Safe and just operating spaces (SJOS) are influenced by complex cross-scale interactions and cascading effects spanning global, regional, and local landscape scales. However, existing SJOS research has often focused on single-scale assessments, overlooking the impacts of multiscale interactions and within-region heterogeneity on urban SJOS. To address this gap, we developed a cross-scale framework for assessing urban SJOS, explicitly incorporating top-down influences from upper-level constraints and bottom-up effects from lower-level heterogeneity. This approach was applied to China's five major metropolises to examine the states and cross-scale dynamics influencing urban SJOS between 1990 and 2020. Our findings reveal that the SJOS of China's metropolises were primarily influenced by factors at national and local landscape scales, with weaker influences from the global and continental scales. A persistent trade-off between social justice and environmental safety was identified across spatiotemporal scales. For instance, Chongqing in southwestern China lagged behind the eastern four metropolises in social performance but exhibited stronger environmental safety due to its extensive natural landscapes, which mitigated the anthropogenic impacts of urban centers. Regional issues, such as the overshoot of PM2.5 and ecological footprints (EF), were primarily driven by the bottom-up accumulation of localized pressures, while the overshoot of CO2 was attributed to national policy constraints and the universal exceedance of safe thresholds across scales. Addressing urban sustainability requires avoiding adverse cascading effects from other levels by emphasizing landscape heterogeneity within metropolises and fostering coordinated collaboration across scales, particularly at the regional landscape and national levels.

Approximately 35 % of Chinese cities are situated in mountainous areas, where rapid urban expansion on slopes has led to the degradation of urban ecosystem health, marked by the loss of natural landscapes, diminished resilience, and reduced ecosystem services. However, the impact of vertical urban growth on ecosystem health, especially in terms of temporal dynamics, distribution, and underlying mechanisms, remains poorly understood. Chongqing, a typical mountainous metropolis, was selected to investigate these impacts over the past two decades. By integrating the slope spectrum (SS), climbing index (CI) of built-up land, and ecosystem health index (EHI), we explored how urban expansion has affected the EHI. Additionally, we developed a method for identifying the expansion advantage slope range (EASR), which can track dynamic slope-climbing urban expansion. Our findings revealed that the built-up land expansion in Chongqing was primarily concentrated in the central areas of the western region. From 2000 to 2010, this expansion occurred primarily in urban built-up areas and shifted to other built-up areas between 2010 and 2020. Although the Climbing Index was -0.11, the EASR results indicated an increasingly significant slope-climbing trend, with slopes of built-up land increasing from [1.17, 8.25] to [1.42, 8.48]. Notably, when expansion occurs on slopes exceeding 12 degrees, the decline in the EHI becomes significantly more pronounced, with the impact coefficient rising from 0.201 to 0.447. This study reveals the fundamental relationship between slope-climbing urban expansion and ecosystems, providing valuable insights for urban planning and sustainable development in mountainous regions.

China has responded to the sustainability challenges via a range of policies with evolving objectives in the Yangtze River Economic Belt (YEB) since the 1990s. However, the multi-scale analysis of YEB's comprehensive sustainability and the human -environment nexus amid policy impact remains unexplored. A comprehensive review and forecast of historical and future sustainability pathways under policy impacts are imperative. Here, we systematically examined sustainability under ten National Policies (NPs) and Regional Development Policies (RDPs), forecasting Shared Socioeconomic Pathways (SSPs) in the 21st Century using the entropy weight method and machine learning models. We found that RDPs have contributed to 1.6 times increase in human development from 2000 to 2018 across dimensions of demography, economy, and society in YEB. However, it also revealed that the west -east disparity has widened from 0.14 to 0.19 during this period. Conservation efforts and national initiatives for ecological civilization have led to environmental improvement in the YEB, especially after the RDP3 in 2014, when the eastern provinces, like Shanghai, have already surpassed the peak inverted U -shape curve of the environmental-human nexus. Among the SSPs, SSP1 shows the most sustainable scenario with the lowest ecological footprint at 6.2 hm2 per capita and the highest value of regional sustainability and environmental subsystem. To achieve SSP1, an iterative, inclusive, and context-specific Science-Policy-Practice dialogue is essential. This enables feedback loops and collaboration among policymakers, scientists, and practitioners to foster regional sustainability by studying the implications of historical and future pathways.

