Effects of Tornado Damage, Prescribed Fire, and Salvage Logging on Natural Oak (Quercus spp.) Regeneration in a Xeric Southern USA Coastal Plain Oak and Pine Forest

摘要

Due in large part to fire exclusion, many oak-dominated (Quercus spp.) forests, woodlands, and savannas throughout eastern North America are being replaced by less diverse forest ecosystems. In the interior coastal plain of the southern United States, these forests are dominated in the mid- and understory by mesophytic species such as Acer rubrum L. and Liquidambar styraciflua L., which may eventually displace overstory oaks. Oak regeneration has been shown to respond positively to open canopies and prescribed burning. In 2008, a severe tornado damaged previously established study plots in a xeric oak and pine (Pinus spp.) forest in northern Mississippi. Some damaged and undamaged plots were treated with prescribed fire in 2010. Additional plots were established in damaged areas, and these plots were salvage-logged. Species composition and growth of saplings were measured to assess the impact of tornado damage and the treatments on oak regeneration. Tornado damage increased overall sapling densities, especially oaks, resulting in increased representation by upland oak species. In burned plots, oak saplings resisted damage and recovered from prescribed fire better than mesophytic saplings. Sapling densities, especially those of oaks, were lower in salvage-logged areas than in damaged areas that were not logged, resulting in greater dominance by saplings of mesophytic species. Results suggest that, on poor soils, oak regeneration requires damaged or thinned canopies and benefits from prescribed burning two years after canopy disturbance. In contrast, natural regeneration of oaks may be incompatible with salvage-logging, especially in areas that receive severe damage from wind.