Fire regimes of plains grassland and prairie ecosystems
Zouhar, Kristin. 2021. Fire regimes of plains grassland and prairie ecosystems. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/fire-regimes/plains-grassland-and-prairie
Monitoring a wildland fire at Highland Creek, Wind Cave National Park, South Dakota; 2002.
Historical fire regimes in plains grassland and prairie ecosystems of central North America are characterized by frequent fires with return intervals ranging from 1 to 35 years. Frequent fires removed accumulated litter, stimulated native grass production, and impeded establishment and spread of cacti and woody plants. Longer intervals occurred in the northern and western part of the region, where the climate was relatively cooler and drier, respectively, and shorter intervals occurred in warmer areas to the south and in areas with more precipitation to the east. Longer intervals also occurred in areas with dissected topography compared to areas with relatively flat topography. Fires were ignited by both lightning and humans, most often in late spring to summer. Grassland fires typically consume most or all of the standing biomass (i.e., high-severity fires). Mixed-severity fires are more likely where shrubs are present. Growing-season fires may be patchier than dormant-season fires due to more variable fuel moisture. Grazing by large ungulates such as bison may alter fuel continuity and result in patchier burns. These once largely continuous grasslands have been fragmented and altered by human settlement, and most of the land has been converted to cropland and rangeland. Therefore, historical fire regimes are no longer functioning, although many grasslands are managed with frequent prescribed fires in spring.
A comprehensive Fire Regime Synthesis for plains grassland and prairie ecosystems has not been published in the Fire Effects Information System. Information from relevant literature reviews is summarized here, and results from primary fire history studies conducted in these ecosystems are described briefly in table A1. Summary information from LANDFIRE succession modeling of plains grassland and prairie Biophysical Settings (BpS) in central North America is given in table 1. The LANDFIRE Biophysical Settings section provides a complete list of BpS and includes links to full BpS descriptions. Common names of plant species are used in this summary. See table A2 for a list of common and scientific plant names.
Figure 1—Distribution of prairie and plains grassland ecosystems.
Plains grassland and prairie ecosystems occur throughout central North America, from the Rocky Mountain foothills east to the deciduous forest-prairie boundary, and from the aspen parkland region of central Canada south to the coast of Texas and Louisiana (fig. 1). Plains grasslands occur from about 1,700 m elevation in the Rocky Mountain foothills to about 460 m, where plant communities transition to prairie ecosystems [12]. Prairies occur down to about 150 m elevation [13]. Plains grasslands are dominated by short-statured grasses such as blue grama and buffalo grass in the west, and medium-statured grasses such as western wheatgrass and needlegrass in the east [12]. Prairies are dominated by tallgrass species such as big bluestem and little bluestem [13]. A variety of other grasses and forbs occur in both ecosystems. Woody plants are occasional in plains grasslands [12] and rare in prairies [13]. Plant community composition of plains grasslands and prairies varies with site characteristics (e.g., slope, aspect, soil type) and disturbance regimes, including management history [2]. Many of these grassland sites have been dramatically altered by disturbances such as cultivation [12,13], herbicide applications, planting of nonnative species—especially cool-season grasses such as smooth brome and Kentucky bluegrass—livestock grazing, and annual mowing for hay. Some sites have been subsequently managed for restoration, including seeding of native species (e.g., [9,21,36,44,50]).
Fuels
Historically, frequent fires played an important role in plains grasslands and prairies by removing accumulated litter, stimulating native grass production, and impeding establishment and spread of cacti and woody plants. Probability of ignition, rate of fire spread, fire patchiness, fire size, and fire severity vary with fuel and weather conditions. Continuity and loading of ground, surface, and woody fuels (i.e., plant community composition) vary across the Great Plains and over time, because they are influenced by interactions of moisture availability (e.g., site and soil type, climate and weather patterns), fire timing and frequency, and grazing patterns [23,46,62]. Information on fuel characteristics and associated fire behavior in tallgrass prairie communities is provided by Twidwell et al. (2016) [53], Kidnie and Wotton (2015) [22], and Wragg (2018) [61]. Leis (2013) provides and overview of fuels management in the Great Plains [28].
Grasses of the tallgrass prairie regrow quickly in previously burned areas.
