Yanshan Mountains Research Articles

Quantitative reconstruction of sedimentary processes, provenance, and binary sources in Horqin Sandy Land, NE China: An integrated approach

As the largest semi-fixed dune field in China, the Horqin Sandy Land (HSL) provides a valuable opportunity to study the surface processes and paleoenvironmental evolution of drylands in the monsoon region. However, limited data and a single qualitative approach hinder our understanding of the sediment erosion and transport process of the HSL. The ability to trace and quantify sediment provenance of the HSL is increasingly needed to properly understand the source-to-sink processes, and to accurately interpret aeolian–fluvial interactions in terms of a comprehensive database and multidisciplinary approach perspective. This study integrates previously existing grain-size, heavy mineral, element geochemistry, Sr-Nd-Hf isotopic, and zircon-geochronological databases with new petrographic, TIMA automation heavy mineral data and statistical analysis. Together, the high degree of recycling of HSL severely limits the provenance identification of element fingerprints, although these elements are largely inherited from the parent rocks and are not affected by chemical weathering. The heavy minerals, Sr-Nd-Hf isotopes, and zircon U-Pb age composition together reveal that the HSL sediments are a binary mixture of the Palaeozoic-Mesozoic igneous rocks in the Great Xing’an Range (GXR) and the Precambrian metamorphic rocks in the Yanshan Mountains. The isotopic end-element mixing models, multidimensional scaling (MDS) diagrams and inverse Monte Carlo models of detrital zircon ages indicate that GXR and Yanshan Mountains account for ∼ 60 % and ∼ 40 % of the source contributions, respectively. Under the strong influence of the northwest to west winds controlled by the Mongolia-Siberian High, detrital material from the GXR is consistently transported to the interior of the dune field and intensively reworked. The Laoha River and the Yangxumu River originating from the Yanshan Mountains provide stable detrital sources for the HSL. In addition, the transverse flow of the Xilamulun River and the West Liao River has provided sufficient space and sediment for the dunes, which is conducive to the full mixing of materials inside the dune field. The sediment in the southeast of HSL shows an obvious Yanshan Mountains source dominance and a grain-size dependence. The coarse fractions (>63 μm) mainly modified from the river channel sand and alluvial plain of the Yangxumu River (∼75.8 %), while the fine fractions (<63 μm) have a strong affinity with the loess deposit of Yanshan Mountains (∼52.4 %). The fluvial-lacustrine deposits during the last glacial maximum served as a temporary transit station, providing a direct dust source for the modern dunes in the HSL region. Aeolian–fluvial interaction controls the geomorphology and landscape evolution of the HSL in the monsoon region; however, it is challenging to derive insights into the landscape evolution from studying surface samples.

Migration and natural attenuation of leachate pollutants in bedrock fissure aquifer at a valley landfill site

Groundwater pollution from valley type landfills is concerning, and natural attenuation by contaminants is increasingly relied upon. However, the reliability of natural attenuation in such complex sites has been called into question due to incomplete understanding of their attenuation mechanisms. Therefore, we conducted field investigations, monitoring analyses, mathematical statistics, and machine learning techniques to elucidate the natural attenuation mechanisms of pollutants within bedrock fissures at a prototypical valley type landfill located in the east Yanshan Mountains, China. Our results indicate that 50% of the monitored indicators showed extreme pollution in bedrock fissure aquifers, due to seepage from the valley type landfill site. Ammonia nitrogen, arsenic, cadmium, lead, iron, manganese, and mercury were among the contaminants that could pose serious risks to human health. Pollutant concentrations in bedrock fissure aquifers were lower during the rainy season compared to the dry season as the aquifer was rapidly recharged by strong rainfall runoff. The initial concentration of bedrock fissure water generally increased during the flow through the landfill. However, significant natural attenuation of total dissolved solids, oxygen consumption, ammonia, cadmium, and lead occurred after passing through the landfill (p < 0.05), with attenuation coefficients of 0.0041 m-1, 2.56 × E−5m−2, 4.18 × E−5m−2、0.0015 m-0.99, and 6.83 × E−33 m−12.49, respectively. The driving mechanisms for natural attenuation include physical migration, leaching, microbiological degradation, and adsorption, primarily occurring within 600–650 m downstream of the landfill boundary. This study makes fundamental contribution to the understanding of the migration and natural attenuation process of leachate pollutants in bedrock fissure aquifer, which will provide a scientific basis for implementation of natural attenuation strategies in complex site remediation. Future research should examine more precise evidence of natural attenuation feasibility in complex sites in conjunction with monitoring networks.

