Northeastern China Research Articles

Hidden magma reservoirs: Insights from helium and carbon isotopic compositions in shallow groundwater beneath the Wudalianchi volcanic field, Northeastern China

The lack of strong geothermal manifestations and limited fumarolic activity has sparked widespread debate about the presence of active magma reservoirs beneath the Wudalianchi volcanic field (WVF). Helium (He) in hydrological systems is sensitive and responsive to the mixture of mantle-derived He, making it an excellent tool for deciphering mantle-derived magmatic processes. Through investigating dissolved He and inorganic carbon (DIC) in shallow groundwater of the WVF, we found that He captures mantle characteristics with R/Ra ratios (R equals to 3He/4He ratios, Ra is atmospheric 3He/4He ratio of 1.39 × 10−6) ranging from 0.07 to 2.27 and the highest proportion of mantle-derived He is 30.38 %. In contrast, DIC shows minimal mantle influence, with low concentrations (1.91–7.39 mmol/L) and depleted δ13C-DIC values ranging from −17.9 ‰ to −13.6 ‰. The calculated mantle 4He fluxes in groundwater are 2–3 orders of magnitude higher than that in stable continents and show the signature of volcanic degassing. The high mantle He fluxes and high upward flow rates suggest the efficient release and transfer of mantle-derived He into shallow groundwater through magma degassing. Magma-aging model effectively constraints the period of magmatic activity to within the last 47 ka. These findings, consistent with seismic noise imaging results, support the presence of magma reservoirs in the upper–middle crust. The absence of magmatic carbon signature in groundwater suggests the decoupling of magmatic He and magmatic CO2. Magmatic CO2 may be removed during ascent, possibly being trapped through dissolution or precipitation processes within the low-resistivity bodies identified at ∼2.5 km depth by magnetotelluric imaging. These findings not only contribute to resolving the controversy surrounding the existence of magma reservoirs beneath the WVF but also have broader implications in guiding the exploration and validation of hidden magmatic systems.

Mechanisms for carbon stock driving and scenario modeling in typical mountainous watersheds of northeastern China.

Watershed ecosystems play a pivotal role in maintaining the global carbon cycle and reducing global warming by serving as vital carbon reservoirs for sustainable ecosystem management. In this study, we based on the "quantity-mechanism-scenario" frameworks, integrate the MCE-CA-Markov and InVEST models to evaluate the spatiotemporal variations of carbon stocks in mid- to high-latitude alpine watersheds in China under historical and future climate scenarios. Additionally, the study employs the Geographic Detector model to explore the driving mechanisms influencing the carbon storage capacity of watershed ecosystems. The results showed that the carbon stock of the watershed increased by about 15.9 Tg from 1980 to 2020. Fractional Vegetation Cover (FVC), Digital Elevation Model (DEM), and Mean Annual Temperature (MAT) had the strongest explanatory power for carbon stocks. Under different climate scenarios, it was found that the SSP2-4.5 scenario had a significant rise in carbon stock from 2020 to 2050, roughly 24.1 Tg. This increase was primarily observed in the southeastern region of the watersheds, with forest and grassland effectively protected. Conversely, according to the SSP5-8.5 scenario, the carbon stock would decrease by about 50.53 Tg with the expansion of cultivated and construction land in the watershed's southwest part. Therefore, given the vulnerability of mid- to high-latitude mountain watersheds, global warming trends continue to pose a greater threat to carbon sequestration in watersheds. Our findings carry important implications for tackling potential ecological threats in mid- to high-latitude watersheds in the Northern Hemisphere and assisting policymakers in creating carbon sequestration plans, as well as for reducing climate change.

