Coupling Coordination Analysis of Cropland Intensification and Agroecosystem Services:Evidence from Loess Plateau in Shaanxi Province,China

One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroecosystem service,the interactive coupling and coordination among these factors remain largely unexplored.In view of this,this study performed a case study of the Loess Plateau in Shaanxi Province,China and constructed comprehensive evaluation models to quantify the cropland intensification and agroecosystem service in this area.Balance analysis and the coupling coordination degree model were used to evaluate the interactive relationship between cropland intensification and agroecosystem service,and statistical analysis and spatial autocorrelation were used to analyze the spatial characteristics and potential mechanism of the coupling coordination.Results show that both the cropland intensification and agroecosystem service in the study area were relatively low yet gradually increased from 2000 to 2020.Agroecosystem service lag was identified as the dominant unbalanced development type.Improving the supply capacity of agroecosystem services plays a key role in the balanced development of cropland in the Loess Plateau.The coupling coordination degree between cropland intensification and agroecosystem service ranges from basic coordination to serious incoordination.Therefore,cropland intensification practices in the area should be optimized to enhance this coordination degree.An upward trend was also observed in the coupling coordination degree from2000 to 2020.The withdrawal of marginal cropland in the Grain for Green program is one of the most important reasons for this trend,especially for the northern region.Around 83.6%of the high-high clusters are concentrated in the southern region of the Loess Plateau,whereas 70.5%of the low-low clusters are distributed in the northern region.These clustering characteristics are mainly attributed to the environmental suitability of these areas for agriculture and their degree of economic development.

Estimating Monthly Surface Air Temperature Using MODIS LST Data and an Artificial Neural Network in the Loess Plateau, China

Air temperature(Ta)datasets with high spatial and temporal resolutions are needed in a wide range of applications,such as hydrology,ecology,agriculture,and climate change studies.Nonetheless,the density of weather station networks is insufficient,especially in sparsely populated regions,greatly limiting the accuracy of estimates of spatially distributed Ta.Due to their continuous spatial coverage,remotely sensed land surface temperature(LST)data provide the possibility of exploring spatial estimates of Ta.However,because of the complex interaction of land and climate,retrieval of Ta from the LST is still far from straightforward.The estimation accuracy varies greatly depending on the model,particularly for maximum Ta.This study estimated monthly average daily minimum temperature(Tmin),average daily maximum temperature(Tmax)and average daily mean temperature(Tmean)over the Loess Plateau in China based on Moderate Resolution Imaging Spectroradiometer(MODIS)LST data(MYD11A2)and some auxiliary data using an artificial neural network(ANN)model.The data from 2003 to 2010 were used to train the ANN models,while 2011 to 2012 weather station temperatures were used to test the trained model.The results showed that the nighttime LST and mean LST provide good estimates of Tmin and Tmean,with root mean square errors(RMSEs)of 1.04℃ and 1.01℃,respectively.Moreover,the best RMSE of Tmax estimation was 1.27℃.Compared with the other two published Ta gridded datasets,the produced 1 km×1 km dataset accurately captured both the temporal and spatial patterns of Ta.The RMSE of Tmin estimation was more sensitive to elevation,while that of Tmax was more sensitive to month.Except for land cover type as the input variable,which reduced the RMSE by approximately 0.01℃,the other vegetation-related variables did not improve the performance of the model.The results of this study indicated that ANN,a type of machine learning method,is effective for long-term and large-scale Ta estimation.

Spatio-temporal variation of soil CO_(2) concentration in Loess Area of northwestern Shanxi Province,China