[Objective] The study of spatial-temporal variations and influencing factors of water-related ecosystem services under complex terrain in Southwest China can serve as a foundation for the ecological management and sustainable development in this region. [Methods] The annual water yield and soil erosion in Southwest China from 1992 to 2020 were evaluated to explore the multi-dimensional (including time, space and elevation) variation characteristics by the InVEST model and universal soil loss equation. In addition, the relative weight analysis method was used to quantify the relative contribution rate of climate and land use change to water-related ecosystem services. [Results] (1) From 1992 to 2020, water yield in Southwest China showed a downward trend, with a notable mutation occurring in 2002; soil erosion showed an increasing trend, with a mutation observed in 1997. (2) The water yield decreased and soil erosion increased with rising altitude. (3) The relative contribution rate of precipitation to both water yield and soil erosion in karst areas was found to be greater than that in non-karst areas. [Conclusion] Climate change has a more significant impact on water yield and soil erosion, while land use change has a less obvious impact. This study will contribute to the ecological protection in complex terrain (with different elevations and different landforms) and provide a scientific basis for land management and ecological restoration measures in karst areas.

Metropolises are pivotal places in mitigating and adapting to climate change, reducing environmental risks, and improving social justice to achieve global sustainability. Thus, here we integrated nine biophysical boundaries and nine social foundations into the Safe and Just Operating Space (SJOS) framework to examine the sustainability of China's five metropolises in 2020 and conduct a cross-scale interactions analysis in the case of Chongqing's SJOS by linking the global contexts to landscape components. We found that neither China as a whole nor the five metropolises (i.e., Beijing, Shanghai, Tianjin, Guangzhou, and Chongqing) all transgressed the environmental ceilings, especially in the aspects of carbon emissions, PM2.5, and footprints of ecology and nitrogen. Four metropolises achieved the basic requirements of social justice, except the Chongqing. However, Chongqing has better environmental conditions, spatially with increased environmental safety along the gradients of urban, rural, and natural landscapes. Taking the metropolises as the focal scale, metropolitan SJOS are affected by context-specific thresholds, top-down constraints from broader contexts, bottom-up cascading effects, governance, and anthropogenic perturbance. Operating within the metropolitan SJOS necessitates collaborations across individuals, landscapes, regions, countries, and the Earth system as a whole.

Context China’s high-speed economic development was accompanied by rapid urbanization for forty years, guided by a series of changing policies enacted by the central government. However, did China become more sustainable both economically and environmentally? Or more specifically, did it operate within or towards a safe and just space (SJS)? Although numerous relevant studies exist, these questions have not been adequately addressed, and a multi-scale landscape perspective is needed. Objectives The main objective of this study was to examine China’s urbanization trends, associated institutional changes, and their impacts on the nation’s sustainability trajectory during the past four decades. Specifically, we intended to analyze the impacts of urbanization and related policies on the spatial patterns, temporal trends, shortfalls, and complex nexus of the different dimensions of SJS across scales in China. Methods We apply the SJS framework, which integrates eight environmental ceilings and seven social justice foundations, to examine China’s urbanization, socioeconomic dynamics, and institutional changes, as well as their impacts on sustainability at multiple spatial scales. Segmented regression and correlation analysis were used to analyze the relationship of SJS with landscape urbanization and governance across China. Results Since the implementation of China’s Western Development Plan, China has faced increasing challenges of overshoots in CO 2 emissions, phosphorus and nitrogen loading, ecological footprint, and material footprint on a per capita basis. However, our analysis showed that, by 2015, China met nearly all basic social justice needs. The pattern of SJS showed geospatial gradients of increasing social justice (except material footprint), multi-footprints, and CO 2 from eastern to central, northeastern, and western regions, and from developed to developing provinces. The tradeoffs between social justice, environmental safety, and regional equality remain pronounced across heterogeneous landscapes with different levels of urbanization. The western region’s material footprint expanded enormously, but mainly for consumption in the eastern region of China. Conclusions China’s development in the past four decades is characterized by enormous economic growth, rapid urbanization, much improved living standards, highly fragmented landscapes, and increasing environmental problems. To promote sustainability, China should continue to implement the strategy of high-quality development and promote ecological civilization. Regional landscape-based approaches are needed to explicitly recognize geospatial heterogeneity and disparities, and better understand the urbanization-governance-landscape nexus for promoting a safer and more just China.

