Recent studies suggest increased fire frequency may impair soil chemistry, but few studies have examined long-term effects of repeated, frequent prescribed fires on forest soil properties in the southeastern Coastal Plain, USA. In this study, forest soil chemistry at the 0–10 and 10–20 cm mineral soil depths of sandy surface horizons (Entisols and Spodosols) were compared among units burned 0, 4, 6, and 8 times between 2004 and 2015 and 0 and 20 times between 1978 and 2015 in a longleaf (Pinus palustris Mill.)–loblolly (Pinus taeda L.) pine savanna at the Tom Yawkey Wildlife Center (Georgetown, SC, USA). At the 0–10 cm soil depth, soil pH (p = 0.00), sulfur (p = 0.01), calcium (p = 0.01), iron (p < 0.01), manganese (p < 0.01), and aluminum (p = 0.02) treatment means differed (2004–2015). Calcium and manganese displayed positive, significant relationships and sulfur displayed a negative, significant relationship with increasing fire frequency (p < 0.05). However, correlation of these relationships was low (r² ≤ 0.23). Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the mean of the unburned compartment, sulfur (p = 0.01) and iron (p < 0.01) were less in soils from the burned compartments. At the 10–20 cm soil depth, soil pH (p = 0.01), manganese (p = 0.04), phosphorus (p = 0.01), potassium (p = 0.02), and iron (p < 0.01) treatment means differed (2004–2015). Potassium displayed a negative, significant relationship and soil pH displayed a positive, significant relationship with increasing fire frequency (p < 0.05). Correlation of these relationships was low (r² ≤ 0.16), however. Using linear contrasts to compare the mean of all fire treatments (20 fires from 1978 to 2015) to the unburned compartment, potassium (p = 0.00) and iron (p < 0.01) were less in soils from burned compartments. These results are inconsistent with studies suggesting that forest soil chemistry is substantially altered by increased fire frequency and support other studies from this region that have documented minimal or temporary soil chemical changes associated with frequent prescribed fires.

Decades of fire exclusion in the Southern Appalachian Mountains led to fuel accumulation and conversion from open oak-pine woodlands to closed-canopy mesic forests dominated by shade-tolerant hardwoods and shrubs that often do not support a diverse understory. Southern Appalachian forest managers and scientists recognize this and are implementing silvicultural treatments such as prescribed burning, mechanical treatments or a combination of these to restore forest structure. In this study, conducted at the Southern Appalachian Fire and Fire Surrogate Study site in Green River Game Land, North Carolina, we assessed the effects of four fuel reduction methods: burned 4x (B), mechanical treatment 2x (M), mechanical treatment 2x + burned 4x (MB), and control (C) on the changes in understory vegetation guilds from pretreatment to post-treatment years (2001–2016). The MB treatment was most effective at meeting the restoration objectives, as it resulted in increases in oak (Δ_MB = 23,400 stems/ha) and pine (Δ_MB = 900 stems/ha) stem density, importance value—calculated as the sum of relative cover and frequency—for graminoids (Δ_MB = 26.0), and density of oak stems >50 cm in height (Δ_MB = 7133 stems/ha). The B and M treatments were generally less effective, but nonetheless met a subset of the restoration objectives. The B treatment reduced ericaceous shrub cover (Δ_B = −1.2%) and increased oak stems 10–50 cm in height (Δ_B = 10,017 stems/ha), while the M treatment resulted in only modest increases of mesic hardwoods, specifically for yellow-poplar (Δ_M = 200 stems/ha) and blackgum (Δ_M = 200 stems/ha) as compared with other treatments, but significantly increased mountain laurel and rhododendron cover (Δ_M = 10.0%). Overall, these fire and fire surrogate treatments had some success in restoring understory structure, but our findings suggest a slow response in understory herbaceous vegetation.

