Abstract
BackgroundMany forests within the southern Appalachian region, USA, have experienced decades of fire exclusion, contributing to regeneration challenges for species such as oaks (Quercus spp. L.) and pines (Pinus spp. L.), and threatening the maintenance of oak-dominated forests in the future. While the use of prescribed fire as a forest management tool is increasing within this region, there remains a lack of information on the potential role of wildfire. A wildfire within the Daniel Boone National Forest, Kentucky, USA, provided an opportunity to investigate how wildfire affected forest vegetation response.ResultsWe examined the effects of fire severity, quantified using composite burn index (CBI), on basal area, stem density, and sapling recruitment for several key species. We also examined the effects of fire severity on understory species richness and illuminated the consequence of non-native species invasions following fire. Our results demonstrated a negative relationship between fire severity and basal area (stems ≥2 cm diameter at breast height; P ≤ 0.001), and a positive relationship with the recruitment of oak and pine saplings (both P ≤ 0.001), oak sapling density (P = 0.012), and non-woody understory species richness (P ≤ 0.001). We also found that increasing fire severity heightened likelihood of invasion by non-native species, specifically princess tree (Paulownia tomentosa [Thunb.] Siebold & Zucc. ex. Steud; P = 0.009) and Chinese silvergrass (Miscanthus sinensis Andersson; P = 0.028).ConclusionsWhere it is feasible, public land managers may be able to generate a range of fire severity during future prescribed fires that approximate some characters of wildfire. These fires, when implemented in southern Appalachian upland forests, may help recruit oaks and pines and boost their potential as future canopy dominants. However, the increased occurrence of non-native invasive species invasion following fire conveys the importance of targeted and timely eradication treatments before new populations of non-native species may become established or reproduce, contradicting the ecological benefits of fire.
Highlights
Many forests within the southern Appalachian region, USA, have experienced decades of fire exclusion, contributing to regeneration challenges for species such as oaks
In the southern Appalachians, Hagan et al (2015) found that wildfires that included moderate to high fire severity resulted in the mortality of large overstory trees, leading to increased sapling stem density, and that twice-burned plots experienced the greatest increases in oak stem density
We found that red maple sapling stem density and relative stem density were unaffected by fire severity nearly six years following a single wildfire, a study of prescribed fire on similar sites found that repeated prescribed fire resulted in significantly increased red maple sapling stem density (Poynter 2017)
Summary
Many forests within the southern Appalachian region, USA, have experienced decades of fire exclusion, contributing to regeneration challenges for species such as oaks In the eastern United States, fires ignited from natural and anthropogenic origins have been an important disturbance agent in the development of plant communities within the Appalachian region for millennia (Abrams 1992, Delcourt and Delcourt 1997, Delcourt et al 1998), in oak In contemporary southern Appalachian forests, overall fire frequency remains lower than historic levels with fire return intervals of 97 to 1196 years, while the area burned is increasing (Lafon et al 2005, Lafon et al 2017). Land managers are increasingly using prescribed fire in an effort to meet multiple management objectives in the Appalachian region (Brose et al 2001)
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