Strategic differentiation of subcommunities composed of evergreen and deciduous woody species associated with leaf functional traits in the subtropical mixed forest

Abstract

The joint assembly of evergreen and deciduous tree species, typical karst vegetation of evergreen and deciduous broad-leaved mixed forests through respective subcommunities, play an important role in maintaining biodiversity in subtropical karst regions, and leaf functional traits can strategically specify plant resource utilization. However, it is unclear how these assembled subcommunities of evergreen and deciduous species maintain differentiation strategies. This study surveyed 53 forest plots of 20 m × 20 m dividing 212 adjacent lattices in a typical karst forest. Leaf traits of woody plants were measured regarding the specific leaf area (SLA), leaf dry matter content (LDMC), leaf tissue density (ltd), and leaf C, N, and P contents. The differences between deciduous and evergreen subcommunities were compared using the community-weighted means (CWM). The SLA and LDMC of the deciduous subcommunity were greater than the evergreen subcommunity; meanwhile, the leaf C, C/N and C/P ratios of the evergreen subcommunity were significantly higher than those of the deciduous subcommunity. However, the leaf N, P and N/P ratios of the deciduous subcommunity were significantly enhanced than the evergreen subcommunity. Moreover, both subcommunities showed significant negative correlations between SLA, leaf N and ltd, LDMC, signifying a trade-off of leaf-economic trait in deciduous and evergreen subcommunities. Furthermore, principal component analysis (PCA) on leaf functional traits specified the strategic differentiation mainly located at the side of the resource acquisition with high SLA and leaf N content for the deciduous subcommunity and situated at the side of the resource conservation with high LDMC and ltd for the evergreen subcommunity. In conclusion, the trade-off correlated with leaf functional trait differentiation suggested a resource acquisition strategy for the deciduous subcommunity and a resource conservation strategy for the evergreen subcommunity in the subtropical climate-dominating mixed forest of karst ecosystem.