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In recent years, global attention to forest ecological environment, carbon, wood yield, and biodiversity has been increasing, which requires forest managers to make reasonable forest planning in time and space to meet the needs of multiobjectives and multi-resources. In this study, the resources of business units in Northeast China were analyzed, and the FPS-ATLAS model was established. A multi-objective decision supporting spatial forest planning scheme for 16629.53 ha of forest in Jingouling forest farm of Wangqing Forestry Bureau in Jilin Province was proposed. In this paper, the volume growth model of six forest types was established, and the carbon storage model was introduced to show the total carbon, biomass carbon, dissolved organic carbon, and total soil carbon of the ecosystem. The dynamic change in carbon during the whole planning period has achieved good results. After 20 time periods, the total soil carbon increased to 7,627,208 Mg (+6.63%), the total ecosystem carbon increased to 14,889,876 Mg (+27.51%), the biomass carbon increased to 5,362,779 Mg (+59.70%), and the dissolved organic carbon increased to 9,531,906 Mg (+14.59%). The purpose of this article is to achieve dynamic management of forest resources, meet multiple constraint settings, achieve multiple management objectives, harvest wood products, and ensure the ecological and social functions of forests so that forests ultimately achieve the ideal state of sustainability. [ABSTRACT FROM AUTHOR]

The seasonal characteristics of fluorescence components in CDOM for lakes in the semi-arid region of Northeast China were examined by excitation-emission matrices fluorescence and parallel factor analysis (EEM-PARAFAC). Two humic-like peaks C1 (Ex/Em = 230, 300/425 nm) and C2 (Ex/Em = 255, 350/460 nm) and two protein-like B (Ex/Em = 220, 275/320 nm) and T (Ex/Em = 225, 290/360 nm) peaks were identified using PARAFAC. The average fluorescence intensity of the four components differed with seasonal variation from June and August 2013 to February and April 2014. The total fluorescence intensity significantly varied from 2.54 ± 0.68 nm-1 in June to the mean value 1.93 ± 0.70 nm-1 in August 2013, and then increased to 2.34 ± 0.92 nm-1 in February and reduced to the lowest 1.57 ± 0.55 nm-1 in April 2014. In general, the fluorescence intensity was dominated by peak C1, indicating that most part of CDOM for inland waters being investigated in this study was originated from phytoplankton degradation. The lowest C2 represents only a small portion of CDOM from terrestrial imported organic matter to water bodies through rainwash and soil leaching. The two protein-like intensities (B and T) formed in situ through microbial activity have almost the same intensity. Especially, in August 2013 and February 2014, the two protein-like peaks showed obviously difference from other seasons and the highest C1 (1.02 nm-1) was present in February 2014. Components 1 and 2 exhibited strong linear correlation (R² = 0.633). There were significantly positive linear relationships between CDOM absorption coefficients a(254) (R² = 0.72, 0.46, p < 0.01), a(280) (R² = 0.77, 0.47, p < 0.01), a(350) (R² = 0.76, 0.78, p < 0.01) and Fmax for two humic-like components (C1 and C2), respectively. A close relationship (R² = 0.931) was found between salinity and DOC. However, almost no obvious correlation was found between salinity and EEM-PARAFAC extracted components except for C3 (R² = 0.469). Results from this investigation demonstrate that the EEM-PARAFAC technique can be used to evaluate the seasonal dynamics of CDOM fluorescence components for inland waters in semiarid regions of Northeast China. [ABSTRACT FROM AUTHOR]

Many factors are known to influence greenhouse gas emissions from coastal wetlands, but it is still unclear which factors are most important under field conditions when they are all acting simultaneously. The objective of this study was to assess the effects of water table, salinity, soil temperature and vegetation on CH4 emissions and ecosystem respiration (Reco) from five coastal wetlands in the Liaohe Delta, northeast China: two Phragmites australis (common reed) wetlands, two Suaeda salsa (sea blite) marshes and a rice (Oryza sativa) paddy. Throughout the growing season, the Suaeda wetlands were net CH4 sinks whereas the Phragmites wetlands and the rice paddy were net CH4 sources emitting 1.2-6.1 gCH4m-2 y-1. The Phragmites wetlands emitted the most CH4 per unit area and the most CH4 relative to CO2 . The main controlling factors for the CH4 emissions were water table, temperature and salinity. The CH4 emission was accelerated at high and constant (or managed) water tables and decreased at water tables below the soil surface. High temperatures enhanced CH4 emissions, and emission rates were consistently low (< 1mgCH4 m-2 h) at soil temperatures < 18 °C. At salinity levels> 18 ppt, the CH4 emission rates were always low (< 1mgCH4 m-2 h-1) probably because methanogens were outcompeted by sulphate reducing bacteria. Saline Phragmites wetlands can, however, emit significant amounts of CH4 as CH4 produced in deep soil layers are transported through the air-space tissue of the plants to the atmosphere. The CH4 emission from coastal wetlands can be reduced by creating fluctuating water tables, including water tables below the soil surface, as well as by occasional flooding by high-salinity water. The effects of water management schemes on the biological communities in the wetlands must, however, be carefully studied prior to the management in order to avoid undesirable effects on the wetland communities. [ABSTRACT FROM AUTHOR]

In China's pursuit of modernization, the government has introduced the rural revitalization strategy to combat rural decline, foster balanced urban–rural development, and reduce the urban–rural gap. Rural human settlements, as key components of this strategy, play a vital role. This paper examines the types and characteristics of human–earth relationships within rural settlements, emphasizing their significance. Using national land use and population census data, we analyze the spatiotemporal evolution of rural settlements at the county level, investigating landscape pattern changes, assessing the degree of coupling coordination between rural population and settlements, categorizing relationship types and features, and estimating the potential for remediation. Our findings reveal a growing trend in the scale of rural human settlements, particularly sourced from arable land, with significant expansions observed in the North China Plain and Northeast Plain, indicating potential for farmland reclamation and village consolidation. Landscape patterns of rural human settlements exhibit increased fragmentation, complex shapes, and aggregation. We categorize the utilization of rural human settlements into two types, each with four distinct features: human–land coordination is observed in regions characterized by either a higher rural population and larger rural settlement areas, or lower rural population and smaller rural settlement areas. Human–land trade-offs are evident in areas where there is either a higher rural population and smaller rural settlement areas, or lower rural population and larger rural settlement areas. This provides valuable insights for the Chinese government's context-specific implementation of the rural revitalization strategy. It also serves as an experiential reference for the governance of rural human settlements in other developing countries. [ABSTRACT FROM AUTHOR]

Boreal peatlands are significant natural sources of methane and especially vulnerable to abrupt climate change. However, the controlling factors of CH4 emission in boreal peatlands are still unclear. In this study, we investigated CH4 fluxes and abiotic factors (temperature, water table depth, active layer depth, and dissolved CH4 concentrations in pore water) during the growing seasons in 2010 and 2011 both in shrub-sphagnum-and sedge-dominated plant communities in continuous permafrost zone of Northeast China. The objective of our study was to examine the effects of vegetation types and abiotic factors on CH4 fluxes from a boreal peatland. In Eriophorum-dominated community, mean CH4emissions were 1.015 and 0.801 mg m-2 h-1 in 2010 and 2011, respectively. CH4 fluxes (0.384 mg m-2h-1) released from the shrub-mosses-dominated community were lower than that from Eriophorum-dominated community. Moreover, in Eriophoru m-dominated community, CH4 fluxes showed a significant temporal pattern with a peak value in late August both in 2010 and 2011. However, no distinct seasonal s variation was observed in the CH4 flux in the shrub-mosses-dominated community. Interestingly, both in Eriophorum- and shrub-sphagnum-dominated communities, CH4 fluxes did not show close correlation with air or soil temperature and water table depth, whereas CH4 emissions correlated well to active layer depth and CH4 concentration in soil pore water, especially in Eriophorum-dominated community. Our results suggest that CH4 released from the thawed CH4-rich permafrost layer may be a key factor controlling CH4 emissions in boreal peatlands, and highlight that CH4 fluxes vary with vegetation type in boreal peatlands. [ABSTRACT FROM AUTHOR]