How Geomorphology Maps the Dispersal Barriers of Large Herbivorous Mammals in China

ABSTRACTAimLiterature and fossil records document the long‐term occurrence sites of large herbivorous mammals in China. These sites exhibit spatially uneven distribution, potentially reflecting constraints on the dispersal of large herbivorous mammals imposed by stable geomorphic factors. In this study, we examine the impact of landforms on the dispersal of four taxa of large herbivorous mammals across China.LocationChina.TaxonRhinocerotidae, Elephantidae, Equus, Camelus.MethodsWe employed the Omniscape algorithm to create a connectivity model from geomorphic data (slope, elevation and ground cover), assessing the extent to which Chinese landforms obstruct large herbivore dispersal. This model utilised historical distribution sites to delineate barrier strips.ResultsDispersal barriers show regional variation, segmenting China into four distinct regions. The Tibetan Plateau, Taklamakan Desert and Qinling Mountains constitute Region A, presenting the most significant barrier. Region B, characterised by dense, continuous mountain ranges and arid landforms in Northwest China, poses a secondary barrier. Region C, with fragmented mountain ranges in Southwest China, exhibits a diminished barrier effect. Region D features the eastern coastal plains with minimal geomorphic constraints.ConclusionsThe edge mountains of the Tibetan Plateau form a continuous barrier strip. The Qinling–Taihang–Yanshan mountain chain constitutes a discontinuous barrier strip. This is because the mountain chain belongs to two geological structural units and is eroded by rivers, creating many corridors.

Patterns of Species Richness and Its Endemism of Beetles in the Beijing–Tianjin–Hebei Region of China

The Beijing–Tianjin–Hebei region lies between the Mongolia-Xinjiang Zoogeographic Region and the Central China Zoogeographic Region in China, harboring relatively rich biodiversity. This study specifically examined the species diversity, richness and endemic areas of beetles in this area. By analyzing 5965 detailed distribution records of 2047 beetle species in the Beijing–Tianjin–Hebei region, the species richness maps were created with a grid size of 0.5°. Additionally, two methods, parsimony analysis of endemism (PAE) and endemicity analysis (EA) were applied to detect areas of endemism (AOEs) with different grid sizes (0.1°, 0.25° and 0.5°), resulting in the identification of three AOEs in the southern mountainous areas of the Taihang Mountains, Yanshan Mountains, and Xiaowutai Mountains. It also verified that AOEs are consistent with the hypothesis that endemic areas are predominantly located in mountain ranges, as proposed by previous related studies. These findings highlight the importance of complex topography and stable climate in shaping AOEs and conserving biodiversity.

National-scale 10 m annual maize maps for China and the contiguous United States using a robust index from Sentinel-2 time series

Accurate and continuous maps of maize distribution are essential for food security and sustainable agricultural development. However, there are no continuous national-scale and fine-resolution maize maps and explicit updated information on the spatiotemporal dynamics of maize for most countries. Maize mapping at the national scale is challenging due to the spectral heterogeneity caused by crop growth conditions, cropping patterns, and inter-annual variations. To this end, this study developed a novel crop index-based algorithm for national-scale maize mapping. Compared to other crops, maize is characterized by large-leaf-dominated canopies and high photosynthetic efficiency. Maize shows significant changes in chlorophyll and anthocyanin content. Therefore, a robust maize index was established by exploring the temporal Variation of the Vegetation-Pigment index (VVP) during the growing period. A simple decision rule was coded on the Google Earth Engine (GEE) platform, which was used for maize mapping based on the Sentinel-2 time series in China and the contiguous United States (US) from 2018 to 2022. The national-scale 10 m annual maize maps for China and the contiguous US were developed and in good agreement with the corresponding agricultural statistics data for many years (R2 > 0.94) and 9,412 reference points (overall accuracy of 90.09 %). Compared with simply applying the vegetation index, the VVP index took account of spectral heterogeneity caused by variations in crop growth conditions, cropping patterns, and inter-annual, and the omission error of maize was reduced by over 20 %. Moreover, the VVP index can significantly improve the spatial transferability of the Random Forest (RF) classifier. The first 10 m annual maize maps for China revealed that the planted area trend decreased and then increased from 2018 to 2022. The year 2020 was the turning point. The maize planted area consisted of 68 % single maize and 32 % double cropping with maize in 2020, with the northern boundary for double cropping with maize in the Yanshan Mountains. The maize planted area in China consistently decreased by 39,352 km2 (about 9 %) from 2018 to 2020. This is mainly due to the adjustment of the maize-planted structure in the “Sickle Bend” region of China (the “Sickle Bend” policy). However, the maize planted area gradually recovered from 2020 to 2022, primarily concentrated in regions with ever-planted. This study will provide essential information for cropping structure adjustment and related agricultural policy formulation and contribute to sustainable agricultural development by mapping maize from a national to a global scale.

