Search

[Display omitted] • A typical risk assessment framework for water shortage region was built according to DPSIR model. • An intuitive three-color map risk zoning method was presented. • Ecological risk in northwest and east of the Ziya watershed is significantly higher than that in the middle area. • Exacerbated water resource shortages resulted in risk deterioration in the plain regions of the Ziya watershed. Over the past few decades, the ecological risk in the Ziya watershed has increased due to rapid economic growth, population expansion, and water resource overexploitation. Therefore, a typical index system for comprehensive ecological risk assessment at the grid scale was constructed under the influences of land use change and water resource shortage. As an essential element for describing droughts and water shortages, the ecological water shortage quota was introduced into the index system. Then, the significant influencing factors of ecological risk change were identified. The results showed that farmland consistently experienced precipitation deficits. In regard to natural vegetation, precipitation in the watershed could not sustain normal growth. Therefore, vegetation water shortages should be considered in risk assessment. Furthermore, the ecological risk showed an increasing tendency from 1990 to 2018, which was dominated by moderate- and middle-high-risk zones. The high-risk areas were primarily located in the plain area of Hebei Province and northeastern part of Shanxi Province, while the low-risk areas were located in the northwestern part of the watershed. Water resource shortages and land use changes are important factors influencing the ecological risk. Based on a county-scale risk source-habitat-risk receptor framework, four ecological risk zones were established, and the major problems in each zone were identified. The results could provide a reference for optimal allocation of agricultural water resources in the Ziya watershed. [ABSTRACT FROM AUTHOR]

• The study aimed to identify drivers of SOM stabilization and composition. • MAOC concentration was the function of bulk SOM aromaticity and slope steepness. • Land use reflects the elemental composition (C/N) of the SOM. • SOM aromaticity is rather related to soil and climate properties. Soil organic matter (SOM) concentration and composition are essential properties that affect most functions and ecosystem services. The relationship between soil and environmental covariates regarding SOM concentration and composition in various pools is not completely understood. This study aimed to identify the most influential drivers of SOM stabilization, focusing on arable lands in Hungary. Hungary is an ideal area for investigating SOM variability because it is at the meeting point of the three main climate effects that trigger a wide range of soil, land use, and topographical conditions. Overall, 87 soil samples were taken from the topsoil (2–20 cm) and fractionated (<20 µm) to separate the mineral phase-associated organic carbon (MAOC) and bulk pools. MAOC concentration varied on a wide range (0.5–14.1 %) and was the function of bulk SOM aromaticity and slope steepness, rather than land use, climatic conditions, or soil properties, indicating that MAOC is also affected by decomposition if the bulk OM is less available for the microbiome. Land use, especially in forest topsoils, reflects the elemental composition of the OM, focusing on the variations of residue composition. In contrast, aromaticity is rather related to soil and climate properties, suggesting increased relevance of transformation processes. As a consequence, SOM composition varies on a wide range in the topsoil, however, the lack of a definite trend at the county level suggests the complexity of the system and highlights the role of local circumstances. [ABSTRACT FROM AUTHOR]

• Wetlands topsoil can sequester more C than farmlands and forestlands. • Soil water content was important factor affecting microbial abundance and enzyme activity. • Higher soil water content can increase soil C storage by stimulating C fixing enzyme activity. • Soil C storage were negatively driven by soil bacterial abundance under different land-use. Soil carbon storage plays a crucial role in mitigating the climate warming and is significantly impacted by the land use pattern. To better understand soil carbon stability and the underlying microbial mechanism, based on qPCR, ELISA, and fluorescence techniques, the effects of land use changes on soil microbial abundance, enzyme activity, and soil carbon storage were investigated in the complex ecosystems of cropland, forestland, and wetland along three typical river (Wolvlan river, Bielahong river, Wusuli river) basin in Sanjiang Plain, China. We hypothesised that croplands soil carbon storage is lower than forestlands and wetlands, which is regulated by soil water content, microbe and enzyme activity. Results showed that topsoil TC in wetlands (85.54 mg·g−1) was higher than those in croplands (33.46 mg·g−1) and forestlands (46.13 mg·g−1). Topsoil water content increased 73.90 % and 71.64 % in wetlands than in farmland and forestlands, respectively. Additionally, reclamation diminished topsoil carbon storage. In croplands, soil dissolved organic carbon, microbial biomass carbon, microbial biomass nitrogen, available nitrogen, bacterial abundance, and soil enzymes (i.e., RubisCO, β-glucosidase, cellobiohydrolase, 1,4-N-acetylglucosaminidase and acid phosphatase) activities were substantially lower than those in wetlands. Structural equation modeling showed that soil carbon storage was positively related to soil water content and RubisCO activity but negatively related to soil bacterial abundance. Soil water content had the largest standardised total positive effect coefficient and indirectly influenced soil carbon storage by affecting RubisCO activity. Soil depth had a greater effect on SMC, hydrolase and site had a greater effect on bacteria and fungi abundance. The results highlight that the alteration of carbon fixing enzyme activity by soil water content is a crucial mechanism for soil carbon sequestration in response to land-use change. Management strategies that conserve natural wetlands, increase soil water content and minimize land disturbance would be effective in maintaining soil carbon stocks. [ABSTRACT FROM AUTHOR]

