Legacy of thinning on woody species composition and structure in southern Appalachian Mountain hardwood forests: restoration implications

Abstract

In the Appalachian Mountains, Liriodendron tulipifera monocultures are widespread, with these forests lacking both species and structural diversity. In this study, we developed models that described the effects of thinning treatments, conducted almost 60 years ago, on the density, composition, and functional identity of the woody understory in L. tulipifera forests. The woody understory of these thinned L. tulipifera forests was diverse, with the small seedling (<1.4 m), large seedling (≥1.4 m and <2.54 cm dbh), and sapling (≥2.54 and <12.7 cm) layers possessing 38, 32, and 23 species, respectively. Although model performance was low to moderate (r 2 = 0.05-0.40), we found that legacy effects, alone or in combination with environmental variables, explained, in part, the variability associated with the density, composition, and functional identity of the small seedling, large seedling, and sapling size classes, with the relative influence of legacy versus environmental effects varying by metric and size class. Post-thinning basal area and/or percent of basal area removed were not the primary legacy effects influencing the woody understory. Instead, legacy effects associated with species composition of the overstory before and/or after thinning along with average stem diameter post-thinning, variation in stem diameter post-thinning, and age at the time of thinning were more influential than density or thinning intensity. This study provides evidence that conserving species diversity during forest management activities can have positive long-term effects on composition and function of the woody understory and increase restoration potential.

Teak (Tectona grandis Linn. f) and Edaphic Factors Affecting the Regeneration of Woody Species and Their Functional Traits in Economic Forest Plantation, Northern Thailand

“…Tinning has been applied to ecological restoration and is thought to be particularly efective at accelerating plant community recovery in some forests that were dominated by a single species [62,63]. Te timing of thinning has a greater infuence on plant regeneration than thinning intensity [64]. Te greater time since the thinning of teak in 30-and 40-year-old teak plantations changed microenvironmental conditions by increasing light levels in open canopy gaps, which improves conditions for the regeneration of fast-growing species with high SLA.…”

Stand and environmental conditions drive functional shifts associated with mesophication in eastern US forests

“…Although these broad scale analyses are useful in identifying trends, they do little to inform the drivers of mesophication at scales more meaningful to management (e.g., at the stand or watershed-scale). Without ecologically informed forest management practices, the functional transition associated with mesophication will likely continue, and may create conditions (e.g., reduced litter flammability; Kane et al, 2021) that make restoration increasingly difficult without considerable investment of resources, including multiple treatments that may include combinations of harvesting, fire, and herbicide conducted across many years and/or decades (Thomas-Van Gundy et al, 2014;Schweitzer et al, 2019;Keyser and Rodrigue, 2022). By understanding the fine-scale variability in mesophication, managers may begin to prioritize portions of the landscape most at risk and develop treatments that will effectively and efficiently slow or reverse this process.…”