Sampling and testing are conducted on groundwater depth and vegetation coverage in the 670 km² of the Sangong River Basin and semi-variance function analysis is made afterwards on the data obtained by the application of geo-statistics. Results showed that the variance curve of the groundwater depth and vegetation coverage displays an exponential model. Analysis of sampling data in 2003 indicates that the groundwater depth and vegetation coverage change similarly in space in this area. The Sangong River Basin is composed of upper oasis, middle ecotone and lower sand dune. In oasis and ecotone, influenced by irrigation of the adjoining oasis, groundwater level has been raised and soil water content also increased compared with sand dune nearby, vegetation developed well. But in the lower reaches of the Sangong River Basin, because of descending of groundwater level, soil water content decreased and vegetation degenerated. From oasis to abandoned land and desert grassland, vegetation coverage and groundwater level changed greatly with significant difference respectively in spatial variation. Distinct but similar spatial variability exists among the groundwater depth and vegetation coverage in the study area, namely, the vegetation coverage decreasing (increasing) as the groundwater depth increases (decreases). This illustrates the great dependence of vegetation coverage on groundwater depth in arid regions and further implies that among the great number of factors affecting vegetation coverage in arid regions, groundwater depth turns out to be the most determinant one.

The environment evolution of Wuliangsuhai wetland since 1986 is analyzed based on the remote sensing principle. The total water area of Wuliangsuhai lake has been increased during the past 17 years. The open water area had an increasing trend before 1987, and the trend was decreasing up to 1996, then the trend has increased again since 2000; the variation of the water area with dense aquatic weed is basically contradictory to the variation of open water area. The natural reed area had been decreased before 1987, and then it has been increased. The areas of shallow water and swamp have been slightly increased, in fact, the variations are quite steady. The artificial reed area has been increased since the reed plantation was started in 1988. The relationships of the water environment, the climate, hydrology and different types of areas are discussed, and then the technological measures for sustainable development and utilization of Wuliangsuhai lake water environment are proposed.

After dividing the source regions of the Yellow River into 38 sub-basins, the paper made use of the SWAT model to simulate streamflow with validation and calibration of the observed yearly and monthly runoff data from the Tangnag hydrological station, and simulation results are satisfactory. Five land-cover scenario models and 24 sets of temperature and precipitation combinations were established to simulate annual runoff and runoff depth under different scenarios. The simulation shows that with the increasing of vegetation coverage annual runoff increases and evapotranspiration decreases in the basin. When temperature decreases by 2^oC and precipitation increases by 20%, catchment runoff will increase by 39.69%, which is the largest situation among all scenarios.

A statistic analysis predicting coastal change of the Yellow River abandoned delta lobe formed from 1964 to 1976 using Landsat TM imagery was conducted by calculating the coastal erosion/accumulation rates obtained from four different classic profiles and plotting the change curves of coastline with time. The studies showed that the regularity of the evolution of the coastline was very obvious after the delta lobe was abandoned. The coastal evolution can be divided into three different phases: erosion phase, transition phase and cyclical change phase. At present, the coast has evolved to the cyclical change phase. The natural coastline change cycle is 4 years between the dam and is 5 years to the west of the dam. In the cyclical change phase, the quasi-equilibrium line of the coast was located near the coastline of 1996, the current coast may recede 1.79 km to reach the natural equilibrium coastline. Therefore, some measures must be taken to protect the dam or the dam will be destroyed by the force of nature. The curves also revealed the magnitude of erosion/accumulation rates would decrease gradually with time. The results of the study offer guidance for coast protection, and proves that the evolution of silty coast actually was a cyclical change process too.

By using GIS and remote sensing techniques, the paper discusses how human activities have changed along the Yellow River in Henan province, China and how these altered activities have influenced the wetland landscape pattern change from 1987 to 2002. Results show that the total area of the wetland reduces dramatically compared to 1987, the total area of wetland reduces by 19.18%, the number of the patches in 2002 increases by 21.17%, the density increases by 50%, and the total perimeter increases by 1,290,491 m. Disturbed by human activities, landscape diversity index decreases from 1.1740 in 1987 to 0.9803 in 2002. During the last 20 years, the total area of the rice wetland increases, while the others decrease. Among those, the area of the bulrush wetland decreases most. In 1987, it takes 0.5% of the total area, but in 2002, it only takes 0.11%. The interpenetration of human influences on the wetland natural system has been long and close. The impacts of human activities on the spatial pattern of the wetland landscape along the Yellow River in Henan from 1987 to 2002 are great.