Microbial communities and functions are structured by vertical geochemical zones in a northern peatland

Northern peatlands are important carbon pools; however, differences in the structure and function of microbiomes inhabiting contrasting geochemical zones within these peatlands have rarely been emphasized. Using 16S rRNA gene sequencing, metagenomic profiling, and detailed geochemical analyses, we investigated the taxonomic composition and genetic potential across various geochemical zones of a typical northern peatland profile in the Changbai Mountains region (Northeastern China). Specifically, we focused on elucidating the turnover of organic carbon, sulfur (S), nitrogen (N), and methane (CH4). Three geochemical zones were identified and characterized according to porewater and solid-phase analyses: the redox interface (<10 cm), shallow peat (10–100 cm), and deep peat (>100 cm). The redox interface and upper shallow peat demonstrated a high availability of labile carbon, which decreased toward deeper peat. In deep peat, anaerobic respiration and methanogenesis were likely constrained by thermodynamics, rather than solely driven by available carbon, as the acetate concentrations reached 90 μmol·L−1. Both the microbial community composition and metabolic potentials were significantly different (p < 0.05) among the redox interface, shallow peat, and deep peat. The redox interface demonstrated a close interaction between N, S, and CH4 cycling, mainly driven by Thermodesulfovibrionia, Bradyrhizobium, and Syntrophorhabdia metagenome-assembled genomes (MAGs). The archaeal Bathyarchaeia were indicated to play a significant role in the organic carbon, N, and S cycling in shallow peat. Although constrained by anaerobic respiration and methanogenesis, deep peat exhibited a higher metabolic potential for organic carbon degradation, primarily mediated by Acidobacteriota. In terms of CH4 turnover, subsurface peat (10–20 cm) was a CH4 production hotspot, with a net turnover rate of ∼2.9 nmol·cm−3·d−1, while the acetoclastic, hydrogenotrophic, and methylotrophic methanogenic pathways all potentially contributed to CH4 production. The results of this study improve our understanding of biogeochemical cycles and CH4 turnover along peatland profiles.

Infection and biogeographical characteristics of Paragonimus westermani and P. skrjabini in humans and animal hosts in China: A systematic review and meta-analysis.

Paragonimiasis, primarily caused by Paragonimus westermani and P. skrjabini in China, is a common food-borne parasitic zoonosis. However, the national distribution of Paragonimus spp. infection and its associated environmental determinants remain poorly understood. In this paper, we summarize the infection of P. westermani and P. skrjabini and describe key biogeographical characteristics of the endemic areas in China. Data on Paragonimus infection in humans and animal hosts were extracted from eight electronic databases, including CNKI, CWFD, Chongqing VIP, SinoMed, Medline, Embase, PubMed, and Web of Science. A random-effects meta-analysis model was used to estimate the pooled prevalence. All survey locations were georeferenced and plotted on China map, and scatter plots were used to illustrate the biogeographical characteristics of regions reporting Paragonimus infection. A total of 28,948 cases of human paragonimiasis have been documented, with 2,401 cases reported after 2010. Among the 11,443 cases with reported ages, 88.05% were children or adolescents. The pooled prevalence of P. skrjabini is 0.45% (95% CI: 0.27-0.66%) in snails, 31.10% (95% CI: 24.77-37.80%) in the second intermediate host, and 20.31% (95% CI: 9.69-33.38%) in animal reservoirs. For P. westermani, the pooled prevalence is 0.06% (95% CI: 0.01-0.13%) in snails, 52.07% (95% CI: 43.56-60.52%) in the second intermediate host, and 21.40% (95% CI: 7.82-38.99%) in animal reservoirs. Paragonimus are primarily distributed in regions with low altitude, high temperature, and high precipitation. In northeastern China, only P. westermani infections have been documented, while in more southern areas, infections of both P. westermani and P. skrjabini have been reported. Paragonimiasis remains prevalent in China, particularly among children and adolescents. Variations exist in the intermediate hosts and geographical distribution of P. westermani and P. skrjabini. Additionally, altitude, temperature, and precipitation may influence the distribution of Paragonimus.

Sustainable Corn Stubble Management Is Site Specific: A Study in Northeastern China

Sustainable Corn Stubble Management Is Site Specific: A Study in Northeastern China

Dynamic of Puccinia striiformis f. sp. tritici urediniospore and its correlation with wheat stripe rust epidemics in Xiangyang of China

