Knowing the variation patterns in plant functional traits and the correlations between different traits across scales have strong ecological implications for revealing the adaptation strategies of plants to the changing environment, and the underlying mechanisms of community assembly. Our objective is to explore variations and correlations of plant functional traits at the species and community levels in Cyclobalanopsis glauca community in the karst area of Guilin city in order to improve our understanding about community assembly mechanisms. We investigated species composition of 20 plots in Cyclobalanopsis glauca community in the karst area of Guilin city, Southwest China and quantified three continuous functional traits (leaf area, specific leaf area, and wood density) for 74 woody species in these plots. We calculated the species abundance-weighted mean community trait values and used trait-gradient analyses (TGA) to partition these three species functional trais into alpha (within site) and beta (among-site) components, and then used Pearson correlation coefficient to analyze the correlations between these three plant functional traits at different scales. The results show that the alpha trait components consistently varied more widely than beta components, meaning that trait variation among species within plots was wider than variation in the mean trait values of plots where species typically grow. The specific leaf area within species had lower variation than that in the community level. There were strong correlations between leaf area and specific leaf area, between specific leaf area and wood density, and between leaf area and wood density in the beta component, whereas no strong correlation or even no correlation was found between leaf area and specific leaf area, between specific leaf area and wood density, and between leaf area and wood density in the alpha components. This suggested that the relationship between plant functional traits within the community in which they occur is stronger than that between plant functional traits of co-occurring species within the community. Also, this implied that species adopted different strategies to adapt to the change in habitats within a community and between communities in Cyclobalanopsis glauca community in the karst area of Guilin city.