The distribution of soil organic matter (SOM) and nitrogen on Gongga Mountain was studied in this paper. The results showed that the content of SOM and nitrogen (N) of A horizon had an ascending trend with the increase of the elevation. The vegetation types distributed higher than the mixed broad-leaved and coniferous forest have the irregular trends. In the transitional zone vegetation such as mixed trees and treeline, the content of SOM and N is higher than other vegetation types. The distribution of SOM and N of A horizon is dependent on the synthetic effect of climate and vegetation types. The vertical distribution of SOM and N in soil profiles has the similar trends for all kinds of vegetation types, i.e., the content of A horizon is higher than that of the B and C horizons, which is the same to the distribution of dead animal and plant in soil. The soil C:N is between 7 and 25, which is relatively low comparing to the appropriate C:N of 25-30. The ratio of soil carbon to nitrogen (C:N) increases with the increase of the elevation, but its vertical distribution in soil horizons varies with different vegetation types. The N exists in SOM mainly in the form of organic nitrogen, and the soil C:N correlates significantly with SOM.

With the long-term data of the geodetic sea level measurements undertaken in the Dongting Basin and the recent sediment data of Dongting Lake, we analyze the tectonic subsidence rate of the Dongting Basin and the sedimentary rate of Dongting Lake. From the point of view of geomorphology and hydrogeology, we distinguish the two different spatial concepts between "the basin of Dongting Lake" and "the Dongting Basin". Then, we discuss the influences of the tectonic subsidence and the siltation on the levees and the space of storing flood. The better quality of levees is required due to the tectonic subsidence and the siltation, and the difficulties of preventing flood disasters are increasing. The space of storing flood is not affected by the tectonic subsidence, but by the siltation. At present, the sedimentary rate of Dongting Lake is higher than the tectonic subsidence rate of the Dongting Basin. The tectonic subsidence capacity of the Dongting Basin counteracts a part of sedimentary capacity, and the shrinking tendency of Dongting Lake is restrained to a certain extent, but the tectonic subsidence is harmful to the situation of preventing flood disasters in the Dongting Lake area.

Sources of uncertainty or error that arise in attempting to scale up the results of laboratory-scale sediment transport studies for predictive modeling of geomorphic systems include: (i) model imperfection, (ii) omission of important processes, (iii) lack of knowledge of initial conditions, (iv) sensitivity to initial conditions, (v) unresolved heterogeneity, (vi) occurrence of external forcing, and (vii) inapplicability of the factor of safety concept. Sources of uncertainty that are unimportant or that can be controlled at small scales and over short time scales become important in large-scale applications and over long time scales. Control and repeatability, hallmarks of laboratory-scale experiments, are usually lacking at the large scales characteristic of geomorphology. Heterogeneity is an important concomitant of size, and tends to make large systems unique. Uniqueness implies that prediction cannot be based upon first-principles quantitative modeling alone, but must be a function of system history as well. Periodic data collection, feedback, and model updating are essential where site-specific prediction is required.

By means of SEDEX, ASPILA and XRF, depth-dependent changes of different phosphorus forms in sediment cores from specific areas of the offshore Changjiang Estuary (Yangtze Estuary) in 1998 were analyzed. Results show that contents of total phosphorus (TP), organic-phosphorus (OP) and iron-phosphorus (Fe-P) decreased down-core, while those of absorbed-phosphorus (Ad-P) and calcium-phosphorus (Ca-P) increased. The distribution tendency of detritus-phosphorus (De-P) is not obvious. Results also show that TP, Fe-P and OP contents at Meso station of the Changjiang Estuary and Hangzhou Bay are higher than that of the other stations. This suggests that the pollutants carried by the Changjiang and the Qiantang rivers from inland have affected the natural environment in offshore area. TP, Fe-P and OP contents of each station become higher from bottom to top, indicating the amount of the terrestrial pollutants carried by the two rivers has been enhanced since the last 30-50 years. Ad-P, Ca-P, Fe-P and OP are all active phosphorus in sediments, and their re-cycling in sediment is closely related to each other.