Stripe rust is one of the main diseases of wheat, which seriously threatens wheat production and food security all over the world. Xiangyang located in the Northwest of Hubei province in China is one of the main winter propagation and spring epidemic regions of Puccinia striiformis f. sp. tritici (Pst), which can provide urediniospores to the major wheat-growing regions in eastern and northeastern China. Understanding the dynamic of Pst urediniospore is important for giving prediction of wheat stripe rust epidemic for eastern and northeastern China and controlling the epidemic of wheat stripe rust. In this study, spore trapper and TaqMan real-time quantitative PCR (TaqMan-qPCR) detection system were employed to monitor Pst urediniospore from December 2018 to December 2022 in Xiangyang. Weather variables including air temperature, relative humidity, sunshine duration and rainfall were collected to clarify the relationship with urediniospore density in the air. In addition, the relationship between disease index of wheat stripe rust and urediniospore density in the air was analyzed. Results showed that Pst urediniospore could be captured in the air all year round. The order of the density of urediniospore from most to least was from April to June, October to December, January to March, and July to September except 2022. The urediniospore density reached the peak when the air temperature was 10–22 °C and the relative humidity was 70%∼85% from April to May in 2019, 2020 and 2021. The density of Pst urediniospores from February to April was linearly related to the total precipitation of 25 days prior to the final day of a 7-day trapping period. There was a significant positive correlation between the disease index of wheat stripe rust and the cumulative urediniospore density 2–4 weeks before the investigation date of wheat stripe rust from March to May (P < 0.05). There was no significant correlation between the disease index and the cumulative urediniospore density from 1–4 weeks after the investigation date of stripe rust from March to May (P > 0.05). This study laid a foundation for the establishment of wheat stripe rust prediction model based on urediniospore density and meteorological factors.

Genetic heterogeneity and potential recombination across hosts of Gyrovirus galga1 in central and eastern China during 2021 to 2024

Gyrovirus galga1 (GyVg1), formerly known as AGV2, was initially identified in chickens in southern Brazil. The prevalence of GyVg1 from 2021 to 2024 in 28 out of the 63 poultry farms located in Jiangsu, Anhui, Henan, Hunan, Shandong, and Hubei provinces in eastern and central China was detected via PCR. The complete genomes of the 28 strains were sequenced and exhibited a full length of 2,376 bp. Similarity analysis of these strains did not suggest definite correlation with evolutionary branching and geographical distribution. Compared with the reference GyVg1 strains, HN2202 shared the highest similarity of 99.71% with HLJ1511 (chicken-originated) from northeastern China in 2015 to 2016. Recombination analysis revealed that AH2102 was a potential recombinant of peafowl-originated HN2019-PF1 and chicken-originated HLJ1506-2, whereas HN2304 was a recombinant of peafowl-originated HN2019-PF1 and the Hungarian ferret strain G13. Mutation site analysis of the capsid protein revealed that highly mutated regions occurred between sites 288 to 316 and 383 to 419. These results indicate that GyVg1 may have undergone an interspecies transmission, which involved complex mutations and recombination. This study may provide a reference for subsequent investigations targeting the molecular epidemiology and viral evolution of GyVg1.

Petroleum migration and accumulation in a shale oil system of the Upper Cretaceous Qingshankou Formation in the Songliao Basin, northeastern China

Petroleum migration and accumulation in a shale oil system of the Upper Cretaceous Qingshankou Formation in the Songliao Basin, northeastern China

Predicting the potential distribution of Taxus cuspidata in northeastern China based on the ensemble model

AbstractClimate change is poised to exert a significant impact on species distribution in the future, and Taxus cuspidata as an endangered species is no exception. Predicting the potential distribution of T. cuspidata is essential for decision‐makers to develop conservation policies and explicitly implement conservation measures. In this study, a combined model was employed to predict potentially suitable habitats for T. cuspidata based on extant data of T. cuspidata distributions in northeastern China. Our findings suggest that mean diurnal range (bio2) and isothermality (bio3) were identified as dominant factors influencing T. cuspidata distribution. Under future climate scenarios, suitable habitat areas increased only in the SSP126 scenario in the 2070s, declining in all other scenarios. In all climate scenarios, the centroid of suitable habitats ultimately shows a trend in northward movement. Decreases in suitable habitat predominantly occurred in Yanbian Korean Autonomous Prefecture, Baishan city, and Tonghua city. Overall, this study highlights a projected habitat reduction due to climate change. Recommendations entail the strategic establishment of nature reserves and the implementation of initiatives aimed at population replenishment.

