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Due to global warming and other climate changes, it is increasingly important to study the response of regional environmental changes and dynamic changes in vegetation to climate change. Based on meteorological data from the last 60 years, this paper calculates the humidity index of western China under a wide range of long time series in different regions and explores the cross-correlation effect between series by offering a comparison with NDVI data, to analyze the cross-correlation between wet and dry changes and changes in vegetation in western China on a spatial scale. The results show that the spatial distribution of the interdecadal humidity index is different between different regions in western China. For example, the semi-arid and the semi-humid zones of the Weihe River region exhibit significant changes, while the Xinjiang and Qinghai–Tibet regions show a trend of constant wetness, on the whole, and the Sichuan and Yunnan–Guizhou regions are relatively humid and the distribution of wetness and dryness is relatively stable. The distribution of high and low values of the humidity index is very obvious and consistent with that of the distribution of desert bare land and precipitation in western China. In common with the distribution in the humidity index, the maximum correlation number between the NDVI and the humidity index in the whole western region is also significantly different in spatial distribution. There is a positive correlation between the NDVI and the humidity index in 99% of the study area. However, the delay in response time of the NDVI to changes in the humidity index in each region is inconsistent. For example, changes in the NDVI lag changes in the humidity index in the Menggan region by generally either 2 months or 5 months, while in the Sichuan region the delay in response time is generally 3 months. The variation and trend in dry and wet areas are closely related to the geographical location, climate zone, and topographic terrain, which may be the reason for the differences in the distribution of vegetation types and the response time to dry and wet changes. There is significant interaction between the humidity index and the vegetation type or precipitation distribution in western China. The positive correlation between the NDVI and the humidity index means that the positive effect is more sensitive, and the response of grassland is the most sensitive in the ecosystem. [ABSTRACT FROM AUTHOR]

This paper quantifies urban land use eco-efficiency (ULUEE) and explores its improvement in the context of western China. We propose a hybrid model that includes the Super-slack-based measure model (Super-SBM) and a varying co-efficient panel model using data from 11 provincial cities in the western regions of China from 2000 to 2018. The results show that overall ULUEE, pure technical efficiency and scale efficiency were ecologically inefficient. Meanwhile, ULUEE differences between cities mainly reflect different levels of pure technical efficiency. Further, the linkage between urban population density and ULUEE can be expressed in inverted-U and U-shape curves, and most cities' industrial development positively affects ULUEE, while most cities' fixed asset investments negatively affect ULUEE. Moreover, land management institutions (LMIs) play a moderator role, shaping the main impacts of industrial development on ULUEE. Therefore, the findings suggest that improving ULUEE in the western region of China should focus on attracting inflows of highly skilled people, optimizing resource allocation, and guiding/regulating local government actions. [Display omitted] • Overall urban land use eco-efficiency (ULUEE), scale efficiency and pure technical efficiency of ULUEE are estimated and found to be eco-inefficient in the studied areas. • Slowing ULUEE improvement during the studied period results from slowing improvement of scale efficiency. • ULUEE differences between cities were mainly caused by pure technical efficiency. • LMI plays a moderator role in reducing the main impacts of industrial development on ULUEE. [ABSTRACT FROM AUTHOR]

• We analysed the influencing factors of urban eco-efficiency in Western China. • The US-SBM model and spatial econometric models were used for 84 cities' data. • Urban eco-efficiency showed a fluctuating upward trend during 2004–2017. • Economic development and urbanization had U-shaped impact on urban eco-efficiency. • Four explanatory variables showed a positive impact on urban eco-efficiency. Improving eco-efficiency can promote sustainable development. This study first evaluated the urban eco-efficiency of 84 cities in Western China from 2004 to 2017 by the undesirable-super-slack-based measure (US-SBM) and analysed their spatiotemporal characteristics, and then investigated its influencing factors using spatial econometric models. The results indicated that the urban eco-efficiency in Western China was at a relatively low level and showed a fluctuating upward trend with the highest average value of 0.65; however, capital cities of Western China have improved their eco-efficiency rapidly. Furthermore, there were obvious spatial spill-over impacts of the urban eco-efficiency in Western China. This paper also found that both the economic development level and urbanization level have "U" shaped impacts on Western China's urban eco-efficiency, which decreases at first and then rises. Similarly, increasing the proportion of secondary industry promotes urban eco-efficiency, and FDI, trade activities, improved environmental regulations as well as technological innovation capabilities have a positive impact on urban eco-efficiency in Western China. This paper also put forward corresponding policy suggestions to promote Western China's urban eco-efficiency. The present study may be helpful for policy-makers to balance economic development and environmental protection in Western China. [ABSTRACT FROM AUTHOR]

Since the implementation of the great western development strategy in 2000, the ecological environment in the western region of China has been significantly improved. In order to explore the temporal and spatial characteristics of vegetation coverage in the western region, this paper adopted the method of Maximum Value Composite (MVC) to obtain the mean Normalized Difference Vegetation Index (NDVI) of vegetation on the basis of the Moderate-resolution Imaging Spector audiometer (MODIS) data of 2000/2005/2010/2015/2018. Thereafter, the spatio-temporal differentiation characteristics of vegetation in western China were analyzed. The results show that: (1) According to the time characteristics of vegetation coverage in the western region, the average annual NDVI value of vegetation coverage in the growing season in the western region fluctuated between 0.12 and 0.15, among which that of 2000 to 2010 fluctuated more greatly but did not show obvious change trend. (2) Based on Sen trend and Mann-Kendall test analysis, the area of vegetation coverage improvement in the western region from 2000 to 2018 was larger than that of significant vegetation degradation. (3) From the perspective of global autocorrelation coefficient, Moran's I values were all positive from 2000 to 2018, which indicates that the vegetation coverage in the west showed strong positive autocorrelation in each period. According to the average value and coefficient of variation of vegetation coverage, the vegetation coverage was lower in 2000, its internal variation was smaller, and the vegetation coverage increased with time. According to the local spatial autocorrelation analysis, the vegetation coverage levels in different regions varied greatly. (4) The standard deviation ellipse method was used to study the spatial distribution and directional transformation of vegetation. It makes the result more intuitive, and the three levels of gravity center shift, direction shift, and angle shift were considered: the vegetation growth condition in the spatial aggregation area improved in 2015; the standard deviation ellipses in 2000 and 2018 overlapped and shifted eastward, which indicates that the vegetation coverage conditions in the two years were similar and got ameliorated. [ABSTRACT FROM AUTHOR]