• Hillslope erosion dynamic model integrating vegetation effect was established. • Unified baseline parameters were obtained across different land uses. • Effect of vegetation on soil detachment and sediment transport was revealed. • Contribution rates of vegetation to sediment reduction along slopes were quantified. Developing a process-based soil erosion model that comprehensively considers the effects of vegetation is complex but crucial for evaluating sediment reduction during vegetation restoration. Current understanding of the effect of vegetation on sediment reduction along hillslopes across different land uses is limited. In this paper, we developed a dynamic model of hillslope erosion that integrates the effects of vegetation on soil detachability and hydrodynamics (VED) based on the feedback mechanism between soil detachment and sediment transport. The VED was calibrated and validated with runoff plot data for woodland, grassland, and farmland in the Wuding, Yan, Jing and Wei Rivers of the Loess Plateau in China. Unified baseline parameters and decay coefficients of vegetation were obtained. The model validation results indicated that the coefficient of determination, Nash–Sutcliffe simulation efficiency and relative error ranged from 0.59 to 0.99, 0.56 to 0.90, and −45.99 % to 46.36 %, respectively. The decay coefficients for soil detachment capacity (Φ), sediment transport capacity (T c), and the sediment reduction effect of vegetation exhibited the following order: woodland > grassland > farmland. Compared with VED, existing process-based soil erosion models failed to effectively characterize the influence of vegetation on Φ and T c on the Loess Plateau, with differences of several orders of magnitude. The individual contributions of runoff, soil detachability, and hydrodynamics with vegetation impact on sediment yield were quantified by VED. The contribution rates of vegetation to sediment reduction decreased gradually with increasing slope length because the soil detachment capacity of bare slopes exceeded that of vegetated slopes, resulting in a faster increase in sediment yield. The contribution rates of vegetation to sediment reduction for woodland, grassland, and farmland with 20 %–60 % vegetation covers were 66.75 %–99.95 %, 57.43 %–99.63 %, and 27.91 %–88.63 % in the boundary conditions of this study, respectively. The results reveal the potential for integrating VED into other distributed watershed hydrological and sediment models to assess the effects of vegetation restoration on sediment reduction at a watershed scale. [ABSTRACT FROM AUTHOR]

[Display omitted] • Infilled gullies are valuable information sources on human–environment interaction. • Initial gullying in the region is associated with Late Neolithic land use. • The sediment infill reflects several cycles of the surface erosion and stabilisation. • Erosion phases relate to periods of the Bronze Age, Hallstatt and La Tène periods. The long-inhabited Central European lowlands have exposed to significant erosion since prehistoric times, primarily due to deforestation and agricultural practices, leading to colluvium formation and erosional features. Infilled erosional gullies, particularly near abandoned settlements, may offer insights into landscape changes and settlement evolution. Our multidisciplinary research at the Přerov-Předmostí archaeological megasite in Czechia integrates geoarchaeological methods, geophysics and extensive development-driven excavations. This site, located on the migratory corridor between the Pannonian and Poland plains, serves as a focal point for studying the interplay between human settlement, land-use development and environmental changes in this region. By combining geophysics and excavation, we investigate settlement and land-use patterns, correlating these with the environmental and pedosedimentary record of an infilled gully. The incision of the gully represents initial phase of erosion at this site. Formed before 2300 BC, it is among the oldest in the region, likely triggered by Late Neolithic land use. Our findings also indicate a cyclical erosion pattern linked to four primary settlement peaks: the Early Bronze Age (2300–1600/1500 BC), the Young/Late Bronze Age (1500–900 BC), the Hallstatt period (900–400 BC) and the La Tène period (400 BC–50 BC/1 AD). These periods of heightened settlement activity alternated with times of reduced or no population pressure, leading to stabilisation and subsequent pedogenesis. [ABSTRACT FROM AUTHOR]