The unprecedented variations in global precipitation regime could profoundly impact terrestrial ecosystem structure and function, with consequent feedback to climatic change. However, little is known about complexity in precipitation effects on grassland ecosystem carbon (C) and nitrogen (N) processes at regional scales. We investigated the patterns of shoot and root biomass, litter mass, soil C and N content, microbial community composition and C and N mineralization at 18 sites along a 1000 km precipitation gradient in native Leymus chinensis grasslands of northeastern China. The results show that, with increasing mean annual precipitation (MAP), the biomass of total plant, shoot and litter gradually increased while root biomass remained nearly constant along the gradient. Surprisingly, both soil C and N mineralization rates showed quadratic relationships with MAP, likely due to the relative changes in temperature, soil arbuscular mycorrhizal fungi biomass and N availability. Although soil total C and N content presented sustained increases with water availability, heavy fractions of C and N content reached stable and saturated phases in mesic sites. Overall, ecosystem C and N sequestration enhanced with water availability in terms of C and N storage in shoot, root, litter, and soil along the precipitation gradient. It was concluded from the current study that regional precipitation regime and the indirect effects of precipitation on changes in soil properties and microbial communities would strongly influence on ecosystem C and N dynamics. The temperate grasslands of northeastern China could be utilized as significant ecosystem C and N sinks in the context of mitigating climate change. [ABSTRACT FROM AUTHOR]

As an important dissolved organic carbon (DOC) reservoir, the mires in the Sanjiang Plain, Northeast China, have been suffering from large scale of reclamation, and thus elevated loss and degradation since the 1960s. This study compares the export dynamics of the dissolved carbons, as well as the chemical characteristics of DOC, in the natural mire, degraded mire and drainage ditches during the growing seasons from 2008 to 2010 with the aim to clarify the final effects of the longterm reclamation on the export dynamics of the dissolved carbons. Results show that the average concentrations of total dissolved carbon (TC) and DOC are much higher in natural mires than that in degraded mire and drainage ditches. The DOC concentration for natural mires, about 35.53±5.15mgl-1 on average, is nearly 2.39 times of that in degraded mire (14.84±4.21mgl-1) and 2.77 times of the average value in ditches (12.84±4.49mgl-1). Similarly, the hydrophobic fraction and SUVA254 of DOC also represent lower values in the degraded mire and ditches, which suggests that mire reclamation has resulted not only in the reduced DOC concentrations but also in the reduced chemical stability. Whereas the inorganic dissolved carbons (DIC) exhibits obvious increased trends in drainage ditches in comparison to natural mires. Analyses of exitation-emission fluorescence spectra reveal that the reclamation has greatly altered the DOC composition with more biological organic substances exporting from the Sanjiang Plain. The presence of protein- and tryptophan-like substances in the ditches indicates there has been extensive agricultural pollution in the surface waters. Changes in the hydrological regime of the mire landscapes by sustained agriculture activities are deemed the prodominant reason, and the trends in the export dynamics of dissolved carbons will keep on if mire reclamation continues in the future. [ABSTRACT FROM AUTHOR]

The Sanjiang Plain located in Northeastern China is one of the major rice producing regions in the country. However, differing from the majority rice regions in Southern China, the Sanjinag Plain possesses a much cooler weather. Could the rice paddies in this domain be an important source of global methane? To answer this question, we calculated methane (CH4) emissions from the region by integrating remote sensing mapping with a process-based biogeochemistry model, Denitrification and Decomposition or DNDC. To quantify regional CH4 emissions from the plain, we first tested the model against a two-year dataset of CH4 fluxes measured at a typical rice field within the domian. A sensitivity test was conducted to find out the most sensitive factors affecting CH4 emissions in the region. Based on the understanding gained from the validation and sensitivity tests, a geographic information system (GIS) database was constructed to hold the spatially differentiated input information to drive DNDC for its regional simulations. The GIS database included a rice map derived from the Landsat TM images, which provided crucial information about the spatial distribution of the rice fields within the domain of 10.93 million hectares. The modeled results showed that the total 1.44 million ha of rice paddies in the plain emitted 0.43-0.58 Tg CH4 -C per year with spatially differentiated annual emission rates ranging between 100-800 kg CH4-C/ha, which are comparable with that observed in Southern China. The modeled data indicated that the high SOC contents, long crop season and high rice biomass enhanced CH4 production in the cool paddies. The modeled results proved that the northern wetland agroecosystems could make important contributions to global green-house gas inventory. [ABSTRACT FROM AUTHOR]

River water irrigation is used to reduce soil salinity in the reed fields of the Shuangtai Estuary Wetland in Northeast China to improve the reed quality for paper industry; however, quantitative effects of this approach have not yet been investigated. In this study, the effect of irrigation was investigated by conducting comprehensive field observations and numerical simulations, and the necessary irrigation water volume was determined. The field observations included determination of (1) the relation between surface soil salinity and reed yield; (2) vertical profile of soil salinity before and after the irrigation period; and (3) variation of depth and salinity of the standing water during irrigation and the rate of rainwater interception by reed leaves. Our findings suggested that (1) the reed yield decreased remarkably when the surface soil salinity exceeded 5‰ and (2) irrigation could reduce salinity to below this level. From our observations, water budget in the irrigated reed fields was evaluated. A numerical model was constructed to simulate the salinity reduction process by assuming that the salinity flux across the ground surface was proportional to the salinity difference between the standing water and the surface soil. The model parameters were calibrated using the results of observation (3) such that the model successfully reproduced the observed time series of standing water salinity. A series of numerical experiments were performed using the model to determine the irrigation water volume necessary for sufficient soil salinity reduction. The results suggested that soil salinity reduction depended greatly on rainfall during the reed growth period. Further, an initial irrigation depth of about 20 cm was sufficient for lowering the salinity to 5‰ even during rainfall shortage that occurred every 10 years on an average. Replacing the saline standing water before intensive rainfall events with rainwater was found to be an effective approach to lower the surface soil salinity. [ABSTRACT FROM AUTHOR]

In recent years, the frequent occurrence of extreme climate disasters has seriously affected agriculture in Northeast China. Based on precipitation data derived from 83 geographical stations in the study area for 60 years (1960–2019), we chose the reliable statistical methods of the Mann–Kendall test, Sen's slope, and the Standardized Precipitation Index, and regarded drought and flood as a whole in this paper, to identify the temporal and spatial variation characteristics of precipitation and extreme climate events in Northeast China. The results show that an increasing trend of disasters was detected at the 95% confidence level (Z = 2.3). According to the timescale analysis, abrupt climate changes started in 2006. Temporal and spatial distribution of extreme climate disasters, mainly drought and flood disasters, showed a significant upward trend from 2006 to 2019. According to the spatial analysis, the precipitation in Northeast China decreased from south to north and fluctuated less from east to west. Moreover, stations with extreme climate trends (trend of climatic anomaly with confidence level > 90%) followed the same spatial pattern as those with a high frequency of extreme climate disasters (more than 17.87 times/decade). The severity and frequency of extreme climate have increasingly threatened Northeast China in the past decade. In particular, the Northeast Plain experienced the most severe and extreme climate events that seriously threatened the study area in 2007, 2009, 2010, and 2019. Our results highlight the urgent need for the development of monitoring and early warning of droughts and flood disasters to reduce economic losses. [ABSTRACT FROM AUTHOR]

Making sense of the spectacular performance of postwar Japanese economy is one of the central issues in Japanese contemporary history. Recently, economic and business historians are debating on the role of the colonial experience in respect of the Japanese postwar economic boom. In the light of this new issue, the analysis of life histories of Japanese commoners who migrated in the colonies is gaining relevance. This paper attempts to contribute to this debate focusing on 69 Japanese who lived Fushun in the first four decades of the 20th Century. Fushun, the "city of coil" of Manchukuo, was a medium-sized company town created by the South Manchurian Railway Company around the local coil mines. The main source of the paper is the biographical annals of notable Japanese people in Manchuria (Manshū shinshiroku), recently collected in a volume by Takenaka Shin'ichi. The evidence gathered for this contribution suggests that Fushun was as a city quite selective towards highly skilled Japanese migrants, and that not a few people had the chance to collect professional experience in Fushun, which could have been an important asset after the war. My analysis was focused on a small sample of male self-employed, employed in small firms, or public servants in Fushun. I plan to extend this survey in a new article considering also a sample of the numerous Railway Company employees in the same city. [ABSTRACT FROM AUTHOR]