Multi-parameters monitoring of geological disasters around the Taihang Mountains-Yanshan area, Hebei Province

The Hebei Taihang Mountains-Yanshan region marks North China’s natural boundary between plains and plateaus. The unique geological and geographical conditions have led to a hazardous environment with frequent geological events. Hence, conducting a comparative analysis of regional geological hazard drivers is necessary. A geological hazard driver analysis model using multiparameter preferential Geodetectors was developed, focusing on the Taihang Mountains-Yanshan region in Hebei. It was divided into zones: Taihang Mountains, Yanshan Mountains and Dam Plateau. The results showed significant differences in the explanatory power of geohazard drivers in various zones, varying with the softening of the natural geological environment and increased human activities. In the Taihang Mountains, the primary geohazard factor is average annual rainfall, whereas in the Yanshan Mountains, it is average annual rainfall and geomorphology. Interactions among factors reveal that annual average rainfall holds the highest explanatory power for geological hazard spatial differences, notably interacting with geomorphological, geological and human activity regions, yielding an escalating effect. The study findings can be crucial references for disaster prevention, mitigation, national land resource development, economic planning and the ‘six belts’ construction in Beijing, Tianjin and Hebei.

Comparison of Three Approaches for Estimating Understory Biomass in Yanshan Mountains

Aboveground biomass (AGB) of shrubs and low-statured trees constitutes a substantial portion of the total carbon pool in temperate forest ecosystems, contributing much to local biodiversity, altering tree-regeneration growth rates, and determining above- and belowground food webs. Accurate quantification of AGB at the shrub layer is crucial for ecological modeling and still remains a challenge. Several methods for estimating understory biomass, including inventory and remote sensing-based methods, need to be evaluated against measured datasets. In this study, we acquired 158 individual terrestrial laser scans (TLS) across 45 sites in the Yanshan Mountains and generated metrics including leaf area and stem volume from TLS data using voxel- and non-voxel-based approaches in both leaf-on and leaf-off scenarios. Allometric equations were applied using field-measured parameters as an inventory approach. The results indicated that allometric equations using crown area and height yielded results with higher accuracy than other inventory approach parameters (R2 and RMSE ranging from 0.47 to 0.91 and 12.38 to 38.11 g, respectively). The voxel-based approach using TLS data provided results with R2 and RMSE ranging from 0.86 to 0.96 and 6.43 to 21.03 g. Additionally, the non-voxel-based approach provided similar or slightly better results compared to the voxel-based approach (R2 and RMSE ranging from 0.93 to 0.96 and 4.23 to 11.27 g, respectively) while avoiding the complexity of selecting the optimal voxel size that arises during voxelization.

Effects of Orography on the High-Temperature Event on 22 June 2023 in North China

An extreme high-temperature event occurred in North China on 22 June 2023, with the maximum temperature reaching 41.8 °C. The high-temperature centers preferentially occurred at the foothills of the Taihang and Yanshan Mountains, indicating an important role of the underlying orography. In the present work, we study the orographic effects of this extreme high-temperature event according to high-resolution numerical simulations using the Weather Research and Forecasting model. The results show that the presence of the mountains in North China contributed notably to the high-temperature event, which can enhance the 2 m air temperature by up to 3 °C. In the daytime, the enhancement of temperature is primarily due to the diabatic heating of sensible heat flux at the terrain surface caused by solar shortwave radiation, whereas the well-known foehn effect has little contribution. Indeed, the dynamically forced downslope flow of foehn is totally suppressed by the upslope flow of the thermally driven mountain-plain circulation. In the nighttime, the sensible heat flux at the terrain surface changes to weakly negative, given the cooling of land surface longwave radiation. As a result, the enhancement of near-surface temperature at the terrain foothill is dominated by the adiabatic warming of downslope flow. Yet, the near-surface temperature far away from the mountain is enhanced by the subsidence warming of a synoptic anomalous anti-cyclone, which is induced by the diabatic heating over the mountains in the daytime. These findings help improve the understanding of the thermal and dynamical effects of orography on the occurrence of high-temperature events.

