Search

Metro transit construction has begun to develop rapidly in northwest China because of the acceleration of urbanization. Accordingly, metro depots are also regarded as an essential auxiliary facility for stopping, operation, and maintenance of trains. Meanwhile, many commercial buildings are constructed over metro depots to improve the utilization rate of land due to the increasingly scarce urban land resources, known as transit-oriented development (TOD). These buildings have a large covered area and transfer concentrated loads to the bases. Therefore, pile bases under metro depots have the bearing characteristics of undertaking large concentrated loads, while lesser loads are placed on the soil between the adjacent pile bases. Additionally, the main ground in northwest China is collapsible loess, so the collapsibility should also be considered. Based on the above background, this research performed static loading tests with and without immersion in a reduced scale of adjacent pile bases under a metro depot in Xi'an. The remolding process of natural loess could destroy its structure and the anisotropy of natural loess could also affect the test results. Therefore, four kinds of artificial collapsible loess with different mass ratios of barite powder, kaolin, river sand, cement, industrial salt, and calcium oxide were made by the free-drop method. This method could make the artificial loess simulate the structure of natural loess reasonably. Then, the artificial loess with the most similar properties to intact loess was selected by comparison. Finally, static loading tests with this artificial loess were implemented. The results showed that the ultimate bearing capacity was 4.5 kN. At the same time, the axial force decreased along depth, since the pile shaft friction was positive, and the load sharing ratio of pile tip force increased to 0.58 when the load exceeded 4.5 kN in the situation without immersion; the settlement of pile bases increased significantly after immersion, while the negative shaft friction occurred at the depth of −8 cm~−35 cm, and the load sharing ratio of pile tip force reached 0.92. [ABSTRACT FROM AUTHOR]

The present study aims to establish how the agricultural lands in Sălcuța Plain, a piedmont subunit of the Romanian Plain, are affected by the presence of micro-depressions on loess deposits. The formation of these microdepressions is closely related to the chemical and mechanical compaction process, which is conditioned by several factors, including the thickness of the loess deposit, the quantity of carbonates in the deposit, local morphometry, paleogeographic evolution, and climatic conditions. Based on satellite imagery from the 2010-2019 period, 303 microdepressions were identified. Out of the total number of depressions, 293 are located on agricultural lands, covering approximately 9.31 km2. On the surface of some of these depressions, soils with stagnant horizons (0.7 km2) have formed due to prolonged excess moisture. These types of soils gradually lead to the long-term degradation of agricultural lands. It is recommended to constantly monitor the evolution of soils with stagnant horizons and implement ameliorative agricultural measures in case an expansion of their area is observed in the long term. [ABSTRACT FROM AUTHOR]

Soil water is a major barrier to ecological restoration and sustainable land use in China's Loess Hilly Region. For the restoration of local vegetation and the optimal use of the region's land resources, both theoretically and practically, it is essential to comprehend the soil water regimes under various land use types. The soil water content in the 0–160 cm soil profile of slope cropland, terraced field, jujube orchard, and grassland was continuously measured using EC-5 soil moisture sensors during the growing season (May–October) in the Yuanzegou catchment in the Loess Hilly Region to characterize the changes in soil water in these four typical land use types. The results showed that in both years of normal precipitation and drought, land use patterns varied in seasonal variability, water storage characteristics, and vertical distribution of soil water. In the dry year of 2015, the terraced field effectively held water. During the growing season, the 0–60 cm soil layer's average soil water content was 2.6%, 4.2%, and 1.8% higher than the slope cropland, jujube orchard, and grassland, respectively (p < 0.05), and the 0–160 cm soil layer's water storage was 43.90, 32.08, and 18.69 mm higher than the slope cropland, jujube orchard, and grassland, respectively. The average soil water content of the 0–60 cm soil layer in the jujube orchard was 2.9%, 3.8%, and 4.5% lower than that of slope cropland, terraced field, and grassland, respectively, during the normal precipitation year (2014) (p < 0.05). Only 35.0% of the total soil water storage was effectively stored in the 0–160 cm soil layer of the jujube orchard during the drought year. There was a significant difference in the grey relational grade between the soil water in the top layer (0–20 cm) and the soil water in the middle layer (20–100 cm) under different land use types, with the terraced field having the highest similarity degree of soil water variation trend, followed by grassland, slope cropland, and jujube orchard. Slope croplands in the study region may be converted into terraced fields to enhance the effective use of rainfall resources and encourage the expansion of ecological agriculture. Proper water management practices must be employed to reduce jujube tree water consumption and other wasteful water usage in order to guarantee the jujube orchard's ability to expand sustainably. This would address the issue of the acute water deficit in the rain-fed jujube orchards in the Loess Hilly Region. [ABSTRACT FROM AUTHOR]

This showed that the sedimentation yields of the GU watershed were similar to those of the TU watershed, even though there was substantially less runoff (19.27% of that in the TU watershed). Due to larger cropland area and lower landscape stability in the GU watershed than that in the TU watershed, the annual sedimentation for the two watersheds was similar, even though the annual runoff in the TU watershed was greater than that in the GU watershed. Keywords: land use/cover change; landscape; runoff; sedimentation; Loess Plateau EN land use/cover change landscape runoff sedimentation Loess Plateau 1688 13 11/17/22 20221101 NES 221101 1. [Extracted from the article]

In this article, we present empirical models for estimating daily mean air temperature (Ta) in the Hurd Peninsula of Livingston Island (Antarctica) using Moderate Resolution Imaging Spectroradiometer (MODIS) Land Surface Temperature (LST) data and spatiotemporal variables. The models were obtained and validated using the daily mean Ta from three Spanish in situ meteorological stations (AEMET stations), Juan Carlos I (JCI), Johnsons Glacier (JG), and Hurd Glacier (HG), and three stations in our team's monitoring sites, Incinerador (INC), Reina Sofía (SOF), and Collado Ramos (CR), as well as daytime and nighttime Terra-MODIS LST and Aqua-MODIS LST data between 2000 and 2016. Two types of multiple linear regression (MLR) models were obtained: models for each individual station (for JCI, INC, SOF, and CR—not for JG and HG due to a lack of data) and global models using all stations. In the study period, the JCI and INC stations were relocated, so we analyzed the data from both locations separately (JCI1 and JCI2; INC1 and INC2). In general, the best individual Ta models were obtained using daytime Terra LST data, the best results for CR being followed by JCI2, SOF, and INC2 (R2 = 0.5–0.7 and RSE = 2 °C). Model cross validation (CV) yielded results similar to those of the models (for the daytime Terra LST data: R2CV = 0.4–0.6, RMSECV = 2.5–2.7 °C, and bias = −0.1 to 0.1 °C). The best global Ta model was also obtained using daytime Terra LST data (R2 = 0.6 and RSE = 2 °C; in its validation: R2CV = 0.5, RMSECV = 3, and bias = −0.03), along with the significant (p < 0.05) variables: linear time (t) and two time harmonics (sine-cosine), distance to the coast (d), slope (s), curvature (c), and hour of LST observation (H). Ta and LST data were carefully corrected and filtered, respectively, prior to its analysis and comparison. The analysis of the Ta time series revealed different cooling/warming trends in the locations, indicating a complex climatic variability at a spatial scale in the Hurd Peninsula. The variation of Ta in each station was obtained by the Locally Weighted Regression (LOESS) method. LST data that was not "good quality" usually underestimated Ta and were filtered, which drastically reduced the LST data (<5% of the studied days). Despite the shortage of "good" MODIS LST data in these cold environments, all months were represented in the final dataset, demonstrating that the MODIS LST data, through the models obtained in this article, are useful for estimating long-term trends in Ta and generating mean Ta maps at a global level (1 km2 spatial resolution) in the Hurd Peninsula of Livingston Island. [ABSTRACT FROM AUTHOR]