This paper presents new research on a lacustrine anoxic event (LAE). These data include stable carbon isotope (δ13Corg), pyrite sulfur isotope (δ34Spy), trace element and biomarker ratios from the Hongmiaozi Basin (North China) and unravel the response of continental lakes under the influence of early Aptian extreme climate conditions. According to the stratigraphic chronology (122–118 Ma) and carbon isotope correlations, terrestrial sediment was influenced by the early Aptian Oceanic Anoxic Event (OAE1a). The results show that the Xiahuapidianzi Group experienced a significant warming process under negative excursions in carbon isotopes due to the influence of increased carbon dioxide partial pressure (pCO2). The climate varied from warm and humid to hot and arid (high Sr/Cu, low Rb/Sr, calcareous mudstone), the evaporation and salinity increased (high Sr/Ba and B/Ga), and land input sources decreased (low Zr, Ti and Th). Moreover, high total organic carbon (TOC) content was source from bacteria, algae (n-alkanes), and euxinic depositional environments (Pr/Ph, Cu/Zn and U V Mo). In the stage of continuous carbon isotopes positive excursion, organic matter accumulated rapidly. A paleolake environment model has provided a better understanding of current global climate issues under global warming caused by increased carbon dioxide concentrations. [ABSTRACT FROM AUTHOR]

To further improve the accuracy of regional-residual separation of potential field data set, this paper presents a novel computation scheme based on different attenuation rate of the fields induced from deep and shallow sources respectively. For the new scheme, the observations are first upward continued to a plane above it to get an updated field. Then, the difference between the original field and the updated field is calculated. Next, a controlling parameter is set to select those data points whose amplitudes have been much reduced. The adverse effects from the residual anomalies on the fitting of the regional trend can be reduced by removing the identified local points from the original field. Finally, a low-order polynomial is utilised for approximating the regional trend, and the corresponding residual field can be obtained by simple subtraction. Compared with gradient-based methods, the proposed new scheme has better noise adaptability for distinguishing different anomalies. The accuracy of the presented scheme was tested on synthetic data with and without noise. All tests showed that the new scheme reduces subjectivity and inaccuracy of the conventional methods significantly. In addition, the scheme was applied to Bouguer gravity anomaly of the Dida orebodies in Jilin Province, northeast China. This application also verified the superiority of the proposed scheme. [ABSTRACT FROM AUTHOR]

This article shows how wartime conditions transformed the waste business in Japan. Hygiene regulations from 1900 to the 1920s followed by an influx of Korean migrant labour disrupted the traditional waste trade. The conquest of Manchuria opened up new export markets for Japanese waste and increased the demand for munitions, causing scrap metal prices to skyrocket. These new economic conditions created opportunities for Korean-owned waste businesses. In 1938 the Japanese Ministry of Commerce and Industry imposed a control system on kuzuya scrap dealers consciously modelled on Nazi Germany to keep scrap prices as low as possible and to prevent criminal activity through extensive surveillance. These price controls privileged wholesalers and harmed waste-pickers; Koreans remained in the trade because of their cheap labour. Economic mobilization under conditions of total war after 1941 temporarily rehabilitated the marginalized image of kuzuya in government propaganda, but the end of the war shattered that illusion. [ABSTRACT FROM AUTHOR]

Under the constraints of limited spaces and imbalanced traffic volumes (for both in and out directions) of container gates, reversible lane layouts become an economical and practical way to improve the service level of container terminal systems and make the maximum use of the current terminal resources. Together with a consideration of minimized total costs (both construction and operating) of terminal gate system, this paper first developed an optimization model to decide the number and scheduling rules of the reversible lanes at a terminal gate. A metaheuristic algorithm was built to solve the optimal model. Meanwhile, to reflect the randomness and dynamics property of the terminal gate system in practice, parameters that cannot be calculated from conventional analytic methods are obtained through a simulation model. Finally, a hub container terminal in the northeast of China was employed to verify the effectiveness of the proposed method and provide a theoretical foundation for the construction and management of terminal gate systems. [ABSTRACT FROM AUTHOR]

Introduction: The transport of full containers and repositioning of empty containers are essential for the operation of a container logistic enterprise. In a large inland region, railway and road transportation take their own advantages for container transportation in terms of transport efficiency and costs. The combination of the two modes creates larger possibility for logistic enterprise to provide efficient service and reduce operation costs. Thus, this paper aims to optimize the inland intermodal transportation of full and empty containers.Methods: Different from cost minimum model, an integer programming model is proposed based on revenue management, making the model more reasonable in practice where logistic enterprises have the right to reject transportation demands from customers considering transport profits and capacity limitations. The real cases of transportation networks of Northeast China and parts of the southern Europe are applied to evaluate and describe the model and performance.Results: The results indicate that the proposed intermodal transportation optimization for both full and empty containers is feasible and profitable for logistic enterprises. The efficiency of container usage increases since we take the conversion of containers during transportation into account. Results also imply an inappropriate pricing strategy at certain inland depots in the case.Conclusions: This paper provides an optimization method for the intermodal transportation of full and empty containers in harbor-inland regions / hinterlands. Different from cost minimization in the literature, this paper models the transportation problem based on revenue management. That is, the model aims to maximize profits of logistic enterprise with the specific constraints in container transportation, as well as demand rejection. The model is proofed to be feasible in the real transportation networks and can create more profits for transportation enterprises. The analysis of real cases show that the total profits can be enlarged by considering the conversion of containers during transportation. In addition, it is verified that the optimization of inland transportation of empty and full containers reduces the operating costs of logistic enterprises. Moreover, results uncover the fact that a governed pricing policy at Suifenhe is not reasonable and may deteriorate the future export environment there. For the case based on part of southern Europe, it seems that the port, customer, inland transport operator and possibly container shipping company in Europe may benefit by establishing appropriate inland depots. [ABSTRACT FROM AUTHOR]

Previous studies have established a link between fluctuations in climate and increased mortality due to coronary artery disease (CAD). However, there remains a need to explore and clarify the evidence for associations between meteorological changes and hospitalization incidences related to CAD and its subtypes, especially in cold regions. This study aimed to systematically investigate the relationship between exposure to meteorological changes, air pollutants, and hospitalization for CAD in cold regions. We conducted a cross-sectional study using hospitalization records of 86,483 CAD patients between January 1, 2009, and December 31, 2019. Poisson regression analysis, based on generalized additive models, was applied to estimating the influence of hospitalization for CAD. Significant associations were found between low ambient temperature [-10°C, RR = 1.65; 95% CI: (1.28–2.13)] and the incidence of hospitalization for CAD within a lag of 0–14 days. Furthermore, O3 [95.50 μg/m3, RR = 12; 95% CI: (1.03–1.21)] and NO2 [48.70 μg/m3, RR = 1.0895% CI: (1.01–1.15)] levels were identified as primary air pollutants affecting the incidence of CAD, ST-segment-elevation myocardial infarction (STEMI), and non-STEMI (NSTEMI) within the same lag period. Furthermore, O3 [95.50 μg/m3, RR = 1.12; 95% CI: (1.03–1.21)] and NO2 [48.70 μg/m3, RR = 1.0895% CI: (1.01–1.15)] levels were identified as primary air pollutants affecting the incidence of CAD, ST-segment-elevation myocardial infarction (STEMI), and non-STEMI (NSTEMI) within the same lag period. The effect curve of CAD hospitalization incidence significantly increased at lag days 2 and 4 when NO2 and O3 concentrations were higher, with a pronounced effect at 7 days, dissipating by lag 14 days. No significant associations were observed between exposure to PM, SO2, air pressure, humidity, or wind speed and hospitalization incidences due to CAD and its subtypes. Our findings suggest a positive correlation between short-term exposure to low ambient temperatures or air pollutants (O3 and NO2) and hospitalizations for CAD, STEMI, and NSTEMI. These results could aid the development of effective preparedness strategies for frequent extreme weather events and support clinical and public health practices aimed at reducing the disease burden associated with current and future abnormal weather events. [ABSTRACT FROM AUTHOR]