Throughout the Great Plains, woody plants were historically mostly restricted to drainages and mesic sites with infrequent fire [39,46]. Moisture availability limits woody plant cover and height potential in dry areas of the Great Plains, and frequent fire is a primary limiting factor of woody plant cover in relatively mesic grassland and tallgrass prairie sites [42,46]. For example, in the Northern Great Plains, lack of moisture limited the spread of woody plants onto dry upland sites, whereas frequent fires slowed the spread of woody plants (such as sagebrush, eastern redcedar, and quaking aspen) on relatively wet upland sites [46].
As woody plants grow and spread, herbaceous fuel loads and continuity decline, thus reducing the probability of fire ignition and spread and allowing continued establishment and spread of woody plants [39]. Dominant woody plant species vary across sites, and flammability of woody fuels varies among species (e.g., Ashe's juniper is more volatile than honey mesquite) [62]. In the south-central Great Plains, relatively dry grasslands (<81 cm mean annual precipitation) are more likely to succeed to shrublands, whereas grasslands in areas with higher annual precipitation are more likely to succeed to woodland or forest in the absence of fire [42].
Spread of woody plants into grassland and savanna ecosystems of the Great Plains is a common topic of study (e.g., [4,24,33,48,60]). For example, Milbauer (2007) examined the effects of fire history on plant community composition in Wisconsin tallgrass prairie remnants [33]; Bowles (1998) examined succession in a fire excluded savanna remnant in Illinois [4]; Starns (2020) studied the effects of fire exclusion on previously fire-managed semiarid savanna ecosystem in Texas [48]; and Widenmaier (2010) described tree establishment and spread into fescue grasslands in southeastern Alberta [60].
Fire Ignition, Season, and Frequency
Timing of historical grassland fires was dictated by ignition source, plant phenology (i.e., fuel moisture), and weather. Most thunderstorms in the Great Plains occur from April to October, and most lightning fires occur between May and September, especially July and August. American Indians set fires in grasslands during both the growing season and the dormant season (both spring and fall) [23,46].
Grassland vegetation typically begins growing in spring and senesces in late summer and fall; sometimes earlier in dry summers. Dry thatch is more flammable than actively growing vegetation, and it composes a large portion of the fine fuel load in the dormant season (fall through early- to mid-spring). In northern climates, snow cover limits thatch drying and shortens the fire season. Typically grasslands can burn any time from March to November, although in mesic grasslands, fuels may be too moist to burn in summer during wet years [23].
Postfire succession varies, in part, due to prefire plant community composition and timing of fires relative to plant phenology [23,62]. Tallgrass prairies were mostly dominated by warm-season grasses, and mixedgrass prairies had varying quantities of warm-season and cool-season grasses. Spring fires tend to stimulate growth of warm-season plants and reduce growth and reproduction of cool-season plants [62]. At Konza Prairie, where cool-season species are only a minor component, tallgrass prairie communities are resilient to fire in any season. Abundance and composition of forbs is dynamic and responds to differences in fire frequency and fire timing, grazing by wild ungulates such as bison, and insect herbivory [23].
Estimates of presettlement fire frequency in grasslands are based on inferences from climate patterns, rate of fine fuel accumulation, time required for woody plants to establish and spread, charcoal in lake sediments, and sometimes from fire-scar chronologies in adjacent savanna and woodland. Rate of fuel accumulation in some grasslands is sufficient to carry fire every year, in others at least 2 years of fuel accumulation is needed, especially in grazed grasslands [23].
Throughout the Great Plains, estimates of historical fire intervals range from 1 to about 35 years (e.g., [35,39,58,62]). Estimates from LANDFIRE succession modeling (table 1) and fire history studies (table A1) suggest mean presettlement fire intervals within this range. Generally, intervals at the long end of this range occurred in the northern and western part of the region, where the climate is relatively cooler and drier, respectively, and shorter intervals generally occurred in warmer areas to the south and areas with more precipitation to the east [17]. In tallgrass prairies, historical mean fire interval estimates are 10 years or less, and in plains grasslands, mean fire interval estimates are 35 years or less [14,35]. Estimates of historical fire intervals in the Northern Great Plains range from about 1 to 30 years (e.g., [15,46]), with longer intervals occurring in areas with dissected topography, shorter intervals on relatively flat topography, and the shortest intervals (1-5 years) in mesic sites [46]. Analyses by Ratajczak et al. (2014) suggest that grasslands in the Central Great Plains transition to shrublands when fire intervals lengthen from 1 to 3 years to 3 to 8 years, and when fire intervals exceed ~10 years they transition to woodlands. Fire-free intervals of these lengths allow shrubs and trees to reproduce and reach sufficient size to survive fire [39].
