Testing phylogenetic signals and phylogenetic niche conservatism in plant functional traits following forest clear-cutting

Forest clear-cutting is a strong disturbance that reshapes plant community structure and functional strategies. In this study, we aimed to examine how woody plant functional traits respond to clear-cutting and whether these responses retain phylogenetic signals or reflect phylogenetic niche conservatism. We measured seven functional traits related to leaf and stem characteristics for 841 individuals belonging to 80 taxa in clear-cut and control plots in southern Korea. Phylogenetic signals were tested using Blomberg's K and Pagel's λ. Meanwhile, local indicators of phylogenetic association and phylogenetic principal component analysis (PPCA) were applied to assess local patterns and multivariate trait-phylogeny relationships. The results showed significant trait shifts, including reduced specific leaf area and increased leaf dry mass and stem dry mass. However, most traits lost overall phylogenetic signals after clear-cutting. Meanwhile, Quercus spp. and Rhododendron spp. exhibited significant local phylogenetic signals, indicating convergent responses among close relatives. PPCA showed no clear separation between clear-cut and control plots, yet could be distinguished between tree and shrub species along key trait axes. These findings suggest that strong disturbances weaken phylogenetic niche conservatism at the community level. Meanwhile, local phylogenetic structures and pre-adaptation shape early recovery pathways. Our study highlights the importance of integrating trait-based and phylogenetic approaches for forest restoration and long-term monitoring.