Northeast China (NEC) is one of the major agricultural production areas in China, producing about 30% of China's total maize output. In the past five decades, maize yields in NEC increased rapidly. However, farmer yields still have potential to be increased. Therefore, it is important to quantify the impacts of agronomic factors, including soil physical properties, cultivar selections, and management practices on yield gaps of maize under the changing climate in NEC in order to provide reliable recommendations to narrow down the yield gaps. In this study, the Agricultural Production Systems Simulator (APSIM)-Maize model was used to separate the contributions of soil physical properties, cultivar selections, and management practices to maize yield gaps. The results indicate that approximately 5%, 12%, and 18% of potential yield loss of maize is attributable to soil physical properties, cultivar selection, and management practices. Simulation analyses showed that potential ascensions of yield of maize by improving soil physical properties PAY s, changing to cultivar with longer maturity PAY c, and improving management practices PAY m for the entire region were 0.6, 1.5, and 2.2 ton ha−1 or 9%, 23%, and 34% increases, respectively, in NEC. In addition, PAY c and PAY m varied considerably from location to location (0.4 to 2.2 and 0.9 to 4.5 ton ha−1 respectively), which may be associated with the spatial variation of growing season temperature and precipitation among climate zones in NEC. Therefore, changing to cultivars with longer growing season requirement and improving management practices are the top strategies for improving yield of maize in NEC, especially for the north and west areas. [ABSTRACT FROM AUTHOR]

As a main grain production area in China, Northeast China (NEC) is highly influenced by the higher warming trend than elsewhere in China or even the globe. As the warming trend goes on, scientific understanding of the changes of thermal conditions in NEC will be essential for taking agricultural adaptation measures. In this paper, the high-resolution (25 km) corrected outputs of PRECIS (Providing Regional Climates for Impacts Studies) under the Representative Concentration Pathway 4.5 (RCP4.5) scenario were used to analyze the changes of the agro-climatic thermal resources in NEC. Results showed that accumulated temperature ≥10 °C (AT10) could increase by 300–500 °C·day, 500–900 °C·day, and 750–1000 °C·day in 2011–2040 (2020s), 2041–2070 (2050s), and 2071–2100 (2080s), respectively, relative to the baseline period of 1961–1990. The potential growing season (PGS) would then be prolonged by 11–19 days, 23–35 days, and 25–37 days in 2020s, 2050s and 2080s, respectively, compared to baseline. The spatial features for the changes of thermal indices would show a large increase of AT10 and an extension of PGS and Frost-free period (FFP) in mountainous areas compared to plains; the increment of AT10 would be greater in southern NEC than that in the north, with over 1000 °C·day in the southern parts and 700–800 °C·day in the northern parts in the 2080s. Additionally, the three thermal indices would increase rapidly from 2020s to 2050s compared to the period from 2050s to the 2080s, coincides with the greenhouse gas concentrations peak around the mid-period of the 21st century, and the decline towards the end of the 21st century under RCP4.5 forcing. The results of this paper could act as a guide to taking advantage of increasing thermal resources in NEC, and would be helpful for local practitioners in decision-making. [ABSTRACT FROM AUTHOR]

Extreme climate events frequently exert serious effects on terrestrial vegetation activity. However, these effects are still uncertain in widely distributed areas with different climate zones. Transect analysis is important to understand how terrestrial vegetation responds to climate change, especially extreme climate events, by substituting space for time. In this paper, seven extreme climate indices and the Normalized Difference Vegetation Index (NDVI) are employed to examine changes in the extreme climate events and vegetation activity. To reduce the uncertainty of the NDVI, two satellite-derived NDVI datasets, including the third generation Global Inventory Monitoring and Modeling System (GIMMS-3g) NDVI dataset and the NDVI from the National Oceanic and Atmospheric Administration (NOAA) satellites on Star Web Servers (SWS), were employed to capture changes in vegetation activity. The impacts of climate extremes on vegetation activity were then assessed over the period of 1982–2012 using the North–South Transect of Eastern China (NSTEC) as a case. The results show that vegetation activity was overall strengthened from 1982 to 2012 in the NSTEC. In addition, extreme high temperature events revealed an increased trend of approximately 5.15 days per decade, while a weakened trend (not significant) was found in extreme cold temperature events. The strengthened vegetation activities could be associated with enhanced extreme high temperature events and weakened extreme cold temperature events over the past decades in most of the NSTEC. Despite this, inversed changes were also found locally between vegetation activity and extreme climate events (e.g., in the Northeast Plain). These phenomena could be associated with differences in vegetation type, human activity, as well as the combined effects of the frequency and intensity of extreme climate events. This study highlights the importance of accounting for the vital roles of extreme climate effects on vegetation activity. [ABSTRACT FROM AUTHOR]

Globally, natural wetlands have suffered severe ecological degradation (vegetation, soil, and biotic community) due to multiple factors. Understanding the spatiotemporal dynamics and driving forces of natural wetlands is the key to natural wetlands' protection and regional restoration. In this study, we first investigated the spatiotemporal evolutionary trends and shifting characteristics of natural wetlands in the Northeast Plain of China from 1990 to 2020. A dataset of driving-force evaluation indicators was constructed with nine indirect (elevation, temperature, road network, etc.) and four direct influencing factors (dryland, paddy field, woodland, grassland). Finally, we built the driving force analysis model of natural wetlands changes to quantitatively refine the contribution of different driving factors for natural wetlands' dynamic change by introducing the sparrow search algorithm (SSA) and extreme gradient boosting algorithm (XGBoost). The results showed that the total area of natural wetlands in the Northeast Plain of China increased by 32% from 1990 to 2020, mainly showing a first decline and then an increasing trend. Combined with the results of transfer intensity, we found that the substantial turn-out phenomenon of natural wetlands occurred in 2000–2005 and was mainly concentrated in the central and eastern parts of the Northeast Plain, while the substantial turn-in phenomenon of 2005–2010 was mainly located in the northeast of the study area. Compared with a traditional regression model, the SSA-XGBoost model not only weakened the multicollinearity of each driver but also significantly improved the generalization ability and interpretability of the model. The coefficient of determination (R2) of the SSA-XGBoost model exceeded 0.6 in both the natural wetland decline and rise cycles, which could effectively quantify the contribution of each driving factor. From the results of the model calculations, agricultural activities consisting of dryland and paddy fields during the entire cycle of natural wetland change were the main driving factors, with relative contributions of 18.59% and 15.40%, respectively. Both meteorological (temperature, precipitation) and topographic factors (elevation, slope) had a driving role in the spatiotemporal variation of natural wetlands. The gross domestic product (GDP) had the lowest contribution to natural wetlands' variation. This study provides a new method of quantitative analysis based on machine learning theory for determining the causes of natural wetland changes; it can be applied to large spatial scale areas, which is essential for a rapid monitoring of natural wetlands' resources and an accurate decision-making on the ecological environment's security. [ABSTRACT FROM AUTHOR]

During the initial period of straw return, a suitable straw return technology can lay the foundation for long-term soil fertility improvement. This study focused on the issues of backward straw return technology and blind fertilizer application in the southern part of the maize-producing area in the Northeast Plain of China. In this study, two straw return modes (2-year no-tillage straw cover + 1-year deep loosening and burying straw returning mode, NPT; 3-year rotary tillage and burying straw returning mode, RT), with RT mode as a control, were combined with different N fertilizer application rates (0, 192, 240 kg/ha). The changes in soil organic carbon (SOC) and its active components (MBC, DOC, and LOC) in the 0–40 cm soil layer were analyzed, and the carbon stratification rate, carbon pool index (CPI), SOC storages of each component, and maize yield were calculated to evaluate the short-term (3-year) differences in soil organic carbon quantity and quality in order to find suitable straw return methods and nitrogen application rate combinations. The results showed that the NPT mode increased the SOC and MBC content in the 20–30 cm soil layer, with an increase of 16.2% to 37.8% and 23.0% to 50.3%, respectively, compared with the RT mode. Under the NPT mode, the carbon pool stability was higher after nitrogen fertilizer addition, with a CPI value of 10.2% to 37.8% higher in the 20–40 cm soil layer compared with the RT mode. The differences in maize yield were not significant (p < 0.05) between the nitrogen application rates of 192 kg/ha and 240 kg/ha, but the SOC storages did not show significant changes. The MBC storage had the highest value under the nitrogen application rate of 192 kg/ha. Therefore, we thought that, in the early stage of straw return, the organic carbon priming effect caused by increased microbial activity was higher under the nitrogen application rate of 192 kg/ha. Considering the aspects of not affecting maize yield and improving SOC stability, it is recommended to use the NPT mode with the application of a 240 kg/ha nitrogen fertilizer rate for straw return. [ABSTRACT FROM AUTHOR]

