Contour Farming Suitability of the Black Soil Region in Northeast China and Its Spatial Characteristics

Contour farming technology plays a key role in reducing soil erosion,enhancing water use efficiency,and fostering sustain-able agricultural development,Despite being a straightforward yet efficacious farming technique,it has not seen widespread implement-ation in China.Considering the deteriorating quality of arable lands in the Black Soil Region of Northeast China(BSR-NEC),it is ne-cessary to investigate spatial patterns and identify suitable areas for contour farming in this region.To achieve this objective,spatial autocorrelation and grouping analysis methods were employed to classify the land into four categories of suitability for contour farming:highly suitable,moderately suitable,generally suitable,and unsuitable.The results reveal that:1)the contour farming suitable area in BSR-NEC covers 89861.32 km^(2),accounting for 21.59%of arable land as of 2020.Heilongjiang Province owns the largest suitable area of 32853.68 km^(2),and Inner Mongolia has the highest proportion of 28.89%.2)In terms of the spatial distribution,regions with higher suitability for contour farming are concentrated in the Da Hinggan Mountains region,particularly Nenjiang City(Heilongjiang Province),which has the highest area of 2593.07 km^(2).Areas with a high proportion of suitable arable lands for contour farming are mainly found in the Da Hinggan Mountains and Changbai Mountains regions,with Ergun City(Inner Mongolia)having the highest pro-portion at 47.2%.Regions with higher suitability and proportion are concentrated in the Da Hinggan Mountains region,primarily cover-ing the Inner Mongolia and Heilongjiang.3)Regarding spatial clustering,both the area and proportion of suitable contour farming areas exhibit noticeable clustering effects,though not entirely consistent.4)Group analysis results designate 148 counties in BSR-NEC as highly suitable areas,predominantly located in the Changbai Mountains region,Liaodong Peninsula,Hulun Buir Plateau,and the north and south regions of the Da Hinggan Mountains.The zoning of suitable areas for contour farming in BSR-NEC informs the strategic de-velopment of policies and measures,allowing for the implementation of targeted policies in distinct areas suitable for contour farming.This provides a valuable reference for promoting contour farming technology more effectively and efficiently.re effectively and effi-ciently.

Spatio-temporal variation of depth to groundwater level and its driving factors in arid and semi-arid regions of India

Climate change and increasing anthropogenic activities,such as over-exploitation of groundwater,are exerting unavoidable stress on groundwater resources.This study investigated the spatio-temporal variation of depth to groundwater level(DGWL)and the impacts of climatic(precipitation,maximum temperature,and minimum temperature)and anthropogenic(gross district product(GDP),population,and net irrigated area(NIA))variables on DGWL during 1994-2020.The study considered DGWL in 113 observation wells and piezometers located in arid western plains(Barmer and Jodhpur districts)and semi-arid eastern plains(Jaipur,Ajmer,Dausa,and Tonk districts)of Rajasthan State,India.Statistical methods were employed to examine the annual and seasonal patterns of DGWL,and the generalized additive model(GAM)was used to determine the impacts of climatic and anthropogenic variables on DGWL.During 1994-2020,except for Barmer District,where the mean annual DGWL was almost constant(around 26.50 m),all other districts exhibited increase in DGWL,with Ajmer District experiencing the most increase.The results also revealed that 36 observation wells and piezometers showed a statistically significant annual increasing trend in DGWL and 34 observation wells and piezometers exhibited a statistically significant decreasing trend in DGWL.Similarly,32 observation wells and piezometers showed an statistically significant increasing trend and 37 observation wells and piezometers showed a statistically significant decreasing trend in winter;33 observation wells and piezometers indicated a statistically significant increasing trend and 34 had a statistically significant decreasing trend in post-monsoon;35 observation wells and piezometers exhibited a statistically significant increasing trend and 32 observation wells and piezometers showed a statistically significant decreasing trend in pre-monsoon;and 36 observation wells and piezometers reflected a statistically significant increasing trend and 30 observation wells and piezometers reflected a statistically significant decreasing trend in monsoon.Interestingly,most of the observation wells and piezometers with increasing trends of DGWL were located in Dausa and Jaipur districts.Furthermore,the GAM analysis revealed that climatic variables,such as precipitation,significantly affected DGWL in Barmer District,and DGWL in all other districts was influenced by anthropogenic variables,including GDP,NIA,and population.As a result,stringent regulations should be implemented to curb excessive groundwater extraction,manage agricultural water demand,initiate proactive aquifer recharge programs,and strengthen sustainable management in these water-scarce regions.

