Abstract Aim Following the near-complete destruction of China's forest ecosystems during the 20th century, recent reforestation programmes have created large-scale mosaics of protected secondary and plantation forests. These restored forests are often assumed to have limited biodiversity conservation value, but large-scale evaluations of their diversity are lacking. In our study, we compared α-diversity and species dissimilarity patterns of vascular plants and ground beetles (Coleoptera: Carabidae) in restored secondary and plantation forests to remnant mature forests across north-eastern temperate China. We also assessed functional traits of beetles and cross-taxon diversity links to evaluate differences in ecosystem functioning among forest types. Location . Northeast China. Methods Vascular plant and ground beetle assemblages were recorded in 159 temperate forest plots. The α-diversity and species compositional dissimilarity of these taxa and the functional traits of beetles were compared between plantation, secondary and mature forest ecosystems. Results Herbaceous plant species richness peaked in mature forests, while carabid and woody plant diversity did not differ between forest types. Species dissimilarity of carabids was lowest in mature forests and highest in plantation forests. Mature forest contained the highest proportion of carnivorous beetles and secondary forests of large-bodied carabids. Carabid diversity and woody plant species richness were positively correlated in mature forests, but not in secondary or plantation forests. Main conclusions While China's mature forests show a great conservation value in harbouring highly diverse herbaceous plant assemblages and an abundance of distinct invertebrate trait groups such as small predatory carabids, China's restored temperate forests also support a high diversity of woody plants and carabids. Overall, our findings offer an encouraging conservation message for biodiversity conservation in China and demonstrate the importance of policy measures that ensure effective long-term protection of both, China's remnant mature forests, but also its new forest ecosystems.