewart; 80% public lands.
Antioch, Georgia	2975	Private lands (Red Hills Region); 2% public lands.
Richmond Hill, Georgia	2403	Fort Stewart, private lands; 33% public lands.
Tallahassee, Florida	1317	Private lands (Red Hills Region); Apalachicola National Forest; 16% public lands.
Crestview, Florida	1246	Blackwater River State Forest; Eglin Air Force Base; 55% public lands.
Holopaw, Florida	1237	Everglades Headwaters National Wildlife Refuge and Conservation Area;
		Three Lakes Wildlife Management Area; 34% public lands.
Clayton, Alabama	1224	Private lands (Alabama); Barbour Wildlife Management Area; 9% public lands.
Bermont, Florida	1179	Babcock Ranch Preserve; private lands; 28% public lands.
Columbus, Georgia	1160	Fort Moore; 67% public lands.
Union Springs, Alabama	1129	Private lands (Alabama); 0% public lands.
East Brewton, Alabama	1128	Blackwater State Forest; Conecuh National Forest; Private lands; 56% public lands.
Yeehaw Junction. Florida	1103	Private lands; Everglades Headwaters National Wildlife Refuge and Conservation
		Area; 62% public lands.
Monticello, Florida	1090	Private lands (Red Hills Region); Middle Aucilla Conservation Area; 2% public lands.
Cacema Town, Florida	1085	Everglades Headwaters National Wildlife Refuge and Conservation Area; Avon
		Park Air Range; Force; 81% public lands.
Beaufort, South Carolina	1030	Ashepoo–Combahee–Edisto (ACE) Basin National Estuarine Research Reserve;
		Ernest F. Hollings Ace Basin National Wildlife Refuge; 40% public lands.
Beck, Alabama	1007	Private lands; Conecuh National Forest; 30% public lands.

).

To examine hot moments (when fires occurred most frequently), we summarized burns by month from 2010 to 2020. We created circular data clock charts to summarize all of the temporal burn data into seasonal patterns over this period, which divides a larger unit of time into smaller sections of temporal bins of months by each year. Calendar heat charts were also developed to aggregate the burn data into a calendar grid to visually assess seasonal patterns over the decade down to the specific days with the highest and lowest hectares burned. From the data provided by the states, we calculated the burn area (ha) by state, county, and ownership (public and private) over the 2010–2020 time period. While some states may have additional overall reported burn areas, this analysis is from the burn permit data made available.

4. Results

4.1. Spatial Patterns of Prescribed Fire

Over the 2010–2020 period, 1,944,036 prescribed burns totaling 23,005,016 ha were reported in the 12 southeastern states (

Table 2. Extent of prescribed burns (ha) by state with average annual burn area (2010–2020; see Table 1 for burn data years for each state).

State	Total ha of Burns	Average Annual Burn ha	Total Number of Burns
FL	8,374,156	761,286	780,702
GA	6,392,042	581,094	819,997
AL	3,652,736	332,066	128,637
SC	2,081,409	189,219	135,423
MS	1,616,547	146,958	40,486
LA	438,155	39,832	2350
NC	276,911	25,173	5754
TN	66,689	6062	26,132
AR	49,955	4541	2011
VA	26,122	2374	2198
OK	15,370	1397	118
TX	14,919	1356	228
TOTAL	23,005,016	2,091,365	1,944,036

). Among these states, Florida (8,374,156 ha) and Georgia (6,392,042 ha) had the greatest prescribed burn areas during this period (Table 2). Florida consistently led the region with an annual extent of 761,287 ha each year, which ranged from 597,278 to 889,235 ha (Figure 1). Florida, Georgia, Alabama, South Carolina, Mississippi, and Louisiana all reported more than 400,000 ha burned during this period (Table 2). The states with the smallest extent of recorded burns were Texas, Oklahoma, and Virginia, which logged fewer than 30,000 ha over the course of the decade. We included a list of the top 25 counties for prescribed fire extent in

Table 3. Top 25 counties in the southeastern U.S. with the most burned hectares.

