The key issues on plant phenology under global change
Plant phenology is an indicator of climate change.Both global warming and extreme climate lead to a critical change in plant phenological characteristics.It is of great importance to elucidate the evolution and mechanism of plant phenology in response to climate change.Natural plant phenological system contains the most direct and effective eco physiological evidences as a product of global environmental change,which acts as an important complement to instrumental records.Plant phenological performance is extensively considered as a series of life history strategies for plants in a changing environment,which is in general closely related to reproduction of plant population and maintenance of biological diversity.It is highly sensitive to climate change and displays fine adaptability to the change as well.The combination of current phenological database with historical phenological records provides a facility to reveal the coupling relationship between climate change and plant phenological cycle.Previous studies showed that long term located observation and relevant integrated analysis on plant phenological performance would help reveal the ecological adaptive characteristics of plant phonology,and assess the positive and negative feedbacks between plant phenology and climate change.With the rise of global change ecology in recent years,great efforts have been made on quantitatively assessing material production and carbon cycle in ecosystem in field of plant phenology,particularly underlying that interaction between plant phenological cycle and carbon cycle in ecosystem has become a hot issue.This paper summarizes major progresses in plant phenology under global change and proposes a few domestic and international hot issues in this field.The research interest of plant phenology has gradually shifted the focus from previous field observations and preliminary statistical analysis to current environmental outcome assessement and regulatory mechanism investigation of phenological cycle.The methodology of plant phenology has been upgraded from the superficial description on the response of plant phenological cycle to climate change to the coupling exploration on plant phenology at the multi scale and multi element scales.With the development of interdisciplinary research,plant phenology has been extended to a systematic evaluation on the impacts of phenological changes on ecosystems,climatic change,agricultural production and even human health.With these transitions,a few key issues has been raised accordingly,such as the differentiate contribution of atmospheric temperature and photoperiod to plant phenological cycle in different temperature belts,the nonlinear characteristics of the change in plant phenology versus climate change,the complexity of plant phenology at the community level,as well as the importance of crop phenology in agricultural ecosystems.It can be argued that the initiative of plant phenology would play a critical role in practical fields such as agricultural production,human health and landscape design,but also significantly boosts the progress in interdisciplinary research involved in ecology,climatology and geography.Finally,a few recommendations are proposed in terms to the construction of phenological observation network,the exploitation and application of new technologies and the integration of relevant research programs.