This paper investigates monthly and seasonal precipitation-temperature relationships (PTRs) over Northeast China using a method proposed in this study. The PTRs are influenced by clouds, latent and sensible heat conversion, precipitation type, etc. In summer, the influences of these factors on temperature decrease are different for various altitudes, latitudes, longitudes, and climate types. Stronger negative PTRs ranging from −0.049 to −0.075 °C/mm mostly occur in the semi-arid region, where the cold frontal-type precipitation dominates. In contrast, weaker negative PTRs ranging from −0.004 to −0.014 °C/mm mainly distribute in Liaoning Province, where rain is mainly orographic rain controlled by the warm and humid air of East Asian summer monsoon. In winter, surface temperature increases owing to the release of latent heat and sensible heat when precipitation occurs. The stronger positive PTRs ranging from 0.963 to 3.786 °C/mm mostly occur at high altitudes and latitudes due to more release of sensible heat. The enhanced atmospheric counter radiation by clouds is the major factor affecting increases of surface temperature in winter and decreases of surface temperature in summer when precipitation occurs. [ABSTRACT FROM AUTHOR]

In Northeast China during the winter, severe snowstorms can occur resulting in both societal and economic damage. In this paper, we explore an effective technique for the seasonal prediction of heavy snow activity, where previous synoptic studies have failed. We employ a year-to-year increment approach and ultimately identify four predictors, x to x. x is the area-averaged soil moisture over the northern part of Northeast China in the preceding month of September and represents the role of land processes. x represents the role of sea-air interactions in winter, x the preceding summer Mascarene High related to the winter SST over the tropical western Pacific, and x is the low-level the thermal condition over Northeast China from the previous year that oppose current year. Cross-validation tests for both 1963-2011 and independent hindcasts between 1983-2010 are performed to validate the prediction ability of our technique. The cross validation test results for 1963-2011 reveal a high correlation coefficient of 0.86 (0.77) between the predicted and observed year-to-year increment of the number of snow days. The model also predicts well the independent hindcast for the years 1983-2011. Therefore, this study provides an effective climate prediction model for Northeast China's heavy snow activities and thus requires preliminary application in operational settings. [ABSTRACT FROM AUTHOR]

In this paper, an integrated indicator-based system is established to map the suitability of spring soybean cultivation in northeast China. The indicator system incorporates both biophysical and socioeconomic factors, including the effects of temperature, precipitation, and sunshine on the individual development stages of the spring soybean life cycle. Spatial estimates of crop suitability derived using this indicator system are also compared with spring soybean planting areas to identify locations where there is scope for structural adjustment in soybean farming. Results of this study indicate that northeast China is moderately suited to spring soybean cultivation. Areas classified as suitable, moderately suitable, and unsuitable for soybean cultivation, respectively, occupy approximately 9.09 × 104, 11.45 × 104, and 7.99 × 104 km2, accounting for 11.5%, 10.11%, and 14.49% of the total area of northeast China. The Songnen and Sanjiang Plains are identified as the most and least suitable places, respectively, for spring soybean growth. A comparative analysis indicates that the suitable, moderately suitable, and unsuitable areas account for 24.78%, 46.30%, and 28.92%, respectively, of the total area presently under soybean cultivation. The analysis suggests that soybean cultivation in Heilongjiang Province is generally unfavorable, with equivalent percentages of 15.39%, 51.70%, and 32.91%. Results suggest that agricultural structural adjustment may be required to encourage farmers to grow spring soybeans. It is anticipated that this study will provide a basis for follow-up studies on crop cultivation suitability. [ABSTRACT FROM AUTHOR]

This paper reviews the current evidence for settlement patterns and ceremonial activity amongst Hongshan Neolithic groups in northeastern China, with particular attention to the well-known ceremonial site at Niuheliang. We consider the location of Hongshan ceremonial sites in their wider landscape settings, arguing that such sites are a chronologically late stage of Hongshan ceremonial investment and that, within these broad complexes, the most impressive architecture and portable goods come from an especially late phase of activity. These more impressive localities were also particularly privileged places in terms of their access to major routes, specific kinds of local geology and integrated patterns of visibility. In contrast to more loosely organized Hongshan residential sites of similar size, ceremonial centres such as Niuheliang (and, within these, certain important sub-localities) clearly functioned as key mechanisms for social, political and regional stratification around roughly the mid 6th millennium BP. [ABSTRACT FROM AUTHOR]

This paper analyzes the large-scale atmospheric circulation characteristics of anomalous cases of January temperatures that occurred in Northeast China during 1960-2008 and precursory oceanic conditions. The January monthly mean surface air temperature (SAT) anomalies and the duration of low temperature are used to define temperature anomaly cases. The anomalous cyclonic circulation over northeast Asia strengthens the northerly flow in cold Januarys, while the anomalous anticyclonic circulation weakens the northerly flow in the warm Januarys. The negative (positive) North Pacific sea surface temperature anomaly (SSTA) and increased (decreased) sea ice concentration in the Barents-Kara seas in the preceding month are probably linked to the cyclonic (anticyclonic) circulation pattern over northeast Asia in the cold (warm) cases. Further analyses indicate that the preceding oceanic conditions play distinct roles in the SAT anomalies over Northeast China on different time scales. Strong relationships exist between North Pacific SSTA and the SAT in Northeast China on the interannual time scale. On the other hand, the sea ice concentration is more closely associated with the interdecadal variations of SAT in Northeast China. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we propose a method to predict ultra-short term wind power production with chaotic time series. Through analysis of the data measured from real wind farm, the ultra-short term prediction model of wind power is established based on the space theory of chaotic time series phase. The wind power of a real wind farm in northeast China in some future time including 15 m, 30 m and 1h are predicted by the prediction model finally. Test results are presented in the paper. [Copyright &y& Elsevier]

The analysis of heavy metals is very important for assessing the feasibility of the agricultural utilization for the municipal sludge. In this paper, a four-step sequential extraction method was applied to extract heavy metals (Cu, Zn, Mn, Cr, and Ni) in municipal sludges from seven individual wastewater treatment plants located in Jilin and Heilongjiang Province, China, for estimating the mobility and bioavailability of the metal ions in the agricultural application. The total concentrations of heavy metals and their chemical fractions after the sequential extraction were determined. Principal component analysis (PCA) was applied to analyze the relations of heavy metals fractions in the municipal sludges. Experimental results indicated that the total concentrations of Cu, Zn, Cr, and Ni in all sludge samples were below the threshold values set out by the Chinese legislation (GB18918-2002). Specially, Zn had a high bioavailability and mobility, Cu and Cr had potential bioavailability, while Mn mainly existed in the residual fraction of municipal sludge. On the other hand, Ni had different mobility in different municipal sludge. PCA results were confirmed by the environmental behavior of heavy metals. [ABSTRACT FROM AUTHOR]

Korean pine (Pinus koraiensis Sieb. et Zucc.) is one of the highly commercial woody species in Northeast China. In this study, six nonlinear equations and artificial neural network (ANN) models were employed to model and validate height-diameter (H-DBH) relationship in three different stand densities of one Korean pine plantation. Data were collected in 12 plots in a 43-year-old even-aged stand of P. koraiensis in Mengjiagang Forest Farm, China. The data were randomly split into two datasets for model development (9 plots) and for model validation (3 plots). All candidate models showed a good perfomance in explaining H-DBH relationship with error estimation of tree height ranging from 0.61 to 1.52 m. Especially, ANN models could reduce the root mean square error (RMSE) by the highest 40%, compared with Power function for the density level of 600 trees. In general, our results showed that ANN models were superior to other six nonlinear models. The H-DBH relationship appeared to differ between stand density levels, thus it is necessary to establish H-DBH models for specific stand densities to provide more accurate estimation of tree height. [ABSTRACT FROM AUTHOR]