A near-distance, nonlinear coupling relationship objectively exists between urbanization and the eco-environment. The issue of how to coordinate the relationship between them has become a global strategic and scientific issue. This study reveals the nature, relationship and intensity of coupling between urbanization and the eco-environment from a theoretical perspective. Based on the strength of coupling, relationships can be characterized as having very-low, low, medium, high, very-high or full coupling intensity, which correspond to the categories of random coupling, indirect coupling, loose coupling, cooperative coupling, close coupling, and controlled coupling. Together, these make up an urbanization and eco-environment “coupling tower.” This study also develops an urbanization and eco-environment coupling circle theory and generates 45 coupling graphs (including linear, exponential-curve, logarithmic-curve, double exponential-curve and S-curve graphs) per 10° of rotation of the coupling circle, with different graphs corresponding to different urban development stages and development models. Of the various coupling graphs, the S-curve graph is considered the optimum, as it reflects the best interactivity scenario between urbanization and the eco-environment. Using an S-curve coupling graph, and with the help of an SD model and based on the complex one-to-one, one-to-many, and many-to-many relationships between the variables, this study develops the Urbanization and Eco-environment Coupler (UEC). The UEC is composed of 11 regulating elements and 201 variables. If one variable changes, it changes the whole, affecting the structure, function and regulation of the entire coupler. The UEC includes three spatio-temporal scales: static regulation between multiple urbanization areas and eco-environment areas at the same time, dynamic regulation between the same urbanization area and eco-environment area at different times, and dynamic regulation between multiple urbanization areas and eco-environment areas at different times. Regulation gradually promotes evolution from low-level coupling to high-level coupling between urbanization and the eco-environment.

As a special outcome of urbanization, mega-towns not only play an important role in the process of socio-economic development, but also are important contributors to urbanization. Based on a spatial database of mega-towns in China, this paper explores the spatial distribution features and growth mechanisms of China’s 238 mega-towns using the nearest neighbour distance method, kernel density estimation, regression analysis, global autocorrelation, local autocorrelation and other spatial analysis methods. Results of spatial distribution features show that: (1) on the national scale, the existing 238 mega-towns mainly gathered in the southeast coastal areas of China; they formed two spatial core agglomerations, several secondary ones and a southeast coastal agglomeration belt; (2) on the regional scale, each economic region’s index was less than 1, indicating that mega-towns in each region tended to be spatially agglomerated due to the close relationship with regional development level and their number; (3) on the provincial scale, 68% of provincial-level units in China tended to be a spatial agglomeration of mega-towns; only one province had a random distribution; the number of mega-towns in those evenly-distributed provinces was generally small. The growth of mega-towns was determined by a combination of various natural and humanistic factors, including topography, location, economy, population, traffic, and national policy. This paper chose digital elevation model (DEM), location advantage, economic density, population density, and highway density distribution as corresponding indicators as quantitative factors. By combining their local autocorrelation analysis, these factors all showed certain influence on the spatial growth of mega-towns and together scheduled it. In the future, provinces and cities should make full use of the mega-town functions to promote their socioeconomic development, especially the central and western regions in China.

The environmental ecology of the Yangtze River Economic Zone (YREZ) faces ecological function decline, deterioration and degradation under intense human activities, long-term development and utilization and its economy has developed rapidly over recent decades. Eco-efficiency is considered as a measure of coordinated development of economy, resources, environment and ecology, and is currently considered a very important issue. In this paper, based on the slack-based measure and data envelope analysis model, we take 129 prefecture-level cities of the YREZ as the study unit and measure the eco-efficiency of the YREZ in 2000, 2005, 2010 and 2015, which considers undesired output. The evaluation of the status quo of the regional eco-efficiency development was carried out at provincial, prefectural and city scales. The spatial autocorrelation test model and standard deviation ellipse were used to analyze the spatially distributed characteristics and the evolutionary regularity of eco-efficiency. Our study suggested that the eco-efficiency value varied significantly at different spatiotemporal scales and the overall distribution presented an “N-shaped” pattern, the value is the largest downstream and the smallest upstream. Regional eco-efficiency presented certain volatility in growth and a clear spatial positive agglomeration trend from 2000 to 2015. The spatial distribution of each agglomeration area was also significantly different, forming some high-high agglomeration areas at the center of the shaft with Shanghai and surrounding cities, and some low-low agglomeration areas at the center with middle reaches and upstream cities. The low-high over-aggregation and high-low polarization clusters were fewer. At the same time, with the change of the research period, the degree of positive agglomeration became increasingly pronounced and the eco-efficiency gap of the neighborhood unit reduced. The regional eco-efficiency value of the YREZ presented a spatial distribution pattern in the northeast-southwest axis and the evolutionary pattern of the regional eco-efficiency similarly showed a northeast-southwest orientation.