SHRIMP zircon U-Pb ages of the tuffite beds in the Tuanshanzi Formation (Changcheng Group) of the Yanshan Mountains, North China Craton

SHRIMP zircon U-Pb ages of the tuffite beds in the Tuanshanzi Formation (Changcheng Group) of the Yanshan Mountains, North China Craton

Optically stimulated luminescence dating of Paleolithic sites reveals population shifts in North China during the last glacial period

The Greater Khingan and Yanshan mountain ranges in northern China not only constitute a significant physical obstacle to the northward movement of monsoon circulation, but also represent a natural barrier for human migration and cultural interactions between in-migrating Paleolithic populations and those indigenous to East Asia during the Late Pleistocene. We dated two Paleolithic sites, Yangzhuangxishan and Taiziling, located in the southern piedmont of the Yanshan Mountains with artifacts typified by simple core and flake technology associated with foraging populations, to ∼39–29 ka and ∼ 52–47 ka respectively, using the optically stimulated luminescence dating method. Our results indicate that northern China as far south as the Yanshan Mountains was occupied mainly by autochthonous East Asian Paleolithic populations using a core and flake lithic technology, although during this period Initial Upper Paleolithic (IUP) modern humans and Mousterian populations dispersed into East Asia. By synthesizing and integrating the ages of Northeast Asian Paleolithic sequences during the last glacial period (ca. 70–10 ka), we analyzed spatio-temporal variations in Late Pleistocene human populations during relatively cold stadial events (MIS 4 & 2) and warmer interstadials (e.g., MIS 3), revealing an “ebb and flow” pattern for migrations of Western IUP/Mousterian populations and indigenous core and flake technology populations in East Asia corresponding to the advance and retreat of the East Asian monsoon regime. The subsequent extremely cold climate phase engendered a major population shift during the Last Glacial Maximum (ca. 26.5–19 ka) which drove the reduction of both these Paleolithic populations, but afterward facilitated the emergence and rapid dispersal of microlithic technologies in East Asia. The peoples associated with microlithic technologies achieved their maximum geographical extent after the Bølling-Allerød Late Glacial interstadial event (ca. 14.7–12.9 ka) and then gradually decreased, perhaps due to the development of agriculture after ∼13 ka with concomitant increasing settlement stability.

Recent Northward Expansion of a Passerine Bird Species, Brownish-Flanked Bush Warbler (Horornis fortipes).

Northward expansions of bird distributions have been commonly observed in the Northern Hemisphere, likely as a result of climate change. The causes and ecological impacts of such range shifts have received extensive attention, but studies on the process of range shifts are still relatively scarce. The Brownish-flanked Bush Warbler (Horornis fortipes) has expanded northward from 35° N to 40° N during the past decade. In this study, we collated 77 records of the species beyond its traditional distribution during the past ten years from citizen science data. Most of the new records were from northeast of its traditional distribution, including the North China Plain, Taihang Mountains, and Taishan Mountain, and a few records from the northern margin of the Qinling Mountains and Qinghai-Tibet Plateau. We concluded that the Brownish-flanked Bush Warbler has bred in this new area in at least six sites. The newly established populations are assumed to belong to the subspecies H. f. davidianus, which can be divided into eastern and western dialect groups based on differences in songs. Song recordings from 10 males from Beijing and its adjacent areas were collected. Bayesian analysis based on the acoustic traits indicated that these males were most likely from the western dialect area, with a posterior probability of 99.975%. Combining topographical data with the habitat preference of the species, we inferred that these individuals spread northeastward from the Qinling Mountains to Taihang Mountains, and further along the Yanshan Mountains. This study is a case study of the distribution expansion of a bird species, which reflects the dynamics of a species in the early stage of its northward expansion.

Diversity and taxonomy of the genus Amanita (Amanitaceae, Agaricales) in the Yanshan Mountains, Northern China.