Even after the Russo-Japanese War, Manchuria remained the powder keg of East Asia. In the war’s aftermath, three empires, the Qing, the Russian and the Japanese, stationed their troops in Manchuria, in a struggle for military supremacy there. There has already been a considerable amount of research on these military activities. However, previous works have not discussed them from a triangular relationship. This paper contends that the history of modern East Asia cannot be understood until one examines the shift in the military balance in Manchuria from a triangular comparative point of view. The results of such examination show that, in Manchuria, each empire was unable to establish military domination alone, and therefore needed an alliance partner. During the Xinhai Revolution, the Russia-Japan ‘alliance’ wielded overwhelming military power against China. However, after the Russian Revolution in 1917, Japan renounced cooperation with a weakened Russia and built a new partnership with China to advance the Siberian intervention. The military triangle of Russia, China and Japan was unable to create a comprehensive regional security system in Manchuria because what was established was based on mutual distrust and fear. [ABSTRACT FROM AUTHOR]

This paper aims to examine the spread of Manchurian plague and the response of the Japanese colonial government. Previous studies of this issue stressed the successful, albeit forced, preventative measures taken by the Japanese colonial government. However, this paper argues that Western powers did not agree with the new theory that pneumonic plague was transmitted through respiratory infections, as discovered by Wu Liande and promoted by Kitasato Shibasaburo. They continued to believe the old Japanese theory that the plague was transmitted through fleas from rodents. The Japanese colonial government focused on reducing the rat population to prevent the spread of plague. Moreover, they had no quarantine hospitals or other equipment, and epidemic prevention programs and measures were inadequate. The success of their efforts was due less to the measures taken by the Japanese colonial government than from the low influx of Chinese laborers into Korea. [ABSTRACT FROM AUTHOR]

In the study, we analyze and assess quantitatively the spatial pattern of vegetation and its ecological degradation information in the Honghe National Nature Reserve (HNNR), a Ramsar-designated site in Northeast China. Statistics from historical survey data are used to measure the degradation of marshes over time and changes in the hydrological regime. Long-term statistical data are also employed to analyze both natural and human impacts on these changes. Both the wetland degradation model and its mechanisms are discussed in this paper. The research finds that the loss of water and other types of degradation in the vegetation habitat caused by the rapid deterioration of the hydrological regime has threatened the status of HNNR as a “storage area of natural genes.” Scientifically constructed strategies are urgently required to ensure sustainable economic benefits that do not adversely affect this nature reserve. [ABSTRACT FROM AUTHOR]

The northernmost border of Japan's informal empire were the Mongol lands and Manchuria. For nearly a century this region lay on the borders between an expanding Russia and a retreating China and was a major area for Japanese ambitions on the Asian mainland. Japan's interest in the Mongol lands (including Manchuria) was spurred by general strategic, economic and ideological factors, and was justified by an academic discourse on geopolitics. Geo-political socialisation was carried out in respective areas and Mongol nationalism was drawn into these affairs. This paper examines the reasons for Japan's interest in these areas, and the arguments used to justify this expansionism. [ABSTRACT FROM AUTHOR]

The increasing severity and intensity of harmful algal blooms (HABs) are of great concern to public health and a threat to ecosystems and have become a global problem in recent decades. Most of the related studies in China have been focused on low-latitude areas, such as Lake Taihu, Chaohu, and Dianchi. However, little attention has been devoted to algal blooms in Northeast China. As a significant Chinese commodity grain production base, the non-point source pollution deteriorated along with the grain production increasing year by year. In fact, the HABs in the little researched Northeast China were exceedingly serious. From 1982 to 2016, there was a total of 271 out of 2186 feasible Landsat images found HABs. The annual total frequencies of the detected HABs increased in fluctuation from 0 in 1982 to 11 times in 2016, and the highest frequency was observed twice, in 2010 and 2014, and was 29 times in both years. The number of lakes and reservoirs detected HABs and the annual sum of normalized HABs area also increased obviously. The tendency was almost coherent with the rising temperature, reduced wind speed, and declining atmospheric pressure. The R 2 and p-value between the annual frequency and the three meteorological indices were (0.274, <0.005), (0.553, <0.0001), and (0.073, 0.126), respectively. Besides, as anthropogenic influence indicators in this paper, we selected fertilizer application amount, industrial wastewater and municipal sewage discharge amount, land use type in 1986, 2000, and 2010. We comprehensively considered lacustrine morphologies and hydrological hydrodynamics and analyzed the driving factors of the spatiotemporal distribution pattern of HABs in Northeast China. [ABSTRACT FROM AUTHOR]

Recent studies on regional haze pollution over China come up in general with strong variability of main causes of heavy polluted episodes, in linkage with local specificities, sources and pollution characteristics. This paper therefore aims at elucidating the main specific sources and formation mechanisms of observed strong haze pollution episodes over 1–15 November 2015 in Northeast region considered as one of biggest megacity clusters in China. The Northeast China mega-city cluster, including Heilong Jiang, Jilin and Liaoning provinces, is adjacent to Russia in the north, Mongolian at the west, North Korea at east, and representing key geographical location in the regional and transnational air pollution issues in China due to the presence of heavy industries and intense economic activities. The present study, based on air quality monitoring, remote sensing satellite data and sensitivity experiments carried on the Nested Air Quality Prediction Modeling System (NAQPMS), quantitatively assesses the impact of meteorological conditions and potential contributions from regional chemical transport, intensive energy combustion, illegal emission and biomass burning emissions to PM 2.5 concentration variation. The results indicate strong inversion occurrence at lower atmosphere with weak near-surface wind speed and high relative humidity, leading to PM 2.5 concentration increase of about 30–50%. Intensive energy combustion (plausibly for heating activities) and illegal emission also significantly enhance the overall PM 2.5 accumulation by 100–200 μg m −3 (60–70% increase), against 75–100 μg m −3 from the biomass burning under the northeast-southwest transport pathway, corresponding to a contribution of 10–20% to PM 2.5 concentration increase. Obviously, stagnant meteorological conditions, energy combustion, illegal emission and biomass burning are main drivers of strong haze formation and spatial distribution over Northeast China megacity cluster. In clear, much effort on emission abatement at both local and regional scales is still an urgent imperative to overcome current critical haze pollution. [ABSTRACT FROM AUTHOR]

Due to the frequent irrigation and excessive fertilization during the rice production in China, diffuse nitrogen (N) and phosphorus (P) pollution from paddy fields has become a serious environment problem and poses great challenges to national water and food security. Considering the regional heterogeneities of climate, cultivation types and cropping systems of rice planting, many water management strategies have been proposed and implemented to control diffuse N and P pollution. However, the water management optimization at different scales (the field scale, the watershed scale and national scale) is lack of comprehensive analyzed. Here, this paper summarized the characteristics of frequent-used water managements and recommended the optimal water managements after identifying the critical risk periods of diffuse N and P runoff losses at the field scale. The effects of water management optimization on diffuse N and P pollution control at the watershed and national scale were also synthetically reviewed. The results indicated that optimized field water management decreased irrigation water use (38.7–40.0%) and reduced diffuse pollution (25.5–38.8%) without significantly compromising rice yield security (−4.20 to 6.5%). The critical risk periods of diffuse pollution were pre-flooding in the Northeast Plain, pre-flooding, regreening stage for transplanting rice (the seeding-three leaf stage for direct seeding rice) and within 2 weeks after topdressing fertilization in the Yangtze River Basin and Southeast Coast in China. The corresponding water managements for these periods has been proposed after considering the climate, precipitation and fertilization characteristics. Ditches and ponds intercepted water and nutrients and mitigated 6.0–39.0% N and P runoff losses in paddy field watersheds. Furthermore, the extensive implementation of paddy water management optimization (paddy fields, ditches and ponds) combined with other advanced agricultural measures, for example, fertilization optimization, would decrease diffuse N and P pollution by 40.7–80.8% at the watershed scale and 44.7–88.1% at the national scale, respectively. This research provided great insights into the specific characteristics of paddy water managements from the fields, watershed and national scale, proposed optimal water management strategies for the realization of sustainable rice production in China, and also summarized the emerging development trends for future research directions. [Display omitted] • Optimal paddy water managements at field, watershed and national scales were analyzed. • Optimal water managements were proposed for critical risk periods at field scale. • Future emerging prospects of paddy water managements from different scales were proposed. [ABSTRACT FROM AUTHOR]