| Fire interval¹ | Fire Severity² | Number of BpS in each fire regime group3 | ||||||
|---|---|---|---|---|---|---|---|---|
| Replacement | Mixed | Low | I | II | III | IV | V | |
| 2–25 years | 95 | 3 | 3 | 3 | 73 | 0 | 0 | 0 |
| ¹Minimum and maximum historical mean fire interval estimates. ²Percentage of fires in each of 3 fire severity classes. Replacement-severity fires cause >75% kill or top-kill of the upper canopy layer; mixed-severity fires cause 26%-75%; low-severity fires cause <26% [3,25]. 3See the FEIS glossary for fire regime group definitions. | ||||||||
Fire Severity, Pattern, and Size
Grassland fires are typically stand-replacement severity, as defined by LANDFIRE (table 1), because dormant-season fires tend to be complete (~100% consumption of biomass), and growing season fires nearly so (~80-95% consumption of biomass) [14,23]. Fires were more likely mixed-severity where shrubs were present [35]. Growing-season fires may be patchier due to more variable fuel moisture, and presettlement fires may have been patchier due to the effects of grazing by large ungulates such as bison. Several studies on the effects of fire timing on postfire response of grassland species highlight the variability in individual species' response to fire timing in relation to plant phenology (reviewed in [23]). Twidwell et al. (2016) describe the historical range of variation in fire behavior in tallgrass prairies based on a review of nine studies [53].
Over much of the Great Plains, native grasslands have been replaced by agriculture, degraded by overgrazing, or lost to the establishment and spread of woody plants, and now only occur in a small portion of their former range and are so fragmented that historical fire regimes are seriously disrupted. Fire exclusion and reduction of fine fuels from livestock grazing have limited the role of fire in contemporary grasslands on many sites [23,62]; however, frequent prescribed fire is widely used in some grassland areas [14,23,62].
Structure and species composition of many native grassland plant communities have been altered by the introduction of nonnative invasive plants and by the spread of native woody plants, some of which alter fuel characteristics such that fire spread and severity is limited in invaded communities [15] (e.g., tall fescue invasion in tallgrass prairie [32]). However, fire simulations suggest that contemporary policies governing prescribed fire management—particularly those governing maximum allowable wind speeds—have a greater impact on fire behavior than invasive plants. Magnitude and variability of flame lengths, fireline intensity, and rate of fire spread are reduced in contemporary prescribed fires compared to historical fires. Reductions resulting from fire management policies were greater than reductions caused by tall fescue invasion and were similar to reductions caused by 2 or more decades of juniper encroachment [53].
An April fire in the Flint Hills (CC BY-ND 2.0).
Fire exclusion during the 20th century has led to an increase in woody plant cover in many grasslands [23]. Contemporary observations in the Central Great Plains suggest that more frequent fires are needed to prevent transition to shrubland, and that management focused on preventing establishment and spread of woody plants is more effective than post hoc restoration efforts. Reintroducing frequent fires after woodlands have established does not restore grasslands in management-relevant time scales (decades) [39].
Some prairies and plains grasslands have a history of management with frequent prescribed fire, typically in spring, although precise timing and frequency vary, as do postfire plant community composition [62]. Common objectives of prescribed burning in grasslands include increasing forage for livestock, reducing abundance of nonnative invasive plants, preventing establishment and spread of woody plants, reducing cover of woody plants, and increasing or restoring native plant diversity on the small, fragmented parcels that remain of these communities [14,23]. Prescribed fire effects depend on many variables such as fire frequency, grassland type, relative abundance of warm-season and cool-season species, successional stage (e.g., time since last fire), grazing history (herbivory), climate and weather, and fire timing relative to plant phenology, such that each fire is unique in its combination of these variables, making comparisons and synthesis of information difficult.
Most prescribed fires are conducted when vegetation is dormant in the early spring or late fall. Tallgrass prairie remnants (e.g., the Flint Hills in Kansas and Oklahoma) are typically burned in late April to promote growth of warm-season grasses for grazing and reduce abundance of nonnative cool-season grasses. Prescribed fire is sometimes used to control nonnative plants by timing burns to coincide with the most vulnerable stage of the target nonnative species while favoring native and desirable species. However, many nonnative species are enhanced by fire. Greater use of growing-season burns—to mimic natural lightning ignitions—have been advocated for restoration. A burn program that includes burning in multiple seasons is most likely to enhance species diversity [23].