The railway is an indispensable feature of a nation’s infrastructure, and the gauge is an internal and objective technical regulation of the railway. In the large-scale regional space, the track gauges reflect the development differences, historical relations and mutual influences between countries and regions. This makes the railway, originally as a regional connection, have special social, political, military and other multiple attributes. Based on this, the paper, from the perspective of railway gauge, takes the Eurasian continent as the case region to explore the spatial pattern, formation mechanism and organizational mode of communication of the Eurasian continental railway geo-system. The results show that 11 kinds of railway gauge structures exist in Eurasia, which respectively belong to three types of wide-gauge, standard-gauge, and narrow-gauge, but the mainstream gauge only includes 1520 mm, 1435 mm and 1067 mm. Considerable variation in the coverage length and space range of different gauges is apparent, which provides a physical and technological basis for railway system differentiation and network fragmentation, which leads to the formation of eight railway geo-systems. Due to different modes for railway transport management in different geographical locations, the geographical pattern and geographical relationship of four transport organizations are formed. What especially important is the emergence of “1435 gauge space” and “1520 gauge space”, as well as the railway geo-space confrontation between them, on the Eurasian continent. Besides, we also find that the railway geo-system of Eurasia is mainly affected by the technology dissemination, path dependence, geopolitics, national defense and the colonial expansion of military latitude, and on this basis, five geo-modes of railway gauge propagation are formed.

There is a lack of basic theory and method to examine the effect of administrative division (AD) adjustment on the regional development. Based on the theory and practice of Chinese AD adjustments, the paper defined the concept of administrative region potential (ARP) and developed the quantitative model to measure the ARP. Then, the model was validated taking Chongqing as an empirical case. The results show that: (1) the ARP consists of energy of position (i.e., geographic space factors) and gravitational potential energy (i.e., administrative levels and management system factors). Administrative division adjustment can change the ARP, thereby changing its path and driving force of regional development. (2) The ARP model of Chongqing city can reflect the effects of administrative division adjustment events on the Chongqing city objectively. Specifically, ARP includes variables of land jurisdiction, human capital level, fixed assets investment capacity, administrative hierarchy of fiscal decentralization and administrative decentralization. (3) The ARP promotion has significant positive influence on the performance of local economic development in Chongqing city. (4) Reasonable AD adjustments will help the region integrate production elements and resources, enhance the political power of the city, improve its ARP, and then promote local economic development. The ARP model is proved to be an efficient way to understand and explain the regional effect of AD adjustment. It provides a new analytical perspective for the planning of AD adjustment in various regions, and can also be used as a practical method for assessing the effects of AD adjustment.

In this paper, meteorological industry standard, daily mean temperature, and an improved multiple regression model are used to calculate China’s climatic seasons, not only to help understand their spatio-temporal distribution, but also to provide a reference for China’s climatic regionalization and crop production. It is found that the improved multiple regression model can accurately show the spatial distribution of climatic seasons. The main results are as follows. There are four climatic seasonal regions in China, namely, the perennial-winter, no-winter, no-summer and discernible regions, and their ranges basically remained stable from 1951 to 2017. The cumulative anomaly curve of the four climatic seasonal regions clarifies that the trend of China’s climatic seasonal regions turned in 1994, after which the area of the perennial-winter and no-summer regions narrowed and the no-winter and discernible regions expanded. The number of sites with significantly reduced winter duration is the largest, followed by the number of sites with increased summer duration, and the number of sites with large changes in spring and autumn is the least. Spring advances and autumn is postponed due to the shortened winter and lengthened summer durations. Sites with significant change in seasonal duration are mainly distributed in Northwest China, the Sichuan Basin, the Huanghe-Huaihe-Haihe (Huang-Huai-Hai) Plain, the Northeast China Plain, and the Southeast Coast.