[Objective] The spatiotemporal interactive coupling characteristics between mountainous urbanization and ecosystem health, and the complex relationship between ecosystem health and urbanization were studied to provide a scientific basis for the scientific management and sustainable development of urban areas in the region. [Methods] The spatial and temporal evolution characteristics of urbanization and ecosystem health subsystems were analyzed for Chongqing City (a mountainous city) from 2000 to 2020 using the entropy value method and the vigor-organizational-resilience-service (V-O-R-S) model to determine the mechanism of the interactive coupling relationship between urbanization and ecosystem health subsystems. [Results] ① The comprehensive urbanization level in Chongqing City from 2000 to 2020 increased year by year. However, there was still a problem of uneven spatial development, and both the core zone and the low-value area were significantly affected by topographic relief. ② The ecosystem health index from 2000 to 2020 was moderate. The ecosystem health of the regions with rapid urbanization deteriorated significantly, while the ecosystem health of Southeast Chongqing and Northeast Chongqing with higher vegetation cover was good. [Conclusion] The interactive coupling between urbanization and ecosystem health subsystems was on the rise, but has not yet reached a highly coordinated stage, and contradictions still exist. To achieve high-quality and sustainable development in Chongqing City, it will still be necessary to take the green development path and solve the problem of spatial and temporal inequality.

Mountainous landscapes are particularly vulnerable and sensitive to climate change and human activities, and a clear understanding of how ecosystem services (ES) and their relationships continuously change over time, across space, and along altitude is therefore essential for ecosystem management. Chongqing, a typical mountainous region, was selected to assess the long-term changes in its key ES and their relationships. From 1992 to 2018, the temporal variation in water yield (WY) revealed that the maximum and minimum WYs occurred in 1998 and 2006, which coincided with El Niño-Southern Oscillation and severe drought events, respectively. Soil export (SE) and WY were consistent with precipitation, which reached their highest values in 1998. During this period, carbon storage (CS) and habitat quality (HQ) both decreased significantly. ES in Chongqing showed large variations in altitude. Generally, WY and SE decreased with increasing altitude, while CS and HQ increased. For spatial distribution, WY and SE showed positive trends in the west and negative trends in the east. In regard to CS and HQ, negative trends dominated the area. Persistent tradeoffs between WY and soil conservation (SC) were found at all altitude gradients. The strong synergies between CS and HQ were maintained over time.

The ecosystem services (ESs) provided by mountain regions can bring about benefits to people living in and around the mountains. Ecosystems in mountain areas are fragile and sensitive to anthropogenic disturbance. Understanding the effect of land use change on ESs and their relationships can lead to sustainable land use management in mountain regions with complex topography. Chongqing, as a typical mountain region, was selected as the site of this research. The long-term impacts of land use change on four key ESs (i.e., water yield (WY), soil conservation (SC), carbon storage (CS), and habitat quality (HQ)) and their relationships were assessed from the past to the future (at five-year intervals, 1995–2050). Three future scenarios were constructed to represent the ecological restoration policy and different socioeconomic developments. From 1995 to 2015, WY and SC experienced overall increases. CS and HQ increased slightly at first and then decreased significantly. A scenario analysis suggested that, if the urban area continues to increase at low altitudes, by 2050, CS and HQ are predicted to decrease moderately. However, great improvements in SC, HQ, and CS are expected to be achieved by the middle of the century if the government continues to make efforts towards vegetation restoration on the steep slopes.