Multiple approaches for heavy metal contamination characterization and source identification of farmland soils in a metal mine impacted area

Heavy metal and metalloid contamination of farmland soils are closely related to human health. Soil contamination caused by small-scale mining activities has been largely neglected, especially in developing countries. This research studies the characteristics and the source of heavy metals and metalloids in farmland soils in the Bailing Cu–Zn deposit area in Northeastern China through multiple approaches. Geochemical mapping conducted by portable X-ray fluorescence (pXRF) spectrometry and elemental fractionation analysis (sequential extraction) revealed the spatial variations in elemental concentration and fractionation of the farmland soils. The elemental variations in the sediment and water samples in a stream passing by the farmland were determined by inductively coupled plasma mass spectroscopy (ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Results indicate elevated As, Zn, Fe, and Mn concentrations in the west bank of the farmland and the associated environmental risks caused by extremely high As concentrations (>500 mg kg−1). The upstream mining activities are identified as a dominated source of contamination in the studied farmland based on the variations of elemental concentrations and fractionations, as well as multivariate analysis results. This study revealed potential ecological risks caused by heavy metal and metalloid contamination in farmland soils in the metal mine impacted area and the stream as a primary pathway for the migration of pollutants associated with mining activities.

Developing ecological protection redline policy for land use pattern optimization in the typical black soil region of Northeastern China

Typical black soil regions in Northeastern China (TBSN) are facing problems of degradation of ecosystem services (ESs) and spatial conflicts between cropland and ecological land. Ecological Protection Redline (EPR) policy is one of the first national policies to utilizing multiple ESs. However, there is no standardized framework of delineation and validation for TBSN. In this study, the framework of Ecological Protection Redline delineation was further improved in three aspects of the ecosystem, namely, service function, ecological sensitivity, and biodiversity. Specifically, the framework considered the conflict between high-quality cropland and ecological land in the TBSN. We examined EPR effectiveness by comparing ESs and trade-off/synergistic relationships of different land use scenarios for 2035. The results show that 1) the EPR delineation threshold for each key indicator was determined to be 15%, considering the quality level of cropland. The ecological redline area of 89,593.63 km2 was identified, which was concentrated in the southwestern part of the Mengdong typical black soil subzone and Songnen typical black soil subzone. 2) Compared to the current ecological protection scenario and current ecological protection redline scenario, the optimized EPR scenario was the best solution to guarantee the sustainable development of the TBSN, maximizing ESs, weakening trade-offs, and strengthening synergistic relationships between them. The results of the study provided a theoretical basis for land use planning and the scientific management of ecosystems in the TBSN.

The application of the analysis framework for compound extreme event dependencies in China

AbstractThe escalation of compound extreme events has resulted in noteworthy economic and property losses. Recognizing the intricate interconnections among these events has become imperative. To tackle this challenge, we have formulated a comprehensive framework for the systematic analysis of their dependencies. This framework consists of three steps. (1) Define extreme events using Mahalanobis distance thresholds. (2) Represent dependencies among multiple extreme events through a point process‐based method. (3) Verify dependencies with residual tail coefficients, determining the final dependency structure. Applying this framework to assess the extreme dependence of precipitation on wind speed and temperature in China, revealed four distinct dependency structures. In northern, Jianghuai, and southern China, precipitation heavily relies on wind speed, while temperatures maintain relative independence. In northeastern and northwestern China, precipitation exhibits relative independence, yet a notable dependence exists between temperatures and wind speed. In southwestern China, precipitation strongly depends on temperature, while wind speed remains relatively independent. The Qinghai–Tibet Plateau region displays a significant dependence relationship among precipitation, wind speed, and temperature, with weaker dependence between extreme wind speed and temperature. This framework is instrumental for analyzing dependencies among extreme values in compound events.