Changes in soil moisture and soil temperature result from the combined effects of several environmental factors. Scientific determination of the response characteristics of soil moisture and soil temperature to environmental factors is critical for adjusting the sloping land use structure and improving the ecological environment in China's loess hilly region. Soybean sloping fields, maize terraced fields, jujube orchards, and grasslands in the loess hilly region were selected as the research areas. The change in characteristics of soil moisture and soil temperature, as well as their interactions and statistical relationships with meteorological factors, were analyzed using continuously measured soil moisture, soil temperature, and meteorological factors. The results revealed that air temperature and humidity were the main controlling factors affecting soil moisture changes in the 0≥60 cm soil layer of soybean sloping fields and grasslands in the normal precipitation year (2014) and the dry year (2015). Humidity and wind speed were the main meteorological factors affecting soil moisture changes in the maize terraced field. Air temperature had a significant negative effect on soil moisture in the jujube orchard. Soil moisture and soil temperature were all negatively correlated under the four sloping land use types. In normal precipitation years, atmospheric humidity had the greatest direct and comprehensive effect on soil moisture in soybean sloping fields, maize terraced fields, and grasslands; soil temperature had a relatively large impact on soil moisture in jujube orchards. The direct and comprehensive effects of soil temperature on soil moisture under all sloping land use types were the largest and most negative in the dry year. Air temperature had a high correlation with soil temperature in the 0≥60 cm soil layer under the four sloping land use types, and the grey relational grade decreased as the soil layer deepened. The coefficient of determination between the 0≥20 cm soil temperature and air temperature in the maize terraced field was low, indicating a weak response to air temperature. The above findings can serve as a scientific foundation for optimizing sloping land use structures and maximizing the efficient and sustainable utilization of sloping land resources in China's loess hilly region. [ABSTRACT FROM AUTHOR]

Deformation Prediction of compacted loess is important for the constructions on the land created with such soil. In this study, in-situ fiber-optic monitoring was employed through a 77 m-deep borehole to obtain the variations of deformation and water content in both compacted and natural loess. The monitoring results were analysed together with the sampled soil properties. Initial field studies indicated that natural loess experienced much smaller deformation than compacted loess because of its cementation and different structure. Further analysis showed that the variations of stress and water content increment are the most significant factors in compacted loess, exhibiting a logarithmic relationship with loess deformation. Dry density is also important but needs to be considered in conjunction with stress in the vertical direction, while initial volumetric water content and clay-size fraction exhibit insignificant effects on the time-dependent deformation of compacted loess. Based on the analysis of these factors, a time-dependent model was developed, allowing the compacted loess deformation to be estimated. The proposed model was further verified by a numerical analysis using the artificial neural network (ANN) method, showing the relevance of the factors identified from the field data analysis and adopted in the proposed model. • Field investigations were conducted through a 77 m-deep fiber-optic borehole. • Coupled influences of various factors on compacted loess deformation were investigated. • A time-dependent deformation prediction model for compacted loess was developed. [ABSTRACT FROM AUTHOR]

The soil organic carbon isotope indicator (δ13C org) is widely used in paleoecology and paleoclimate reconstruction due to its ability to record the history of paleovegetation change. Although it has been used as a proxy for precipitation reconstruction, increasing evidence suggests that temperature has played a crucial role in influencing the relative abundance of C 3 /C 4 plants in the mid-latitudes during the interglacial period. This opens up the possibility of reconstructing Holocene temperature using δ13C org. In this study, the variation of δ13C org values in a Holocene loess profile (GLH profile), located in the eastern Hunshandake Sandy Land, China, was investigated. And we analyzed the correlation between δ13C org values and modern temperatures for a total of 792 surface soil samples from mid-latitudes of the Northern Hemisphere, which had thermal conditions comparable to the GLH profile. Strong positive correlations were found between δ13C org values of surface soil samples and both summer temperatures (r = 0.672, p < 0.001) and growing season temperatures (r = 0.669, p < 0.001). Additionally, δ13C org values showed significant positive correlations with accumulated temperatures above 10 °C (r = 0.641, p < 0.001) and above 0 °C (r = 0.527, p < 0.001). However, the correlation with mean annual temperature was weak (r = 0.280, p < 0.001). The δ13C org variation in the GLH profile recorded a mixed C 3 /C 4 vegetation composition, with C 4 plants comprising between 23.40% and 1.70% of the total abundance during the Holocene. The combined evidence from modern processes and profile variations confirms that warm-season temperature was the main factor driving variations in the δ13C org values in the GLH profile. Therefore, we used δ13C org –temperature conversion equations to quantify Holocene seasonal and accumulated temperatures based on the GLH profile. The reconstructed summer temperatures peaked at 9.3 ka, followed by a fluctuating downward trend during the mid- and late-Holocene, which is consistent with variations in summer solar insolation. Mean summer temperatures were relatively high at 23.3 °C and 22.5 °C in the early and mid-Holocene, respectively, while the lowest mean summer temperature of 20.5 °C occurred in the late Holocene. Accumulated temperatures above 10 °C and above 0 °C in the early Holocene were 3722 °C·d and 4641 °C·d, respectively, similar to modern observations in the Beijing area, indicating a southward shift of the temperature zone by nearly three degrees of latitude since the early Holocene. These reconstruction results are supported by modern observations, TraCE21 simulations, and other studies. This study is significant for extending the application of the δ13C org indicator for quantitative paleoclimate reconstructions. It verifies its effectiveness in quantifying Holocene temperatures in the marginal zone of the East Asian summer monsoon. • Attempt to reconstruct paleotemperatures quantitatively using the δ13C org indicator. • Conversion equations established between δ13C org - temperature in mid-latitude regions. • Holocene summer temperature and accumulated temperature (T ≥ 0 °C, T ≥ 10 °C) obtained. • Holocene summer temperature peaked at 9.3 ka and was controlled by solar insolation forcing. • Temperature zone shifted nearly three latitudes southward since early Holocene. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multiple isotopes revealed nitrate transport and transformation processes. • Old apple orchards had large water deficit and nitrate accumulation. • High transpiration effects resulted in no water and nitrate fluxes in deep layers. • The fertilizer-based nitrate bombs would reach the aquifers after hundreds of years. The deep-rooted economic trees decrease water storage but increase nitrate-nitrogen (NO 3 –N) accumulation in the soil due to the root water uptake and excessive use of fertilizers. Knowing how the NO 3 accumulates in the soil and to what extent it can be flushed out or transformed can provide insights on the processes controlling N flux to waterways. We sampled cultivated farmland and orchards with varying ages of apple and peach trees in the loess deposits to > 15 m depth to measure the contents and isotopes of water and NO 3 in soils. The novelty of this study is that the water isotopes are used to analyze water and NO 3 transport, while the NO 3 isotopes are further employed for NO 3 source and transformation analysis. The parabolic NO 3 –N profiles (258–3579 kg N ha−1) were mainly observed within 0–5 m under different land use types. The surface-aggregated NO 3 reservoirs under old apple orchard were about six times of farmland due to the overuse of chemical fertilizers, while those of peach orchard were only half of farmland because of less fertilizer inputs and possible root absorption effects. Piston flow resulted in the overall slow water movement and low NO 3 flux under different land use types in deep loess deposits. Despite the soil water recharge by precipitation and low surface evaporation, the strong transpiration effects further resulted in no water and NO 3 fluxes in the deep layers under old apple orchard. Nitrate reservoirs were mainly contributed by soil organic N (44 % ± 26 %) and ammonium N fertilizer (36 % ± 20 %), but their transformation was dominated by nitrification under old apple orchard and by mineralization in deep layers. The risks of NO 3 bombs are temporarily weakened by lower dried soil layers under deep rooted plants; however, with lower water movement rates and limited denitrification potential, NO 3 would eventually reach the aquifers in a few hundred years or more. This study provides new insights for clarifying NO 3 transport and transformation processes by combing multiple isotopes, and the NO 3 bombs would chronically endanger the sustainable development of terrestrial ecosystems and the environment in arid regions. [ABSTRACT FROM AUTHOR]

