Across the past hundred years, most land managers did everything they could to suppress fires despite evidence that fires sustain structure and biodiversity in many fire-dependent ecosystems. Climates have also started to change at unprecedented rates. Understanding how plant communities respond to these changes is crucial for biodiversity conservation. Pine barrens in central Wisconsin provide habitat for many endangered species and have experienced both fire suppression and climate change over the past half-century. Using historical baseline data from 1958, I investigated the effects of fire suppression and climate change on these communities. I tested whether, how, and why plant taxonomic and functional composition of these communities have changed over the past 54 years. I also assessed how well measured functional traits serve to explain the community phylogenetic patterns observed in these communities. The structure and composition of these communities have changed dramatically over the past 54 years. These communities are succeeding into closed-canopy upland forests from fire-maintained pine barrens. Shade-tolerant plants have replaced fire-adapted ones in both the over- and understory. As increases in mid- and late-successional species exceed declines in the original xeric ones, local plant species richness and functional diversity have both increased, by 12% and 15%, respectively. This may be temporary, with likely risk of losing local species and functional diversity. Nevertheless, like other communities in Wisconsin, these pine barren forests are converging in composition (biotic homogenization) with declines in both taxonomic and functional beta diversity (24.1% and 35.3%, respectively). Increases in canopy coverage and native species have driven most of the taxonomic biotic homogenization but fire suppression and climate change interacted to change local functional diversity. Many measured functional traits still cannot account for all the phylogenetic signal in species abundance, suggesting that phylogenetic information should be included to fully understand patterns and processes underlying community dynamics. Overall, this research provides insights into long-term dynamics of pine barrens in central Wisconsin, which can be used to inform land management and anticipate likely changes under future climate change and fire management. It also demonstrates the importance of traits and phylogenies when studying plant communities.