Study on the Promotion of Digital Trade to Northeast Asian Regional Economy

Society is currently transitioning from the era of informatization and digitization to the era of intelligence.Advanced technologies such as artificial intelligence,the Internet of Things,and big data are permeating every aspect of production and life.This penetration presents a rare opportunity for the development of digital trade and catalyzes innovation in traditional trade patterns.This paper first analyzes the inevitability of digital trade development in Northeast Asia.Secondly,it delves into the challenges faced by digital trade development and explores in-depth the promotion strategy for digital trade’s impact on the economic development of the Northeast Asia region,providing insights from various perspectives for reference.

Analysis on Status and Development Trend of Wind Erosion in Black Earth Region of Northeast China

In this paper,areas and main factors of wind erosion in black earth region of Northeast China were systematically analyzed,as well as the development trend of wind erosion in black earth region of Northeast China.In addition,development trend of wind erosion in black earth region of Northeast China was analyzed from the aspects of the geographic position,climatic change law in recent 40 years and effects of northeast sand land desertification on wind erosion in black earth region,which had provided references for the research and prevention of wind erosion in soil of black earth region of Northeast China.

Economic Development Status and Regulation Countermeasures of Tourist County in Northeast China Region

Through deep analysis on causes of poor economy in tourist county,the study pointed out that to seek for future development approaches would be the key for economic development of tourist county in Northeast Region.On the basis of identification of connotation,scope and types of tourist county in Northeast Region,economic development status of tourist county in Northeast Region was analyzed by using a large number of statistics,the main existing problems were pointed out and corresponding regulating countermeasures were proposed pertinently.

Spatiotemporal Variations and Regional Transport of Air Pollutants in Two Urban Agglomerations in Northeast China Plain

Characteristics of air pollution in Northeast China(NEC) received less research attention in the past comparing to other heavily polluted regions in China.Spatiotemporal variations of six criteria air pollutants(PM10, PM2.5, SO2, NO2, O3 and CO) in Central Liaoning Urban Agglomeration(CLUA) and Harbin-Changchun Urban Agglomeration(HCUA) in NEC Plain were analyzed in this study based on three-year hourly observations of air pollutants and meteorological variables from 2015 to 2017.The results indicated that the annual mean concentrations of air pollutants are generally higher in the middle and southern regions in NEC Plain and lower in the northern region.Megacities such as Shenyang, Harbin and Changchun experience severe air pollution, with a three-year averaged air quality index(AQI) larger than 80, far exceeding the daily AQI standard at the first-level of 50 in China.The annual mean PM and SO2 concentrations decrease most significantly in NEC urban agglomerations from 2015 to 2017, followed by CO and NO2, while O3 shows a slight increasing trend.All the six pollutants exhibit obvious seasonal and diurnal variations, and these variations are dictated by local emission and meteorological conditions.PM2.5 and O3 concentrations in NEC urban agglomerations strongly depend on wind conditions.High O3 concentrations at different cities usually occur in presence of strong winds but are independent on wind direction(WD), while high PM2.5 is usually accompanied by weak winds and poor dispersion condition, and sometimes also occur when the northerly or southerly winds are strong.Regional transport of air pollutants between NEC urban agglomerations is common.A severe haze event on November 1–4, 2017 is examined to demonstrate the role of regional transport on pollution.

