This study attempts to measure the eco-environmental effects of land use transformation in northwest China from 2000 to 2020 based on the perspective of land “production-living-ecological” function. For this, the study employs the eco-environmental quality index and ecological contribution rate model, and comprehensively uses hot-spots analysis tool, Geo-detectors tool, and other methods to discuss the evolution characteristics and differentiation mechanism of eco-environmental quality. The findings of this study show: (1) The “production-living-ecological” space in northwest China shows significant spatial differentiation, indicating an increasing trend of production and living space and a decreasing trend of ecological space. (2) The eco-environmental quality index increased from 0.22720 in 2000 to 0.22724 in 2010 and then decreased to 0.22699 in 2020, although the overall eco-environmental quality remained relatively stable. The change in eco-environmental quality exhibited both improvement and deterioration. The improvement of eco-environmental quality mainly depends on the protection of regional ecological space, while the deterioration of eco-environmental quality is that agricultural production land occupies ecological land in pastoral areas. (3) The eco-environmental quality is spatially characterized by “high in the southeast, second in the northwest, low in the middle”. The cold-spots and hot-spots in the evolution of the eco-environmental quality pattern are mainly concentrated in the southeast and northwest regions and have the same spatial distribution as the population and industry in the area. (4) The proportions of ecological land use, normalized vegetation index, and human active index were the leading factor of spatial differentiation of eco-environmental quality; the interactions between the influencing factors mainly include nonlinear enhancement and bi-factor enhancement. The internal interaction of natural factors and the interaction between natural factors and socio-economic factors affected the spatial differentiation characteristics of eco-environmental quality in northwest China. The results of this study may provide a theoretical basis for the optimization of the national land spatial pattern and ecological environment protection in northwest China.

There are more than 54 spots of Danxia landforms in Shaanxi Province, northwest China, which are distributed in the Weibei Uplift and Yishan Slope of the Ordos Basin. In terms of landscape, both positive and negative Danxia landforms have considerable regional differentiation from southwest to northeast of the province. The sandstones of aeolian desert facies with mainly near horizontal or gently inclined Danxia occurrences are the most widely distributed. They are characterized by gully Danxia, wave Danxia, and colored hills, and most of them are in their early stage. The spatial structure type of Danxia landform distribution in Shaanxi Province is condensed, with two high-density areas (Ganquan-Zhidan-Ansai-Fuxian Danxia area and Yulin Jingbian Danxia area), one medium-density area (Zhaojin-Xunyi-Binxian Danxia area), and two low-density areas (Baoji Jiulongshan area and Fugu Lianhuachan area) according to the nearest neighbor index and nuclear density analysis methods. From the viewpoint of the formation mechanism, Mesozoic sedimentation in the Ordos Basin laid the material foundation for the Danxia landform, regional tectonic evolution controls the distribution of positive and negative landforms, and characteristics of joints and fissures are critical in the landscape pattern of the Danxia landform, and water and wind erosions are the leading forces shaping the landscape form of the Danxia landform.

Arid and semi-arid areas account for approximately 47% of China’s total land area. Most of these areas are deserts, with simple ecological structures and fragile ecosystems. To evaluate the ecological quality of arid and semi-arid areas more objectively and accurately, this study improves the remote sensing ecological index (RSEI), and proposes a drought remote sensing ecological index (DRSEI) suitable for arid areas, which is a coupling of five ecological factors, namely, soil-adjusted vegetation index, wetness, normalized difference built-up and soil index, desertification index, and land surface temperature. DRSEI is more sensitive to vegetation and has a higher resolution to impermeable water surfaces, land, and sandy land than RSEI, which is suitable for ecological quality assessment in arid and semi-arid areas. DRSEI was used to dynamically monitor and evaluate the ecological quality of Gulang County, Gansu Province, China from 1994 to 2020. The results show that the overall ecological quality of Gulang County improved from 1994 to 2020, increasing the vegetation coverage in the central and southeast regions and considerably improving the ecological environment. The northern Tengger Desert has poor ecological quality, whereas the eastern branches of the southern Qilian Mountains have excellent, good, and middle ecological quality. The quantitative evaluation of the ecological quality in the arid and semi-arid areas based on DRSEI is of great practical significance for guiding the ecological environment improvement and sustainable development in the arid and semi-arid areas in China.

The Gurbantunggut Desert (GGD), the largest fixed and semi-fixed desert in northwestern China, is the region most obviously affected by westerly circulation in China. Holocene environmental evolution and its response to global climate change have important scientific significance in understanding the modern surface process and future environmental evolution trends in the GGD. The previously studies on the Holocene environmental evolution of the GGD and its surrounding areas are controversial: some studies have concluded that optimal periods of precipitation/humidity happened in the Middle-Late Holocene, while others concluded that the optimal periods occurred in the Middle Holocene and that the genetic mechanism is in dispute between the monsoon intruding inland and the overall control by the westerly. This study reconstructs the Holocene climate/humidity variation using dimensionality reduction and integrated analysis based on the multiarchive records published in the study area, and synthesizes the Holocene aeolian sand activity history by sorting out the chronological distribution of the regional aeolian sedimentary stratigraphy. The coupling relationship between regional aeolian activity and humidity change is also examined. The results show that the early Middle Holocene (12-6 ka) in this area was arid, with considerable aeolian activity; the humidity gradually increased and the aeolian activity gradually weakened from the Middle to the Late Holocene. According to the comparative analysis on the regional and hemispheric scales, it is concluded that the environmental evolution process in the GGD is mainly controlled by the westerly circulation.