Long-term herbicide residues affect soil multifunctionality and the soil microbial community

Residues of herbicides with the extensive applications may impact the soil ecosystem and ultimately threaten agricultural sustainability. However, the effects of long-term herbicide residues on soil multifunctionality and the soil microbial community remain poorly understood. Here, we evaluated relationships between soil multifunctionality and soil microbial communities with residual herbicide concentrations by surveying and analyzing 62 black soil samples collected from an agricultural area in northeastern China. Total residual herbicide concentrations varied from 35 to 568 μg/kg in the soil samples. The response of soil multifunctionality to increasing residual herbicide concentrations exhibited an inverted U-shaped relationship with a peak at approximately 310 μg/kg, with net mineralized organic nitrogen (Nm) and total nitrogen (TN) exhibiting the same trend. Microbial community richness was significantly lower in soil samples with high residual herbicide concentrations (> 310 μg/kg, HG) compared to low residual herbicide concentrations (< 310 μg/kg, LG). In addition, the relative abundances of specific keystone microbial genera differed significantly between LG and HG: norank_f_Acetobacteraceae, norank_f_Caldilineaceae, Candidatus_Alysiosphaera, and Gonytrichum. The relative abundances of these genera were also significantly correlated with soil multifunctionality. Structural equation models (SEMs) further showed that herbicide residues influenced soil multifunctionality by affecting these specific keystone genera. Our study demonstrates that long-term herbicide residues significantly impact the multifunctionality of agricultural black soil, where low concentrations stimulate while high concentrations inhibit, underscoring the need for reasonable application of herbicides to maintain soil ecosystem health.

Adaptive changes to Korean vernacular houses in Northeast China: the influence of changing family patterns on spatial capacity

PurposeThis study explores the spatial adaptive changes to different ancestral origins of Korean vernacular houses in Northeastern China and discusses the influence of changing family patterns on spatial capacity.Design/methodology/approachThis study uses quantitative and comparative methods to explore changes to space arrangement, space area, and furniture forms in Korean vernacular houses. This study also explores the correlation between changes in family patterns and the changing characteristics of spatial capacity.FindingsThe results elucidate the changing characteristics of Korean houses' spatial capacity. While the changing individual needs of Korean family members have led to increased spatial accessibility, there is a weak correlation variability in remodelling outcomes and changes in individual needs. Moreover, the per capita living area of Korean vernacular houses has increased, and furniture forms tend to be simpler, smaller, and more integrated. These developments reflect the changes in the way of life, production, and family structure.Research limitations/implicationsThis study provides a unique perspective on the sociology and architecture of ethnic minority families in China. Its results can help architects and construction firms more intuitively understand Korean houses. This study also provides a reference for the future renewal of Korean houses in the region.Originality/valueAlthough a growing number of studies have examined Korean vernacular houses and family patterns, none have explored the impact of changing family patterns on the spatial organisation of different ancestral origins of Korean vernacular houses. Therefore, this novel study addresses this gap, enriching the literature and providing practical insights.

First Genomic Evidence of California Hare Coltivirus from Natural Populations of Ixodes persulcatus Ticks in Northeast China.

Background: California hare coltivirus (CHCV) was isolated in California in 1976 from a hare. Despite its long history, it remained unclear whether CHCV was exclusively distributed in California with limited host ranges. Main body: By next-generation sequencing (NGS), we obtained a complete sequence of CHCV from Ixodes persulcatus collected in 2019 in northeast China. An expanded epidemiological investigation was subsequently performed on ticks belonging to four species (Ix. persulcatus, Haemaphysalis concinna, Devmacentor silvarum, Haemaphysalis longicornis) collected in northeastern China by applying CHCV-specific RT-PCR and sequencing. CHCV RNA-positive results were found in 1.56% of the tick samples. Positive ticks were obtained in three of four sampled locations, with the highest rate observed in Inner Mongolia (2.69%), followed by Heilongjiang (1.94%) and Jilin provinces (0.55%). All positive results were derived from Ix. persulcatus ticks (2.33%), while no positive detection was found in the other tick species, even at the same location. Sequence analysis revealed that the current CHCV showed a high genetic identity (>80% amino acid identity) with the previously reported CHCV in all segments except segment seven (64.59% amino acid identity). Phylogenetic analysis based on RNA-dependent RNA polymerase (RdRp) amino acid sequences demonstrated that both the current and previously reported CHCV strains were grouped phylogenetically into the genus Coltivirus. Both CHCV strains formed a distinct clade, clustering with three human pathogenic coltiviruses (Colorado tick fever virus, Salmon River virus, and Eyach virus), and were distant from the other coltiviruses. Conclusions: We report the identification and characterization of CHCV for the first time in Ix. persulcatus ticks, expanding the currently known geographic scope, host, and genetic heterogeneity in CHCV.