Study on the Method of Soil Productivity Assessment in Black Soil Region of Northeast China

The objective of this paper is to investigate a simple and practical method for soil productivity assessment in the black soil region of Northeast China. Firstly, eight kinds of physicochemical properties for each of 120 soil samples collected from 25 black soil profiles were analyzed using cluster and correlation analysis. Subsequently, parameter indices were calculated using physicochemical properties. Finally, a modified productivity index （MPI） model were developed and validated. The results showed that the suitable parameters for soil productivity assessment in black soil region of Northeast China were soil available water, soil pH, clay content, and organic matter content. Compared with original productivity index （PI） model, MPI model added clay content and organic matter content in parameters while omitted bulk density. Simulation results of original PI model and MPI model were compared using crop yield of land block where investigated soil profiles were located. MPI model was proven to perform better with a higher significant correlation with maize yield. The correlation equation between MPI and yield was： Y= 3.2002Ln（MP/）＋ 10.056, R^2 = 0.7564. The results showed that MPI model was an effective and practical method to assess soil productivity in the research area.

Effect of farmland shelterbelts on gully erosion in the black soil region of Northeast China

The black soil region of northeast China is one of the most important grain-producing areas in China. Increasingly severe gully erosion in this region has destroyed much farmland and reduced grain production. We analyzed SPOT5 imagery from 2007 and TM imagery from 2008 to describe the distributions of gullies and farmland shelterbelts in Kedong County and to assess the effect of farmland shelterbelts on gully erosion. The ima- gery revealed 2311 gullies with average density of 418.51 m km-2, indicating very serious gully erosion. With increasing slope gradient there was an inverse trend between gully density and shelterbelt density, indicating that farmland shelterbelts can prevent gully erosion. The defense effect of farmland shelterbelts against gullyerosion varied with distance： for distances 〈120 m, the defense effect was consistent and very strong; for distances of 120-240 m, a weak linear decrease was found in the defense effect; and for distances 〉240 m, the defense effect of the shelterbelts was significantly weaker. We recommend an optimal planting density of farmland shel- terbelts for the prevention of gully erosion at 1100-1300 m km-2.

Numerical Study of Impacts of Soil Moisture on the Diurnal and Seasonal Cycles of Sensible/Latent Heat Fluxes over Semi-arid Region

The semi-arid regions, as climatic and ecosystem transitional zones, are the most vulnerable to global environmental change. Earlier researches indicate that the semi-arid regions are characterized by strong landatmosphere coupling in which soil moisture is the crucial variable in land surface processes. In this paper, we investigate the sensitivity of the sensible/latent heat fluxes to soil moisture during the growing season based on the enhanced observations at Tongyu in the Jilin province of China, a reference site of international Coordinated Energy and Water Cycle Observations Project （CEOP） in the semi-arid regions, by using a sophisticated land surface model （NCAR_CLM3.0）. Comparisons between the observed and simulated sensible/latent heat fluxes indicate that the soil moisture has obvious effects on the sensible/latent heat fluxes in terms of diurnal cycle and seasonal evolution. Better representation of the soil moisture could improve the model performance to a large degree. Therefore, for the purpose of simulating the land-atmosphere interaction and predicting the climate and water resource changes in semi-arid regions, it is necessary to enhance the description of the soil moisture distribution both in the way of observation and its treatment in land surface models.

Can climate change influence agricultural GTFP in arid and semi-arid regions of Northwest China?

