Interspecific Differences and Correlation among Leaf Structural Traits of Three Plant Seedlings of Lauraceae in the Mid-Subtropical Zone of China

Following manual collection of seeds stored in sand under low temperature and then cultivated in greenhouse, Machilus pauhoi,Cinnamomum camphora and Phoebe bournei (Lauraceae) seedlings from the mid-subtropical zone of China were transplanted to the common garden in the Jiangxi Dagangshan Forest Ecosystem Research Station.Interspecific differences and correlations in leaf size, leaf thickness, leaf volume, leaf tissue density, specific leaf area, leaf dry matter content, leaf nitrogen concentration, leaf phosphorus concentration, and ratio of nitrogen and phosphorus concentration of two-year old seedlings in the growing season were investigated to provide basic data and scientific reference material on the responses of the leaf functional traits to global climate change.Results showed that: (1) Among the three plant seedlings, leaf size, leaf thickness, leaf volume, leaf nitrogen content and ratio of leaf nitrogen and phosphorus concentration were highest in C.camphora, and leaf tissue density was lowest.Leaf tissue density, leaf dry matter content and leaf phosphorus concentration were highest in P.bournei,while leaf size, leaf volume, specific leaf size, ratio of leaf nitrogen and phosphorus concentration, and leaf nitrogen content were lowest.Specific leaf area was highest in M.pauhoi, while leaf thickness, leaf dry matter content, and leaf phosphorus concentration were lowest.Leaf thickness of the three plant seedling species showed no significant differences; (2) Pearson and line regression analyses indicated that leaf size showed highly significant positive correlation with leaf volume (P < 0.01), and highly significant negative correlation with leaf dry matter content and leaf phosphorus concentration (P < 0.01).The correlations between leaf size and leaf tissue density and leaf nitrogen concentration were significantly negative and positive, respectively (P < 0.05).The correlations between leaf thickness and specific leaf area and leaf dry matter content were significantly negative and positive, respectively (P < 0.05).The correlations between leaf volume and leaf tissue density and leaf nitrogen concentration were highly significantly negative and positive, respectively (P < 0.01).Leaf volume also showed significant negative correlation with leaf phosphorus concentration (P < 0.05).Leaf tissue density showed significant positive correlation with leaf phosphorus concentration (P < 0.05).Specific leaf area exhibited highly significant positive correlation with leaf dry matter content and leaf phosphorus concentration, respectively (P < 0.01).Leaf dry matter content showed highly significant positive correlation with leaf phosphorus concentration (P < 0.01).The nine leaf structural traits of the three plant seedlings of Lauraceae exhibited certain interspecific differences, but the order and significance were different.Furthermore, the correlations and significance of the nine leaf structural traits of the three plant seedlings were different.