###### Abstract
[16] compared this dataset with data from Ecosystem Model-Data Intercomparison (EMDI, obtained from the Oak Ridge National Laboratories) and 21 eddy flux measurement sites worldwide separately, yielding a high degree of consistency. China added 1.35 \(\times\) 10\({}^{6}\) km\({}^{2}\) of new leaf area from 2000 to 2017, constituting 25% of the world's net growth rate [17]. Meanwhile, with continued global warming, the northern boundary of the eastern subtropical and temperate zones in China has generally shifted northward, with profound effects on vegetation phenology [18]. Climate and vegetation changes in China can directly or indirectly alter its carbon sequestration and water cycle characteristics in terrestrial ecosystems [19]. Given the challenges of effective ecosystem management and addressing global change, a large number of studies have investigated the spatiotemporal variability of China's vegetation GPP and WUE in recent years, and their responses to climatic factors. For example, [PERSON] et al. [20] found that GPP in China increased significantly during 1982-2015 and the national GPP response to temperature was much higher than precipitation and radiation factors. [PERSON] et al. [21] concluded that GPP variations in China's 128 vegetated ecosystems were different and highly sensitive to both precipitation and temperature. Regarding WUE, [PERSON] et al. [22] divided China into eight different vegetation ecosystem zones and found an overall decreasing trend in WUE in China since 1982. Meanwhile, temperature had a greater influence on WUE across China, while specific humidity, precipitation, and short-wave radiation were only prominent in individual ecosystems. [PERSON] et al. [23] found that the WUE of China exhibited a slight upward trend since 2000, with precipitation influencing WUE to a greater extent than temperature. The above studies have established a foundation for understanding the state of GPP and WUE in China in a changing environment. However, due to the differences in spatiotemporal scales, climatic conditions and vegetation types, the interannual variation patterns of GPP or WUE and their responses to climatic factors varied among studies. Recent global examinations have reported the contradiction of GPP and WUE with aridity of different regions [24; 25]. [PERSON] et al. [16] also indicated that the responses of each vegetation ecosystem GPP and WUE to climate variables varied with the changes in hydrothermal conditions in different aridity gradients. Therefore, specific arid-humid zones can be delineated to further investigate the response of GPP and WUE to climatic factors for various vegetation types [26; 27]. For observing GPP and WUE in specific spatial regions, studies are available that document the patterns of variation between the GPP and WUE across ecosystems, latitudes, or elevations [28; 29]. It has been proposed that the frequency and intensity of aridity in northern, mid- and high latitudes will increase in the context of climate change. Drought can change both components (GPP and ET) of WUE, ultimately leading to its increase or decrease [30]. Studying the variation patterns of GPP and WUE in different drought gradients can lead to a better assessment of the response of the terrestrial ecosystem to climate change. Few studies in China have explored specific changes in GPP and WUE for various vegetation types in the context of different aridity gradients, and few have attempted to uncover the underlying mechanisms between climate change and these spatial variabilities [31]. There is a necessity to continue research in this important subject area. This not only enables a comprehensive exploration of spatiotemporal variability of GPP and WUE, but we also need to further our understanding of ecosystem responses to climate change as global drylands expand. The main objective of this study is to investigate the spatiotemporal variability of GPP and WUE in response to climate change under different arid-humid zones.