Variations of Quercus variabilis leaf traits in relation to climatic factors at regional scale

Leaf is the plant organ which is sensitive to the environmental changes in the process of evolution,and may exhibit phenotypic plasticity as a response to climate change. Quercus variabilis (Oriental oak) is one of the most widely distributed tree species in Asia,stretching from temperate to subtropical zone. With the leaf samples collected from 25 natural Q. variabilis populations across east-central China,this paper quantitatively investigated the leaf physiognomy,including petiole length,leaf length,leaf width,leaf area,dry weight,specific leaf area (SLA),and leaf index (ratio of leaf length to width),and correlated it with geographical and climatic factors at regional scale. The results showed that the leaf traits of Q. variabilis varied significantly within and among the populations. The leaf area and leaf width were significantly positively correlated with latitude,and the leaf width was significantly negatively correlated with mean annual temperature,which suggested that leaf area and leaf width were more sensitive to climatic variables,compared with other leaf traits,and temperature might have effects on the variation pattern of leaf size at regional scale. This study provided an understanding how Q. variabilis adapts to the changes in climate at regional scale in the context of global change.