County	State	Burn ha Sum	Average Annual Burn ha
Thomas	Georgia	463,103	42,116
Osceola	Florida	403,745	36,702
Leon	Florida	401,740	36,509
Okaloosa	Florida	374,678	34,062
Santa Rosa	Florida	354,175	32,198
Collier	Florida	323,128	29,375
Polk	Florida	297,660	27,056
Franklin	Florida	289,103	26,281
Jefferson	Florida	286,747	26,117
Charlotte	Florida	262,212	23,848
Decatur	Georgia	261,749	23,795
Palm Beach	Florida	251,661	22,878
Berkeley	South Carolina	248,048	22,536
Walton	Florida	237,582	21,596
Wakulla	Florida	234,202	21,202
Highlands	Florida	225,433	20,494
Escambia	Alabama	222,685	22,122
Bullock	Alabama	211,343	21,227
Liberty	Florida	210,340	19,122
Okeechobee	Florida	205,299	18,664
Russell	Alabama	201,717	18,338
Miami-Dade	Florida	197,110	17,920
Glades	Florida	194,431	17,676
Covington	Alabama	192,697	19,133
Baker	Georgia	189,689	17,248

(Appendix A, Figure A1); notably, Florida counties comprise 9 of the top 10.

The heat maps using the kernel density method show a spatially aggregated pattern of prescribed fire, with conspicuous hot spots of permit density weighted by fire size visible across the southeastern region (Figure 2) both for public and private land ownership (Figure A2 and Figure A3). The Hot Spot Analysis displays hot spots at confidence levels ≥90 percent (Figure 3). These hot spots included 7.15 percent of the total burn records, with 45.9 percent on public lands and 54.02 percent on private lands.

4.2. Temporal Patterns of Prescribed Fire

Prescribed fire activity was greatest from January to April during the decade of the dataset, with the months of March and February having the highest burn area (Figure 4). Late February until mid-March was the hottest moment (

Table 4. Total number of burns by month in the southeastern U.S. (2010–2020).

Month	Jan.	Feb.	Mar.	Apr.	May	Jun.	Jul.	Aug.	Sep.	Oct.	Nov.	Dec.	Total by Year
Year
2010	16,849	18,569	41,371	29,188	13,573	11,871	10,207	9198	9704	9213	10,233	12,514	192,490
2011	19,647	38,300	32,628	17,484	8020	3219	10,591	11,004	10,336	11,805	11,594	15,424	190,052
2012	22,164	25,221	30,839	12,407	10,538	10,632	10,009	9000	10,804	11,538	14,359	12,542	180,053
2013	27,708	23,244	34,409	19,753	12,520	11,609	7553	9522	11,101	14,860	10,904	13,664	196,847
2014	15,883	25,877	35,050	20,673	12,578	13,146	9939	10,857	9345	15,145	12,081	14,576	195,150
2015	21,730	22,105	28,904	16,684	12,968	10,800	9514	9764	9797	12,274	10,134	11,277	175,951
2016	15,464	31,380	35,108	16,971	11,496	9515	8559	9623	10,486	8378	5771	14,186	176,937
2017	23,180	37,203	32,698	13,380	6430	11,664	10,722	10,900	10,705	8996	6256	2922	175,056
2018	19,533	23,906	23,589	16,985	8499	9582	7346	8837	8121	10,201	6907	5635	149,141
2019	14,343	20,452	29,660	15,779	10,245	8385	8857	8939	8500	9842	14,394	10,643	160,039
2020	16,661	17,408	25,180	14,076	5759	8938	9711	9414	8853	11,698	9841	13,366	150,905

). All of the top 10 dates for burning occurred in these two months (

Table 5. Top 10 dates (month and day) for the greatest number of burns over an eleven-year period (2010–2020) across 12 southeastern states.

Month	Day of Month	Total Number of Burns	Average Number of Burns
Mar.	8	19,038	1731
Mar.	9	18,077	1643
Feb.	20	16,471	1497
Mar.	7	15,746	1431
Mar.	16	14,860	1351
Mar.	15	14,396	1309
Feb.	19	14,308	1301
Mar.	20	14,042	1277
Feb.	18	13,829	1257
Mar.	14	13,427	1221

). During the six-month period after May and before November, very few (28 percent) prescribed fires were reported across the region.

4.3. Spatial–Temporal Patterns of Prescribed Fire

Looking at both the results of the Hot Spot Analysis (Getis–Ord Gi*) as well as temporal patterns, we examined the top 17 firesheds (Appendix C Table A1) for their seasonal burn trends for 2010–2020. Nine locations were selected in total to represent each geographic location across the Southeast with a high rate of hot spots (greater than or equal to 1000) with over 90 percent confidence (

Table 6. Table of nine firesheds selected from the Hot Spot Analysis results with highest number (greater than or equal to 1000) of hot spots with over 90 percent confidence, as well as public and private lands determined by percent public lands within each fireshed.