There are eight provinces and autonomous regions(Gansu Province,Ningxia Hui Autonomous Region,Xinjiang Uygur Autonomous Region,Inner Mongolia Autonomous Region,Tibet Autonomous Region,Qinghai Province,Shanxi Province,and Shaanxi Province)in Northwest China,most areas of which are located in arid and semi-arid regions(northwest of the 400 mm precipitation line),accounting for 58.74%of the country's land area and sustaining approximately 7.84×10^6 people.Because of drought conditions and fragile ecology,these regions cannot develop agriculture at the expense of the environment.Given the challenges of global warming,the green total factor productivity(GTFP),taking CO2 emissions as an undesirable output,is an effective index for measuring the sustainability of agricultural development.Agricultural GTFP can be influenced by both internal production factors(labor force,machinery,land,agricultural plastic film,diesel,pesticide,and fertilizer)and external climate factors(temperature,precipitation,and sunshine duration).In this study,we used the Super-slacks-based measure(Super-SBM)model to measure agricultural GTFP during the period 2000-2016 at the regional level.Our results show that the average agricultural GTFP of most provinces and autonomous regions in arid and semi-arid regions underwent a fluctuating increase during the study period(2000-2016),and the fluctuation was caused by the production factors(input and output factors).To improve agricultural GTFP,Shaanxi,Shanxi,and Gansu should reduce agricultural labor force input;Shaanxi,Inner Mongolia,Gansu,and Shanxi should decrease machinery input;Shaanxi,Inner Mongolia,Xinjiang,and Shanxi should reduce fertilizer input;Shaanxi,Xinjiang,Gansu,and Ningxia should reduce diesel input;Xinjiang and Gansu should decrease plastic film input;and Gansu,Shanxi,and Inner Mongolia should cut pesticide input.Desirable output agricultural earnings should be increased in Qinghai and Tibet,and undesirable output(CO2 emissions)should be reduced in Inner Mongolia,Xinjiang,Gansu,and Shaanxi.Agricultural GTFP is influenced not only by internal production factors but also by external climate factors.To determine the influence of climate factors on GTFP in these provinces and autonomous regions,we used a Geographical Detector(Geodetector)model to analyze the influence of climate factors(temperature,precipitation,and sunshine duration)and identify the relationships between different climate factors and GTFP.We found that temperature played a significant role in the spatial heterogeneity of GTFP among provinces and autonomous regions in arid and semi-arid regions.For Xinjiang,Inner Mongolia,and Tibet,a suitable average annual temperature would be in the range of 7℃-9℃;for Gansu,Shanxi,and Ningxia,it would be 11℃-13℃;and for Shaanxi,it would be 15℃-17℃.Stable climatic conditions and more efficient production are prerequisites for the development of sustainable agriculture.Hence,in the agricultural production process,reducing the redundancy of input factors is the best way to reduce CO2 emissions and to maintain temperatures,thereby improving the agricultural GTFP.The significance of this study is that it explores the impact of both internal production factors and external climatic factors on the development of sustainable agriculture in arid and semi-arid regions,identifying an effective way forward for the arid and semi-arid regions of Northwest China.

Spatial Autocorrelation Analysis on Regional Economic Disparity of Northeast Economic Region in China

Popular regional inequality indexes such as variation coefficient and Gini coefficient can only reveal overall inequality, and have limited ability in revealing spatial dependence or spatial agglomeration. Recently some methods of exploratory spatial data analysis such as spatial autocorrelation have provided effective tools to analyze spatial agglomeration and cluster, which can reveal the pattern of regional inequality. This article attempts to use spatial autocorrelation at county level to get refined spatial pattern of regional disparity in Chinese northeast economic region over 2000-2006 (2001 absent). The result indicates that the basic trend of regional economy is an increasing concentration of growth among counties in northeast economic region, and there are two geographical clusters of poorer counties including the counties in western Liaoning Province and adjacent counties in Inner Mongolia, poorer counties of Heihe, Qiqihar and Suihua in Heilongjiang Province. This article also reveals that we can use the methods of exploratory spatial data analysis as the supplementary analysis methods in regional economic analysis.