Promoting land use planning through ecosystem service (ES) protection is a crucial approach for maintaining landscape sustainability. Identifying ES bundles to serve landscape functional zoning can provide a new perspective for sustainable land use planning. Taking the Beijing metropolitan region as a study area, we quantitatively assessed the spatiotemporal distributions of multiple ESs, from 1980 to 2017, based on land use changes. By combining ES patterns and comprehensive ecosystem service (CES), distinct ES bundles were identified through the clustering method. Based on the ES bundles, landscape functional zones were then established. We further developed improved land use scenarios to conserve ESs in selected towns of different functional zones by exploring dominant factors influencing ESs. Results showed that most of ESs decreased due to the expansion of developed lands. According to the classification of ES bundles, Beijing can be classified into three landscape functional zones at town level: the ecological conservation region (ECR), food production region (FPR), and urban development region (UDR). For each landscape functional zone, the town with the greatest decline in CES value was selected. Associated with the influencing factors of ESs, local land use patterns, and ecological protection policies, corresponding multi-step improved land use scenarios were designed. These scenarios were demonstrated to be effective in conserving ESs in the selected towns: (1) the agricultural expansion scenario, which enhanced food provision services in the ECR; (2) the forest conservation scenario, which enhanced habitat and recreational services in the FPR; and (3) the developed land optimization scenario, which enhanced a range of regulating services in the UDR. Overall, this study used landscape functional zoning as a nexus to connect ES patterns and land use management. The optimized land use strategies can provide references for conserving ESs and enhancing landscape sustainability in Beijing and other similar metropolitan areas worldwide.

Landscape urbanization has profound influences in the structure, function, and dynamics of the coupled human-environmental systems (CHESs). However, due to the spatial heterogeneity of urban landscape and its socioeconomic attributes, there are many limitations in our understanding of how to render urban systems more sustainable across different administrative levels and geospatial scales. Place-based and cross-level research must be conducted to provide realistic and context-specific pathways to regional sustainability. Thus, the main objectives of this study were to investigate the multiscale spatiotemporal patterns, divers, and sustainability impacts of landscape urbanization at the levels of nation, economic development zones, urban agglomerations (UAs), and cities, with a focus on the Yangtze River Economic Belt (YREB). We explored the linkages among the landscape urbanization, national development plans, and regional sustainability from the hierarchical landscape perspective, using landscape metrics and bivariate regressions. Our main findings include: (1) the YREB's built-up area expanded from 9000 to 40,000 km(2) during 1990-2015, and the general spatiotemporal patterns of landscape urbanization were similar to those in other major urban regions worldwide; (2) influenced by national development plans, the east-west disparities of landscape urbanization continued to widen in the YREB and China as a whole during 1990-2015; (3) the overall landscape urbanization pattern of the YREB was characterized by an east-west gradient interwoven with hierarchies of UAs and cities that were influenced mainly by geography, demography, and top-down governmental policies; (4) positive feedbacks between landscape urbanization and socioeconomic development underpinned rapid urbanization, resulting in insufficient public green space, deteriorated air quality, freshwater shortages and pollution, and inadequate infrastructure development, especially in the coastal urban agglomerations (UAs), megacities and super megacities. To achieve sustainability of the YREB region, future policies need to address the geospatial disparities and minimize the gradients of socioeconomic development. The hierarchical landscape approach provides new insights for improving regional landscape planning and management for sustainability.

Loess-like sediments are widely distributed in the northern subtropics of China, stretching beyond the traditional boundary of typical loess. Compared with well-researched typical loess, loess-like sediments are much less studied and their origin (eolian or fluvial) and movement pathways under evolving environments remain unclear. Micromorphology offers novel insights into explaining sediment-forming mechanisms through reconstructing the sedimentary history. To examine the debates comprehensively, multiple micromorphological metrics were systematically analyzed, and three main results were derived from the analysis: (a) Hanjiang loess-like sediment can be directly diagnosed as eolian loess based on its differences from fluvial sediment with regard to particle composition and quartz roundness; (b) combined analyses of quartz configurations with the distribution patterns of modern winter winds/dust storms indicated that a portion of the small particles were transported by upper flow in the East Asian winter monsoon from the northwestern Gobi Desert, whereas coarse grains were mainly derived from the adjacent floodplain by creep and saltation; and (c) vertical heterogeneity of configurations and compositions among layers was mainly caused by different degrees of chemical/biological/physical weathering since the latest glaciation. All measurements showed the weathering intensity of sediments decreased in the order of S-0/T-s, L-t, L-0, L-1, meaning that the East Asian summer monsoon weakened in this order during different formation periods. In summary, these metrics reconstructed the formation process and evolutionary history of monsoons in subtropical China excellently and would rival traditional indexes, but are easier to observe.

