Leaf and male cone phenophases of Chinese pine (Pinus tabulaeformis Carr.) along a rural-urban gradient in Beijing, China

Abstract Numerous studies have shown that plant phenology has advanced due to urbanization. However, large uncertainties remain because different indicators and methods have been used to characterize plant phenology. In this study, by means of photograph identification and logistic curve fitting, the phenophases of leaves and male cones of Chinese pine ( Pinus tabuliformis Carr.) were divided into seven and six phases, respectively. The rural-urban gradient in phenology of leaves and male cones varied significantly in ranges of 0.36–1.92 and 0.41–0.66 days/km, respectively, depending on the phenophase defined. Interestingly, the rural-urban gradient of leaf phenology increased with leaf development. Thus, fine separation of phenophases is necessary to provide more precise criterion for assessing urbanization-induced plant phenology across different studies or regions. For Chinese pine, the timings of maximum leaf elongation rate achievement and male cones maturation were key phenophases for investigating the effect of urbanization.