Impact of Wetland Change on Local Climate in Semi-arid Zone of Northeast China

Wetlands are sensitive to climate change, in the same time, wetlands can influence climate. This study analyzed the spa- rio-temporal characteristics of wetland change in the semi-arid zone of Northeast China from 1985 to 2010, and investigated the impact of large area of wetland change on local climate. Results showed that the total area of wetlands was on a rise in the study area. Although natural wetlands （marshes, riparians and lakes） decreased, constructed wetlands （rice fields） increased significantly, and the highest in- crease rate in many places exceeded 30%. Anthropogenic activities are major driving factors for wetland change. Wetland change pro- duced an impact on local climate, mainly on maximum temperature and precipitation during the period of May-September. The increase （or decrease） of wetland area could reduce （or increase） the increment of maximum temperature and the decrement of precipitation. The changes in both maximum temperature and precipitation corresponded with wetland change in spatial distribution. Wetland change played a more important role in moderating local climate compared to the contribution of woodland and grassland changes in the study area. Cold-humid effect of wetlands was main way to moderating local climate as well as alleviating climatic wanning and drying in the study area, and heterogeneity of underlying surface broadened the cold-humid effect of wetlands.

Soil respiration response to precipitation reduction in a grassland and a Mongolian pine plantation in semi-arid northeast China

Climate change is predicted to alter global precipitation regimes.However,the response of soil carbon and nitrogen cycles and soil microorganisms to precipitation reduction is poorly understood but is dependent on ecosystem type.To evaluate the impacts of reduced precipitation on soil respiration,soil inorganic nitrogen(i.e.,NH4^+–N and NO3^-–N),nitrogen mineralization,and soil microbial community composition,a precipitation manipulation experiment was initiated in a Mongolian pine plantation and a naturally restored grassland in semi-arid northeast China.Precipitation reduction led to decreases of soil respiration rates by 14 and 8%in 2014 and 2015 in the Mongolian pine plantation but no changes in the grassland.Soil inorganic nitrogen,ammonification and nitrification rate,and soil phospholipids fatty acids were not significantly changed by reduced precipitation but significantly differed between the two ecosystems and among growing seasons.Our results suggest that the impacts of precipitation reduction on soil respiration were different between the Mongolian pine plantation and the grassland,and that ecosystem type and growing season had more pronounced impacts on soil carbon and nitrogen cycles.

Emergy-based study on eco-economic system of arid and semi-arid region:a case of Gansu province,China

Taking Gansu province as a model case,this study provides an integrated analysis on the eco-economic system of arid and semi-arid region based on emergy synthesis theory. Through calculating the values of renewable emergy flow,non-renewable resources,imported emergy,exported emergy,waste emergy,and total emergy during the period of 1978-2007,the performance of Gansu eco-economic system was analyzed. The results indicated that the renewable emergy flow within the province basically remained steady state which was estimated at 2.99×1022 solar emjoules (sej) from 1978 to 2007. The imported emergy and exported emergy were estimated at 3.75×1017 sej and 2.99×1020 sej in 1978 and increased to 1.07×1022 sej and 1.44×1022 sej respectively in 2007. The nonrenewable emergy flow was estimated at 1.62×1022 sej and increased to 1.85×1023 sej,with annual growth rate of 8.7%,while the estimated total emergy was 4.58×1022 sej in 1978 and increased to 2.11×1023 sej in 2007,with annual growth rate of 5.41%. Our results indicate a deteriorate situation between economic development and environmental protection in the region. The rapid economic growth in the past thirty years was based on a great consumption of nonrenewable resource and caused continuous decrease in the capacity of sustainable development. The environmental loading ratio was 0.53 in 1978,increased to 6.06 in 2007,indicating a rapid degradation of the regional environment quality. We calculated that the actual population was 1.53 times the renewable resource population in 1978,increased to 7.06 times in 2007. During the period of 1978-2007,the emergy rose from 2.45×1015 sej/(capita·a) to 8.07×1015 sej/(capita·a). Our analysis revealed that the emergy density presented a trend of gradual increase,and then the emergy currency ratio in Gansu decreased from 7.08×1013 sej/Chinese Yuan to 7.82×1012 sej/Chinese Yuan.