Various land use types have been implemented by the government in the loess hilly region of China to facilitate sustainable land use. Understanding the variability in soil moisture and temperature under various sloping land use types can aid the ecological restoration and sustainable utilization of sloping land resources. The objective of this study was to use approximate entropy (ApEn) to reveal the variations in soil moisture and temperature under different land use types, because ApEn only requires a short data series to obtain robust estimates, with a strong anti-interference ability. An experiment was conducted with four typical land use scenarios (i.e., soybean sloping field, maize terraced field, jujube orchard, and grassland) over two consecutive plant growing seasons (2014 and 2015), and the time series of soil moisture and temperature within different soil depth layers of each land use type were measured in both seasons. The results showed that the changing amplitude, degree of variation, and active layer of soil moisture in the 0–160 cm soil depth layer, as well as the changing amplitude and degree of variation of soil temperature in the 0–100 cm soil layer increased in the jujube orchard over the two growing seasons. The changing amplitude, degree of variation, and active layer of soil moisture all decreased in the maize terraced field, as did the changing amplitude and degree of variation of soil temperature. The ApEn of the soil moisture series was the lowest in the 0–160 cm soil layer in the maize terraced field, and the ApEn of the soil temperature series was the highest in the 0–100 cm layer in the jujube orchard in the two growing seasons. Finally, the jujube orchard soil moisture and temperature change process were more variable, whereas the changes in the maize terraced field were more stable, with a stable soil moisture and temperature. This work highlights the usefulness of ApEn for revealing soil moisture and temperature changes and to guide the management and development of sloping fields. [ABSTRACT FROM AUTHOR]

Changes in land use are very important factors affecting soil quality and especially the concentration and stock of soil organic carbon (SOC) and total nitrogen (TN). Very little is known about changes in spectroscopic properties of SOM after conversion of forestland to cropland. Therefore, the main aim of this study was to determine impact of agriculture on the concentration and stock of SOC and TN as well as spectroscopic properties of SOM in the topsoil horizons of Retisols in the Carpathian Foothills in southern Poland. Topsoil Ap horizons of arable soils are characterized by a significantly lower concentration of SOC and TN in comparison with topsoil Oi and Ah horizons of forestland soils. Topsoil Ap horizons feature higher SOC and TN stocks than topsoil Oi and Ah horizons. Significantly higher concentrations of SOC and TN in Oi horizons in comparison with Ah and Ap horizons are responsible for significantly higher mean absorbance values of all FTIR-ATR absorption bands originating from SOM in Oi horizons versus Ah and Ap horizons. Significantly higher concentrations of SOC and TN in Ah horizons of forestland soils versus those in Ap horizons of arable soils do not significantly affect mean absorbance values of FTIR-ATR bands. [ABSTRACT FROM AUTHOR]

Land use/cover plays a crucial role in gully head retreat (GHR). However, little is known about how land use/cover influences GHR rates. An in situ simulation experiment of rainfall and upstream inflow was conducted in a gullied loess region to investigate hydraulic erosion, mass movements, and linear GHR processes under three types of land use/cover (bare land, grassland, and shrub‐grass land). The results showed that the average linear GHR rates on grassland and shrub‐grass land were 87–89% and 72–81% lower than that on bare land (0.99–2.06 cm min−1), respectively. Gully heads retreat by hydraulic and gravitational erosion. In the case of hydraulic erosion, upstream runoff incision is dominant on bare land, while undercutting by on‐wall and jet flow dominates on grassland and shrub‐grass land. In the case of mass movement, collapse dominates with a frequency of 62–100%, of which gully sidewall collapse is most common, especially on bare land and it acts to widen the gully. Gully headwall collapse dominates on grassland and shrub‐grass land to cause retreat of the gully head. Overall, on bare land, upstream runoff incision dominates GHR. However, on grassland/shrub‐grass land GHR is mainly driven by the undercutting of on‐wall and jet flow and subsequent gully headwall collapses. As a consequence, the GHR length on bare land exponentially increases over time, while on grassland or shrub‐grass land, it discretely increases as an analogous step function. Moreover, the average linear GHR rate on grassland was considerably lower than that on shrub‐grass land, implying that an optimized vegetation restoration pattern enhances GHR control. [ABSTRACT FROM AUTHOR]

The objective of this investigation was assessment of physical and chemical parameters ofsoil and sediment in loess lands under different land uses, in the north of Iran. A yearly soilsampling was carried out randomly in three land uses (cultivated, forest and pasture) inQarnave and Yelcheshme watersheds. Sediment samples were taken monthly in thewatersheds at the hydrometrical station of Tamer located in downstream of the watersheds.The results showed that soil texture was silty clay loam and silty loam in forests andcultivated lands, respectively. In both watersheds, the highest amount of pH, carbonatecalcium, available phosphorus (P) and bulk density (BD) was observed in cultivated lands,whereas the highest amount of total nitrogen (TN), mean weight diameter (MWD) andorganic carbon (OC) was observed in forest. The highest amount of TN was observed inautumn, whereas the maximum amount of K was observed in summer, in both soil andsediment samples. The highest amount of P in soil and sediment was observed in summerand winter respectively. Also, the highest percentage of OC in soil and sediment wasobserved in autumn and summer respectively. The results showed that tillage and soilcultivation in cultivated lands may lead to reduction of OC and BD, therefore, decreasingthe MWD.

In spite of positive expectations for environmental protection, payments for ecosystem services (PES) can bring about unintended disturbances to rural livelihoods. Based on resilience thinking, this article investigates livelihood resilience building at farm level through the interaction between farm adaptation and disturbances induced by China's Grain for Green project (GGP). Cluster analysis was conducted to investigate the complexity and diversity of farm adaptation; the crafting of composite indexes was designed to value resilience through disturbance, sensitivity, and adaptability; regression analyses linked the resilience indexes and farm adaptation with access to resources. The results show three adaptation typologies (i.e. reclamation of retired lands, contractive farming, and expansive farming) with distinct land use structures and resilience scores, and highlight the need to improving farmers' access and endowment of tangible (e.g. farming facilities) and intangible resources (e.g. skill training) for resilience-building practices in light of the GGP. The findings imply that policy interventions combining environmental restrictions with widening resource access to support alternative livelihoods can offset the unintended effects and amplify the success of PES programmes. [ABSTRACT FROM AUTHOR]

• Land-use types, seasons, slope position significantly affected SOC and SWC. • Revegetation increased SWS consumption and SOC accumulation. • There was a positive linear relationship between SOC and SWC. • Planting grass and shrubs is recommended in the semi-arid hilly and gully regions. Understanding the response of soil organic carbon (SOC) and moisture to different land-use types, slope positions, seasonal variations, and their interactions has great significance for land use and management. However, the coupling effects of SOC and soil moisture in typical hilly and gully regions are still elusive. Therefore, in this study, five different land-use types, including cropland, abandoned land, grassland, shrubland, and forestland were selected in a typical Chinese loess hilly-gully region, and soil samples were collected from 0 to 200 cm profiles at the upper, middle, and lower slope positions in four seasons. The results demonstrated that the distributions of SOC and soil moisture were jointly significantly affected by land-use types, seasons, and slope positions (P < 0.01). Average SOC content was found to be highest in the shrubland, followed by grassland, abandoned land, forestland, and cropland. SOC storage at the lower slope position was 10.97% higher than that at the upper slope position. SOC storage in winter was 45.47% higher than that in summer. SOC storages of abandoned land, grassland, shrubland, and forestland were 17.38%, 33.08%, 52.52% and 1.26% more than that of cropland, respectively. Soil moisture fluctuated greatly in 0–100 cm layers and was stable beneath the 100 cm layers, which was highest in autumn, and lowest in summer. Whereas, under different land-use types, the soil moisture of cropland was the highest, especially significantly higher than all revegetated treatments in the 60–200 cm soil layers. Compared with cropland, soil water storage at other land-use types was averagely 36.45 % lower in the entire 200 cm soil profile. SOC was positively correlated with soil moisture under different factors. Thus, we recommend planting shrub and grass in watersheds with serious soil erosion in the semi-arid hilly and gully region, because they can sequestrate more SOC and retain more soil water. [ABSTRACT FROM AUTHOR]