Simple Summary: The phenomenon of global climate change can impact the geographic range and abundance of species, thereby heightening the vulnerability of rare species to extinction. The reed parrotbill (Paradoxornis heudei David, 1872) is endemic to central and eastern China and is considered a near-threatened species according to the International Union for Conservation of Nature (IUCN). This study shows that temperature annual range, annual precipitation, and isothermality were the principal climatic factors to limit the habitat suitability of P. heudei. Presently, the suitable habitat for P. heudei is predominantly found in the central–eastern and northeast plains of China, especially the eastern coastal area. P. heudei is sensitive to climate change. In the future, northeastern China may serve as a potential suitable habitat for P. heudei. The phenomenon of global climate change can impact the geographic range and biodiversity, thereby heightening the vulnerability of rare species to extinction. The reed parrotbill (Paradoxornis heudei David, 1872) is endemic to central and eastern China, it is mainly distributed in the middle and lower reaches of the Yangtze River Plain and the Northeast Plain. In this study, eight of ten algorithms of the species distribution model (SDM) were used to evaluate the impact of climate change on the potential distribution of P. heudei under current and future climate scenarios and to analyze the possible related climate factors. After checking the collected data, 97 occurrence records of P. heudei were used. The relative contribution rate shows that among the selected climatic variables, temperature annual range (bio7), annual precipitation (bio12), and isothermality (bio3) were the principal climatic factors to limit the habitat suitability of P. heudei. The suitable habitat for P. heudei is primarily concentrated in the central–eastern and northeast plains of China, particularly in the eastern coastal region, spanning a mere area of 57,841 km2. The habitat suitability of P. heudei under different representative concentration pathway (RCP) scenarios was predicted to be different under future climatic conditions, but all of them had a larger range than the current one. The species distribution range could expand by more than 100% on average compared with the current range under the four scenarios in 2050, while it could contract by approximately 30% on average relative to the 2050 range in 2070 under different climate change scenarios. In the future, northeastern China may serve as a potential suitable habitat for P. heudei. The changes in the spatial and temporal distributions of P. heudei's range are of utmost importance in identifying high-priority conservation regions and devising effective management strategies for its preservation. [ABSTRACT FROM AUTHOR]

Forest soil carbon is a major carbon pool of terrestrial ecosystems, and accurate estimation of soil organic carbon (SOC) stocks in forest ecosystems is rather challenging. This study compared the prediction performance of three empirical model approaches namely, regression kriging (RK), multiple stepwise regression (MSR), random forest (RF), and boosted regression trees (BRT) to predict SOC stocks in Northeast China for 1990 and 2015. Furthermore, the spatial variation of SOC stocks and the main controlling environmental factors during the past 25 years were identified. A total of 82 (in 1990) and 157 (in 2015) topsoil (0-20 cm) samples with 12 environmental factors (soil property, climate, topography and biology) were selected for model construction. Randomly selected 80% of the soil sample data were used to train the models and the other 20% data for model verification using mean absolute error, root mean square error, coefficient of determination and Lin's consistency correlation coefficient indices. We found BRT model as the best prediction model and it could explain 67% and 60% spatial variation of SOC stocks, in 1990, and 2015, respectively. Predicted maps of all models in both periods showed similar spatial distribution characteristics, with the lower SOC in northeast and higher SOC in southwest. Mean annual temperature and elevation were the key environmental factors influencing the spatial variation of SOC stock in both periods. SOC stocks were mainly stored under Cambosols, Gleyosols and Isohumosols, accounting for 95.6% (1990) and 95.9% (2015). Overall, SOC stocks increased by 471 Tg C during the past 25 years. Our study found that the BRT model employing common environmental factors was the most robust method for forest topsoil SOC stocks inventories. The spatial resolution of BRT model enabled us to pinpoint in which areas of Northeast China that new forest tree planting would be most effective for enhancing forest C stocks. Overall, our approach is likely to be useful in forestry management and ecological restoration at and beyond the regional scale. [ABSTRACT FROM AUTHOR]

In the semiarid sandy region of Northeast China, Mongolian pine (Pinus sylvestris var. mongolica) suffers dieback after the age of 35, while Japanese red pine (Pinus densiflora) and Chinese pine (Pinus tabuliformis) stay healthy. Foliar nutrient retranslocation reflects the nutrient conservation and utilization mechanism of plants in response to their habitats. However, the nutrient retranslocation strategies employed by three Pinus tree species to cope with nutrient limitations remain largely unknown. For this study, we investigated the seasonal variations in nitrogen (N) and phosphorus (P) concentrations of Mongolian pine, Japanese red pine, and Chinese pine plantations in terms of the green needles of all ages, senesced needles, and soil. Further, the N retranslocation efficiency (NRE), and P retranslocation efficiency (PRE), and correlations between the N:P ratios of needles and soil were analyzed. The results showed that, except for the spring NRE in 1-year-old needles of Mongolian pine, the spring NRE and PRE in 1- and 2-year-old needles of the three tree species were greater than zero. The autumn PRE was higher than zero for Mongolian pine, but lower than zero for Japanese red pine and Chinese pine. Among the three Pinus species, Mongolian pine showed greater spring PRE in 2-year-old needles, and PRE from 1- to 2-yearold needles, and from 2-year-old needles to litter. However, Japanese red pine had higher P concentrations and lower N:P ratios in senesced needles, while greater PRE was found in Chinese pine litter. Significant relationships between the N:P ratios were found in the current year and 1-year-old needles and soil in the Mongolian pine plantation, while there was an insignificant relationship between the N:P ratios of the needles and soil in the Chinese pine plantation. Thus, for Mongolian pine, the removal of P from needles in autumn, and higher P translocation from older needles under P-deficient soil may have contributed to the tree dieback. In contrast, Japanese red pine and Chinese pine stored P in their needles during autumn. Japanese red pine returned more P to the soil via litter, while Chinese pine maintained N:P homeostasis and increased P withdrawal prior to needle abscission. [ABSTRACT FROM AUTHOR]

The residual levels of 25 monitored pesticides in 6,229 brown rice samples obtained from the 17 provinces of the three main rice-growing regions in China during 2016–2020 were analyzed, and the cumulative risks of chronic and acute exposure to pesticides for the Chinese population were assessed. The QuEChERS extraction coupled with liquid chromatography-mass spectrometry for simultaneous determination of 25 pesticide residues in brown rice was developed and validated with good accuracy and precision (recoveries of 70%–120% and RSD ≤20%). The overall detection rate and over the maximum residue limit (MRL) rate of pesticides in brown rice decreased from 39.15% and 3.59% in 2016 to 34.11% and 1.53% in 2020, respectively. The Yangtze River basin had a higher detection rate and over MRL rate (43.14% and 2.88%, respectively) compared with the Southeast Coastal region (37.28% and 2.77%) and the Northeast Plain (11.28% and 0.17%). Isoprothiolane (13.57%) and carbendazim (8.32%) were the most frequently detected in rice samples. Pesticide residues exceeding the MRLs were found most often in triazophos (0.75%) and isocarbophos (0.51%). The risk ranking of pesticide residues based on the ranking matrix showed that carbofuran, methamidophos, and isocarbophos had the highest residual risk scores of 25.09, 25.01, and 25.00, respectively. 17.7% of rice samples contained two or more pesticide residues. The cumulative risk assessments based on the relative potency factor (RPF) approach revealed that the cumulative risks of chronic and acute dietary exposure to organophosphorus, neonicotinoid insecticides, and triazole fungicides from rice ranged from 7.43 × 10−4 to 3.36 × 10−2, which were not considered of health concern. The study provides national-scale information on the contamination levels and health risks of pesticide residues in rice, which can help develop continuous monitoring programs for pesticide residue contamination in rice in China. [ABSTRACT FROM AUTHOR]