Fire season and fire intensity influence the outcome of prescribed fires intended to reduce cover of woody plants that are already established. Fire season affects the rate of recovery due to seasonal differences in carbohydrate storage [23]. High-intensity fires result in greater mortality and damage of growing parts on sprouting shrubs than typical, low-intensity prescribed fires [52].
Extent of contemporary fires is limited because prescribed fires are conducted most often in spring when fuels are relatively moist, and due to fragmentation from roads, agriculture, and grazing patterns of livestock and wildlife [46]. Large wildfires were largely absent from the Great Plains during the 20th century. However, trends in large wildfire (>400 ha) activity from 1985 to 2014 in the Great Plains indicate that frequency of and total area burned by large wildfires was greater from 2005 to 2014 than from 1985 to 1994. Seasonality of large wildfires was similar between the two time periods [8]. Midlatitude regions of the Great Plains (Wyoming, eastern Colorado, Nebraska, Kansas, and South Dakota) are expected to have the greatest increase in annual fire probability with climate change, whereas annual fire probability is expected to decrease in parts of Texas due to fuel limitations [17].
Additional information on fire management considerations in grasslands and rangelands of the Great Plains can be found in the following publications: Eisenberg et al. (2019) [10], Limb et al. (2016) [56], Twidwell et al. (2015) [54], Twidwell et al. (2013) [51], Fuhlendorf et al. (2011) [11], Reid and Fuhlendorf (2011) [57], Romo (2003) [40].
| Code | Region | Formation | FRG | MFI | % Low | % Mixed | % Replace |
|---|---|---|---|---|---|---|---|
| Series 11320 - Central Mixedgrass Prairie | |||||||
| 3511320 | South-Central US | Grassland | II | 6 | 0 | 5 | 95 |
| 3411320 | South-Central US | Grassland | II | 11 | 0 | 0 | 100 |
| 3211320 | South-Central US | Grassland | II | 6 | 0 | 5 | 95 |
| 4311320 | Northern Great Plains | Grassland | II | 23 | 0 | 0 | 100 |
| 4211320 | Northern Great Plains | Grassland | II | 8 | 0 | 0 | 100 |
| 3911320 | Northern Great Plains | Grassland | II | 8 | 0 | 0 | 100 |
| 3811320 | Northern Great Plains | Grassland | II | 23 | 0 | 0 | 100 |
| 3311320 | Northern Great Plains | Grassland | II | 15 | 0 | 0 | 100 |
| 3111320 | Northern Great Plains | Grassland | II | 8 | 0 | 0 | 100 |
| 3011320 | Northern Great Plains | Grassland | II | 11 | 0 | 0 | 100 |
| Series 11350 - Inter-Mountain Basins Semi-Desert Grassland | |||||||
| 2911350 | Northern and Central Rockies | Grassland | I | 25 | 0 | 67 | 33 |
| 2211350 | Northern and Central Rockies | Grassland | I | 25 | 0 | 67 | 33 |
| Series 11410 - Northwestern Great Plains Mixedgrass Prairie | |||||||
| 4011410 | Northern Great Plains | Grassland | II | 8 | 0 | 0 | 100 |
| 3911410 | Northern Great Plains | Grassland | II | 8 | 0 | 0 | 100 |
| 3111410 | Northern Great Plains | Grassland | II | 8 | 0 | 0 | 100 |
| 3011410 | Northern Great Plains | Grassland | II | 13 | 0 | 0 | 100 |
| 2911410 | Northern and Central Rockies | Grassland | II | 13 | 0 | 0 | 100 |
| 2211410 | Northern and Central Rockies | Grassland | II | 15 | 0 | 0 | 100 |
| 2011410 | Northern and Central Rockies | Grassland | II | 15 | 0 | 0 | 100 |