Fireshed Name	Hot Spot Count	Fireshed Location Description of Hot Spots
Camilla, Georgia	6243	Private lands (Albany, Ichauway section); 2% public lands
Hinesville, Georgia	3379	Fort Stewart; $81\%$ public lands
Antioch, Georgia	2975	Private lands (Red Hills Region); 2% public lands
Crestview, Florida	1246	Blackwater River State Forest; Eglin Air 55% Force Base; public lands
Holopaw, Florida	1237	Everglades Headwaters National Wildlife Refuge and Conservation Area;
		Three Lakes Wildlife Management Area; 8% public lands
Clayton, Alabama	1224	Private lands (Alabama); Barbour Wildlife Management Area; 9% public lands
Bermont, Florida	1179	Babcock Ranch Preserve; private lands; 28% public lands
Columbus, Georgia	1160	Fort Moore; 67% public lands
Beaufort, South Carolina	1030	Ashepoo–Combahee–Edisto (ACE) Basin National Estuarine Research Reserve;
		Ernest F. Hollings Ace Basin National Wildlife Refuge; 40% public lands

). If there was a cluster of adjacent firesheds that had a high level of hot spots, then the fireshed with the highest hot spot value was selected to represent the geographic area in terms of temporal patterns.

The following data clocks (Figure 5) show the seasonal variations between specific public and private land firesheds, as well as from variable regions (from Central Florida to South Carolina). Similar to the number of burns across the entire southeastern region (Figure 4), the Antioch, GA/FL; Beaufort, SC; Columbus, GA; Clayton, AL; and Camilla, GA (Figure 5) firesheds all follow the same pattern of having the most active prescribed fires between January and April in the data clock charts, with March being the month of greatest activity. The Hinesville, GA fireshed has an expanded prescribed burn window, mainly due to Fort Stewart’s military base. Fort Stewart conducts prescribed burning not only for ecological reasons but also to reduce fuel loading for military training exercises, which frequently occur between 01 December and 30 June [31]. The Holopaw, FL fireshed in the Everglades Headwaters National Wildlife Refuge and Conservation Area has a noticeably different pattern, with prescribed fires occurring throughout the year, but with the majority occurring between January and July. It should be noted that the Everglades Headwaters National Wildlife Refuge and Conservation Area is a large tract prairie and savanna habitat that experiences the typical peninsular subtropical weather pattern of a relatively dry winter and spring with a wet summer and autumn, in contrast to a wet winter and summer and a dry spring and autumn pattern in the Florida panhandle and farther north [32].

We found differences in several burn metrics between public and private lands (Appendix D Figure A6 and Figure A7). Private lands contained the bulk of the reported burned area over the 11-year period, totaling 14,065,721 ha (61.1 percent of all burned extent). Public lands, despite only representing 18 percent of all lands in the region, had a total burned area of 8,939,295 ha (38.9 percent of all burned extent). The mean burn size differed strongly between private (10.7 ha) and public (77.7 ha) lands (Appendix D Figure A8 and Figure A9).

5. Discussion

Our analysis of prescribed fire extent across the southeastern U.S. revealed significant aggregation patterns in space and time and illuminated qualitative differences. While it has long been known that burning in the southeastern U.S. is concentrated in only five states (Florida, Georgia, Alabama, South Carolina, and Mississippi) [33], what has been less appreciated is the high concentration of burning over a few limited areas within these states. We identified hot spots across the region, specifically in the Florida panhandle, central Florida, southwestern Georgia, and lower Alabama, where prescribed fire closely aligns with the recommended 2–3-year fire frequency for southeastern U.S. habitats housing wildlife species of special concern and supporting ecosystem services [34,35,36,37]. Guyette and others [38] estimated a 2-year pre-settlement fire return interval for much of the southeastern U.S. region (longer in the southern Appalachians and interior plateaus). Tree-ring fire scar evidence supports the supposition that these areas historically had such high fire frequencies [39,40,41]. These hot spots are also the primary locations where otherwise rare or declining species have stable or growing populations [42,43].

According to the burn permit dataset, the counties listed in Table 2 have the highest burn extents in the region for the 2010–2020 time period. Counties with a substantial amount of burning on private lands, such as in the Red Hills Region, which includes Thomas County, Georgia, and Leon County, Florida, are managing properties for high-end recreational and hunting uses. Prime hunting areas for northern bobwhite quail (Colinus virginianus) must be managed through prescribed burning to maintain its habitat, which in turn benefits several other threatened or endangered species [10,43]. Many counties with high prescribed burn coverage have substantial public lands, such as Blackwater State Forest and Eglin Air Force Base in Florida, and Conecuh National Forest in Alabama (Appendix B Figure A4). Blackwater State Forest, Eglin Air Force Base, and Conecuh National Forest conduct prescribed fires to maintain the longleaf pine (Pinus palustris) habitat for the red-cockaded woodpecker (Dryobates borealis) and other rare plant and animal species [44]. Public and private land managers face different motivations and challenges in promoting and maintaining prescribed fire in the region [6].

