Abstract: Leaf functional traits, which reflect life history strategy of plant species, influence regeneration success and individual numbers. To explore the mechanisms of understory regeneration during vegetation restoration from the perspective of leaf functional traits, we investigated the canopy and regeneration layers of a near-natural forest on the Ecological Island at East China Normal University’s Minhang Campus. Nine leaf functional traits of dominant species in both layers were measured. Regression analysis and principal component analysis were employed to assess the interspecific differences in the number of regenerating individuals under the forest and their associations with leaf functional traits. The canopy comprised both evergreen and deciduous trees, while evergreen species were more prevalent in the regeneration layer. Species in both layers had higher leaf carbon/nitrogen and carbon/phosphorus ratios, and lower specific leaf area, nitrogen, and phosphorus contents than those presented in the canopy only. The density and dominance of species in the regeneration layer were negatively correlated with specific leaf area and leaf phosphorus content but positively correlated with leaf carbon/phosphorus ratio. The principal component analysis of leaf traits reflected a leaf economics spectrum along the first axis, with species scores on this axis negatively correlated with density and dominance in regeneration layer. This suggests that species favoring a slow investment-return strategy tend to have higher density and dominance. In summary, leaf economics traits reliably predict understory regeneration in urban near-natural forests, providing guidance for species selection in near-natural restoration of urban forests.

Key words: urban forest, understory regeneration, leaf economics spectrum, vegetation restoration