| Series 11470 - Western Great Plains Foothill and Piedmont Grassland | |||||||
| 2811470 | Southwest | Grassland | II | 10 | 0 | 13 | 87 |
| 2711470 | Southwest | Grassland | II | 20 | 0 | 0 | 100 |
| 2511470 | Southwest | Grassland | II | 17 | 0 | 0 | 100 |
| 2611470 | South-Central US | Grassland | II | 17 | 0 | 0 | 100 |
| 3311470 | Northern Great Plains | Grassland | II | 20 | 0 | 0 | 100 |
| 3111470 | Northern Great Plains | Grassland | II | 20 | 0 | 0 | 100 |
| 3011470 | Northern Great Plains | Grassland | II | 12 | 0 | 0 | 100 |
| 2911470 | Northern and Central Rockies | Grassland | II | 12 | 0 | 0 | 100 |
| Series 11480 - Western Great Plains Sand Prairie | |||||||
| 3511480 | South-Central US | Grassland | II | 13 | 0 | 0 | 100 |
| 3411480 | South-Central US | Grassland | II | 13 | 0 | 0 | 100 |
| 3211480 | South-Central US | Grassland | II | 13 | 0 | 0 | 100 |
| 4011480 | Northern Great Plains | Grassland | II | 10 | 0 | 0 | 100 |
| 3911480 | Northern Great Plains | Grassland | II | 10 | 0 | 0 | 100 |
| 3811480 | Northern Great Plains | Grassland | II | 10 | 0 | 0 | 100 |
| 3111480 | Northern Great Plains | Grassland | II | 10 | 0 | 0 | 100 |
| 3011480 | Northern Great Plains | Grassland | II | 20 | 0 | 0 | 100 |
| 2911480 | Northern and Central Rockies | Grassland | II | 20 | 0 | 0 | 100 |
| 2011480 | Northern and Central Rockies | Grassland | II | 20 | 0 | 0 | 100 |
| Series 11490 - Western Great Plains Shortgrass Prairie | |||||||
| 2811490 | Southwest | Grassland | II | 10 | 0 | 15 | 85 |
| 2711490 | Southwest | Grassland | II | 22 | 0 | 0 | 100 |
| 2511490 | Southwest | Grassland | II | 20 | 0 | 0 | 100 |
| 3511490 | South-Central US | Grassland | II | 14 | 0 | 0 | 100 |
| 3411490 | South-Central US | Grassland | II | 14 | 0 | 0 | 100 |
| 2611490 | South-Central US | Grassland | II | 5 | 0 | 0 | 100 |
| 3811490 | Northern Great Plains | Grassland | II | 22 | 0 | 0 | 100 |
| 3311490 | Northern Great Plains | Grassland | II | 22 | 0 | 0 | 100 |
| 3111490 | Northern Great Plains | Grassland | II | 22 | 0 | 0 | 100 |
| 3011490 | Northern Great Plains | Grassland | II | 22 | 0 | 0 | 100 |
| 2911490 | Northern and Central Rockies | Grassland | II | 22 | 0 | 0 | 100 |
| Series 11500 - Western Great Plains Tallgrass Prairie | |||||||
| 4011500 | Northern Great Plains | Grassland | II | 5 | 2 | 0 | 98 |
| 3911500 | Northern Great Plains | Grassland | II | 5 | 2 | 0 | 98 |
| 3811500 | Northern Great Plains | Grassland | II | 5 | 2 | 0 | 98 |
| 3111500 | Northern Great Plains | Grassland | II | 5 | 2 | 0 | 98 |
| Series 14110 - Great Lakes Wet-Mesic Lakeplain Prairie | |||||||
| 6214110 | Great Lakes | Grassland | II | 19 | 0 | 0 | 100 |
| 5214110 | Great Lakes | Grassland | II | 24 | 0 | 0 | 100 |
| 5114110 | Great Lakes | Grassland | II | 15 | 0 | 0 | 100 |
| 5014110 | Great Lakes | Grassland | II | 15 | 0 | 0 | 100 |
| 4914110 | Great Lakes | Grassland | II | 24 | 0 | 0 | 100 |
| Series 14120 - North-Central Interior Sand and Gravel Tallgrass Prairie | |||||||
| 4314120 | Northern Great Plains | Grassland | II | 3 | 4 | 0 | 96 |
| 4214120 | Northern Great Plains | Grassland | II | 3 | 4 | 0 | 96 |
| 4014120 | Northern Great Plains | Grassland | II | 4 | 4 | 0 | 96 |
| 3914120 | Northern Great Plains | Grassland | II | 4 | 4 | 0 | 96 |
| 3814120 | Northern Great Plains | Grassland | II | 3 | 4 | 0 | 96 |