Globally, the species of Amanita are key components of ectomycorrhizal ecosystems. Some of them are widely known as poisonous or edible fungi. Although many new Amanita species from China have been described, the species diversity of Yanshan Mountains remains unknown. We here describe three new species, namely, A. borealis sp. nov. (Sect. Amanita), A. brunneola sp. nov. (Sect. Caesareae), and A. yanshanensis sp. nov. (Sect. Validae), based on morphological observations and molecular phylogenetic analyses. In addition, nine known species, namely, A. caesareoides (Sect. Caesareae), A. chiui (Sect. Vaginatae), A. muscaria (Sect. Amanita), A. oberwinklerana (Sect. Roanokenses), A. ovalispora (Sect. Vaginatae), A. subglobosa (Sect. Amanita), A. subjunquillea (Sect. phalloideae), A. vaginata var. vaginata (Sect. Vaginatae), and A. virosa (Sect. phalloideae), were reported from Yanshan Mountains for the first time. Our results emphasize that China has a high diversity of Amanita species and that additional studies are required to understand the exact species number. These findings play a crucial role in Amanita toxin research and ecological conservation. This study investigated the areas where Amanita species-related research is lacking. The study also attempted to better understand Amanita distribution and thus contribute to related research. This study enriches the species diversity of Amanita in Yanshan Mountains and offers additional data supporting the macrofungal systematics, toxin research, and diversity and ecological studies of Amanita in future studies.

A new species of Russula subgenus Russula (Russulaceae, Russulales) from Yanshan Mountains, North China

A new species of Russula subgenus Russula, Russula pseudosinoparva, is described from the Yanshan Mountains in northern China based on morphology and phylogenetic analysis of the nrITS and nrLSU-rpb2-mtSSU-tef1α gene regions. Russula pseudosinoparva is characterized macroscopically by small basidiomata with a dark red to dark pink pileus; lamellae usually forked near the stipe, with a small number of lamellulae; and microscopically by a suprapellis made up of loose and upright hyphae. Phylogenetic and morphological analyses placed the new species in the lineages of subsect. Puellarinae. As well as an illustrated description we provide a key to the species of Russula subgenus Russula distributed in China.

Continuous crustal thinning of the North China Craton in the Early Cretaceous: Evidence from A-type granites

Widespread crust-derived granitoids in North China provide evidence of Mesozoic lithospheric thinning and destruction of the North China Craton. However, the link between lower crust and lithospheric mantle reactivation remains poorly understood. We present whole-rock geochemistry and zircon O-Hf isotopes for Early Cretaceous peralkaline A-type granites (i.e., Xiwanzi, Xiangshan, and Yansehu) from the Yanshan Mountains of the eastern block of the North China Craton. The Xiwanzi granite has a U-Pb age of 134.3 ± 0.4 Ma, with homogeneous whole-rock Nd isotopes [εNd(t) = −7.7 to −7.5] but highly variable zircon O-Hf isotopes [δ18O = 5.1‰ to 7.2‰ and εHf(t) = −7.7 to +9.6]. Such isotopic variations likely resulted from a hybrid juvenile source consisting of partial melting of newly underplated basaltic rocks derived from both the metasomatized ancient and juvenile sub-continental lithospheric mantle. In contrast, the Xiangshan (117.4 ± 1.0 Ma) and Yansehu (116.3 ± 1.4 Ma) granites have relatively uniform isotopic compositions [whole-rock εNd(t) = −12.2 to −10.8, zircon δ18O = 5.2‰ to 6.4‰, and εHf(t) = −17.1 to −4.7], close to those of the Proterozoic mafic granulite xenoliths from the ancient lower crust. The isotopic variations of the Early Cretaceous A-type granites suggest a continuous change in the melting model from the underplated juvenile lowermost crust to the overlying ancient lower crust at high temperatures in an extensional environment. Our results indicate that A-type granites can be used to probe the nature and reactivation of the lower crust of an Archean craton. Significantly, large-scale continuous thinning of lower continental crust provides key insights into the generation of the widespread Mesozoic crust-derived granitoids in North China.

