Accurate quantification of human activity intensity (HAI) is crucial for understanding land surface changes. The Qinling-Daba Mountains (QDM), spanning six provincial-level regions in China's north-south transitional zone, exhibit complex human-environment interactions due to their ecological significance and long history of anthropogenic influence. This study integrates seven indicators from socio-economic and geographical dimensions, including population density, road density, land transformation degree, distance from roads, distance from settlements, topography and river density, to map HAI distribution across the QDM for 2000 and 2015. HAI changes were analyzed at regional, county, and nature reserve scales. The results showed that: (1) The HAI distribution shows obvious spatial heterogeneity. Some 53.36% of the QDM exhibits moderate-to-higher HAI, with hotspots in the eastern QDM, the Hanshui River Valley and the Western Jialing River Basin as well as the southern flank of the Daba Mountains; while high-altitude mountainous areas (e.g., the Daba Mountains, the central-to-western Qinling Mountains) show lower HAI. (2) The HAI changes of the QDM from 2000 to 2015 show an increasing trend, including 62.31% of the QDM, 61.68% of the counties and 65.45% of nature reserves. (3) The HAI Changes also show a clear spatial differentiation. The southern flank of the Daba Mountains, the eastern Qinling Mountains, the Hanshui River Valley and the Jialing River basin experience an obvious increasing trend; while the northern flank of the Qinling Mountains, the western Qinling Mountains, and the South-to-North Water Diversion Water Resource Breeding Area basically show a decreasing trend, no significant change, or a slight increasing trend. (4) HAI and its changes in the QDM exhibit altitude variations. Low-altitude areas (<1500 m) display stronger HAI and more significant changes, whereas high-altitude areas (>2000 m) show low HAI and negligible variation. The HAI datasets enable quantitative assessment of human impacts on vegetation and ecosystem functions, and provide an important basis for identification of ecological fragility for conservation prioritization in this biodiversity hotspot.

The development process of relief degree of land surface (RDLS) faces several challenges, including the unclear applicability of multi-source digital elevation models (DEMs), poor interpretability of the optimal analysis window, and strong subjectivity in its application to topographic suitability of human settlements (TSHS) zoning. Using Nepal, a typical mountainous country globally, as a case study, we employed five DEM products (ALOS PALSAR, ASTER GDEM V3, NASA SRTM V3, ALOS AW3D30 V3.2 and NASA SRTM V4) to refine the window selection method for RDLS generation and to explore factors influencing the optimal analysis window. By comparing the accuracy of the five derived RDLS products, a 90 m-RDLS dataset for Nepal was developed. Integrated with WorldPop population density data, the TSHS and its associated spatiotemporal population distribution dynamics in Nepal were further evaluated. The main conclusions are as follows: (1) The optimal analysis window size exhibits a positive correlation with DEM spatial resolution, with larger optimal windows typically found in areas of higher terrain relief. (2) Finer-resolution DEMs yield lower RDLS values, and vice versa. Among the tested 30-m DEMs, SRTM V3 and AW3D30 demonstrated superior performance in characterizing regional terrain relief, showing highly consistent results. (3) RDLS values across Nepal are generally high. Areas of low relief constitute less than 1/4 of the country, while high-relief areas account for over 2/5. (4) TSHS in Nepal is primarily categorized as moderately suitable. Over 90% of the population is concentrated in suitable zones (covering less than 50% of the land area). Population distribution maintains a stable, weak negative correlation with RDLS, with no significant shift observed in the overall spatial pattern of population agglomeration. Population growth has been concentrated predominantly in highly suitable and moderately suitable zones. This study provides methodological insights for global RDLS mapping and TSHS assessment, and contributes to deepening the understanding of human-land relationships from an integrated terrain relief perspective.