| 5214120 | Great Lakes | Grassland | II | 3 | 4 | 0 | 96 |
| 5114120 | Great Lakes | Grassland | II | 3 | 4 | 0 | 96 |
| 5014120 | Great Lakes | Grassland | II | 3 | 4 | 0 | 96 |
| 4914120 | Great Lakes | Grassland | II | 3 | 4 | 0 | 96 |
| 4114120 | Great Lakes | Grassland | II | 3 | 4 | 0 | 96 |
| Series 14200 - Northern Tallgrass Prairie | |||||||
| 4214200 | Northern Great Plains | Grassland | II | 6 | 0 | 0 | 100 |
| 4014200 | Northern Great Plains | Grassland | II | 6 | 0 | 0 | 100 |
| 3914200 | Northern Great Plains | Grassland | II | 6 | 0 | 0 | 100 |
| 4114200 | Great Lakes | Grassland | II | 4 | 0 | 0 | 100 |
| Series 14210 - Central Tallgrass Prairie | |||||||
| 5214210 | Great Lakes | Grassland | II | 4 | 0 | 0 | 100 |
| 5114210 | Great Lakes | Grassland | II | 4 | 0 | 0 | 100 |
| 5014210 | Great Lakes | Grassland | II | 4 | 0 | 0 | 100 |
| 4914210 | Great Lakes | Grassland | II | 4 | 0 | 0 | 100 |
| 4314210 | Northern Great Plains | Grassland | II | 4 | 0 | 0 | 100 |
| 4214210 | Northern Great Plains | Grassland | II | 4 | 0 | 0 | 100 |
| 3814210 | Northern Great Plains | Grassland | II | 4 | 0 | 0 | 100 |
| 3114210 | Northern Great Plains | Grassland | II | 4 | 0 | 0 | 100 |
| 4414210 | South-Central US | Grassland | II | 4 | 0 | 0 | 100 |
| Series 14220 - Southern Blackland Tallgrass Prairie | |||||||
| 3714220 | South-Central US | Grassland | II | 3 | 8 | 2 | 91 |
| 3614220 | South-Central US | Grassland | II | 3 | 8 | 2 | 91 |
| 3514220 | South-Central US | Grassland | II | 3 | 8 | 2 | 91 |
| 3214220 | South-Central US | Grassland | II | 3 | 8 | 2 | 91 |
| Series 14230 - Southeastern Great Plains Tallgrass Prairie | |||||||
| 4314230 | Northern Great Plains | Grassland | II | 2 | 0 | 2 | 98 |
| 3814230 | Northern Great Plains | Grassland | II | 2 | 0 | 3 | 96 |
| 4414230 | South-Central US | Grassland | II | 2 | 0 | 2 | 98 |
| 3514230 | South-Central US | Grassland | II | 2 | 0 | 2 | 97 |
| 3214230 | South-Central US | Grassland | II | 2 | 0 | 2 | 97 |
| Series 14280 - West Gulf Coastal Plain Northern Calcareous Prairie | |||||||
| 3214280 | South-Central US | Grassland | I | 3 | 50 | 50 | 0 |
| 4414280 | South-Central US | Grassland | I | 3 | 50 | 50 | 0 |
| 3714280 | South-Central US | Grassland | I | 3 | 50 | 50 | 0 |
| Series 14290 - West Gulf Coastal Plain Southern Calcareous Prairie | |||||||
| 4514290 | South-Central US | Grassland | II | 4 | 15 | 0 | 85 |
| 3714290 | South-Central US | Grassland | II | 4 | 15 | 0 | 85 |
| Series 14340 - Texas-Louisiana Coastal Prairie | |||||||
| 9814340 | South-Central US | Grassland | II | 5 | 0 | 5 | 95 |
| 3714340 | South-Central US | Grassland | II | 5 | 0 | 5 | 95 |
| 3614340 | South-Central US | Grassland | II | 3 | 0 | 0 | 100 |
| Series 14370 - Central and Upper Texas Coast Dune and Coastal Grassland | |||||||
| 3614370 | South-Central US | Grassland | II | 3 | 0 | 0 | 100 |
| Series 15080 - Ozark Prairie and Woodland | |||||||
| 4415080 | South-Central US | Woodland | II | 2 | 0 | 2 | 98 |
| Summary | |||||||
| Minimum | 2 | 0 | 0 | 0 | |||
| Maximum | 25 | 50 | 67 | 100 | |||
| Mean | 10 | 3 | 4 | 94 | |||
| Median | 8 | 0 | 0 | 100 | |||
| FRG = Fire Regime Group; MFI = Mean Fire Interval | |||||||
Table A1—Fire history studies conducted in plains grassland and prairie ecosystems.