This is a paper about the speed and intensity with which new and intensive human land use in a semi-arid environment can bring about large-scale environmental change. In particular, this paper pinpoints how and why it was that the Yellow River shifted from a long-term condition of relative stability to a later state of frequent floods and course changes in the eleventh century. It is possible to trace the environmental history of this dramatic and sudden change of state with precision and confidence. Historical sources that record the dates and characteristics of flood events downstream align well with those that note the locations and dates of human activity upstream. More important, each aligns well not only with one another, but also with information from environmental science: sediment cores that preserve soil and pollen evidence for the timing and processes of systematic change. [ABSTRACT FROM AUTHOR]

Land use and land cover change induced by large scale ecological restoration programs has a significant impact on the terrestrial ecosystem carbon cycle, especially on the net primary productivity (NPP) in arid and semi-arid regions. This study investigated the change in NPP caused by the large-scale ecological restoration in the Chinese Loess Plateau (LPR) region from 1986 to 2015 based on land cover datasets and NPP calculated using the Carnegie-Ames-Stanford Approach model. The results indicated that the annual total NPP exhibited a significant uptrend (P < 0.01) throughout the whole vegetation restoration region during the last 30 years, with an annual increase of 0.137 Tg C. A significant abrupt change was detected in 2006 for the annual total NPP series. Over half of the restoration region showed an increase in NPP in the past three decades, however, about 30~40% of the vegetation restoration region exhibited NPP loss before 2006, but subsequently NPP loss was found in only approximately 20% of the study region. Overall, the increase in NPP attributed to the vegetation restoration reached 51.14 Tg C in the past three decades, indicating that these large-scale vegetation restoration programs increased the carbon sequestration capacity of terrestrial ecosystems in the Loess Plateau. The findings of this study improve our understanding of the effects of the green campaign on terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

The final interpretation result of Gaoshanhe Gp. outcrops (anomalies), being overlaid on the natural color image background. • Our study objective was to conduct a case study of Landsat-based remote-sensing interpretation for the Gaoshanhe Group, which is an essential source bed for the mineralization of noble metals in central China. • Terrain analysis seems to be a significant factor in the high-precision interpretation of rock-minerals information. • The spatial aggregation of anomalous polygons is an important indication of a true anomaly. We studied the applicability of Landsat Operational Land Imager (OLI) data for extraction of Gaoshanhe-Group outcrops in a heavily loess-covered area in the northern Baoji district of China, which is always a crucial but challenging issue in geological remote-sensing mapping. An integrated approach was employed to process the remote-sensing data: first, the interpretation target area of interest was clipped using certain slope and elevation difference thresholds (topographical analysis); second, band ratio (B4/B2) and fractal summation algorithms were conducted in succession to extract the bedrock-induced anomalies; third, spatial clumping and hot-spot analysis were performed in order to eliminate residual false anomalies; and finally, we introduced high-resolution Worldview 2 data for visual interpretation and further spectral analysis. The findings show that the rocky outcrops were somewhat spectrally indistinguishable, and they were identified mainly due to their generally moderate degree of spatial clustering. Thirteen anomalous pixels were extracted from nearly 200,000 pixels covering the study area, and our field reconnaissance verified the results. This research constitutes the first useful case study on the applicability of Landsat data-derived lithology interpretation in China's loess plateau region. [ABSTRACT FROM AUTHOR]

• We integrated sediment records and modeling to investigate lateral carbon movement. • Carbon loss recorded in sediment deposition is valuable for modeling lateral carbon movement. • LULC changes reversed deterioration of lateral carbon loss on the Loess Plateau. Modeling of lateral carbon movement is critical for investigating carbon cycle in inland waters, but it is quite challenging especially in headwater regions due mainly to the shortage of observations. In this study, long-term soil and carbon losses documented by sediment deposition before check dam were firstly integrated to the widely-used Soil and Water Assessment Toll (SWAT) for investigating the lateral movement of soil and carbon in a typical ungagged headwater basin on the Chinese Loess Plateau (CLP). Then, the effects of land use and land cover (LULC) changes on soil and carbon losses in the typical Loess watershed, Fangta River Basin (FTRB), were investigated. Our case study suggested that sediment and carbon fluxes documented by sediment records could provide key information for model calibration and validation in ungagged headwater regions, and the satisfactory performance suggested the promising use of sediment records in modeling of lateral carbon movement. Headwater regions on the CLP suffered serious soil and carbon losses during the past decades, and soil and carbon loss intensities were 6,821.6 t⋅km−2⋅yr−1 and 16.9 t⋅km−2⋅yr−1 during the study period (1976–2016), respectively. LULC changes characterized by conversion from cropland to forest, reversed the deterioration of soil and carbon losses caused by climate change. Our study identified the integration of sediment records and hydrological model in soil and lateral carbon movement investigation under dramatic environmental changes. [ABSTRACT FROM AUTHOR]

Abstract: Soil profiles keep records of the legacies of historical land uses on soil physicochemical properties with deep‐soil (3‐m depth) profiles providing information on centuries‐old dynamics. By combining geohistorical archives on past land uses and management practices together with soil pH data from 19 plots scattered across five study areas in North France, we analyzed the effect of two contrasting historical land‐use change trajectories (afforestation of former arable land vs. cultivation after deforestation) on the acidification and alkalinization dynamics along 3‐m‐depth loessic Luvisols profiles. An analysis of covariance and a generalized additive model were used to test the interaction effect between depth and the two studied chronosequences levels on soil pH. Results show two contrasting alkalinization dynamics for formerly acidic forest soils converted to arable land depending on past management practices. One century of liming practices based on hydrated lime is enough for a complete deprotonation, whereas alkalinization dynamic was much slower (two to four centuries are necessary to neutralize the relictual acidity below 2 m) under liming based on chalk‐blocks supply. Per contra, afforestation of former arable land cultivated and limed during at least 2–4 centuries keep an alkaline ‘memory’ effect over more than a millennium. The acidification process is progressive through time from the surface to deeper soil horizons. This suggests that soil pH profiles can be used to estimate time since afforestation of former arable land. Linking deep‐soil pH profiles with chronosequences is a powerful tool to understand the potential impact of future land‐use change trajectories on soil physicochemical properties. [ABSTRACT FROM AUTHOR]

Land-use type under different topographic conditions and human activities affects soil development. We investigated the effects of land-use, topography and human activity on soil classification changes in the Toshan watershed in northern Iran. Seven representative pedons derived from loess parent materials were studied on different land-uses and topographic positions. The studied pedons in forest (FO) on backslopes and footslope were classified as Calcic Haploxeralfs and Typic Haploxeralfs, respectively. The soils in abandoned lands (AB) and orchards (OR), where formerly under natural forests, located on the shoulder and backslopes positions were classified as Calcic Haploxeralfs and Vertic Haploxeralfs, respectively. Well-developed argillic horizons as indicators for higher degrees of soil evolution were observed in more-stable areas under the natural forest or less disturbed areas. Clay lessivage through these soil profiles have led to formation of Typic or Calcic Haploxeralfs, while under croplands (CP) were classified as Typic Calcixerepts. Conversion of sloping deforested areas to CP along with inappropriate management have accelerated soil erosion, resulting in unstable conditions in which decalcification and formation of developed soils cannot occur. Paddy cultivation in flat areas has caused to reduced conditions and formation of Typic Haplaquepts. Because of unfavorable conditions for chemical weathering (e.g. lower water retention compared to more-stable areas) no vermiculite was detected in the CP. The results showed that evolution and classification of the studied soils were strongly affected by land-use type, topography and management. [ABSTRACT FROM AUTHOR]