Farmland reforestation can contribute substantially to ecological restoration. Previous studies have extensively examined the ecological effects of farmland reforestation, but few of them have investigated the spatiotemporal responses of broad-scale landscape connectivity to reforestation. By using a typical agro-pastoral ecotone in northern China as a case study, we addressed this issue based on an innovative integration of circuit theory approach and counterfactual analysis. The forest connectivity through multiple dispersal pathways was measured using the circuit theory approach, and its spatiotemporal changes after reforestation were evaluated by counterfactual analysis. The results showed that from 2000-2015, the reforested farmland occupied 2095 km², and 12.5% was on steeply sloped land. Farmland reforestation caused a greater increase in ecological connectivity by adding new ecological corridors and stepping stones in scattered forest areas rather than in areas with dense forest distributions. The newly added corridors and stepping stones were fragmented, short and narrow and thus deserve powerful protection. Future reforestation to improve landscape connectivity should highlight pinch point protection and obstacle removal as well as the tradeoff between farmland loss and farmer survival. Our findings are expected to inform the optimization of the Grain for Green policy from the perspective of broad-scale biodiversity conservation.

The urban-rural transformation from dichotomy to integration is a gradual process. Like rural areas in many countries, Chinese rural society is experiencing a decline in all spheres due to depopulation, aging, lack of economic opportunity, and so on. Aiming at solving the serious rural issues, China proposed the implementation of a rural revitalization strategy and the promotion of an integrated urban-rural development for the first time in 2017. This proposal marks the transformation of the urban-rural relationship, and the integrated urban-rural development reflects a significant conceptual change. Researches on issues of rural decline are urgently needed to determine the most effective method for rural revitalization and development from the perspective of the urban-rural dynamics. In this context, this paper focuses on studying the theory, technology and management of rural revitalization and development. We construct a theoretical framework for urban-rural integration based on population-land-industry-right between the urban and rural systems, regarding land engineering for land capacity building as the technical support and the rural land system reform and reconstruction as the policy support for management. This research will provide theoretical support for the implementation of China’s rural revitalization strategy.

Investigating the spatio-temporal transmission features and process of novel coronavirus disease 2019 (COVID-19) mitigation strategies are of great practical significance to understand the development of COVID-19 and establish international cooperation for prevention and control. In this paper, the cumulative number of confirmed cases, number of confirmed cases per day and cumulative number of deaths, were used to compare transmission paths, outbreaks timelines, and coping strategies of COVID-19 in China and the US. The results revealed that: first, the COVID-19 outbreaks in both China and the US exhibited a 6-week initiation stage. In China, the COVID-19 erupted in late January. It lasted only a short period of time and was almost completely contained within 6-8 weeks. But the COVID-19 erupted in early March in the US and was still in the peak or post-peak stage. Second, in China, the COVID-19 emerged in Wuhan and spread to other regions of Hubei Province and then nationwide, exhibiting a cross(“+”)-shaped of spread with Wuhan city as the center. Importantly, the COVID-19 in China had a large concentration and there were no national outbreaks. In contrast, the COVID-19 in the US first spread through New York and the western and eastern coasts but has since emerged throughout the entire country. Third, the lack of emergency response planning in both countries in the early stage (about 6-week) hampered COVID-19 prevention. However, actively high-pressure prevention and control measures were used to basically control COVID-19 in early March in China. And then China has gradually resumed business and production activities. Unfortunately, the US government missed the best opportunity to contain the epidemic. Faced with the choice between economic recovery and coronavirus containment, the US removed the quarantine and restriction measures too early. The COVID-19 is continuing to spread in the country and blossom everywhere, still showing no signs of receding.