| Location | Plant Community | Title | Summary of Findings | Citation |
|---|---|---|---|---|
| Throughout the Holocene | ||||
| North America, Global | grasslands | Global fire history of grassland biomes | Fire activity increased in North America around 2,000 years ago, coincident with both fire use by American Indians and warm, dry conditions. | Leys 2018 [31] |
| Comstock Lake, WI | prairie-forest ecotone | Holocene fire regimes, vegetation and biogeochemistry of an ecotone site in the Great Lakes Region of North America | Five distinct fire regimes were identified over the Holocene, ranging from frequent, low-intensity fires to infrequent, high-intensity crown fires. Plant communities included varying amounts of coniferous forest, deciduous forest, and savanna. | Morris 2014 [34] |
| Great Plains (northern), Kettle Lake, ND | mixedgrass prairie | Fire cycles in North American interior grasslands and their relation to prairie drought | Fire activity oscillated with climate, and was greater during relatively moist periods (when grass cover was extensive); fire cycles had periodicity of about 160 yrs. | Brown 2005 [5] |
| Great Plains (central) | shortgrass, tallgrass, and mixedgrass prairies | Reconstructing grassland fire history using sedimentary charcoal: Considering count, size and shape | • Charcoal particles produced by grassland fires are smaller than those produced by forest fires. • Width to length ratio of 0.5 or smaller appears to indicate a predominantly herbaceous fuel type suggesting at least 40% grassland. • Area burned within 1,060 m of the depositional environment explained both count and area of charcoal particles. | Leys 2017 [30] |
| Presettlement | ||||
| Great Plains, 14 national park sites | post oak, eastern redcedar, and ponderosa pine savanna and woodland | A quantitative analysis of fire history at national parks in the Great Plains | • Presettlement MFI1 (before about 1850) averaged 13.2 years and ranged from 4.8 to >28 years across 14 sites. Longer intervals likely occurred in cooler northern regions and on sites with topographic features that inhibited fire spread and fuel production (e.g., badlands). • Mean annual temperature was the most important variable explaining differences in fire frequency among study sites. • Mean annual precipitation had a complex but important relationship with fire frequency. • A model broadening the inference to the entire Great Plains estimates that ~86% of the Great Plains had historical MFI between 3 and 13 years. | Guyette 2011 [16] |
| Great Plains (northern); sites in MT, ND, and SD | mixedgrass and tallgrass prairie | Recent fire history of the Northern Great Plains | High fire activity from 1700-1740 and 1850-1900; lower fire activity after Euro-American settlement period than before | Umbanhowar 1996 [55] |
| Great Plains (northern); ND, SD, MT | mixedgrass prairie | Lightning fires in North Dakota grasslands and in pine-savanna lands of South Dakota and Montana | Number of lightning fires/10,000 km2: • 6/year in eastern ND • 22.4/year in south-central ND • 24.7/year in western ND • 91.7/year in pine-savanna in northwestern SD and southeastern MT | Higgins 1984 [18] |
| Great Lakes; sites in WI, MI, IL, IN | All inclusive | Visualizing the ecological importance of pre-Euro-American settlement fire across three Midwestern landscapes | Spatial patterns of percentage of pyrophilic and pyrophobic species of bearing trees recorded in public land surveys from 1806-1807, 1819-1820, and 1821-1840 showed fire-dominated landscapes interspersed with patches of pyrophobic vegetation; the latter was generally restricted to the leeside of water bodies. | Thomas-VanGundy 2020 [49] |
| Great Plains (northern) | All inclusive | Interpretation and compendium of historical fire accounts in the Northern Great Plains | • Most historical accounts described fires ignited by American Indians from March to May (mostly April), and from July to early November (mostly October). • Timing of fires was likely influenced by bison movements. • Grassland fuels burned readily in all seasons. | Higgins 1986 [19] |
| Rochelle Hills, Thunder Basin National Grasslands, WY | mixedgrass prairie with Rocky Mountain juniper and ponderosa pine woodlands in narrow bands | Fire history of the Rochelle Hills Thunder Basin National Grasslands | • WMPI2: 7.4 years (1565-1988); 7.9 years (1565-1939); 6.7 years (1940-1988) • Most fires occurred in late growing season or dormant period. | Perryman 2000 [37], Perryman 1996 [38] |