The effects of Chinese pine (Pinus tabuliformis) on soil variables after afforestation have been established, but microbial community changes still need to be explored. Using high-throughput sequencing technology, we analyzed bacterial and fungal community composition and diversity in soils from three stands of different-aged, designated 12-year-old (PF1), 29-year-old (PF2), and 53-year-old (PF3), on a Chinese pine plantation and from a natural secondary forest (NSF) stand that was almost 80 years old. Abandoned farmland (BL) was also analyzed. Shannon index values of both bacterial and fungal community in PF1 were greater than those in PF2, PF3 and NSF. Proteobacteria had the lowest abundance in BL, and the abundance increased with stand age. The abundance of Actinobacteria was greater in BL and PF1 soils than those in other sites. Among fungal communities, the dominant taxa were Ascomycota in BL and PF1 and Basidiomycota in PF2, PF3 and NSF, which reflected the successional patterns of fungal communities during the development of Chinese pine plantations. Therefore, the diversity and dominant taxa of soil microbial community in stands 12 and 29 years of age appear to have undergone significant changes; afterward, the soil microbial community achieved a relatively stable state. Furthermore, the abundances of the most dominant bacterial and fungal communities correlated significantly with organic C, total N, C:N, available N, and available P, indicating the dependence of these microbes on soil nutrients. Overall, our findings suggest that the large changes in the soil microbial community structure of Chinese pine plantation forests may be attributed to the phyla present (e.g., Proteobacteria, Actinobacteria, Ascomycota and Basidiomycota) which were affected by soil carbon and nutrients in the Loess Plateau. [ABSTRACT FROM AUTHOR]

In this study, two typical watersheds, i.e., the Dalihe watershed in the loess hilly-gully region of, and the Hailiutuhe watershed in the windy-sandy region of the Wudinghe Basin, were selected as study objects to evaluate the relationship between landscape indices and runoff and sediment, with the long-series data of runoff, sediment, and land use, using the GIS and Fragstats platforms. The results showed that between two watersheds showed that all of the contagion index, Shannon's diversity index, and patch cohesion index exhibited an ascending trend in the Dalihe watershed, and a descending trend in the Hailiutuhe watershed. In the Dalihe watershed, only Shannon's diversity index had a very significantly negative correlation with the runoff, whereas in the Hailiutuhe watershed, the contagion index had a significantly negative correlation with the runoff, and all of the Shannon's diversity index, the Shannon's evenness index, and the Simpson's evenness index had a significantly positive correlation with the runoff. In respect of correlation of sediment with landscape pattern, the sediment had a very significantly negative correlation only with Shannon's diversity index in the Dalihe watershed, whereas in the Hailiutuhe watershed, the sediment had a significantly negative correlation with all of the number of patches, the patch density, and the landscape shape index, and a very significantly positive correlation with the aggregation index. The importance of each landscape index in the regression equation and the positive or negative correlations indicated that erosion in watersheds could be reduced by strengthening the control function of the dominant patch, thoroughly improving the evenness of the landscape patch types, enriching the landscape types, reducing the physical connectivity between patches, and enhancing the degree of aggregation in landscape patches. [ABSTRACT FROM AUTHOR]

Protection of the environment by returning farmland to forest and grassland through enclosing areas of land to permit regeneration of native flora is being implemented in the Loess hill region of China. Soil physical properties are important components of ecological systems, as comparisons between cultivated and enclosed areas demonstrate. The results showed: the soil moisture content in the enclosed area was 14.6% and that in the cultivated area was 14%; the soil bulk density and soil porosity were respectively 1.45 g/cm3 and 45.28% in the enclosed areas, and respectively 1.46 g/cm3 and 44.79% in cultivated land. The alteration of soil physical properties was not big between cultivated areas and enclosed areas in the short term. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) storage is a basic measure used to study soil productivity, hydrology and the balance among greenhouse gases. Variation of SOC is controlled by environmental factors such as land use and topography. Toshan watershed located in northern Iran was selected to study the effects of different land uses i.e. forest (FO), cropland (CP), orchard (OR) and abandoned land (AB) on different slope gradients and aspects on SOC both in surface (0–30 cm) and subsurface (30–100 cm) layers. A total of 364 soil samples plus 1638 undisturbed ones were collected from two soil layers in 182 sampling sites. Results showed that the surface 30 cm soil layer was solely responsible for 54.8% of SOC density. On average, FO with 22.84 kg m − 2 had the highest SOC density in 0–100 cm layer. Deforestation and agricultural activities have resulted in a significant 48.2% decrease of SOC density in 0–30 cm soil layer. North facing slope (N) aspect and also flat area of all land uses had the higher SOC density compared to east (E) and west facing slope (W) aspects in this subhumid region in 0–100 cm layer. Generally, in the upper 100 cm soil layer of deforested lands, gentle and moderate slopes had higher SOC density than steeper slopes. There was a positive significant correlation between SOC density and clay content. The largest amount of SOC storage was observed in the surface 30 cm layer accounting for 74,907.94 Mg (54.4% of total SOC storage), indicating the important key role of topsoil in conserving SOC. FO with one-third proportion of the total area stored the largest amount of SOC (39,325.55 Mg; 52.5%) in surface layer. In conclusion, protection of forest lands is higher important to increase SOC storage. Agricultural activities on steep E and W aspects in deforested lands must be reduced or prohibited. The subsoil has almost the same contribution to SOC storage and therefore should be carefully considered for management measures. Generally, interaction between environmental factors on storing SOC and also rate of carbon loss to the atmosphere was significant. [ABSTRACT FROM AUTHOR]

ABSTRACT The Land Use and Cover Area frame Statistical survey (LUCAS) database on topsoil properties in Europe was used to map aeolian deposits. The points which satisfy the grain-size criteria of coversands, loess and transitional facies were extracted from the rasters of predicted soil texture established by kriging of the LUCAS data by Ballabio et al. (). A comparison with already available maps, derived from a conventional field approach, shows a good fit in most of the tested areas. The new map, however, suggests a greater extension of loess, which seems related to the inclusion of thin loess covers, usually omitted by conventional mapping, and the presence of previously unmapped areas due to lack of survey or misinterpretation. The main source of aeolian particles corresponds to glacio-fluvial sediments at the margin of the Scandinavian and Alpine ice sheets. Coversands and loess form a broad band across northern Europe, and in the Rhône, Rhine and Danube valleys. Large areas on the outskirts of these deposits also received a significant loess contribution, which has been reworked in slope deposits. Conversely, southern Europe is characterized by much less loess accumulation. The Atlantic coast has transgressive dune fields that penetrate inland to varying degrees. [ABSTRACT FROM AUTHOR]

Prehistoric land use at the Guobei site and its relationship with the local environment are examined by applying OSL dating, micromorphological examination and geo-physical analysis. The majority of the OSL dates are of early to middle Holocene ages and are thus comparable to many OSL dates derived from other studies in the same region. According to the particle size analysis, silt-sized particles (2–60 μm) were predominant throughout the profiles examined. However, there are spatial and temporal variations of different size groups of particles throughout the profiles, which provide complementary information for the micromorphological interpretation. The total organic component of the samples examined through LOI is relatively high (all > 2%), with those of the overlying Holocene deposits higher than those of the underlying Malan loess by about 0.2%. Moreover, in all three profiles, the highest organic contents appear in the palaeosols, confirming that there was greater organic accumulation during soil formation periods. The groundmass of most slides collected from the early to middle Holocene horizons displays a very homogeneous pattern, while the abundance and distribution of different kinds of pedo-features, mainly including clay textural, calcitic, iron/Mn and crustal features, vary greatly temporally and spatially. These different lines of information demonstrate diversified pedo/sedimentary processes due to variations in micro-environmental conditions and cultural activities. We discuss the importance of a palaeo-ecological perspective, allowed by the geoarchaeological study, to an improved understanding of the relationship between loess, changing hydrology, prehistoric farming practice and land use, and long-term landscape change in the Chinese Loess area. This will thus contribute to a comparison on the dynamic relationship between loess and prehistoric farming in other regions of the world such as Europe and North America. [ABSTRACT FROM AUTHOR]

