Temperate forests of eastern North America have been transformed by centuries of disturbance. Before European Colonization, these oak- (Quercus spp.) and pine-dominated (Pinus spp.) forests were maintained by recurring fires, which have declined as forests recovered from clearing and logging. Today, forests are transitioning from oak dominance to increasing dominance by mesophytic species due to long-term fire exclusion—a hypothesized process termed “mesophication.” However, alternative explanations exist, and these focus on biogeochemical mechanisms. For instance, elevated atmospheric nitrogen deposition has been implicated in the increasing dominance of arbuscular mycorrhizal (AM) trees over ectomycorrhizal (ECM) trees. Additionally, exotic earthworm introductions appear to favor tree species that produce nutrient-rich, palatable litter over those that do not. As these hypotheses have been investigated independently, it is unclear whether fire exclusion and biogeochemical processes contribute to the same species transition. Further, it is unclear how the return of fire, either wildfire or prescribed, affects these forests under transition. Here, I sought to fill these knowledge gaps. First, I characterized wildfire effects, after a century of fire exclusion, on soil fauna communities and litter decomposition in a southern Appalachian forest undergoing mesophication. I found that wildfire altered fauna communities in litter, but not soil, and sped litter decomposition, and that detritivores were more abundant in mesophytic and AM-dominated forests. Second, I considered how forest change in the eastern United States might be due to both fire exclusion and biogeochemical changes. I found relationships between fire-adaptations and nutrient conservation across tree species and across forests of the region. I proposed a framework that expands the mesophication hypothesis to consider soil biogeochemical processes, which together reinforce forest change and resist a return to the former state. Third, I analyzed data from a 20-year, forest management experiment in the southern Appalachians in which three strategies were compared to untreated controls, to determine which may return forests to oak dominance. I found that basal area reduction through combined mechanical felling and repeated prescribed fires increased sapling-stage oak abundance. Together, this work integrates multiple frameworks of forest change towards the ultimate goal of understanding how to best manage these ecosystems.