The temporal patterns for prescribed fire were not unexpected, tracking past work in the region [16,45]. Fires in the dataset were concentrated from December to April across the region, with March as the most common (cf. February for Florida; [16]). Burning during this period is most common due to available burn windows based on atmospheric instability, predictable winds, and frequent cold front precipitation events that allow for better fire control and protect firefighter safety [16,46]. In addition to Nowell et al.’s (2018) day-of-week analysis for Florida, we also evaluated individual days. U.S. holidays had the least burning (particularly Christmas, Christmas Eve, and Independence Day), and the weeks containing Christmas and Thanksgiving were exceptionally low (

Table 7. The five days with the lowest number of burns with national holidays listed.

Month	Day of Month	Number of Burns	Holiday
Dec.	25	282	Christmas Day
Dec.	24	1230	Christmas Eve
Jul.	4	1461	Independence Day
Jan.	1	1971	New Year’s Day
Nov.	27	2522	Thanksgiving

). Peak days were in early March and late February (Table 4 and Table 5).

The Southeast is a major contributor to the nationally prescribed fire extent and is estimated to account for 70 percent of all burning nationwide in the U.S. (Melvin 2020). Using the permit data, burning in the region is overwhelmingly concentrated in only five states (Florida, Georgia, Alabama, South Carolina, and Mississippi), where approximately 2 million hectares burn annually (Table 1). These results support the national survey [11], with these five states representing nearly half of all prescribed burning reported nationwide.

The slight decline in reported 2020 prescribed burns on public lands is likely temporary and could be due to a multitude of factors, including a lack of burning during the COVID-19 pandemic; causes ranging from societal pressures to not compound respiratory-related issues in neighboring communities to fire crew staff becoming sick themselves with COVID-19 [47]. It might also represent the beginning of a regional decline (Figure 1; Appendix D Figure A6) as burns are conducted in an increasingly urbanized southeast, with rapidly growing smoke-sensitive areas (e.g., hospitals, roads, schools). Smoke management and air quality concerns rise with an increase in development in the wildland–urban interface (WUI) [48].

The Prescribed Fire Permit Database has shortcomings. This regional permit database represents planned activities, and thus some fires might not have been conducted. The spatial mapping of locations that were actually burned vs. intended to be burned is critical for analyses of emissions, spatially explicit fire return intervals, or evaluations of conservation successes in fire-dependent habitats. Landsat Burned Area products can provide additional information on unknown burn locations in the Southeast, including smaller fires, when used in concert with permit data [15]. Similarly, records of prescribed fire permits may help to overcome the inability of burned area products to distinguish between wildfire and prescribed fire. Thus, combining burned area products with burn authorization and wildfire datasets may offer valuable insight regarding seasonality, size of burns, and wildfire versus prescribed fires [21,22,23].

Prescribed burn windows in the future may become increasingly limited with climate change projections of a hotter and drier climate in the Southeast [49], so historical fire frequency datasets can pinpoint areas of needed treatment. Further studies may include examining burn frequency in specific ecoregions, fuel types, WUI areas, or wildfire risk zones. While this effort focuses on the southeastern region of the U.S., expanding the database to other regions of the country is a critical data need, particularly in regions where agricultural burning activities are not tracked or captured by state or federal records. Prescribed fire is increasingly needed to mitigate wildfire risks and sustain biodiversity in regions beyond the Southeast. The accurate and regional analysis of its use and practice is foundational to sustaining this important practice under increasing pressure from urbanization and air quality concerns [50].

6. Conclusions

Our objectives here were to mesh diverse datasets into a regional analysis of the spatial and temporal patterns of prescribed fire activity in the southeastern US. We aggregated burn permit data into various ‘hot spots’ and ‘hot moments’ across the Southeast from 2010 to 2020. While not a complete dataset, the burn permit geodatabase can help establish a foundation for additional studies, as well as help validate findings from remote sensing products and other regional reporting systems on prescribed burning. We hope the results of this dataset can provide insight into the possibilities of having historical data on prescribed burn data and the exploration of the ‘when’ and ‘where’ of prescribed burning in the Southeast.