Based on the element geochemistry, magnetic susceptibility and grain size indexes of lacustrine sediments in Gucheng Lake, we reconstructed the hydrological-climatic changes with high resolution in the Jiangsu-Anhui Plain along the Yangtze River since the Holocene. At the same time, combined with the spatial and temporal distribution characteristics of archaeological sites in the pre-Qin period, the evolution of human-land relationship in the study area was discussed. The results show that from 11.5 to 7.0 cal ka BP, after the Younger Dryas event (YD), the climate quickly turned into the warmest and wettest period, but the fluctuation was frequent; From 7.0 to 5.0 cal ka BP, there was a trend that the climate changed to cold and drought in the early stage, but the climate was warm and humid in the later stage, and the lake water level was stable; From 5.0 to 4.0 cal ka BP, the precipitation dropped progressively and the climate became drier; From 4.0 to 1.5 cal ka BP, the climate fluctuated frequently and underwent a ‘wet-dry-wet’ transition. From 1.5 cal ka BP to now, the environment has been influenced obviously by intensified human activities. The above-mentioned hydrological and climatic evolution process has affected the spatial distribution of archaeological sites, agricultural development and cultural rise and fall. The early Neolithic climate fluctuated frequently, and human beings were too dependent on the environment, resulting in the slow development of civilization. In the middle and late Neolithic period, the stable hydrological climate laid a habitat foundation for agricultural development and promoted population expansion. In Xia Dynasty period, the sharp deterioration of the climate led to the ruins plummeted and the culture declined. In Shang and Zhou dynasties, the hydrological climate was so harsh that the local inhabitants had to seek their own survival and development by changing production strategies and technological innovations. The change of hydrological environment has not only a positive impact but also a negative impact on human survival and development in the Jiangsu-Anhui Plain along the Yangtze River since the Holocene. With the improvement of productivity level, the dominant factor of the evolution of human-land relationship is gradually inclined from natural to human factors. Both the cold-dry and warm-humid climate were conducive to the development of human civilization within a limitation. The transition of human societies from passive to proactive adjustment towards the natural environment reflects the interplay between human beings and the natural environment.

The Chinese Loess Plateau (CLP) fostered a series of influential Neolithic cultures. Reconstructing paleoclimatic variations across this region is essential for understanding the relationship between climate change and local cultural evolution. Land snail shells are among the most abundant and best-preserved biogenic carbonates across the CLP. However, it remains unclear whether the stable isotopic compositions of archaeological snail shells can reliably record local climatic conditions during site occupations. In this study, we analyzed the carbon (δ¹³Cₛₕₑₗₗ) and oxygen (δ¹⁸Oₛₕₑₗₗ) isotopic compositions of land snail shells collected from modern surface soils, the cultural layers of the Nanzuo site (5100-4700 cal a BP), and the Shuaibao loess section. A total of 20, 26, and 11 paired δ¹³C_shell and δ¹⁸O_shell datasets were obtained from the modern soils, the Nanzuo site, and the Shuaibao loess section, respectively. Our results show that during the Nanzuo occupation, the mean δ¹³C_shell and δ¹⁸O_shell values were -8.11‰ and -9.23‰, respectively, which were approximately 1‰ and 4.65‰, lower than the modern values, -7.07‰ and -4.58‰, respectively. Considering the established relationship between snail shell isotopic values and local precipitation, these results indicate that mean annual precipitation (MAP) during the Nanzuo occupation was significantly higher than modern levels. Based on the relationship between modern δ¹³C_shell values and MAP across the CLP, where δ¹³C_shell decreases by about 1‰ for every 100 mm increase in MAP, we estimate that the MAP during the Nanzuo occupation reached approximately 600-650 mm, around 100 mm higher than today. This estimate is consistent with paleoclimatic reconstructions derived from phytolith, pollen, and stalagmite records in adjacent regions. Our results demonstrate that the isotopic composition of land snail shells from archaeological contexts can serve as a reliable proxy for paleoclimate reconstructions on the CLP. This approach establishes a new framework for environmental reconstruction in archaeological contexts across the Chinese Loess Plateau and inland East Asia, shedding light on prehistoric human-environment interactions and adaptation to climate change.

Empowering improved urban land use performance through the digital economy represents a pivotal pathway for realizing the efficient allocation of urban spatial resources and alleviating the constraints imposed by land resource scarcity. From the distinctive perspective of geographical factors, this study draws on panel data covering 280 prefecture-level cities and above in China over the period 2006-2022. Employing econometric tools such as a fixed effects model, difference-in-differences model, and moderating effect model, it empirically examines the impact of the digital economy on urban land use performance and further analyses the actual role of geographical factors in this relationship. The findings are as follows: (1) The development of the digital economy can significantly improve urban land use performance, primarily exerting its influence through the talent dividend, industrial structure optimization, and policy agglomeration. (2) Among geographical and climatic conditions, sunshine duration has a negative moderating effect on the impact of the digital economy on urban land use performance, whereas average temperature and precipitation have positive moderating effects. (3) Affected by geographical location, the promoting effect of the digital economy on urban land use performance is more prominent in southern cities, eastern cities, and cities that are transportation hubs. Drawing on the integrated disciplinary strengths of geography, this study makes two distinct contributions to the extant academic literature. On the one hand, it provides systematic theoretical interpretations, a rigorous analytical framework, and empirically validated evidence to clarify the causal mechanisms underlying the interaction between the digital economy and urban land use performance. On the other hand, it lays a solid academic foundation and offers pragmatic decision-making insights for the in-depth integration of digital technologies into specialized practice domains such as territorial spatial planning and urban governance.