Ecological restoration programs, which mainly affect land use distribution, may eventually alter the supply of ecosystem services (ESs). Although some positive results have been achieved, the sustainability and long-term effects of ecological restoration program on ecosystem service still remain uncertain. To compare the ES outcomes of ecological restoration programs, the design of alternative land use scenarios is critical for ecological management. This paper presents a case study aiming to explore how the implementation of the Plains Afforestation Program (PAP) and alternative land use scenarios affect the provision of a set of ecosystem services in an urbanizing watershed. We selected 7 ESs, including three water-related services and four ecosystem services (food production (FP), carbon storage (CS), habitat quality (HQ), and air pollution removal(APR)). And the comprehensive ecosystem service (CES) index was adopted to reflect the total provision of multiple ESs. The trade-offs among various ESs through correlation analysis were further conducted. Finally, four alternative scenarios were designed to provide insights into the future design and implementation of ecological restoration programs. The results indicated that the PAP implementation enhanced regulating services (SC, WP, CS, and APR) and supporting services (HQ) and reduced provisioning services (WY and FP). Converting cropland to forestland could not simultaneously lead to an enhancement in all ecosystem services. Our results also showed synergies between supporting (HQ) and regulating services (CS, WP, and APR). It is worth noting that soil conservation showed trade-offs between supporting (HQ) and regulating services (CS, WP). The region with a large proportion of woodland improved habitat quality, water purification and carbon storage, but it failed to enhance soil conservation effectively because of its steeper slopes. After the implementation of PAP, no transition occurred in the relationships among the ecosystem services, whereas the trade-offs between water yield and other supporting services and regulating services have been weakened. After the land use scenarios were analyzed, the RB-400 scenario with the highest CES value of all the scenarios can be considered the optimal option because it showed the largest increase in water purification (34%) and habitat quality (3%). Moreover, water purification and habitat quality account for greater proportions of weight in our research area. This scenario provided policy implications for the land-use planning.

The transitional pedogenic characteristics of loess deposits in the Yunxian Basin have provided solid evidence for understanding the mechanisms of dust transportation, deposition, and detailed documentation of climate instability since the Last Glacial Maximum (LGM) in the northern subtropics of China. The Heinrich Stadial 1b (HS 1b, 16.9-14.7 ka B.P.) event, Bolling/Allerod (B/A, 13.9-13 ka B.P.) period, Younger Dryas (YD, 12.9-11.7 ka B.P.) event, and an environmental event (5-4 ka B.P.) during the Holocene Optimum were imprinted by the high-resolution multi-proxy of loess-paleosol in the Yunxian Basin, China. Based on granularity and chemical analyses, the loess in the Yunxian Basin can be classified as a fine, clayey loess zone that experienced a moderate degree of chemical weathering. The mechanism forming the transitional pedogenic characteristics was explained by the dust storm frequency data (1957-2007), particle-size data, and multi-proxy records of chemical weathering extent, which was mainly caused by the moderate transport distance from the common provenance and the transitional climatic characteristics of the northern subtropical zone.

This paper aims to compare the geochemical characteristics of loess-paleosol sequences in the upper reaches of the Hanjiang and Weihe river valleys, which are located in the semi-humid temperate zone and humid subtropical zone, respectively. The Mituosi (MTS) profile in the upper reaches of the Hanjiang River valley and the Yaohecun (YHC) profile in the Weihe River valley were selected for this comparative research. The stratigraphic characteristics, composition, chemical weathering intensity, leaching rates of Ca and Na, mobility of major elements, and transport features of Na and Fe were analyzed with respect to depth and compared between the two profiles. This study reached the following conclusions. (1) The composition of the loess-paleosol sequences in two regions are quite similar to the average composition of the upper continental crust (UCC), indicating that the loess in the two regions came from multiple sources and was mixed well. Therefore, the loess in the two regions is considered aeolian loess. (2) Compared with the loess-paleosol sequence in the Weihe River valley, the loess-paleosol sequence in the upper reaches of the Hanjiang River valley features a darker color; a higher chemical index of alteration (CIA) value; higher leaching rates of Na and Ca; higher migration ratio (relative to K) of Al, Si, Mg, and Na; and lower migration ratio of Fe and Ca. This evidence indicates that the loess-paleosol sequence in the humid subtropical environment experienced stronger chemical weathering intensity than the loess-paleosol sequence in the semi-humid temperate zone. (3) Both the YHC profile and MTS profile record a period of climate deterioration at 6000–5000 a BP. The period punctuated the mid-Holocene Climatic Optimum (8500–3100 a BP) in the study area.

