Regulation of climatic variables and drought on vegetation dynamics in China from 2001 to 2020

Vegetation can reduce the adverse effect of climate change. Under the frequent droughts and global warming, it is critical to clear vegetation dynamics and response to climatic variables. However, it is unclear how drought and climatic variables affect vegetation dynamics. In this study, we used the vegetation condition index (VCI) to examine vegetation dynamics in China between 2001 and 2020. The average annual value of VCI had increased during the period of 2001 to 2020, and 90.63% of the study regions had a rising trend in VCI. A large portion of the area had a 3-month time lag between VCI and temperature and precipitation. The time-lag response of VCI to drought was mainly 9 months, with a cumulative effect on drought of 1 month and 12 months. The VCI of evergreen needleleaf forests (ENF), deciduous needleleaf forests (DNF), deciduous broadleaf forests (DBF), and mixed forests (MF) in northern China displayed long time-lag response to drought. Except for DBF in the north and DNF in the central south regions, the cumulative effect of drought on other forest VCI was great in northern China. Except for DNF, DBF, and MF in the central south and DBF in the southwest regions, drought had less time-lag effects on VCI for ENF, evergreen broadleaf forests (EBF), DNF, and MF in southern China. The cumulative effect of drought on VCI of forests in southern China was short. The responses of various types of the grassland and shrubland to drought were similar as those of forests. However, the time-lag effect of drought on grassland and shrubland VCI was shorter than that of forests, making the grassland and shrubland more vulnerable to the short-term cumulative effects of drought. The result of this study can help us understand how the vegetation responds to climate change and drought under global warming scenarios.