Superimposed effects of typical local circulations driven by mountainous topography and aerosol–radiation interaction on heavy haze in the Beijing–Tianjin–Hebei central and southern plains in winter

Abstract. Although China's air quality has substantially improved in recent years due to the vigorous emissions reduction, the Beijing–Tianjin–Hebei (BTH) region, especially its central and southern plains at the eastern foot of the Taihang Mountains, has been the most polluted area in China, with persistent and severe haze in winter. Combining meteorology–chemistry coupled model simulations and multiple observations, this study explored the causes of several heavy haze events in this area in January 2017, focusing on local circulations related to mountain terrain. The study results showed that on the weather scale, the configuration of the upper, middle, and lower atmosphere provided favorable weather and water vapor transport conditions for the development of haze pollution. Under the weak weather-scale systems, local circulation played a dominant role in the regional distribution and extreme values of PM2.5. Influenced by the Taihang and Yanshan mountains, vertical circulations and wind convergence zone were formed between the plain and mountain slopes. The vertical distribution of pollutants strongly depended on the intensity and location of the circulation. The circulation with high intensity and low altitude was more unfavorable for the vertical and horizontal diffusion of near-surface pollutants. More importantly, we found that the aerosol–radiation interaction (ARI) significantly amplified the impacts of local vertical circulations on heavy haze by two mechanisms. First, the ARI strengthened the vertical circulations at the lower levels, with the zonal wind speeds increasing by 0.3–0.8 m s−1. Meanwhile, the ARI could cause a substantial downward shift in the vertical circulations (∼ 100 m). Second, the ARI weakened the horizontal diffusion of pollutants by reducing the westerly winds and enhancing wind convergence and southerly winds. Under these two mechanisms, pollutants could only recirculate in a limited space. This superposition of the typical local circulation and the ARI eventually contributed to the accumulation of pollutants and the consequent deterioration of haze pollution in the region.

Effects of climate and afforestation on carbon sequestration change in northern China

AbstractIn recent decades, carbon sequestration (CS) capacity in Northern China has changed significantly, but the main factors leading to the spatial heterogeneity of CS change were still unclear. In this study, we analyzed the spatio‐temporal characteristics of CS change from 2000 to 2020 in Northern China, and further used correlation analysis and multiple linear regression model (MLR) to identify the main factors leading to the spatial differentiation of CS change. Furthermore, we adopted random forest model (RF) to compare the importance of these factors and geographically weighted regression (GWR) to spatially illustrate the heterogeneity of their influence on CS change. Our results showed that the most obvious increases of CS were concentrated in the Loess Plateau, Yanshan Mountains and Taihang Mountains. After eliminating redundant and low‐impact variables, we screened six factors that can well predict the spatial differentiation of CS change in Northern China. Based on the selected predictors, the MLR could explain 62.9% of the spatial variation of CS change, while the RF and GWR could explain 82.2% and 65.7% under the same predictors, respectively. Meanwhile, the spatial feature of each predictor's influence on CS change showed obvious differences. Among all predictors, afforestation was the most important factor leading to the spatial variation of CS change, and aridity index had the largest contribution among the climatic factors. In addition, we found that aridity index and potential evapotranspiration could explain better than commonly used precipitation and temperature. This study deepens the understanding of the spatial heterogeneity of CS change in Northern China and provides further suggestions for improving regional CS capacity.

Rural Transformation Development and Its Influencing Factors in China’s Poverty-Stricken Areas: A Case Study of Yanshan-Taihang Mountains

Rural China has undergone a rapid transformation in the past few decades, especially the poverty-stricken areas, making a historic leap from inadequate subsistence to full well-off status. Based on rural regional system theory, this study analyzes the connotation of rural transformation development (RTD), explores the spatio-temporal patterns of RTD in the Yanshan-Taihang Mountainous, and diagnoses its influencing factors using a geographically and temporally weighted regression model. The results show that RTD is a dynamic process of qualitative changes in rural regional systems based on the accumulation of quantitative changes of elements, and the key to its measurement lies in analyzing the coupling coordination degree between quantitative changes of elements. From 2000 to 2020, the rapid development of urban population share, non-agricultural industry share, construction land share and NDVI in the Yanshan-Taihang Mountains contributed to a leap in RTD status, and the proportion of counties in a coupling coordination state increased from 24.24% to 96.97%. Spatially, the RTD level in the Taihang Mountains was significantly superior to that in the Yanshan Mountains. Average years of schooling, road density, per capita GDP and urban–rural dual structure were the main influencing factors of RTD, of which the first three were positive factors and the last one presented a negative correlation. To promote RTD to a higher level, it is an urgent matter to boost the high-quality development of county economy and rural education, improve public transportation infrastructure and innovate the policy system.

