Variations in leaf traits of native and introduced tree species in Cunninghamia lanceolata plantations

Leaf traits of plants play crucial roles in determining resource utilization and survival strategies. Single-layered monoculture plantations are converted to multi-layered mixed plantations is an effective measure to improve plantation quality. To study the variation of the leaf traits of introduced and native species is beneficial to select the associated tree species under forest. This study assessed the traits of leaf morphology, photosynthetic pigments, carbon, nitrogen and phosphorus ecological stoichiometry, and non-structural carbohydrates of introduced arbors and shrubs species(such as Phoebe bournei and Distylium racemosum) and native arbors and shrubs species(such as Castanopsis sclerophylla and Callicarpa rubella). The results showed that leaf length and specific leaf area of native arbors were significantly smaller than those of the introduced species and native shrubs, and the other leaf morphological traits were little difference between introduced and native species. Photosynthetic pigment content differed markedly between the introduced and native species, and the chlorophyll content of native arbors was significantly lower than that of the introduced arbors. The relationship of specific leaf area and chlorophyll varied among different functional groups. The leaf carbon content of the introduced tree species was distinctly higher than that of the native tree species, and the leaf nitrogen and phosphorus contents were significantly higher than those of the native arbors. The coefficients of variation of nutrient contents of the introduced species and native shrubs were higher than that of the native arbors. The variations in leaf carbon, nitrogen, and phosphorus eco-stoichiometry differed in the introduced and native tree species. The soluble sugar content in the introduced shrubs and the starch content in the native shrubs were markedly higher than those of arbors, and the content of the non-structural carbohydrates in the shrubs was distinctly higher than that in the arbors. The leaf traits of the introduced and native tree species showed a significant synergistic change. For the arbor and shrub species, there was a marked positive correlation among the leaf area, chlorophyll content, and leaf nitrogen and phosphorus contents. Based on principal component analysis(PCA), the leaf traits were similar between the introduced arbors and shrubs. The differences of leaf traits were relatively smaller between introduced tree species and native shr