Population migration, especially population inflow from epidemic areas, is a key source of the risk related to the coronavirus disease 2019 (COVID-19) epidemic. This paper selects Guangdong Province, China, for a case study. It utilizes big data on population migration and the geospatial analysis technique to develop a model to achieve spatiotemporal analysis of COVID-19 risk. The model takes into consideration the risk differential between the source cities of population migration as well as the heterogeneity in the socioeconomic characteristics of the destination cities of population migration. It further incorporates a time-lag process based on the time distribution of the onset of the imported cases. In theory, the model will be able to predict the evolutional trend and spatial distribution of the COVID-19 risk for a certain time period in the future and provide support for advanced planning and targeted prevention measures. The research findings indicate the following: (1) The COVID-19 epidemic in Guangdong Province reached a turning point on January 29, 2020, after which it showed a gradual decreasing trend. (2) Based on the time-lag analysis of the onset of the imported cases, it is common for a time interval to exist between case importation and illness onset, and the proportion of the cases with an interval of 1-14 days is relatively high. (3) There is evident spatial heterogeneity in the epidemic risk; the risk varies significantly between different areas based on their imported risk, susceptibility risk, and ability to prevent the spread. (4) The degree of connectedness and the scale of population migration between Guangdong’s prefecture-level cities and their counterparts in the source regions of the epidemic, as well as the transportation and location factors of the cities in Guangdong, have a significant impact on the risk classification of the cities in Guangdong. The first-tier cities - Shenzhen and Guangzhou - are high-risk regions. The cities in the Pearl River Delta that are adjacent to Shenzhen and Guangzhou, including Dongguan, Foshan, Huizhou, Zhuhai, Zhongshan, are medium-risk cities. The eastern, northern, and western parts of Guangdong, which are outside of the metropolitan areas of the Pearl River Delta, are considered to have low risks. Therefore, the government should develop prevention and control measures that are specific to different regions based on their risk classification to enable targeted prevention and ensure the smooth operation of society.

Widespread aeolian deposits on the Tibetan Plateau (TP) have provided valuable palaeoclimatic information. However, the primary factors (e.g., climate factors, human activity, and vegetation cover) controlling aeolian deposition remain elusive. In this paper, we use a dataset that comprises new and published ages of Holocene aeolian sand and loess in the middle reaches of the Yarlung Zangbo River to identify the primary controlling factors and palaeoclimatic implications of aeolian deposition. Several intervals of enhanced aeolian accumulation centered at 8.5-7.8, 6.4-5.8, 4.5-4.0, 3.1-1.8, and 0.9 ka are identified, generally consistent with regional low rainfall events and weak Indian summer monsoon (ISM). This suggests that regional wetness, dominated by the ISM, may play a key role in modulating dust emissions and aeolian deposition on centennial timescales. Our results show that on centennial- to millennial-scales, ISM activity can be reconstructed by non-continuous aeolian deposits in the monsoon dominated TP.

Land use and land cover (LULC) alteration has changed original energy balance and heat fluxes between land and atmosphere, and thus affects the structure characteristics of temperature and humidity fields over urban heterogeneous surfaces in different spatio-temporal scales. Lanzhou is the most typical river valley city of China, it is chosen as the case study. Typical river valley terrain, rapid urbanization and severe air pollution have caused unique urban climate and urban heat island (UHI) effects in Lanzhou. Firstly, the spatial structure characteristics and dynamic evolution of temperature and humidity fields in autumn are simulated by mobile measurement experiment and GIS spatial analysis method. The results show that temperature and humidity fields have significant dynamic change within a day, and have multiple center and multiple intensity level characteristics. Then, LULC and normalized difference vegetation index (NDVI) are extracted from remote sensing images, the distribution patterns of temperature and humidity fields have close relationships with LULC and NDVI. Moreover, there is a significant positive correlation between impervious surface area and thermal field intensity. A positive correlation between NDVI value and humidity field intensity has been found as well as a negative correlation between NDVI value and thermal field intensity. Finally, heat fluxes and energy balance characteristics between ground and atmosphere are analyzed based on the Bowen-ratio System experiments. This study could provide theoretical support and practical guidance for urban planning, urban eco-environment construction and air pollution prevention of river valley city.

Since 2007, the Chinese government has initiated the building of national eco-cultural protection areas (NECPAs), thereby embarking on a signi?cant transformation of the model of intangible cultural heritage (ICH) protection in China. To understand the origin and outputs of this policy, this paper demonstrates the context of China’s NECPAs. It proposes a conceptual NECPA framework that mainly features regional overall ICH protection. This is followed by an examination of the case of Xiangxi in Western Hunan as a pilot zone for China’s eco-cultural protection. Xiangxi has performed much related work to promote NECPAs and made great progress in regional overall ICH protection. This insight suggests that there are bene?ts and costs associated with promotion of China’s NECPAs and regional overall ICH protection. Despite the advantages of institutional innovation, the unexpected side effects actually undermine the success of plan implementation.

