Vegetation phenology response to climate change in China

This article reviews response mechanisms of vegetation phenology to climate change, clarifies impacts of vegetation phenological changes on carbon, water, and energy cycles of terrestrial ecosystems, and feedback mechanisms of vegetation phenological changes on local climate and the climate system through atmospheric circulations．The start of the vegetation growing season in China was found to have an advanced trend (about 1-6 d•(10 a)^–1), the end of the growing season has a delayed trend (about 2-5 d•(10 a)^–1), growing season significantly extended．Responses of vegetation phenology to temperature in mid-high latitudes are now significantly higher than in subtropical and tropical regions．Temperatures were found to play multiple roles in controlling vegetation phenology．Precipitation was found to mainly affect vegetation phenology in arid and semi-arid regions．Vegetation phenological changes (growing season prolonged, photosynthesis of vegetation greater than respiration, thereby fixing more carbon) were found to increase productivity of terrestrial ecosystems and increase China’s carbon sink．Vegetation phenological changes could adjust vegetation evapotranspiration, thereby changing China’s watershed-scale river runoff．Vegetation phenological changes have a negative feedback effect on climate system in most parts of China, and affect atmospheric circulation process．Therefore, temporal and spatial characteristics and trends of vegetation phenology provide reference for reducing emissions and increasing carbon in different regions of China．Although works on vegetation phenology in China have been done, certain uncertainties remain to be resolved．Future works should pay more attention to inversion accuracy of remote sensing data, clarify scale effect of phenological response to climate change, combine machine learning, manipulative experiments and ecophysiological methods to improve accuracy of phenology simulation．Also we should focus on crop phenology to ensure food insecurity, strengthen researches on combination of phenology and forest management to improve carbon sink capacity of ecosystem．We must face opportunities and challenges brought about by carbon neutrality．