Impacts of repeated wildfire on long-unburned plant communities of the southern Appalachian Mountains

Abstract

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.

Post-wildfire recovery of an upland oak−pine forest on the Cumberland Plateau, Kentucky, USA

“…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. The authors attributed the increase in sapling density to the mortality of large overstory trees, vigorous resprouting, and the establishment of new individuals (Hagan et al 2015). Similarly, following a wildfire in a table mountain−pitch pine forest in the southern Appalachians, areas that burned with high fire severity experienced nearly complete stand mortality (Groeschl et al 1992).…”

“…For instance, Kuddes-Fisher and Arthur (2002) found increased native herbaceous species richness following a single moderate-severity, late-winter prescribed fire on ridgetops within an oak−pine forest. In another oak−pine-dominated forest within the Appalachian region, total species richness increased following a single wildfire, in which upper slopes and ridges burned with high severity, and also increased in areas twice-burned by wildfire; however, the greatest increases in species richness occurred in areas burned twice (Hagan et al 2015).…”

“…In addition to the effects of fire on individual tree species, the alteration of forest structure may result in increased light availability and decreased vegetative competition in the understory, leading to greater resource availability at ground level (Reilly et al 2006, Zouhar et al 2008. Thus, fires that burn across a range of fire severity may promote increased species richness (Reilly et al 2006, Hagan et al 2015. For instance, Kuddes-Fisher and Arthur (2002) found increased native herbaceous species richness following a single moderate-severity, late-winter prescribed fire on ridgetops within an oak−pine forest.…”

Repeated Application of Fuel Reduction Treatments in the Southern Appalachian Mountains, USA: Implications for Achieving Management Goals

“…Predictive models suggest that these wildfires would be very intense and have rapid spread rates (Waldrop et al 2010). If such fires were to occur, desirable levels of overstory mortality, herbaceous layer establishment, and oak regeneration could result (Hagan et al 2015). However, relying on a wildfire to meet restoration objectives is not recommended.…”

Forests, shrubs, and terrain: top‐down and bottom‐up controls on forest structure

“…Increased evergreen understory may also have led to changes in leaf litter chemistry, decomposition rates, and other ecosystem properties (Monk et al 1985, Wurzburger and Hendrick 2007. Kalmia latifolia impacts on tree regeneration are less well studied, but it is generally the most common evergreen understory species on xeric sites in the southern Appalachians, and it also appears to suppress overstory tree regeneration (Moser et al 1996, Arthur et al 1998, Waldrop and Brose 1999, Abella et al 2003, Elliott et al 2009, Hagan et al 2015, Brose 2016.…”