CO_(2) released by soil serves as an important link between terrestrial ecosystems and atmospheric CO_(2), whose small chang‐es may significantly affect the global carbon cycle. In order to reveal the spatio-temporal variations of CO_(2) concentrations in deep loess, this paper takes Qingliangsi Gully watershed in northwestern Shanxi Province, China as an example to sys‐tematically study soil CO_(2)concentration and its spatio-temporal variations and carbon sink significance under different watershed locations and different land use types. Results show that: (1) The release potential of the loess soil is larger in the depth range of 2 m, which is much more likely to be the CO_(2) release area. (2) Grassland and forest are more advanta‐geous in terms of soil microbial activity and soil carbon reserve compared with farmland. In addition, the change of land use type from farmland to grassland can increase soil organic carbon reserve, which is of far-reaching significance to the global carbon cycle. This is especially true in an area like the Loess Plateau with densely covered hills, gullies, and serious soil erosion in an area of 64×104 km2. (3) In the study area, the diurnal concentration of soil CO_(2) at different depths shows a weak "high-low-high-low" trend from 08:00 to 07:00 next day;and in deep soil it has a lag time compared with the daily change of temperature, generally about 4−12 h, which may be caused largely by the more compact loess structure. It is worth pointing out that the Loess Plateau in China, with a thickness of the loess of tens to hundreds of meters, has the most abundant soil resources in the world, and also stores a large amount of terrestrial soil carbon, which carries the hope of promoting the research of global carbon cycle.

Relationship Between Agriculture and Ecological Deterioration,Restoration and Reconstruction in Loess Plateau Areas of Northwest China

A comprehensive analysis was conducted on the current situation as well as historic succession processor agriculture and ecological conditions in Northwest China, in particular in the Loess Plateau, by means of a inter-disciplinary approach of ecology, agro-geohistory, and agronomy. It was concluded that the fundamental causes responsible for the ecological deterioration, signed by the poor agro-productivity and serious soil erosion, had been the extensive cropping system by ever-increasing reclamation on semi-drought slope land, where initiated a natural vegetation of brushy grasses with sparse trees, thus suitable only for animal husbandry. Based on an identification of specific actual status of China, several countermeasures of correctly dealing with the relationship between agricultural development and the ecological restoration and reconstruction were proposed, including to get breakthrough first in the transection area by means of the rational use of resources and the raising of agro-system productivity, to promoting 'water conservancy-type ecological agriculture' through the radical shift of traditional production pattern, and the adoption of a policy of proper degree of grain self-reliance, as well as to construct livestock industry base in Northwest China.

Seasonal Responses of Net Primary Productivity of Vegetation to Phenological Dynamics in the Loess Plateau, China

With global warming, the great changes in the patterns of plant growth have occurred. The conditions in early spring and late autumn have changed the process of vegetation photosynthesis, which are expected to have a significant impact on net primary productivity(NPP) and affect the global carbon cycle. Currently, the seasonal response characteristics of NPP to phenological changes in dryland ecosystems are still not well defined. This article calibrated and analyzed the normalized difference vegetation index(NDVI)time series of Advanced Very-High-Resolution Radiometer(AVHRR) data from 1982 to 2015 in the Loess Plateau, China. The spatial and temporal distributions of vegetation phenology and NPP in the Loess Plateau under semihumid and semiarid conditions were investigated. The seasonal variation in the NPP response to vegetation phenology under the climate change was also analyzed. The results showed that, different from the northern forest, there was distinct spatial heterogeneity in the effect of climate change on the dynamic change in vegetation growth in the Loess Plateau: 1) an advance of the start of the growing season(SOS) and a delay of the end of the growing season(EOS) significantly increased the NPP in spring and autumn, respectively, in the humid southeast;2) in the arid northwest, the NPP did not significantly increase in spring and autumn but significantly decreased in summer.

Age-related Changes of Carbon Accumulation and Allocation in Plants and Soil of Black Locust Forest on Loess Plateau in Ansai County, Shaanxi Province of China