Analysis of Ecological Environment Quality and Its Driving Factors in the Beijing-Tianjin-Hebei Region of China

This study aims to explore the evolution of the pattern of ecological environment quality and its driving factors in the Beijing-Tianjin-Hebei (BTH) region, providing a basis for developing regional ecological protection policies. Based on remote sensing image data, the study developed a remote-sensing eco-environmental index (REI) from two dimensions, namely ecological quality and environmental quality, and evaluated the spatiotemporal changes of the eco-environment quality in the BTH region from 2000 to 2020. The main factors affecting the eco-environment quality and the changing trend of the eco-environment quality were subsequently analyzed using the geographic detector model and the GM1.1 model. The results show that the eco-environmental quality of the BTH region shows a fluctuating downward trend and distinct regional differences during the study period. The Yanshan Mountain in the north and the Taihang Mountain in the west have high ecological quality, while the Zhangjiakou area in the northwestern part of Hebei Province and the urban center in the southeastern part of Hebei Province suffer low ecological quality. Natural factors played a dominant role in influencing eco-environmental factors, but the proportion of economic and social factors increased over time. It is predicted that the number of counties in the region with poor eco-environmental factors will increase significantly. Therefore, the comprehensive assessment of regional ecological quality can be effectively achieved based on REI, thus providing a reference for the green and high-quality development of the regional social economy.

Coupling between Cenozoic extensional exhumation in North China and the subduction of the Pacific Plate

Both the timing and mechanism for the formation of the topographic stepping in East Asia along the North-South Gravity Lineament (NSGL) are critical to understand the coupled influence of tectonics, climate, and surface processes on landscape evolution. The Yanshan Mountains lie in the central portion of the NSGL and offer a chance to reveal the link between surficial tectonic deformation and the underlying subduction to understand the continental dynamics and paleoclimate of NSGL. In this study, we report 22 new apatite (UTh)/He (AHe) data from the Yanshan Mountains. Age-elevation profiles indicate a period of rapid exhumation initiated at ∼27–26 Ma, while the AHe ages generally increase with the distance from the fault coincides with northwestward tilting of the fault footwall. Combining a series of shallow extensional events in East Asia with deep process of the Pacific plate subduction, we suggest that the widely-distributed late Oligocene rapid exhumation represents a phase of Cenozoic re-destruction of the North China Craton (NCC). The Cenozoic re-destruction of the NCC and topographic stepping along the NSGL may be related to the retreat, dehydration, and decarbonization of the underlying stagnant Pacific slab.

Monitoring insect biodiversity and comparison of sampling strategies using metabarcoding: A case study in the Yanshan Mountains, China.

Insects are the richest and most diverse group of animals and yet there remains a lack, not only of systematic research into their distribution across some key regions of the planet, but of standardized sampling strategies for their study. The Yanshan Mountains, being the boundary range between the Inner Mongolian Plateau and the North China Plain, present an indispensable piece of the insect biodiversity puzzle: both requiring systematic study and offering opportunities for the development of standardized methodologies. This is the first use of DNA metabarcoding to survey the insect biodiversity of the Yanshan Mountains. The study focuses on differences of community composition among samples collected via different methods and from different habitat types. In total, 74 bulk samples were collected from five habitat types (scrubland, woodland, wetland, farmland and grassland) using three collection methods (sweep netting, Malaise traps and light traps). After DNA extraction, PCR amplification, sequencing and diversity analysis were performed, a total of 7427 Operational Taxonomic Units (OTUs) at ≥97% sequence similarity level were delimited, of which 7083 OTUs were identified as belonging to Insecta. Orthoptera, Diptera, Coleoptera and Hemiptera were found to be the dominant orders according to community composition analysis. Nonmetric multidimensional scaling (NMDS) analysis based on Bray-Curtis distances revealed highly divergent estimates of insect community composition among samples differentiated by the collection method (R = .524802, p = .001), but nonsignificant difference among samples differentiated according to habitat (R = .051102, p = .078). The study therefore appears to indicate that the concurrent use of varied collection methods is essential to the accurate monitoring of insect biodiversity.