Investigating the contribution of different land use types to the carbon cycle of terrestrial ecosystems is of considerable importance in studying global climate change. The objective of this study is to determine the temporal variation of soil respiration rates in different land uses (maize, wheat stubble, and bare land) and their responses to environmental factors for the Loess Tableland, using an improved multi-channel automatic flux chamber system. Results showed that the soil respiration rate indicates a clear diurnal and seasonal variations. The mean soil carbon emission rates were 0.94, 1.94 and 2.38 gC·m-2·d-1 in bare land, wheat stubble field, and maize field, respectively. The determination coefficient of soil surface temperature on the diurnal soil respiration rate was more significant than that of deeper layers. The Q10 value was used to represent the temperature sensitivity of soil respiration in three different land uses, soil respiration in the maize field showed the largest temperature sensitivity. The soil respiration was found to increase exponentially with the increase in air temperature, whereas the relationship between soil respiration and soil moisture was quadratic. The trend of rainfall-affected soil respiration after the sudden rain and continuous light rain showed large differences, meanwhile, a clear difference in the sensitivity of soil respiration to rainfall exists for the different land uses. [ABSTRACT FROM AUTHOR]

In the Loess Hilly Region of China, the widespread conversion of cropland to forestland and grassland has resulted in great increased in organic carbon (C), nitrogen (N) and phosphorus (P) stocks in the shallow soil layers. However, knowledge regarding changes in C, N, and P in deep soil is still limited. To elucidate the responses of deep soil C, N, and P stocks and stoichiometry in response to changes in land use, the soil from a 0–200 cm soil profile was collected from the following three typical land use patterns in the heartland of the region: forestland, grassland, and cropland. Compared with cropland, forestland and grassland had improved soil organic carbon (SOC) and total nitrogen (TN) contents and stocks at most soil depths but decreased total phosphorus (TP) contents and stocks. At soil depths of 0–200 cm in the forestland and grassland, the cumulative SOC stocks were improved by 34.97% and 7.61%, respectively, and the TN stocks were improved by 54.54% and 12.47%, respectively. The forestland had higher SOC, TN and TP contents and stocks compared to the grassland in almost all soil layers. The soil depths of 100–200 cm contained the highest percentages of SOC, TN and TP stocks (47.80%–49.93%, 46.08%–50.05% and 49.09%–52.98%, respectively). Additionally, the forestland and grassland showed enhanced soil C:P, N:P and C:N:P ratios, and the forestland had higher C:P, N:P and C:N:P ratios compared to the grassland. Furthermore, the SOC and TN stocks had significant impacts on the soil C:N, C:P and N:P ratios. It was concluded that afforestation was the best choice for soil nutrient restoration of degraded land, and deep soil provided an extremely important resource for evaluating soil C, N and P pools and cycling. [ABSTRACT FROM AUTHOR]

Artificial vegetation restoration can induce variations in accumulation and distribution of soil carbon (C), nitrogen (N) and phosphorus (P). However, little is known about variations in soil C, N and P nutrient fraction stratification following artificial vegetation in Loess Plateau China. Based on the hypothesis that re-vegetated can improve soil quality and stratification ratios (SR) can be used as an indicator to evaluate soil quality. This study measured contents and storages of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP) and their SRs in topsoil (0–20 cm) and subsoil (20–60 cm) in three 30-year re-vegetated lands that had been converted from arable land (Robinia pseudoacacia L., Caragana Korshinskii Kom. and abandoned cropland with low interferences and few management measures) and one slope cropland (SC) as a control for three soil profiles(0–20 cm, 20–40 cm and 40–60 cm) from June 2009 to June 2013. The results showed that the contents and storages of SOC, TN and TP in re-vegetated land were significantly higher than those in the SC in both topsoil and subsoil. The storages of SOC, TN and TP in the topsoil (0–20 cm) of the re-vegetated lands increased by 16.2%-26.4%, 12.7%-28.4% and 16.5%-20.9%, respectively, and increased by smaller but significant amounts in subsoil from 2009 to 2013. The SRs for SOC, TN and TP in the re-vegetated lands were mostly >2 (either for 0–20:20–40 cm or 0–20:40–60 cm) and greater than that in the SC. The SRs showed an increasing trend with increasing restoration age. The results also showed that the land use type and soil depth were the most influential factors for the SRs and storages, and the SRs of SOC and TN had significantly positive correlations with their storages. The SRs were concluded to be a good indicator for evaluating the soil quality, which can be significantly enhanced through vegetation restoration. Moreover, vegetation restoration can significantly enhance SOC, TN and TP accumulation in both topsoil and subsoil. [ABSTRACT FROM AUTHOR]

In the Loess Plateau, soil erosion has not only caused serious ecological and environmental problems but has also impacted downstream areas. Therefore, a model is needed to guide the comprehensive control of soil erosion. In this study, we introduced the WEPP model to simulate soil erosion both at the slope and watershed scales. Our analyses showed that: the simulated values at the slope scale were very close to the measured. However, both the runoff and soil erosion simulated values at the watershed scale were higher than the measured. At the slope scale, under different coverage, the simulated erosion was slightly higher than the measured. When the coverage is 40%, the simulated results of both runoff and erosion are the best. At the watershed scale, the actual annual runoff of the Liudaogou watershed is 83m3; sediment content is 0.097 t/m3, annual erosion sediment 8.057t and erosion intensity 0.288 t ha-1 yr-1. Both the simulated values of soil erosion and runoff are higher than the measured, especially the runoff. But the simulated erosion trend is relatively accurate after the farmland is returned to grassland. We concluded that the WEPP model can be used to establish a reasonable vegetation restoration model and guide the vegetation restoration of the Loess Plateau. [ABSTRACT FROM AUTHOR]

[Display omitted] • The interannual ecosystem service value (ESV) increased slowly, and its geographical distribution fluctuated in a non-stationary pattern. • Significant value transformations existed among ecosystem service types and among land use types. • ESV was primarily positively governed by annual precipitation extremely negatively regulated by the synergistic effect of land use degree and population density. • The values of regulating, supporting, and cultural services interacted synergistically in significant ways. Geographic and temporal patterns of ecosystem service value (ESV) and their dynamic coupling response to human activity and climate change are critical for allocating land resources and maintaining healthy ecosystems in the loess hills. Based on five phases of land use data and climate data in Yan'an from 2000 to 2020, our study utilized the value-equivalent method and statistical analysis to systematically reveal the spatio-temporal dynamics of human activity and climate change, as well as their coupled driving mechanisms on ESV, and to establish and optimize synergy/trade-off strategies between them. The findings revealed that land use degree diminished between 2000 and 2020, population distribution increasingly widened. The precipitation fluctuated and increased, but the dryness trend persisted. Significant contributions were made by regulating services, supporting services, grassland, and forest to the interannual total ESV, which grew steadily at a rate of 6.89 % and reached 722.59 trillion in 2020. The total geographical distribution pattern of ESV was unstable, with a medium level of aggregation (0.02–0.06 trillion) in the northern districts and counties and a high level of aggregation (0.06–0.08 trillion) in the southwest and southeast on the grid scale of 1 km × 1 km. ESV had a highly significant synergistic relationship with annual precipitation (AP), but it showed pronounced trade-offs with population density (PD), comprehensive index of land use degree (LUI) and annual mean surface temperature (AMT). Simultaneously, there were profound synergies between the value of regulating, supporting, and cultural services. ESV was primarily positively governed by AP extremely negatively regulated by the synergistic effect of LUI and PD, the optimal regulatory thresholds of LUI, PD and AP for ESV levels of ≥0.06 trillion on the grid scale of 1 km × 1 km were 260, 30,000–50,000 people km−2, and 400–520 mm, respectively. Essentially, controlling the land use degree, expanding farmland and water areas, and stimulating climate humidification were crucial synergistic/trade-off strategies for further balancing and enhancing the value of various ecosystem service functions in sustainable ecological restoration of Yan'an. [ABSTRACT FROM AUTHOR]