Basted on ArcGIS and Geoda software and quantitative methods of variation in standard devia‐tion ,weighted variation ,economic growth index ,and the correlation analysis of ESDA ,the temporal evo‐lution tendencies and spatial differentiation characteristics were quantitatively analyzed .This paper took GDP per capita as indicator to study the evolvement of economy in Hubei Yangtze River economic Zone at the county level from 2002 to 2014 .The results are as follows :Firstly ,the absolute difference of county e‐conomic had a strengthening trend to increase ,and the relative difference obviously decreased after the first slowly increased on time series ;the development of the county economy was slowed during these 10 years .Secondly ,from the spatial distribution pattern ,the county economy of Hubei Province Yangtze Riv‐er Economic Zone had a significant spatial autocorrelation ,and it showed regionally heterogeneous at the large scale and homogeneous at the small scale .The spatial distribution gradually formed three main growth poles in the county which under the jurisdiction of Wuhan ,Yichang ,and Huangshi cities .Finally , the spatial pattern of economic grow th showed a trend from random distribution and instability .

以汉江上游谷地一级阶地的上覆黄土—古土壤序列为研究对象,分析包括Ni、Mn、Cu、Zn、As、Ti、V、Pb在内的8种土壤重金属含量及其分布特征,选取铷锶比(Rb/Sr)、磁化率及黏粒含量作辅助指标,研究汉江上游黄土—古土壤序列的成壤强度及所反映的气候演化特征.结果表明:Cu、Ni、Pb、As、Mn、V与成壤强度指标(磁化率、黏粒含量、Rb/Sr值)呈显著相关关系,说明该6种重金属迁移、富集程度受区域气候演变所驱动.依据重金属垂向分布特征,可判断自一级阶地抬升以来,汉江上游谷地共经历了5个气候阶段,其中,全新世中期气候整体温暖湿润,但在6～5 ka B.P.发生了一次干冷气候事件.

以丹凤县茶房村黄土—古土壤剖面为对象,研究了该区黄土色度参数的变化规律及其主控因素.结果表明,L+(亮度)在黄土层中出现峰值,a+(红度)、a*/b*(红度/黄度)在古土壤层出现峰值,色度参数的峰谷变化特征与该区黄土—古土壤地层旋回相吻合.L*(亮度)的变化与有机质含量密切相关;a+(红度)、a*/b*(红度/黄度)的变化则受控于铁氧化物的种类和含量.尽管三者的受控因素不同,但都与风化成壤强度密切相关,且与磁化率形成良好的对比,可作为良好的气候代用指标,间接地反映该区气候和成壤环境的变化规律.

对湖北汉江郧县弥陀寺河段的地貌进行了考察,在该河段一级阶地上发现了黄土-古土壤剖面.对剖面进行了样品采集和详细的分析.结果表明,剖面中记录了一期古洪水事件.通过OSL断代及地层对比,确定此期古洪水事件发生于北宋时期(公元900-1000年).用两种方法确定了古洪水的水位高程,并对两种方法所得的结果进行了对比.这次古洪水事件的洪峰流量在58620～64270 m3/s之间.研究结果可供汉江上游的防洪工程建设参考.

比较汉江上游谷地及渭河谷地典型黄土剖面的元素组成、化学风化强度及常量元素迁移特征,揭示秦岭南北两侧黄土—古土壤剖面的成壤强度及其所指示的环境演变特征,两者差异及共性如下:①两剖面化学组成均以SiO2、A12O3和Fe2O3为主,元素组成均一且高度混合,与上部陆地壳(UCC)的化学成分十分接近,该些证据均指示两区域黄土是来源广泛并经过充分混合的风尘堆积产物.②据CIA值可判定MTS及YHC剖面均经历了中等风化作用,比较两剖面CIW值、A-CN-K三角图投点特征及元素迁移率知,汉江上游谷地的黄土—古土壤序列经历的化学风化作用更强,Ca及Na元素的丢失率更高,A1、Na、Mg、Si等常量元素的迁出率更大.③依据Fe、Na迁移率的全剖面变化曲线知,汉江上游谷地与渭河谷地自全新世以来经历了相同的气候演变阶段,均记录了6000-5000a BP的干冷气候事件.