The history of dune landform changes and dust activity at mid-latitudes is a good archive for exploring environmental changes and related landscape response. In this study, the dynamic changes, material sources, dust activity history and the influencing factors of typical sand dunes in the Hexi Corridor were comprehensively analyzed from the aspects of aeolian geomorphology, grain-size sedimentology, geochemistry and climatology. The results show that in the past half century, the typical crescent-shaped dunes and chains of crescent-shaped dunes in the study area have moved or swayed greatly, with an average speed ranging from 0.8 m/a (Dunhuang) to 6.2 m/a (Minqin). The dynamic changes of sand dunes are mainly affected by annual precipitation, annual average wind speed and annual gale days, which indicates that climate is the primary influencing factor of dune landform changes. The three-stage grain-size curve model of dune sands is obviously different from that of gobi sediments (two-stage), revealing the “immaturity” of the latter in sedimentology, while the former has experienced efficiently aeolian differentiation and non-local origin. The comprehensive evidences of paleogeography, sedimentology and geochemistry reveal that the source materials of sand dunes are mainly alluvial/proluvial and palaeo-fluvial sediments, including clastic sediments in the denudation/erosion zones of the north and south piedmonts. Indicators such as the proportion of surface fine particles, the coverage of surface salt crusts, and the content of erodible sandy materials indicate that the western gobi areas are not the main source areas of wind-blown dust in the central and eastern parts of the Hexi Corridor. The spatial distribution of the movement direction of sand dunes is similar to that of the regional dominant wind direction, which indicates that the difference in the dynamic evolution of dune landforms between the east and west of the Hexi Corridor should be controlled by the regional-scale wind system, that is, controlled by the dynamic mechanism rather than the difference in material sources. The warming and humidification of the Hexi climate is a synchronous response to the global warming and the strengthening of the Asian Summer Monsoon. It is also the main reason for the reduction of dust storms in the study area, which means that a potential inverse desertification process exists in the Hexi Corridor during the same period and it is also controlled by climate change. However, the process of desertification in the oasis areas during the period is caused by groundwater fluctuation affected by human activities.

The spatial distributions and variation mechanism of key soil indices in the Qinling-Daba Mountains are important indicators for the identification of the transitional effect and regional characteristics of the north-south transitional zone in China. This manuscript analyzes the spatial variations in soil organic carbon (SOC) and total nitrogen (TN) and corresponding relationships with major geographical factors based on spatial analysis and geostatistics considering data obtained from the Second National Soil Survey. The results indicate that the spatial distributions of the SOC and TN contents are consistent, and three high-content areas, one secondary high-content area and one low-content area are observed. High content values are located in the high-altitude regions of the Qinling-Daba Mountains and mountainous areas to the west of the Jialing River, the low-content area occurs on the north slope of the Qinling Mountains, and the secondary high-content area mainly encompasses both sides of the Hanjiang River and regions in the Qinling-Daba Mountains at altitudes below 1000 m. The SOC and TN contents vary between the above two ranges, with the gradual increase in content revealing a horn-shaped pattern. Considering the spatial variations and functions of vegetation, topography and climate factors, it is found that the SOC/TN range in the secondary high-content area remains consistent along the 1000 m contour line, the upper limit of the transitional mountain altitudinal belt, the 0°C isotherm line in January and the 24°C isotherm line in July. This region constitutes the main body of the transitional zone between the subtropical and warm temperate zones, and the northern boundary is roughly distributed along the Dujiangyan-Maoxian-Pingwu-Wenxian line to the west of the Jialing River and the 1000 m contour line on the southern slope of the Qinling Mountains, while the southern boundary occurs along the Dujiangyan-Beichuan-Qingchuan line to the west of the Jialing River and the 1000 m contour line on the northern slope of the Daba Mountains. SOC/TN spatial variation provides a reference for the demarcation of the subtropical and warm temperate zones, and further identification of the soil processes and ecological effects in typical regions can help reveal multidimensional transitional characteristics and variation mechanisms.