The infrequent occurrence of large wildfires in the southern Appalachian Mountains over the last several decades has offered few opportunities to study their impacts. From 2000 to 2008, five wildfires burned a large portion of the area in and surrounding the Linville Gorge Wilderness in North Carolina. Areas were burned either once or twice. The response of acid cove and thermic oak plant communities (structure, cover, richness, diversity) was measured in 78 vegetation monitoring plots, established in 1992 and remeasured in 2010–11. Fire altered forest structure in both communities, resulting in the mortality of larger trees and increases in the abundance of smaller (<5 cm diameter at breast height (DBH)) stems. Burning twice decreased stem counts for mountain laurel (Kalmia latifolia) in both communities, whereas oaks (Quercus spp.) responded positively to burning twice in the thermic oak community. Table Mountain pine stem counts increased in acid cove and thermic oak communities burned once. Fire appears to promote princesstree (Paulownia tomentosa) invasion. Herbaceous species cover responded positively to fire (once or twice; both communities), with concurrent increases in woody species richness and diversity. Tree species composition in acid cove plots was not affected by burning, although some slight changes occurred in thermic oak plots burned twice.

The national Fire and Fire Surrogate (FFS) study was initiated more than two decades ago with the goal of evaluating the ecological impacts of mechanical treatments and prescribed fire in different ecosystems across the United States. Since then, 4 of the original 12 sites remain active in managing and monitoring the original FFS study which provides a unique opportunity to look at the long‐term effects of these treatments in different regions. These sites include California (Blodgett Forest Research Station), Montana (Lubrecht Experimental Forest), North Carolina (Green River Game Land), and Ohio (Ohio Hills). Although regions differed in ecosystem type (e.g., conifer‐ vs. hardwood‐dominated), the overall goals of the FFS study were to promote desirable, fire‐adapted species, reduce fire hazard, and improve understory diversity. Our study uses multivariate techniques to compare how these desired outcomes were maintained over the last 20 years and discusses whether we would modify the original treatments given what we know now. Our findings indicate that mechanical treatments and prescribed fire can promote desired tree species, mitigate potential fire behavior by reducing fuels and retaining larger‐sized trees, decrease tree mortality, and stimulate regeneration—effects that are still apparent even after 20 years. However, we also found that maintaining desired outcomes was regionally specific with western sites (California and Montana) showing more desirable characteristics under mechanical treatments, while the eastern sites (North Carolina and Ohio) showed more desirable characteristics after prescribed burning. The beneficial effects of treatment were also more apparent in the long term when sites followed up with repeated treatments, which can be adapted to meet new objectives and conditions. These findings highlight the FFS study as an invaluable resource for research and provide evidence for meeting long‐term restoration goals if treatments can be adapted to ecosystem type, be maintained by repeated treatments, and accommodate new goals by adapting treatments to changing conditions.

Background: Despite the widespread use of prescribed fire throughout much of the southeastern USA, temporal considerations of fire behavior and its effects often remain unclear. Opportunities to burn within prescriptive meteorological windows vary seasonally and along biogeographical gradients, particularly in mountainous terrain where topography can alter fire behavior. Managers often seek to expand the number of burn days available to accomplish their management objectives, such as hazardous fuel reduction, control of less desired vegetation, and wildlife habitat establishment and maintenance. For this study, we compared prescribed burns conducted in the dormant and early growing seasons in the southern Appalachian Mountains to evaluate how burn outcomes may be affected by environmental factors related to season of burn. The early growing season was defined as the narrow phenological window between bud break and full leaf-out. Proportion of plot area burned, surface fuel consumption, and time-integrated thermocouple heating were quantified and evaluated to determine potential relationships with fuel moisture and topographic and meteorological variables.Results: Our results suggested that both time-integrated thermocouple heating and its variability were greater in early growing season burns than in dormant season burns. These differences were noted even though fuel consumption did not vary by season of burn. The variability of litter consumption and woody fuelbed height reduction were greater in dormant season burns than in early growing season burns. Warmer air temperatures and lower fuel moisture, interacting with topography, likely contributed to these seasonal differences and resulted in more burn coverage in early growing season burns than in dormant season burns.Conclusions: Dormant season and early growing season burns in southern Appalachian forests consumed similar amounts of fuel where fire spread. Notwithstanding, warmer conditions in early growing season burns are likely to result in fire spread to parts of the landscape left unburnt in dormant season burns. We conclude that early growing season burns may offer a viable option for furthering the pace and scale of prescribed fire to achieve management objectives.