Plastic-film-side seeding,as an alternative to traditional film mulching,improves yield stability and income in maize production in semi-arid regions

Planting under plastic-film mulches is widely used in spring maize production in arid-cold regions for water conservation and warming the soil.To ameliorate the associated issues such as plastic-film residues and additional labor during the“seedling release”in spring maize production,we have developed a plastic-film-side seeding(PSS)technology with the supporting machinery.In the semi-arid regions of Northwest China,a 7-year trial demonstrated that PSS increased plant number per hectare by 6547 and maize yield by 1686 kg ha–1compared with the traditional method of seeding under plastic-film mulch(PM).Two-year experiments were conducted in two semi-arid regions to further understand the effects of PSS on three important aspects of production:(i)the moisture and temperature of soil,(ii)maize development,yield output,and water use efficiency(WUE),and(iii)the revenue and plastic-film residuals in comparison with that of flat planting(CK)and PM.Continuous monitoring of the soil status demonstrated that,compared with CK,the PSS treatment significantly increased the temperature and moisture of the 0–20 cm soil in the seeding row at the early stage of maize development,and it also promoted grain yield(at 884–1089 kg ha^(–1))and WUE,achieving a similar effect as the PM treatment.Economically,the labor inputs of PSS were equal to CK,whereas the PM cost an additional 960 CNY ha–1in labor for releasing the seedlings from below the film.Overall,the PSS system increased profits by 5.83%(547 CNY ha^(–1)yr^(–1))and 8.16%(748 CNY ha^(–1)yr^(–1))compared with CK and PM,respectively.Environmentally,PSS achieved a residual film recovery rate of nearly 100%and eliminated 96 to 130 kg ha^(–1)of residual plastic-film in PM in 3–5 years of maize production.Collectively,these results show that PSS is an eco-friendly technique for improving yield stability and incomes for the sustainable production of maize in semi-arid regions.

Effects of the Northeast China Revitalization Strategy on Regional Economic Growth and Social Development

Measuring the economic and social effects of the Northeast China Revitalization Strategy is critical to addressing regional sustainable development in China. To shed light on this issue, an integrated perspective was adopted that is combined with the difference-in-differences method to measure the effects of the strategy on economic growth and social development in Northeast China. The findings suggest that the strategy has significantly improved regional economic growth and per-capita income by increasing its gross domestic product(GDP) and GDP per capita by 25.70% and 46.00%, respectively. However, the strategy has significantly worsened the regional employment in the secondary industry of the region. In addition, the strategy has not significantly improved regional infrastructural road, education investment or social security, and has had no significant effect on mitigating regional disparity. In addition, the policy effects are highly heterogeneous across cities based on city size and characteristics. Therefore, there is no simple answer regarding whether the Northeast China Revitalization Strategy has reached its original goals from an integrated perspective. The next phase of the strategy should emphasize improving research and development(R&D) and human capital investments based on urban heterogeneity to prevent conservative path-dependency and the lock-in of outdated technologies.

Relationship Between Soil and Water Conservation Practices and Soil Conditions in Low Mountain and Hilly Region of Northeast China

The soil and water conservation practices of ecological restoration(ER),fish scale pit(FP),furrow and ridge tillage across the slope(FR),shrub strips(SS),and vegetation-covered ridge(VR)are characteristic of the Jixing small watershed of the low mountain and hilly region of Jilin Province,Northeast China.This study aims to elucidate the effects of soil and water conservation practices on soil conditions after the short-term implementation of practices.Soil samples were collected from five soil and water conservation sites(ER,FP,FR,SS,and VR)and two controls(BL and CT)to investigate their properties.To evaluate the influence of soil and water conservation practices on soil quality,an integrated quantitative index,soil quality index(QI),was developed to compare the soil quality under the different soil and water conservation practices.The results show that not all soil and water conservation practices can improve the soil conditions and not all soil properties,especially soil organic carbon(SOC),can be recovered under soil and water conservation practice in short-term.Moreover,the QI in the five soil and water conservation practices and two controls was in the following order:ER>VR>BL>FR>CT>SS>FP.ER exhibited a higher soil quality value on a slope scale.In the low mountain and hilly region of Northeast China,ER is a better choice than the conversion of farmlands to planted grasslands and woodlands early in the soil and water conservation program.