在高原生态系统吸引了的瓷器黄土的碳(C) 隐遁上的重新造林的效果很在最近的年里研究注意。黑蝗虫树(Robinia pseudoacacia L.) 在重新造林和水和土壤保存努力为他们的重要使用被珍视。这种森林类型越过黄土高原是普遍的，并且一定是任何在这个易碎的生态的区域为 C 隐遁努力计划的一个必要部件。在重新造林仍然保持不明确以后，看台的长期的效果在 C 累积和分配上变老。我们在黄土高原上检验了黑蝗虫森林(后来种的 5， 9， 20， 30， 38，和 56 年) 的年龄顺序在植物(树，灌木，牧草，和叶垃圾) 和土壤(0100 厘米) 评估 C 累积和分配。Allometric 方程为估计树部件的生物资源被开发(叶，树枝，茎没有吠叫，吠叫并且根) 与一个破坏采样方法。我们的结果证明那个黑蝗虫森林生态系统常常积累了 C，从 31.42 Mg C/ 哈(1 Mg = 10 < 啜 class= “ a-plus-plus ” > 6 g ) 在到在 38 年的 79.44 Mg C/ha 的 5 年。在旧森林阶段(38 ～ 56 年) ，在植物生物资源的 C 的数量显著地减少了(从 45.32 ～ 34.52 Mg C/ha ) 由于树的高死亡。然而，旧森林能在土壤连续地积累 C (从 33.66 ～ 41.00 Mg C/ha ) 。在灌木生物资源的 C 与看台年龄增加了，当在牧草层和叶垃圾的 C 股票是年龄无关的时。重新造林在森林土壤导致了 C 重新分配。C 存货与看台年龄常常增加了的表层土(020 厘米) 。然而，在 2030， 3050， 50100，和 20100 厘米层，在亚顶土壤的 C 存储是年龄无关的。这些结果建议作为一个时间的因素，继任在植被在地区性的 C 动力学在黑蝗虫森林里并且也在 C 累积和重新分配起一个关键作用。

De-farming and Ecological Restoration in the Loess Hilly-gully Region in Northern China

De-farming has been a powerful measure taken by the central and local governments of China for ecological restoration in the loess hilly-gully region since 2000. In years past, aid-based de-farming pattern was far and wide popularized in the region and terrace-based de-farming pattern demonstrated in a few small watersheds was also rather effective for ecological restoration. After summing up the features of three patterns (aid-based de-farming slope farmland more than 25°(AD25), aid-based de-farming slope farmland more than 15° (AD15) and terrace-based de-farming (TD)), this paper analyzed the regional difference of these patterns in de-farming area, ecological restoration, investment demand and so on. The results show that there are two crucial areas in the loess hilly-gully region for ecological restoration at the moment, the policies adaptation to the different areas should be constituted as soon as possible and the limited fund should be devoted to the two crucial areas.

Estimation and testing of linkages between forest structure and rainfall interception characteristics of a Robinia pseudoacacia plantation on China’s Loess Plateau

Understanding the interaction between canopy structure and the parameters of interception loss is essential in predicting the variations in partitioning rainfall and water resources as affected by changes in canopy structure and in implementing water-based management in semiarid forest plantations.In this study,seasonal variations in rainfall interception loss and canopy storage capacity as driven by canopy structure were predicted and the linkages were tested using seasonal filed measurements.The study was conducted in nine 50 m×50 m Robinia pseudoacacia plots in the semiarid region of China’s Loess Plateau.Gross rain-fall,throughfall and stemflow were measured in seasons with and without leaves in 2015 and 2016.Results show that measured average interception loss for the nine plots were 17.9% and 9.4% of gross rainfall during periods with leaves (the growing season) and without leaves, respectively. Average canopy storage capacity estimated using an indirect method was 1.3 mm in the growing season and 0.2 mm in the leafless season. Correlations of relative interception loss and canopy storage capacity to canopy variables were highest for leaf/wood area index (LAI/WAI) and canopy cover, fol-lowed by bark area, basal area, tree height and stand density. Combined canopy cover, leaf/wood area index and bark area multiple regression models of interception loss and canopy storage capacity were established for the growing season and in the leafless season in 2015. It explained 97% and 96% of the variations in relative interception loss during seasons with and without leaves, respectively. It also explained 98% and 99% of the variations in canopy storage capacity during seasons with and without leaves, respectively. The empiri-cal regression models were validated using field data col-lected in 2016. The models satisfactorily predicted relative interception loss and canopy storage capacity during seasons with and without leaves. This study provides greater under-standing about the effects of changes in tree canopy structure (e.g., dieback or mortality) on hydrological processes.