Impacts of Climatic Fluctuations and Vegetation Greening on Regional Hydrological Processes: A Case Study in the Xiaoxinganling Mountains–Sanjiang Plain Region, Northeastern China

The Xiaoxinganling Mountains–Sanjiang Plain region represents a crucial ecological security barrier for the Northeast China Plain and serves as a vital region for national grain production. Over the past two decades, the region has undergone numerous ecological restoration projects. Nevertheless, the combined impact of enhanced vegetation greening and global climate change on the regional hydrological cycle remains inadequately understood. This study employed the distributed hydrological model ESSI-3, reanalysis datasets, and multi-source satellite remote sensing data to quantitatively evaluate the influences of climate change and vegetation dynamics on regional hydrological processes. The study period spans from 2000 to 2020, during which there were significant increases in regional precipitation and leaf area index (p &lt; 0.05). The hydrological simulation results exhibited strong agreement with observed river discharge, evapotranspiration, and terrestrial water storage anomalies, thereby affirming the ESSI-3 model’s reliability in hydrological change assessment. By employing both a constant scenario that solely considered climate change and a dynamic scenario that integrated vegetation dynamics, the findings reveal that: (1) Regionally, climate change driven by increased precipitation significantly augmented runoff fluxes (0.4 mm/year) and water storage components (2.57 mm/year), while evapotranspiration trends downward, attributed primarily to reductions in solar radiation and wind speed; (2) Vegetation greening reversed the decreasing trend in evapotranspiration to an increasing trend, thus exerting a negative impact on runoff and water storage. However, long-term simulations demonstrated that regional runoff fluxes (0.38 mm/year) and water storage components (2.21 mm/year) continue to increase, mainly due to precipitation increments surpassing those of evapotranspiration; (3) Spatially, vegetation greening altered the surface soil moisture content trend in the eastern forested areas from an increase to a decrease. These findings suggested that sub-regional ecological restoration initiatives, such as afforestation, significantly influence the hydrological cycle, especially in areas with higher vegetation greening. Nevertheless, persistent increases in precipitation could effectively mitigate the moisture deficits induced by vegetation greening. The study’s outcomes provide a basis for alleviating concerns regarding potential water consumption risks associated with future ecological restoration and extensive vegetation greening projects, thereby offering scientific guidance for sustainable water resource management.

Evaluating the surface water pollution risk of mineral resource exploitation via an improved approach: a case study in Liaoning Province, Northeastern China.

Pollution from mineral exploitation is an important risk factor affecting surface water environment in mineral regions. It is urgent to construct a simple and accurate model to assess the surface water pollution risk from mineral exploitation in the regional scale. Thus, taking a mining province namely Liaoning in northeastern China as the study area, we proposed a framework to simulate the transport process of pollutants from mineral exploitation points to the surrounding surface water based on the "source-sink" theory. In our framework, we adopted the regional growth method (RGM) to extract the potential polluted water area as the certain "sink"considering the influence of the topography, and then applied Minimum Cumulative Resistance (MCR) model to assess the surface water pollution risk from mineral exploitation. The results revealed that: (1) 9.5% of the water areas were located at the potential impact area of MEPs. (2) The total value of resistance surface in Liaoningis relatively low, and gradually decreased from west to east. (3) MEPs in Liaoning had a high risk and seriously threatened the surface water environment, among 2125 MEPs, 733 MEPs (32.99%) were assessed as extremely high risk level, and about 35% of the MEPs were distributed within 10KM buffer zone of surface water. (4) Water pollution risk of MEPs in Dalian, Tieling, Fuxin and Dandong need to be emphasized. (5) Compared to previous studies, we considered the topographical influence before applying MCR model directly, so the results of water pollution risk were more reliable. This study provides a methodological support and scientific reference for the water environment protection and regional sustainable development.