Reconstruction of the spatiotemporal changes in historical cropland area provides a fundamental basis for revealing long-term human-environment interactions. This study focuses on the Hubei-Hunan region, an area with intensive reclamation activities during the Ming and Qing dynasties (1368-1911). Using historical documents as the primary source, we reconstructed cropland areas at the county-level for multiple time points. Given the socioeconomic history and natural environmental conditions, we applied different reconstruction methods. We directly used registered land records from Ming-Qing local gazetteers to reconstruct the cropland area at the county-level in plains, hills, and low mountains, while indirectly estimated the cropland area at the county-level in western mountainous areas based on population records. The results indicate that: (1) Between 1391 and 1850, cropland area in the Hubei-Hunan region underwent a process of growth-decline-recovery-stabilization. Cropland expanded rapidly in the Ming Dynasty (1368-1644), up from 1.96×10⁴ km² in 1391 to 5.79×10⁴ km² in 1582, or an increase of 193.9%. It declined sharply during the mid-17th-century Ming-Qing transition, with the area in 1681 dropping to only 50.6% of its level in 1582. During the Qing Dynasty (1644-1911), cropland area entered a period of recovery and stabilization. In 1750 and 1850, the cropland area reached 6.18×10⁴ km² and 6.59×10⁴ km², which was equivalent to 106.6% and 113.8% of its 1582 level, respectively. After centuries of land reclamation, the cropland area by 1850 had expanded to approximately 334.5% of its 1391 level. (2) Spatially, land reclamation exhibited a clear gradient pattern. Land reclamation tended to prioritize plains and the surrounding hills, then gradually advanced to low mountains and hills, and finally expanded to mountainous areas. In 1582, 44.7% of counties in the central plains and hills had a cropland fraction exceeding 20%, a proportion that rose to over 60% by 1750. The hilly and low-mountain areas in the north and south also became major zones of cropland expansion during the Ming and Qing dynasties. In the northern hills and low mountains, the proportion of counties with a cropland fraction above 20% increased from 16.7% in 1582 to 41.7% in 1750; a similar trend occurred in the south, though at a lower overall level. Land reclamation in the western mountains occurred relatively late: only 2.5% of counties had a cropland fraction exceeding 10% in 1750, rising to 7.5% by 1850. (3) Although the registered land records from Ming-Qing local gazetteers were not the result of standard precise measurement, the records themselves were continuous and followed a relatively consistent format. After historical data processing and methodological correction, these records can serve as a reliable basis for reconstructing the cropland area in the Ming and Qing dynasties, especially from the late Ming Dynasty to the mid-Qing Dynasty.

Mangrove ecosystems play a key role in biodiversity conservation, coastal protection, and carbon sequestration. A thorough understanding of the evolutionary history of mangroves and the factors driving their changes is crucial for accurately predicting their future development trends and devising scientific conservation strategies. This study analyzed 21 surface sediment samples and 3 sediment cores collected from the core distribution area of mangroves in Yingluo Bay. Using pollen analysis, supplemented by ²¹⁰Pb and AMS ¹⁴C dating, grain-size analysis, and organic matter source identification of the core sediments, we reconstructed the evolutionary history of mangroves in Yingluo Bay over the past 700 years. Furthermore, the results were compared with other mangrove reconstruction records along the South China coast to explore the driving factors underlying these changes. We found that from the early 15th century to the late 19th century, the mangroves in Yingluo Bay and the coastal areas of South China generally developed poorly due to the low-temperature climate of the Little Ice Age. From the late 19th century to the 1980s, the mangroves in the northern part of Yingluo Bay began to flourish as the temperature rose, while the mangroves in other coastal areas continued to decline due to human activities. Since 1980, large-scale aquaculture ponds led to a general decline in South China's coastal mangroves. However, owing to effective conservation measures, the trend of mangrove degradation in Yingluo Bay was temporarily reversed between 2000 and 2010, though it has resumed since 2010, reflecting that the impact of aquaculture ponds still exists. Coastal mangroves in South China are projected to suffer varying degrees of threat from sea-level rise. In the northern part of Yingluo Bay, however, the abundant fluvial sediment supply has resulted in sedimentation rates that significantly exceed the local rate of sea-level rise, thereby reducing the vulnerability of mangroves in this region. Therefore, future mangrove conservation strategies in this region should prioritize the control and management of aquaculture activities.