The Relationship between Microtexture Types and Indices of Physico-Mechanical Properties of Loess in China

The paper deals mainly with the relationship between the microtexture types and the indices of physicomechanical properties of loess. The results of study demonstrate that the study of microtextures of loess is of importance in the prediction and preliminary evaluation of engineering geological properties of loess in a region.

Study on Daily ET Based on SEBAL Model in a Typical Watershed of the Loess Plateau of China

Under the double impact of global climate change and human intervention, surface evapotranspiration (ET), as an important part of hydrological cycle, is affecting watershed land-use planning and economic development. The Loess Plateau is mostly arid and semi-arid areas and its ecological environment is fragile. Drought and soil erosion not only reflects the regional climate change, but also human social activities and ecosystems. In particular, these processes are directly related to the thermal and water gradients exchange in the soil-vegetation-atmosphere system. Luoyugou watershed, a typical Loess Plateau watershed, is selected for this study. Estimating ET through SEBAL (Surface Energy Balance Algorithm for Land) model demonstrates that the SEBAL model in the watershed is more applicable. At the same time, ET seasonal variation is got, combined with the corresponding periods of the land-use changes for analysis. The results show that ET in the Northwest of the basin is higher than the East on the spatial distribution, especially in the high vegetation coverage area. Land use changes significantly in the watershed over the past 20 years, mainly transferring from sloping terraces to the terraces and woodland. ET significantly increased area accounts for 47.6% of the total area in the valley, however, conspicuously reduced area accounts for 13.2%. The daily ET of different land use types had significant differences with the ET of water land and wood land was the largest. It is important that this study on the ET distribution can aid policy and decision makers for land use planning and environmental construction in Luoyugou watershed.

Response of Vegetation Cover to Climate Change and Influence of Dusty Weather in the Desertloess Transitional Zone of China

[Objective]This study aimed to analyze the relationships of the normalized difference vegetation index(NDVI)(1981-2006)in the desert-loess transitional zone of China with precipitation and temperature.[Method]The average method and the correlation function were applied in this study.[Result]The results indicated that during the growing season NDVI was positively correlated with precipitation in the current month,last month and the month before last,especially the last month.NDVI mostly negatively correlated with temperature,especially the temperature in the last month,which shows that the higher temperature,the more adverse the conditions for vegetation growth.[Conclusion]NDVI from August to October clearly is one of the significant factors influencing dust storm weather in spring of the next year.

NEW STATUS OF THE LOESS PLATEAU IN CHINA'S ECONOMIC DEVELOPMENT

impovensnment ana backwardness usea 10 be me common impression the me Loess Plateau. In thewake of the current reform drive and "open-door" policy, the Loess Plateau has seen a burgeoning development in the regional economy that is now driven by a new momentum. Viewed from the increase of its grain output, exploitation of the land resources and fruit production, establishment of energy bases, soil-and-water conservation and other aspects, this article delineates a brand-new and panoramic blueprint for the Plateau’s future. So a new status in the development of China’s national economy is endowed to the Plateau.

Research on the Development Model of Ecological Agriculture in Loess Hilly-Gully Region of Northern Shannxi, China

On the Loess Plateau of China, facing the vulnerable environment, local people have to try their best to guarantee the security of food, and at the same time, to control the most serious soil erosion in the world. The paper introduces two typical models of ecological agriculture: ecological agriculture with commodity and agriculture with soil and water conservation. According to the local natural condition, the model of eco-agriculture with commodity could be characterized by the structure of “agriculture-byproduct”, “agriculture-fruit” or “agriculture-forestry-husbandry”. The development of agriculture with soil and water conservation has decreased the soil erosion rate from 12, 184 ton/kin^2 in 1980 to 458.4 ton/kin^2 in 1999, while the farmers' income has increasingly risen. Analyses on the two models' benefits both in terms of ecological and agricultural economy show that there is a great possibility to construct or restore good eco-environment with comprehensive control in the hilly-gully area of north Shannxi. Further more, the paper points out the potential problems of foodstuff production and stockbreeding development in forming ecological agriculture and eco-environmental restoration.

