# Responses to the Impact of Drought on Carbon and Water Use Efficiency in Inner Mongolia
###### Abstract
In recent years, remote sensing and data assimilation technology have developed rapidly, and the product data produced by using these technologies are rapid, macroscopic, and dynamic, which can overcome the shortcomings of traditional methods and enable the study of CUE and WUE to achieve a leap from points to the surface, providing the development of a new direction for research [20; 21]. For example, when [PERSON] et al. [22] and [PERSON] et al. [23] studied changes in CUE, they found that the CUE in sparsely vegetated areas had higher values than those in heavily vegetated areas. [PERSON] et al. [24] found that there is a high carbon sink in farmland ecosystems in semi-arid regions. Based on multi-model integration of NPP, ET data, and soil moisture data, [PERSON] et al. [25] analyzed the variation in global WUE and found that GPP dominated the variation in WUE in wet areas, while ET dominated the variation in WUE in arid areas. Temperature and precipitation are frequently used in studies of the variables influencing the CUE and WUE of vegetation because they have direct impacts on the nutrient cycle of plants [26]. It has been shown that temperature and precipitation have an approximate parabolic relationship with CUE, while there is a threshold effect on the effect of WUE [27]. Drought mitigation strategies also have the potential to significantly alter vegetation's CUE and WUE. Therefore, further studies are needed regarding the impacts of drought on dryland plants' carbon and water cycles, as well as its severity and longevity [28]. A typical arid and semi-arid region, Inner Mongolia has a delicate environment and is particularly vulnerable to climate change. Water resources in Inner Mongolia have been getting scarcer and more degraded over the past few decades as a result of both human activity and climate change. This has had a serious impact on the resilience of local ecosystems and the efficiency of the growth of vegetation, and its ecological and environmental issues have been receiving more attention. Studies on Inner Mongolia's changing plant cover, hydrological processes, and climate factors are becoming more in depth [29]. Meanwhile, the efficiency of different plant species in Inner Mongolia's climate in using water and carbon has received less attention. With the goal of better comprehending the underlying patterns of the carbon and water cycles of terrestrial ecosystems in Inner Mongolia and their response to drought, CUE, WUE, and DSI indices were calculated from 2001 to 2020,based on MODIS NDVI, GPP, NPP, ET, and PET data, and the spatiotemporal dynamics of CUE, WUE, and their responses to drought in areas with different vegetation cover were investigated by correlation analyses. This research aimed to better understand the interplay between the carbon and water cycles in arid and semi-arid terrestrial ecosystems in the context of global climate change and to serve as a scientific reference for the efficient administration of soil and water resources and the sustainable growth of Inner Mongolia's ecosystems. This study also seeks to shed light on the underlying patterns of carbon and water cycles in Inner Mongolia's terrestrial ecosystems and their responses to drought.