Estimating the dynamics of ecosystem functions under climate change in a temperate forest region

Understanding the dynamics and spatial patterns of forest biodiversity and functioning is vital for effective conservation and management. This study introduces a new framework for estimating the spatio-temporal dynamics of biodiversity and ecosystem functions in northeastern China. Our novel approach evaluates 96 future scenarios, including four points in time, four socio-economic pathways, and six global climate models based on an extensive network of permanent field plots with specific bioclimatic, topographic, and soil data. Our findings indicate a future trend of diminishing biodiversity and forest biomass productivity and increasing biomass density and carbon storage. The relationship between biodiversity and ecosystem functionality indicates a non-linear response to changes in temperature and precipitation, and a stable correlation between biodiversity and ecosystem stability across most of the socio-economic pathways. Unravelling the complex relationship between biodiversity, ecosystem functions, and stability of production, in the face of global change, requires new methods of analysis that were used in this study, including machine learning and other advanced methods.

Mapping Characteristics in Vaccinium uliginosum Populations Predicted Using Filtered Machine Learning Modeling

Bog bilberry (Vaccinium uliginosum L.) is considered a highly valued non-wood forest product (NWFP) species with edible and medicinal uses in East Asia. It grows in the northeastern forests of China, where stand attributes and structure jointly determine its population characteristics and individuals’ growth. Mapping the regional distributions of its population characteristics can be beneficial in the management of its natural resources, and this mapping should be predicted using machine learning modeling to obtain accurate results. In this study, a total of 60 stands were randomly chosen and screened to investigate natural bog bilberry populations in the eastern mountains of Heilongjiang and Jilin provinces in northeastern China. Individual height, canopy cover area, and fresh weight all increased in stands at higher latitudes, and shoot height was also higher in the eastern stands. The rootstock grove density showed a polynomial quadratic distribution pattern along increasing topographical gradients, resulting in a minimum density of 0.43–0.52 groves m−2 in stands in the southern part (44.3016° N, 129.4558° E) of Heilongjiang. Multivariate linear regression indicated that the bog bilberry density was depressed by host forest tree species diversity; this was assessed using both the Simpson and Shannon–Wiener indices, which also showed polynomial quadratic distribution patterns (with a modeling minimum of 0.27 and a maximum of 1.21, respectively) in response to the increase in latitude. Structural equation models identified positive contributions of tree diameter at breast height and latitude to shoot height and a negative contribution of longitude to the bog bilberry canopy area. Random forest modeling indicated that dense populations with heavy individuals were distributed in eastern Heilongjiang, and large-canopy individuals were distributed in Mudanjiang and Tonghua. In conclusion, bog bilberry populations showed better attributes in northeastern stands where host forest trees had low species diversity, but the dominant species had strong trunks.

Ground Temperature Monitoring and Simulation of Temperature Field Changes in Block-Stone Material Replacement Foundation for the Shiwei–Labudalin Highway

The current thermal balance of permafrost in northeastern China has been upset by human engineering construction disturbances and global warming. This has resulted in a rise in ground temperature and a fall in the permafrost table, which has a major impact on the stability, longevity, and operational safety of highway subgrades. To solve the issues above, the ground temperature monitoring data at K60+230 of the Shiwei–Labudalin highway were analyzed, and the numerical simulation of the temperature field change over 15 years was carried out for the ordinary subgrade as well as for sections of block-stone material subgrade with 1 m of straight-filled and different thicknesses of replacement fill (1 m, 2 m, 3 m, 4 m) by applying Comsol Multiphysis software. The results show that the temperature field of the subgrade exhibits significant asymmetry. There are variations in the rate of decline at different sites during the course of the 15 years when compared to where the permafrost table was located at the start of the study. Still, the rate of decline of the permafrost table is decreasing yearly. The straight-filled 1 m block-stone subgrade has a permafrost table 0.77 m higher in the bottom portion of its top surface than the ordinary subgrade. The replacement 1 m, 2 m, 3 m, and 4 m block-stone subgrade has a permafrost table in the lower portion of the top surface that is 1.05 m, 2.12 m, 3.32 m, and 4.75 m higher than the ordinary subgrade. The replacement block-stone subgrades, as opposed to ordinary subgrades, can strengthen the foundation, raise the permafrost table, and effectively reduce the impact of the upper boundary temperature on the lower permafrost. They can also increase the stability of permafrost subgrades. Of them, the block-stone filling with a thickness of 4 m and a particle size of 6–8 cm had the best impact.