Evaluation of SEBS Algorithm for Estimation of Daily Evapotranspiration Using Landsat-8 Dataset in a Semi-Arid Region of Central Iran

Evapotranspiration is one the most important parameters in the hydrological cycle and plays a significant role in energy balance of the earth’s surface. Traditional field-based measurements approaches for calculation of daily evapotranspiration are valid only for local scales. Using advanced remote sensing technology, the spatial distribution of evapotranspiration may now be quantified more accurately. At the present study, daily evapotranspiration is estimated using Landsat 8 datasets based on the Surface Energy Balance System (SEBS) algorithm over the Zayanderud Dam area in central Iran. For this purpose, three Landsat 8 datasets in the years 2013, 2014 and 2015 covering the study area were atmospherically corrected using the FLAASH approach. The biophysical parameters of the earth’s surface for SEBS algorithm, such as normalized difference vegetation index (NDVI), Leaf area index (LAI), fractional vegetation cover (FC) were extracted from the visible and near infrared bands and land surface temperature was computed from thermal bands the Landsat 8 datasets. The spatial distribution of daily ET was provided separately for each year. In addition to the SEBS algorithm, the Penman-Monteith method was applied to estimate the daily ET from meteorological datasets which was obtained from two synoptic stations within the study area. Finally, the simulated daily ET values from both SEBS and Penman-Monteith method were compared to observed values obtained from a lysimeter within the study area. Although the estimated results from both SEBS and Penman-Monteith show a strong correlation with the observed values, the derived ET maps and following analysis demonstrated SEBS has higher accuracy and strength in estimation of daily ET in Zayanderud Dam region.

Regional Evolution Features and Coordinated Development Strategies for Northeast China

Northeast China, as the most important production base of agriculture, forestry, and livestock-breeding as well as the old industrial base in the whole country, has been playin a key role in the construction and development of China＇s economy. However, after the policy of reform and open-up was taken in China. the economic development speed and efficiency ofthis area have turned to be evidently lower than those of coastal area and the national average level as well, which is so-called ＇Northeast Phenomenon＇ and ＇Neo-Northeast Phenomenon＇. In terms of those phenomena, this paper firstly reviews the spatial and temporal features of the regional evolution of this area so as to unveil the profound forming causes of ＇Northeast Phenomena＇ and ＇Neo-Northeast Phenomena＇. And then the paper makes a further exploration into the status quo of this region and its forming causes by analyzing its economy gross, industrial structure, product structure, regional eco-categories, etc. At the end of the paper, the authors put forward the basic coordinated development strategies for Northeast China. namely we can revitalize this area by means of adjustment of economic structure, regional coordination, planning urban and rural areas as a whole, institutional innovation, etc.

Impact of rainfed and irrigated agriculture systems on soil carbon stock under different climate scenarios in the semi-arid region of Brazil

Understanding the dynamics of soil organic carbon(SOC) is of fundamental importance in land use and management, whether in the current researches or in future scenarios of agriculture systems considering climate change. In order to evaluate SOC stock of the three districts(Delmiro Gouveia, Pariconha, and Inhapi districts) in the semi-arid region of Brazil in rainfed and irrigated agriculture systems under different climate scenarios using the Century model, we obtained RCP4.5 and RCP8.5 climate scenarios derived from the Eta Regional Climate Model(Eta-Had GEM2-ES and Eta-MIROC5) from the National Institute for Space Research, and then input the data of bulk density, p H, soil texture, maximum temperature, minimum temperature, and rainfall into the soil and climate files of the Century model. The results of this study showed that the Eta-Had GEM2-ES model was effective in estimating air temperature in the future period. In rainfed agriculture system, SOC stock under the baseline scenario was lower than that under RCP4.5 and RCP8.5 climate scenarios, while in irrigated agriculture system, SOC stock in the almost all climate scenarios(RCP4.5 and RCP8.5) and models(Eta-Had GEM2-ES and Eta-MIROC5) will increase by 2100. The results of this study will help producers in the semi-arid region of Brazil adopt specific agriculture systems aimed at mitigating greenhouse gas emissions.