Variation characteristics of CO_(2) in a newly-excavated soil profile,Chinese Loess Plateau:Excavation-induced ancient soil organic carbon decomposition

Soils of the Chinese Loess Plateau(CLP)contain substantial amounts of soil inorganic carbon(SIC),as well as recent and ancient soil organic carbon(SOC).With the advent of the Anthropocene,human perturbation,including excavation,has increased soil CO_(2) emission from the huge loess carbon pool.This study aims to determine the potential of loess CO_(2) emission induced by excavation.Soil CO_(2) were continuously monitored for seven years on a newly-excavated profile in the central CLP and the stable C isotope compositions of soil CO_(2) and SOC were used to identify their sources.The results showed that the soil CO_(2) concentrations ranged from 830μL·L^(-1) to 11190μL·L^(-1) with an annually reducing trend after excavation,indicating that the human excavation can induce CO_(2) production in loess profile.Theδ^(13) C of CO_(2) ranged from–21.27‰to–19.22‰(mean:–20.11‰),with positive deviation from top to bottom.The range of δ^(13)CSOC was–24.0‰to–21.1‰with an average of–23.1‰.Theδ^(13) C-CO_(2) in this study has a positive relationship with the reversed CO_(2) concentration,and it is calculated that 80.22%of the soil CO_(2) in this profile is from the microbial decomposition of SOC and 19.78%from the degasification during carbonate precipitation.We conclude that the human excavation can significantly enhance the decomposition of the ancient OC in loess during the first two years after perturbation,producing and releasing soil CO_(2) to atmosphere.

Infiltration characteristics of non-aqueous phase liquids in undisturbed loessal soil cores

The widespread contamination of soils and aquifers by non-aqueous phase liquids （NAPL）, such as crude oil, poses serious environmental and health hazards globally. Understanding the infiltration characteristics of NAPL in soil is crucial in mitigating or remediating soil contamination. The infiltration characteristics of crude and diesel oils into undisturbed loessal soil cores, collected in polymethyl methacrylate cylindrical columns, were investigated under a constant fluid head （3 era） of either crude oil or diesel oil. The infiltration rate of both crude and diesel oils decreased exponentially as wetting depth increased with time. Soil core size and bulk density both had significant effects on NAPL infiltration through the undisturbed soil cores; a smaller core size or a greater bulk density could reduce oil penetration to depth. Compacting soil in areas susceptible to oil spills may be an effective stratage to reduce contamination. The infiltration of NAPL into soil cores was spatially anisotropic and heterogeneous, thus recording the data at four points on the soil core is a good stratage to improve the accuracy of experimental results. Our results revealed that crude and diesel oils, rather than their components, have a practical value for remediation of contaminated loessal soils.

LOESS四维客观分析在中国近海的应用

利用全国海洋综合调查资料和世界大洋数据库(WOD)资料,运用局部加权回归法(LOESS)四维客观分析方案对中国近海的温度场进行了客观分析,将散布在空间中的温度资料点插值到均一的网格中。在分析中充分考虑了中国海曲折复杂的海岸特点,将底深调整系统(TAR)和障碍调整系统(BAR)整合到四维插值系统中,使得资料点空间权重的计算更为合理。计算结果显示,LOESS客观分析方案充分考虑了空间因素(经度、纬度、深度)和时间因素,能客观反映出中国近海一年四季的温度时间-空间结构。通过与Kriging插值方法的对比,发现LOESS方法能更精确地把中国近海温度结构反映出来。

Effect of Root Architecture on Structural Stability and Erodibility of Topsoils during Concentrated Flow in Hilly Loess Plateau