A gathering pipeline in a gas field in Northeast China transporting mainly natural gas and also some water and sands was welded using two 20G pipes with different wall thicknesses. The internal corrosion of this pipeline was inhomogeneous. The unequal wall thickness welded joint suffered more serious corrosion damage than did other parts of the pipe and was found to fail during routine maintenance. In this paper, the corrosion damage at this joint was studied based on inhomogeneity. Internal and external factors affecting corrosion, such as the mechanical and electrochemical properties of materials, stress distribution at the joint, and the flow condition in the pipe, and their combined action were investigated. Failure attribution was performed on this basis. Specifically, a hardness test was conducted on different zones of the joint, including the base metal (BM), heat-affected zone (HAZ) and weld metal (WM), to investigate the abrasive wear resistance at the joint. Microstructures of the three zones were characterized by optical microscopy. The morphology and composition of the corrosion film covering the inner surface of the welded joint were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and X-ray powder diffraction (XRD). Potentiodynamic polarization experiments and electrochemical impedance spectroscopy (EIS) were conducted on samples from the three zones to investigate their electrochemical performances. Moreover, a computational fluid dynamics (CFD) analysis was performed to obtain the flow condition near the joint, and a finite element method (FEM) was used to calculate the stress distribution at the joint. The results showed that the internal corrosion mechanism of the pipeline was CO 2 corrosion accelerated by detrimental Cl − . The geometric discontinuity of the welded joint was the main cause of the accelerated corrosion damage at the joint. The change in wall thickness of the welded pipe not only produced gas vortices but also led to stress concentration. Both of these conditions can further accelerate corrosion by destroying the protectiveness of the corrosion film. It is suggested that the corrosion can be prevented by eliminating the inhomogeneities of fluid flow and stress distribution. [ABSTRACT FROM AUTHOR]

In this paper, a trace-transform-based radial trace time frequency peak-filtering method (RT-TFPF) with temporal-spatial directions is proposed. It utilizes the similarity of data along the reflection event and computes the temporal–spatial radial directions by seeking the local maximum value of a constructed trace function. This method takes advantage of the TFPF in non-stationary signal estimation, especially with no prior knowledge. Furthermore, applying the filtering in the temporal–spatial domain results in less biased TFPF estimation. Within the framework of the trace transform, the specified trace function first calculates the centroid and then accumulates the energy of the reflected signal along the trajectory, helping to find the locally optimal filtering directions automatically. Experiments on both synthetic record and field data in North-East China demonstrates good performance–strong random noise can be attenuated, while at the same time, the estimated reflection signal is more accurate for use in interpretation. [ABSTRACT FROM AUTHOR]

A long-term (18 years) effect of different fertilization and tillage management practices- fallowing treatment (no fertilizer, no cultivation); CK (no fertilizer, cultivation); N (nitrogen fertilizer); NP (nitrogen and phosphorus fertilizer); NK (nitrogen and potassium fertilizer); PK (phosphorus and potassium fertilizer); NPK (nitrogen, phosphorus, and potassium fertilizer); M1NPK (chemical fertilizer plus manure); 1.5M1NPK (1.5 times M1NPK); NPKS (mineral fertilizer plus straw); Rot (3-year crop rotation of maize-maize-soybean with M1NPK), and M2NPK (2 times manure plus mineral fertilizer) - on the content of total nitrogen and organic forms of nitrogen and the nitrogen content in different particle-size fractions were studied in topsoil (0-20 cm) in Black Soil of NE China by using the methods of Bremner. The results showed that the combined application of organic and mineral fertilizers could significantly increase the contents and proportions of total nitrogen and organic nitrogen forms in soil. Comparing to CK treatment, the content of total nitrogen and hydrolyzable nitrogen increased in the fallow and organic materials treatments. Compared with M1NPK treatment, rotation was more beneficial to increasing organic nitrogen content, especially remarkably increasing amino acid nitrogen. The nitrogen response of sand, silt, and clay was most sensitive on manure; the effects of fallow and manure treatments on sand were notable, the nitrogen content in sand with NPKS increased by 40.86% compared with CK treatment. Our results imply that fallow/rotation managements, and manure/straw application can improve soil fertility. [ABSTRACT FROM AUTHOR]

Riverine source-bordering sand dunes, as a result of active fluvial–aeolian interactions, are a pronounced feature on the semiarid Xiliaohe Plain, Northeast China. By means of satellite imagery analysis, and both field survey and observation, this paper presents a new type of riverine source-bordering sand dunes — deflated rims, on the downwind margins of the Xiangshui River. They largely result from the deflation of escarpments on the downwind side of valley by local prevailing winds of NW direction, not from the reworking of point bars on floodplain by wind. In general, a rim is primarily composed of three distinct zones: 1) the upwind frontal escarpment zone with variable plan-form shape, gradient and relief, which is formed by either active lateral erosion by river or significant erosion by wind and transient slope runoff; 2) the deflation zone with gentle slopes of 8–18° and small-scale aeolian bedforms, i.e. ripples of fine sand, ridges of coarse sand; and 3) the downwind dynamic deposition zone with distinctive bedforms with variable superficial texture and slip faces. The sand mass on rims derives overwhelmingly from underlying loose late Quaternary sediments, is sufficient and sustainable by successive retreats of the escarpment, and is gradually transported downwind by pulse motions of bedforms, coupled with high wind events. Essentially, deflated rims are a starting point and the incipient phase of mature riverine dunefields. The superimposed bedforms on rims are fundamentally governed by windflow dynamics, sand sediments and antecedent bedform, exhibiting in turn the manner and intensity of rim development. Consequently, the upwind river valley and downwind deflated rim can jointly stimulate marked wave-like motion of both windflow and aeolian bedforms at different scales, especially when high wind events occur. This study sheds some light on the understanding of the origin and development of riverine source-bordering dunefields, and offers new insights into the mechanisms of fluvial–aeolian interactions on drylands worldwide. [ABSTRACT FROM AUTHOR]

Decadal to centennial land use and land cover change has been consistently singled out as a key element and an important driver of global environmental change, playing an essential role in balancing energy use. Understanding long-term human-environment interactions requires historical reconstruction of past land use and land cover changes. Most of the existing historical reconstructions have insufficient spatial and thematic detail and do not consider various land change types. In this context, this paper explored the possibility of using a cellular automata-Markov model in 90 m × 90 m spatial resolution to reconstruct historical land use in the 1930s in Zhenlai County, China. Then the three-map comparison methodology was employed to assess the predictive accuracy of the transition modeling. The model could produce backward projections by analyzing land use changes in recent decades, assuming that the present land use pattern is dynamically dependent on the historical one. The reconstruction results indicated that in the 1930s most of the study area was occupied by grasslands, followed by wetlands and arable land, while other land categories occupied relatively small areas. Analysis of the three-map comparison illustrated that the major differences among the three maps have less to do with the simulation model and more to do with the inconsistencies among the land categories during the study period. Different information provided by topographic maps and remote sensing images must be recognized. [ABSTRACT FROM AUTHOR]

In this study, the structures of external costs are built in line with coal-fired and biomass power plant life cycle activities in Northeast China. The external cost of coal-fired and biomass power plants was compared, using the lifecycle approach. In addition, the external costs of a biomass power plant are calculated for each stage for comparison with those of a coal-fired power plant. The results highlight that the external costs of a coal-fired plant are 0.072 US $/kWh, which are much higher than that of a biomass power plant, 0.00012 US$/kWh. The external cost of coal-fired power generation is as much as 90% of the current price of electricity generated by coal, while the external cost of a biomass power plant is 1/1000 of the current price of electricity generated by biomass. In addition, for a biomass power plant, the external cost associated with SO2, NOX, and PM2.5 are particularly lower than those of a coal-fired power plant. The prospect of establishing precise estimations for external cost mechanisms and sustainable energy policies is discussed to show a possible direction for future energy schemes in China. The paper has significant value for supporting the biomass power industry and taxing or regulating coal-fired power industry to optimize the energy structure in China. [ABSTRACT FROM AUTHOR]

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