The Responses Of Plant Phenology To Air Temperature And Humidity Along The Urban-Rural Gradient In Shanghai,China

With the rapid development of social economy,the process of urbanization has greatly accelerated,urbanization on the one hand to bring great convenience to our lives,but on the other hand by the urbanization of urban heat island effect of the city changed the temperature,humidity,and other factors.Plant phenology as the most sensitive indicators of environmental changes,changes in environmental factors will make plant phenology changes.In this paper,continuous repeated photographic techniques were used to observe the phenology of 18 species in the urban and rural gradients of Shanghai in the spring of 2015(January-June).Based on the meteorological data of the study area,the effects of plant phenology on temperature and humidity and the Sigmoidal model was used to fit the percentage of phytochemicals of the plant with the accumulated temperature and cumulative absolute humidity to explore the relationship between temperature and humidity and plant phenology.The results are as follows:(1)The air temperature and absolute air humidity increased but with higher variations over time in the Spring and earlier Summer time.The air temperature in the central urban area was higher than that in the urban fringe and suburban area,while the absolute air humidity exhibited an inverse spatial pattern.(2)Temperature and humidity affected the phenophases of bud burst,leaf unfolding and flowering of each plant species.The phenophases of the plant living in central urban area were advanced than those in urban fringe and suburban area except the leaf unfolding in urban fringe was advanced than that in central urban area due to the absolute humidity reduction.(3)Logistic relationship was found between the accumulative temperature(?5?)and accumulative absolute air humidity and the rate of phenophase of bud burst,leaf unfolding and flowering,respectively for each plant species at three sites along the urban-rural gradient,which demonstrated that both air temperature and humidity influenced plant spring phenophases.These findings support the hypothesis of higher air humidity leads to earlier/later.