Studying an ecological restoration zoning process under the background of ecological security patterns is of great significance to the rapid adjustment and optimization of a landscape pattern. In this study, a remote sensing ecological index and a morphological spatial pattern analysis method were used to assess the quality of habitats and identify ecological sources in the city of Ningbo; ecological corridors, ecological pinch points, and ecological barrier points were extracted by using a circuit theory to construct ecological security patterns and ecological restoration zones. The results indicate: (1) There were 47 ecological sources, and 83 key ecological corridors in Ningbo, and the ecological land area was about 1898.39 km², accounting for 19.89% of the total study area. (2) The ecological source areas were distributed in “one patch and three belts”, and the low-resistance ecological corridors were concentrated in southern Yuyao city, western Haishu district, and central and western Fenghua district; the ecological network in the western and southern regions was dense. (3) There were four types of ecological restoration zones that need to be established, which were prioritized restoration zones, prioritized protection zones, key conservation zones, and general conservation zones distributed hierarchically from inner part towards outside. (4) Ninghai county, Yuyao city, and Fenghua district had large ecological land areas, however, prioritized restoration and protection zones in Ninghai and Fenghua were also large. The analysis results are expected to provide a reference for optimizing a territorial ecological space in a city.

Land ecological security (LES) is an important part of China’s ecological civilization construction, which plays a vital role in ensuring the sustainable development of its society and economy. Based on the Driving force-Pressure-State-Impact-Response (DPSIR) framework, this study quantified the spatiotemporal changes of LES in 28 counties of the southern Shaanxi Province from 2009 to 2018. The influencing factors of LES in Yangxian County were explored to clarify the mechanisms that rely on the land ecological advantages to develop organic agriculture and boost poverty alleviation. Results show that the LES of Yangxian always ranked in the top six in 28 counties of the southern Shaanxi region during 2009-2018. The LES in Yangxian increased from 0.385 in 2009 to 0.533 in 2018, and the LES level changed from relatively unsafe to safe. The indicators of rural per capita net income, grain output per unit area of arable land, and grazing intensity could explain 99.8% of the LES variance in Yangxian. Relying on ecological resources, Yangxian increased farmers’ income and boosted alleviation of poverty through innovative land policies, developing organic agriculture, and rural tourism. These findings will provide theoretical support and model reference for balancing ecological protection and poverty alleviation in restricted development zones.

Land use patterns (LUPs) are the form in which various land use types are combined spatially, evidently impacting soil water. However, the influence mechanism by which LUPs form remains unclear. In this study, the soil water content (SWC) in the 0-160-cm soil depth was observed in shrubland (SL), mature forestland (MF), grassland (GL) and young forestland (YF) sites on four slopes with different LUPs in the Yangjuangou catchment of the Chinese Loess Plateau. The SWC in SL-YF-SL (13.28%) was significantly greater than that in YF-MF (9.93%), MF-GL-YF (10.38%) and SL-MF (10.83%) and was temporally stable during the study period. The spatial distribution of SWC along the slope differed among the four LUPs. Vegetation characteristics and soil texture mainly determined the spatial variations in SWC in the shallow soil layers (0-40 cm), while topographic factors were the determinants in the deep soil layers (60-160 cm) as well as in the entire soil profile (0-160 cm). The significance of SWC differences among the various land use patterns increased with decreasing precipitation during the growing seasons. YF-MF (77.8 mm) and SL-YF-GL (73.9 mm) required more rainwater than SL-MF (68.2 mm) and MF-GL-MF (67.5 mm) to compensate for the loss of soil water on the monthly scale during the rainy season. Therefore, vegetation restoration should consider land use patterns on hillslopes for soil water conservation.

During the 21st century, artificial intelligence methods have been broadly applied in geosciences to simulate complex dynamic ecosystems, but the use of artificial intelligence (AI) methods to reproduce land-use/cover change (LUCC) in arid ecosystems remains rare. This paper presents a hybrid modeling approach to understand the complexity in LUCC. Fuzzy logic, equation-based systems, and expert systems are combined to predict LUCC as determined by water resources and other factors. The driving factors of LUCC in this study include climate change, ecological flooding, groundwater conditions, and human activities. The increase of natural flooding was found to be effective in preventing vegetation degradation. LUCCs are sensitive under different climate projections of RCP2.6, RCP4.5, and RCP8.5. Simulation results indicate that the increase of precipitation is not able to compensate for the additional evaporation losses resulting from temperature increases. The results indicate that grassland, shrub, and riparian forest regions will shrink in this study area. The change in grasslands has a strong negative correlation with the change in groundwater salinity, whereas forest change had a strong positive correlation with ecological flooding. The application of artificial intelligence to study LUCC can guide land management policies and make predictions regarding land degradation.