Effects of seasonal variability of climatic factors on vegetation coverage across drylands in northern China

The relationships between vegetation and climatic factors are extremely complex and nonlinear. To identifying these relationships across the drylands in northern China, we analysed the driving effects of air temperature, precipitation, actual evapotranspiration, and reference crop evapotranspiration (i.e., potential evapotranspiration) on the seasonal variability of the leaf area index (LAI) in various locations including Horqin, Hulun Buir, Otindag, Mu Us, Tengger, and Junggar by using convergent cross mapping and multivariate empirical dynamic modelling based on meteorological datasets of 421 stations and remote sensing datasets at 8-day intervals during 2000 to 2014. Over the study period, the strengths of the driving effects of the climatic factors on LAI were related to their own seasonality. Except in Junggar, the sensitivity of LAI to the climatic factors weakened with decreases in the aridity index, and these relationships changed over different seasons, but LAI was most vulnerable to the effects of climatic factors in the early growing season. Our results show that vegetation in the eastern drylands (e.g., Horqin, Hulun Buir, and Otindag) of northern China is more sensitive to seasonal climatic variations than that in the western drylands (e.g., Mu Us and Tengger), which suggests that vegetation in the eastern drylands may face greater risks of degradation under climate change. On the basis of our results, we recommend the application of differential management strategies for the drylands in northern China to prevent ongoing desertification and to achieve the target of land degradation neutrality by 2030.