| Great Plains (northern), Wind Cave National Park, Black Hills, SD | prairie-ponderosa pine ecotone | Historical variability in fire at the ponderosa pine-northern Great Plains prairie ecotone, southeastern Black Hills, South Dakota | MFI (savanna): 10-12 years (1528-1912) | Brown 1999 [6] |
| Castle Mound Pine Forest State Natural Area, WI | prairie, oak savanna, red pine and eastern white pine forest | Fire history at the confluence of the Driftless Area and Central Sand plains of Wisconsin: A case study from Castle Mound Pine Forest State Natural Area | • Fires were recorded in 15 years between 1788 and 2006. • MFI: 6 years, between the first recorded fire in 1841 and the last recorded fire in 1923 • Most fire scars were in earlywood, indicating spring and early summer fires. | Larson 2017 [27] |
| Fults HP Nature Preserve, IL | prairie and forest | Eastern redcedar dendrochronology links hill prairie decline with decoupling from climatic control of fire regime and reduced fire frequency | Median fire interval: <2 years (1850-1959), 5 years (1960-2007) | Jones 2016 [20] |
| Brickyard Hill Conservation Area, MO | prairie and oak forest mosaic | Fire history at the eastern Great Plains margin, Missouri River Loess Hills | MFI: 6.6 years (1672-1820); 5.2 years (1672-1980) | Stambaugh 2006 [47] |
| Scotts Bluff National Monument, NE | mixedgrass prairie | The fire history of Scotts Bluff National Monument | Presettlement (pre-1935): • MFI: 15-30 years • Most fires occurred in late summer and early fall. Postsettlement: • MFI: >50 years • Most fires occurred in spring. | Wendtland 1992 [59] |
| Tallgrass Prairie Preserve, OK | Cross Timbers and prairie ecotone | Fire history of a prairie/forest boundary: more than 250 years of frequent fire in a North American tallgrass prairie | MFI: 2.59 years (1729-2005) | Allen 2011 [1] |
| Tallgrass Prairie Preserve, OK | savanna, grassland, forest | Tornado damage and fire history in the cross timbers of the Tallgrass Prairie Preserve, Oklahoma | • MFI: 1.35 years (1947-1992) • Most fires in early spring | Shirakura 2003 [45] |
| Keystone Ancient Forest Preserve, OK | prairie, savanna, and post oak or eastern redcedar woodland | The historic fire regime on the edge of the prairie: A case study from the Cross Timbers of Oklahoma | Median fire interval: 2.5-6.0 years | Clark 2007 [7] |
| TX, OK | prairie-post oak woodland transition zone | Multi-scale synthesis of historical fire regimes along the south-central US prairie–forest border presettlement | • MFI: 3-10 years • Most fires were low severity and occurred during the dormant season, but this pattern was temporally and spatially variable. | Rooney 2019 [41] |
| Contemporary | ||||
| Great Plains | grasslands | Surging wildfire activity in a grassland biome | Comparing large wildfires that occurred between 1985 and 1994 to those that occurred between 2005 and 2014: • Average number of large wildfires increased from 33.4 ± 5.6 per year to 116.8 ±28.8 per year. • Total area burned increased 400%. • Over half the ecoregions had >70% probability of a large wildfire occurring in the last decade. • Seasonality of large wildfires was similar. | Donovan 2017 [8] |
| Great Plains | All inclusive | Quantifying variance across spatial scales as part of fire regime classification | Variance of fire interval increased and percentage of area burned increased as spatial grain increased. | Scholtz 2018 [43]; also see Leis 2018 [29] for summary |
Table A2―Common and scientific names of plant species mentioned in this summary.
| Common name | Scientific name |
|---|---|
| Trees and shrubs | |
| Ashe's juniper | Juniperus ashei |
| eastern redcedar | Juniperus virginiana |
| eastern white pine | Pinus strobus |
| honey mesquite | Prosopis glandulosa |
| juniper | Juniperus spp. |
| ponderosa pine | Pinus ponderosa var. brachyptera |
| Pinus pondersa var. scopulorum | |
| post oak | Quercus stellata |
| quaking aspen | Populus tremuloides |
| red pine | Pinus resinosa |
| Rocky Mountain juniper | Juniperus scopulorum |
| sagebrush | Artemisia spp. |
| Graminoids | |
| big bluestem | Andropogon gerardii |
| blue grama | Bouteloua gracilis |
| buffalograss | Bouteloua dactyloides |
| fescue | Festuca spp. |
| little bluestem | Schizachyrium scoparium |
| needlegrass | Achnatherum spp. and Nassella spp. |
| smooth brome | Bromus inermis |
| tall fescue | Schedonorus arundinaceus |
| western wheatgrass | Pascopyrum smithii |
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