Relationships Between Leaf Traits Of Castanopsis Species And The Environmental Factors In The North-south Transect Of China

Based on the constructive species of Sub-tropical Evergreen Broad-leaved forest in the south part of North-South Transect of Eastern China—Castanopsis , this study firstly analysed the geographic distribution and community characteristics of main genus Castanopsis in China, and the relationships among different leaf functional traits and the relationships between plant functional traits and environmental factors. Furthermore, the adaptation strategy of Castanopsis species in response to environmental changes was explored, for better undersanding the relationships between plant functional traits and environmental factors.The results were shown as follows:(1) The leaf traits of genus Castanopsis were correlated with each other. Leaf photosynthetic capacity per unit _area (A_max^a) increased with the increase of leaf nitrogen concentration (N_area) and phosphorus concentration (P_area); While Leaf photosynthetic capacity per unit mass (A_max^m) decreased significantly with increase of leaf mass per mass (LMA) and leaf thickness (LT). LMA was positively correlated with leaf nitrogen concentration(N_area) (r=0.830,P<0.01) and phosphorus concentration(P_area) (r=0.468,P<0.01). Additionally, LMA of 99 evergreen broadleaved species in the Transect were positively correlated with LT (r=0.431, p<0.01) and leaf dry matter content (LDMC) (r=0.628, p<0.01).(2) Obvious correlations were found between leaf traits of Castanopsis species and environmental factors (such as mean annual temperature MAT, mean annual precipitation MAP, photosynthetic available radiation PAR). Leaf photosynthetic capacity per unit _area (A_max^a) decreased with increase of mean annual temperature (MAT) and increased with increase of photosynthetic available radiation (PAR), and LMA decreased with increase of mean annual temperature (MAT) and mean annual precipitation (MAP). However, no significant correlations were found between leaf N content, leaf P content of Castanopsis species and latitude, mean annual temperature.(3) As the ecological indicator for nutrient limitation, leaf N/P indicates the limit degree to the different nutrition elements in plant growth. The leaf N/P of genus Castanopsis was 8～16, which indicated that the growth of Castanopsis was N-limited rather than P-limited.(4) As for Castanopsis , A_max^a ranged from 9.73μmol m^-2s^-1 to 22.17μmol m^-2s^-1,A_max^m ranged from 17.94 nmol g^-1s^-1 to 223.33 nmol g^-1s^-1, LMA ranged from 51.58 g m² to 127.19 g m², N_mass ranged from 12.07 mg g^-1 to 21.74 mg g^-1,P_mass ranged from 0.88 mg g^-1to 3.05 mg g^-1,K_mass ranged from 5.45 mg g^-1 to 12.26 mg g^-1,N/P ranged from 8 to 16, LT ranged from 103μm to 648μm.