Traditional vegetation techniques for the control of concentrated flow erosion are widely recognized, whereas only a few studies have experimentally investigated the impacts of belowground roots on the erodibility of topsoils in semi-arid areas. To quantify the effects of root architectures on soil erodibility and its relevant structural properties, simulated flow experiments were conducted at six-week intervals from 18 July to 20 October in 2012 in the hilly Loess Plateau. Five treatments were: 1) bare(control), 2) purple alfalfa(Medicago sativa), representing tap roots(T), 3) switchgrass(Panicum virgatum), representing fibrous roots(F), 4) purple alfalfa and switchgrass, representing both tap and fibrous roots(T + F), and 5) natural recovery(N). For each treatment, soil structural properties and root characteristics were measured at an interval of six weeks. Soil anti-scouribility was calculated. Results showed that grass planting slightly reduced soil bulk density, but increased soil aggregate content by 19.1%, 10.6%, 28.5%, and 41.2% in the treatments T, F, T + F, and N, respectively. Soil shear strength(cohesion and angle of internal friction(φ)) significantly increased after the grass was planted. As roots grew, soil cohesion increased by 115.2%–135.5%, while soil disintegration rate decreased by 39.0%–58.1% in the 21 th week compared with the recorded value in the 9th week. Meanwhile, root density and root surface area density increased by 64.0%–104.7% and 75.9%–157.1%, respectively. No significant differences in soil anti-scouribility were observed between the treatments of T and F or of T + F and N, but the treatments of T + F and N performed more effectively than T or F treatment alone in retarding concentrated flow. Soil aggregation and root surface-area density explained the observed soil anti-scouribility during concentrated flow well for the different treatments. This result proved that the restoration of natural vegetation might be the most appropriate strategy in soil reinforcement in the hilly Loess Plateau.

Study on the Climate Changes Characteristics in the Hilly Region of the Loess Plateau and Its Influence on Agricultural Production

[Objective] The aim was to study the climate changes characteristics in the hilly region of the loess plateau and its influence on agricultural production.[Method] Taking Yan’an City as an example,and by dint of temperature and precipitation in nine meteorological stations from 1957 to 2007 and accumulated anomaly curve,linear regression and relevant analysis,the climate changes characteristics in 51 years in Yan’an were expounded.The climate changes in the hilly region of the loess plateau were studied and its influences on agricultural production were concluded.[Result] The characteristics of climate changes in the hilly region were as follow:high temperature in winter and warm winter trend was clearly;the temperature in spring enhanced fast and the drought disaster was increasing worse;rainy days occurred now and then in autumn.The climate changes had different levels of influences on agricultural production in Yan’an City.Because of rising temperature in winter,facility agriculture was vigorously developed and the apple range expanded;in the meantime,because of rising temperature in spring,drought was worsen and sowing in spring can not proceed;constant rain in autumn damaged the quality of date.[Conclusion] The study provided theoretical basis for the regional agricultural production and agricultural structure adjustment.

Study on Rural Domestic Waste Treatment in Loess Plateau Region——Taking Longfang Town in Shaanxi Province as Example

With the continuous development of economy and changes in people’s lifestyle,rural domestic waste brought about serious harm to water,air,human health,ecological landscape and so forth.In this paper,taking Longfang Town in Loess Plateau region as example,the source,amount and harms of rural domestic waste were analyzed firstly,as well as the current situation and existing problems of treatment,and then a suitable waste disposal technology for the town was chosen,finally the reasonable treatment methods combining new countryside and non-new countryside with township was summed up,so as to realize the reduction,harmless and resource treatment of rural domestic waste.

Interannual Changes of Land Surface Radiation Components in Loess Plateau and Their Responses to Climate Change

In this paper,land surface observation data at semi-arid climate and environmental observation station（ SACOL station） of Lanzhou University during 2006- 2012 and the data of Yuzhong meteorological station were used to analyze the responses of land surface radiation budget components to climate fluctuation,study the interannual variability of surface albedo,and discuss the feedback of various land surface process parameters on the interannual fluctuations of temperature and precipitation in Loess Plateau. According to the type of precipitation in Loess Plateau,the year was divided into winter and summer in order to get more significant interannual variability and correlation. The results showed that the trends of temperature and precipitation during 2006- 2012 were consistent with the warming and drying total trend in recent years in Loess Plateau. Shallow surface soil moisture and temperature showed a good response to temperature and precipitation,and the annual variation of summer half year had greater impact on the trend in the whole year. Incident solar radiation increase was major reason for climate warming in the Loess Plateau region.The combined effect of climatic factors was the reason for the change of surface albedo. Through the distinguish inquiry by winter and summer data,it was obtained that most correlations between summer radiation components and climatic factors have been improved,and partial correlations between winter radiation components and climatic factors have been increased.