Assessing phylogenetic diversity metrics in terrestrial ecological restoration: global trends and gaps

Phylogenetic diversity (PD) metrics estimate community diversity through evolutionary relationships, yet their potential in restoration ecology remains underutilized. This study reviews the literature on ecological restoration of terrestrial vegetation to evaluate the use of PD metrics, focusing on their application, global trends, and existing research gaps. Most studies were conducted in the United States, China, and Brazil, primarily in temperate broadleaf mixed forests (36.36%) and tropical and subtropical moist broadleaf forests (33.33%). Half of the papers were based on observational studies of restorations, and the other half were experimental studies. Plant PD was the primary focus in 90.09% of papers, with grasses and trees being the most studied life forms. Standardized effect size of the mean pairwise distance and mean nearest taxonomic distance metrics were the most commonly used metrics. The majority of studies used PD as a response variable and restoration indicators (e.g. age, initial seed/seedling mixture, and restoration impact) as explanatory variables. Research bias toward grassland and limited studies in Africa and Oceania were noted. Future studies should broaden geographic coverage in restoration to provide a more comprehensive understanding of PD dynamics globally. Also, efforts should be made to expand the taxonomic scope beyond to capture the full spectrum of biodiversity in restoration assessments.