• Combined effects of multiple factors were explored for soil water and nitrate. • Land use is the key factor regulating deep soil water and nitrate reservoirs. • Soil water was influenced by magnetic susceptibility and sand. • Nitrate was affected by soil water, pH, and soil organic carbon. Identifying the environmental factors controlling deep soil water and nitrate is important for the sustainability of vegetation and ecosystems. However, the combined effects of multiple factors at varying scales have been poorly understood, especially in those regions with thick vadose zones and deep-rooted plants. The aim of this study is to identify the multivariate controls of water and nitrate in seven > 13 m deep boreholes under different land use types on China's Loess Plateau. After measuring soil water and nitrate contents, the combined effects of climatic factors (precipitation, temperature, and potential evapotranspiration) and soil properties (soil texture, magnetic susceptibility, pH, EC, and soil organic carbon) were explored by wavelet analysis. Land use is the key factor regulating deep soil water and nitrate reservoirs, with high water deficit and low nitrate accumulation within 0–10 m under non-fertilized forestlands and shrublands. The positive and negative standardized ratios respectively suggested the synergistic and antagonistic relationships of water and nitrate under shallow- and deep-rooted vegetation. As the important agent for nitrate leaching, soil water is influenced by magnetic susceptibility and sand. Furthermore, soil water, pH, EC, and soil organic carbon are individually or simultaneously responsible for nitrate transport and transformation, especially at large scales (> 7.5 m). This study provides novel insights for vegetation and environmental management, and benefits the parameterizing of process-based hydrological and biogeochemical models at regional or global scales, especially in the deep unsaturated zones. [ABSTRACT FROM AUTHOR]

Little is known about the association of soil pipe collapse features with soil properties or land use history. Three loess covered catchments in northern Mississippi, USA were characterized to investigate these relationships. Soil pipe collapses were characterized for their size, type feature and spatial location along with soil properties across the three catchments. Although mapped as the same soil, one of the catchments did not contain pipe collapse features while the other two had 29.4 and 15.4 pipe collapses per hectare. These loess soils contained fragipan layers that are suspected of perching water, thereby initiating the piping processes. Pipe collapses associated with subsurface flow paths were not always consistent with surface topography. The surface layer tended to be non-erodible while layers below, even the upper fragipan layers, were susceptible to erosion by pipeflow. Soil properties of the lowest fragipan layer were highly variable but tended to prevent further downward erosion of soil pipes and thus formed a lower boundary for gullies. Middle to lower landscape positions in one of the piped catchments contained anthropic soils that were highly erodible. These anthropic soils were previously gullies that were filled-in in the 1950s when forested areas, assumed to have been established when land was previously converted from crop to forest land, were converted to pasture. Three decades after this land use change from forest to pasture, pipe collapses became evident. In contrast, the adjacent catchment that does not exhibit pipe collapse features experienced severe sheet and rill erosion prior to the 1930s while in cotton production. The surface horizons above the lower fragipan layer were completely removed during this period, thus the top-soil layer that tends to form a bridge above soil pipes in the more erodible subsoil layers was removed. This study showed that knowledge of soil characteristics or topography alone do not explain the distribution of soil pipe collapses as past land use can play a definitive role. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

With the rapid modernization of China's infrastructure construction, disposal of the massive amount of construction and demolition waste (CDW) produced each year has gradually developed into a national concern due to its increasingly adverse effect on the environment. Additionally, in northwestern China, ground deformation triggered by collapsible loess has caused severe damage to local infrastructure. In an attempt to address both problems simultaneously, this paper proposes the novel approach of applying CDW as a pile filler for the down-hole dynamic compaction. The concept, construction process, and design principles of this new method are described, and its efficiency and feasibility are validated in detailed studies of four practical cases in different locations in China. Problems that arise in certain aspects of this method, i.e., code revision with consideration of the variable loess conditions and CDW in different locations, are also discussed. Case studies and relevant discussions indicate a promising future for this environmentally friendly and eco-efficient method that is broadly applicable in many locations. [ABSTRACT FROM AUTHOR]

The socio-economic effect of the occurrence of specific forms of relief, is a significant research problem in applied geomorphology. The objective of this study was to assess the impact of permanent gullies on land cover and agriculture within the loess areas of Eastern (E.) Poland. We analyzed the relationships between an area consisting of gullies and selected environmental and socio-economic indices. We used the following statistical methods: Pearson's linear correlation, ANOVA, PCA and cluster analysis. It was found that districts with a similar gully density are characterized by the occurrence of a similar set of economic characteristics found within agriculture (cluster analysis). The most distinct impact of the occurrence of gullies on the potential of agriculture was observed when gullies covered more than 2% of the district. We identified the relationships between the area covered by gullies and present-day forest cover (Pearson correlation index 0.5), changes in the forest cover in the 20th century (0.7), the area of landscape parks and reserves (0.8) and the share of big farms (− 0.5). Weak negative correlations occurred between the gully area and the economic aspects of agriculture (indices from − 0.2 to − 0.4). The correlations between the area of gullies, area of forests and share of farms larger than 20 ha were confirmed by ANOVA. The PCA method showed a negative correlation between the area of gullies, the share of arable lands and the share of farms with good prospects. A positive correlation was found in the case of protected areas, steep slopes and forests. In the future, gullies may turn out to be a challenge to the development of efficient agriculture; they are an obstacle to land consolidation and farm enlargement. Areas characterized by a high density of gullies require special spatial management to reduce negative economic effects. [ABSTRACT FROM AUTHOR]

Land utilization of sewage sludge has become one of the major issues in environmental mitigation in China. This is particularly important in the Loess Plateau of Northwest China. Sludge enriched with organic matter and nutrients might effectively help to resolve the problems of silty loess soils as evidenced by porosity defect, structural alterations and absence of fertility. After sludge flows into the loess, irrigation water contains heavy metals that leach and migrate into sludge and consequently related human health risks may occur that raise concerns; and this situation needs to be rectified. The characteristics of the vertical migration and composition form change of Cu, Zn, and Cd from composted sludge to loess, and corresponding influencing factors, were investigated by performing a soil column simulation test under the leaching treatment of a one-year irrigation water capacity. Results demonstrated that: (1) composted sludge significantly improved loess fertility, and irrigation leaching transported only a small quantity of organic matter in sludge in the plough layer; (2) although some of the Cu, Zn, and Cd in composted sludge migrated to and concentrated in the middle and upper layers of the soil column during leaching, these metals were mostly retained in the plough layer; and (3) after the leaching treatment of the one-year irrigation water capacity, the compositions of Cu, Zn, and Cd (particularly Cu and Zn) in both plough layer and loess began to stabilize with low concentrations in the exudate. These findings confirmed the applicability of composted sludge in loess regions. This study provided a new insight into the sludge reuse in alkaline soils in arid and semi-arid region. [ABSTRACT FROM PUBLISHER]

This paper takes Hejiaou river region as the research object by time-space mutual substitution method to probe biodiversity and biomass of 29 sample abandoned lands. The results show that: (1) Biodiversity of vegetation changes along with the abandoned age of biomass. Simpson index, Shannon-Weiner index, Margalef richness index and Pielou evenness index reach the maximum when the abandoned age is 10 or 11 years. And biomass increases along with the growth of the abandoned age. (2) Biodiversity and biomass of different site types vary from one to another. For Simpson index, sunny slope>cloudy slope>semi-cloudy slope>semi-sunny slope. For Shannon-Weiner index and Pielou evenness index, sunny slope>cloudy slope>semi-sunny slope>semi-cloudy slope. For Margalef richness index, semi-sunny slope>semi-cloudy slope>cloudy slope>sunny slope. For biomass, cloudy slope>semi-cloudy slope>sunny slope>semi-sunny slope. The difference among Simpson index, Margalef richness index and Pielou evenness index is not apparent in terms of site type. But sunny slope and semi-cloudy slope of Shannon-Weiner index are distinguished from each other (p<0.05). And there is a great difference among biomass of four site types (p<0.05). (3) Simpson index, Shannon-Weiner index, Margalef richness index and Pielou evenness index have no linear correlation with biomass, indicating that biodiversity and biomass are not correlated. [ABSTRACT FROM AUTHOR]

Shoulder lines are the most important landform demarcations for geographical analysis, soil erosion modeling and land use planning in the Loess Plateau area of China. This paper proposes an automatic, effective and accurate method of determining loess shoulder line from DEMs by integrating a hydrological D8 algorithm and a snake model. The watershed boundary line is adopted as the initial contour which evolves to identify the exact position of loess shoulder-line by the guidance of an external force of snake model from DEMs. Experiments show that the method overcomes the difficulties in both threshold selection for edge detection and the disconnecting issues in former extraction approaches. The accuracy evaluation of shoulder-line maps from the two test sites of the loess plateau area show obvious improvements in the extraction. The average contour matching distance of the new method is 12.0 m on 5 m resolution DEM, and shows improvement in the accuracy and continuity. The comparisons of accuracy evaluations of the two test sites show that the snake model method performs better in the loess plain area than in the area with high gully density. [ABSTRACT FROM AUTHOR]

The Nałęczów Plateau is characterised by the presence of a peculiar complex of loess relief forms, among which closed depressions are the most characteristic features (Maruszczak 1958). 1,761 closed depressions were documented within the Nałęczów Plateau (Kołodyńska-Gawrysiak, Chabudziński 2012). They are small landforms with peculiar distribution and morphometric characteristics such as the dimensions of their longer axis and their size. The longer axis of more than half of the depressions (51.39%) is within the narrow range from 25 to 50 m. The size of 70% of all forms does not exceed 1,500 m2. These forms are also typified by a characteristic distribution in relation to the elements of loess relief. Their greatest concentration is on the plateau tops where 72% of all forms were documented. Closed depressions also occur in denudation troughs (16% of the forms), bottoms of erosion-denudation valleys (5%) and slopes (7%). Areas of concentration with 30-40 forms per km2 can be clearly distinguished in the spatial arrangement. Eleven areas of concentration, referred to as closed depression microregions, were identified in the study area (Kołodyńska-Gawrysiak, Chabudziński 2012). So far, the origins of closed depressions in the loess areas in Poland have been linked with the development of piping processes within initial depressions associated with the dynamics of the loess cover sedimentation (Maruszczak 1954). The most recent research indicates that the development of closed depressions may have been determined by cryogenic processes (Kołodyńska-Gawrysiak et al. in print). In Poland, closed depressions were studied in the loess areas of the Lublin Upland (Maruszczak 1954; Konecka-Betley, Maruszczak 1993; Kołodyńska-Gawrysiak, Chabudziński 2012; Kołodyńska-Gawrysiak et al. 2012), Sandomierz Upland (Czarnecki, Lewartowska-Urbańska 1987; Czarnecki, Solnceva 1992) and Carpathian Foothills (Wojtanowicz 1997). Closed depressions were also studied in France (Pissart 1958), the United Kingdom (Prince 1961), central Belgium (Gillijns et al. 2005; Vanwalleghem et al. 2007; Etienne et al. 2011) and Russia (Zanin 1952). The landscape of the Nałęczów Plateau is determined not only by the peculiar land relief but also the type of land use - which is determined by the former (Zgłobicki, Baran-Zgłobicka 2012). In terms of land use, agricultural landscape dominates in the Nałęczów Plateau. More than 82% of the region is covered by agricultural land, mostly arable fields accounting for more than 53%. Forest areas have been preserved in the form of small complexes covering a total of 4,239 ha, i.e. 8.5% of the region (Corine Landcover 2006) Zagłębienia bezodpływowe należą do głównych, a jednocześnie osobliwych elementów rzeźby obszarów lessowych. Celem badań była próba klasyfikacji zagłębień na podstawie ich cech zewnętrznych oraz określenie funkcji, jaką formy te pełnią we współczesnym krajobrazie obszarów lessowych Płaskowyżu Nałęczowskiego. Klasyfikacji zagłębień dokonano w oparciu o kryteria geomorfologiczne, hydrograficzne oraz użytkowanie terenu. Zagłębienia bezodpływowe, mimo iż są to drobne formy rzeźby, pełnią ważną funkcję we współczesnym krajobrazie Płaskowyżu Nałęczowskiego. Funkcję tę można rozpatrywać w aspekcie geomorfologicznym, ekologicznym oraz estetycznym. Z punktu widzenia geomorfologicznego, funkcja zagłębień wyraża się w ich wpływie na georóżnorodność obszarów lessowych. Na terenie wierzchowin tworzą one specyficzny mikrorelief, który urozmaica rzeźbę. W aspekcie ekologicznym, zagłębienia bezodpływowe korzystnie wpływają na bioróżnorodność obszarów użytkowanych rolniczo. Największe znaczenie pod tym względem mają zagłębienia z wodą stałą oraz periodyczną. Dzięki porastającej je roślinności leśnej oraz wodno- i wilgociolubnej bezpośrednio sąsiadującej z roślinnością pól uprawnych, wprowadzają one do krajobrazu kontrasty przyrodnicze oraz zróżnicowanie siedlisk, wpływające korzystnie na różnorodność gatunkową. Zagłębienia periodycznie wypełniające się wodą stanowią swoistego rodzaju wyspy kontrastujące typem roślinności z otaczającymi terenami pól uprawnych. Kępy drzew i zarośli stanowią osobliwe dominanty w krajobrazie monotonnych, silnie odlesionych wierzchowin lessowych, podnosząc ich walory estetyczne [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the role of soil characteristics and land use in the development of soil pipes in the loess belt of Belgium. First, we tested the hypothesis that discontinuities in the soil profile enhance lateral flow and piping by impeding vertical infiltration. We focus on discontinuities in soil characteristics that can vary with soil depth, including texture, saturated hydraulic conductivity, penetration resistance, and bulk density. These characteristics as well as soil biological activity were studied in detail on 12 representative soil profiles for different land use types. Twelve sites were selected in the Flemish Ardennes (Belgium): four pastures with collapsed pipes (CP), four pastures without CP, two sites under arable land without CP and two sites under forest without CP. Secondly, this study aimed at evaluating the interaction of groundwater table positions (through soil augerings) and CP in a larger area, with a focus on pastures. Pasture is the land use where almost all CP in the study area are observed. Therefore, the position of the groundwater table was compared for 15 pastures with CP and 14 pastures without CP, having comparable topographical characteristics in terms of slope gradient and contributing area. Finally, the effect of land use history on the occurrence of pipe collapse was evaluated for a database of 84 parcels with CP and 84 parcels without CP, currently under pasture. As to the first hypothesis, no clear discontinuities for abiotic soil characteristics in soil profiles were observed at the depth where pipes occur, but pastures with CP had significantly more earthworm channels and mole burrows at larger depths (>120cm: mean of >200 earthworm channels per m2) than pastures without CP, arable land or forest (>120cm depth, a few or no earthworm channels left). The land use history appeared to be similar for the pastures with and without CP. Combining all results from soil profiles and soil augering indicates that intense biological activity (especially by earthworms and moles), in combination with a sufficiently high groundwater table, favours the development of soil pipes in the study area. [Copyright &y& Elsevier]

ABSTRACT The analysis of the spatial variability of soil properties is important for land management and construction of an ecological environment. The objectives of this study were to investigate the spatial variability of saturated hydraulic conductivity ( KS), total porosity ( TP), capillary porosity ( CP) and bulk density ( BD) in relation to land use in a 0·54 km2 watershed on the Loess Plateau. Topsoil samples (0-5 cm) from 154 sites within the watershed were collected and analyzed by classical and geostatistical statistics in the summer of 2009. The results from the classical statistical analyses indicated that TP, CP and BD had low variability whereas KS had high variability with the watershed. Farmland had significantly lower BD and higher TP and CP than grassland, shrubland and woodland ( p < 0·05). Geostatistical analyses revealed that the KS semivariogram was best fit by a spherical model, the CP semivariogram was best fit by an exponential model and the TP and BD semivariograms were best fit by Gaussian models. The nugget to sill ratios and fractal dimension values indicated that all four soil properties had strong spatial dependence. Moran's I analysis showed that a 100-m sampling interval would be adequate for detecting the spatial structure of the four soil physical properties within the watershed. Spatial interpolation maps could provide useful information for precision agriculture practices and ecological management. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]