• Soil erosion is estimated at 2.32 Mg/ha/yr across all LULC classes in the US. • Croplands are responsible for 44% of soil erosion on 17% of US land. • Cultivated and other vegetated lands contribute to 90% of soil erosion. • The highest soil erosion rates are seen in corn, soybean, and wheat lands. • Future urban and cropland expansion will increase soil erosion rates in the US. Brought on by anthropogenic actions, accelerated soil erosion inflicts extreme changes in terrestrial and aquatic ecosystems. These field-scale (30 m) changes have neither been fully surveyed in the present, nor predicted for a probable future. Water-driven soil erosion (i.e., sheet and rill erosion) rates across the contiguous United States were estimated for the present, and then predicted for the future using three alternative Shared Socioeconomic Pathway and Representative Concentration Pathway (SSP-RCP) scenarios (2.6, 4.5, and 8.5) of the Coupled Model Intercomparison Project Phase 6 (CMIP6). The G2 erosion model which is integrated with Machine Learning (ML) and Remote Sensing (RS) techniques were used to estimate soil erosion based on gauge observations of long-term precipitation, and climate and land use land cover (LULC) scenarios. The baseline model (2020) estimated soil erosion rates of 2.32 Mg ha−1 yr−1 under current conservation agriculture practices (CPs). Maintaining current CPs, future scenarios predict an 8 % to 21 % increase in soil erosion under different combinations of SSP-RCP climate and LULC change scenarios. The findings of this study can help policy makers for future conservation planning on maintaining soil fertility, mitigating environmental impacts, and promoting food security. [ABSTRACT FROM AUTHOR]

• Long-term expansion rates of 46 Urban Gullies in Kinshasa and Bukavu are quantified. • Gully widening is responsible for most of the gully expansion. • Expansion rates in sandy soils are mainly controlled by land cover and road density. • Expansion rates in clayey soils appear influenced by landslide dynamics. Urban gullies (UGs) are a growing concern in many tropical cities of the Global South. Addressing this new geo-hydrological hazard requires good insights into the rates and controlling factors of this process. Therefore, we investigate the expansion rates of a representative sample of UGs in Kinshasa (n = 17) and Bukavu (n = 29), two contrasting cities in D.R. Congo. We reconstruct long-term (10–17 years) expansion rates, making a distinction between headcut retreat and sidewall widening, and analyse the environmental factors potentially explaining these rates. Total expansion rates varying between 12.6 and 863 m2y-1. Most of this expansion happens through sidewall widening. In Kinshasa, which is mainly characterized by sandy soils, contrasts in expansion rates are mainly correlated to the characteristics of the upslope drainage area of the gullies. Especially the road density and a hypothetical runoff index (combining drainage area, land use and soil characteristics) explain a significant part of the observed variation. In Bukavu, such trends are less apparent. This is likely because the clayey nature of the soils provides more resistance against gullying, resulting in overall smaller and less actives UGs. Furthermore, the already low infiltration rates of these soils probably make the relative impact of urbanization on runoff production smaller. Our results also indicate that UGs located in recent landslides have higher gully expansion rates. The mechanisms behind remain poorly understood. Overall, our work opens promising perspectives to model and predict gully expansion rates in urban settings but may also guide efforts aiming to stabilize UGs. [ABSTRACT FROM AUTHOR]

• Soil water content (SWC) is determined as the outcomes of land use changes. • A significant correlation occurred between δ13C and δ15N values in wetlands, but underwent considerable changes after wetland conversion. • The shifts in organic matter sources over time and distinct mechanisms of degradation and preservation of SOM were underscore in wetlands following land use changes. Land use change in wetlands leads to significant losses of soil organic matter (SOM). Stable carbon (C) and nitrogen (N) isotopes offer insights into changes in C3/C4 vegetation, SOM sources, and decomposition processes. Yet, predicting the spatial–temporal dynamics of SOM contents and isotopes under land use changes remains challenging. This study delves into the effects of land use changes on soil organic carbon (SOC), total nitrogen (TN), δ13C and δ15N values, and soil physico-chemical properties and lignin phenols. Our results highlight the significance of soil water content (SWC) in determining the outcomes of land use changes. The conversion of wetland to cropland, forestland and construction land, led to notable reductions in SOC contents (8.71–56.33 %), and TN contents (7.87–37.12 %). Wetland conversion resulted in an enrichment of 13C and 15N abundance, with wetlands exhibiting the lowest δ13C (−25.57 to –22.89 ‰) and δ15N (2.66 to 6.67 ‰) values. A significant correlation occurred between δ13C and δ15N values in wetlands, but underwent considerable changes after wetland conversion. Key parameters, including bulk density (BD), C:N, the acid-to-aldehyde of vanillyl ((Ad/Al)v), lignin content (Λ 8), and total phosphorus (TP), were identified as influencing factors for both SOC and TN contents. When evaluating δ13C values, the most influential factors included silt, C:N, SOC, sand, and BD. These indicate the importance of soil chemical group (from 41 % to 21 %) in elucidating δ13C values declined, while lignin group's (from 9 % to 28 %) importance increased from topsoil to subsoil. The acid-to-aldehyde of syringyl ((Ad/Al)s), Λ 8 , C:N, BD and the cinnamyl-to-vanillyl ratio (C/V) were identified as the primary factors influencing δ15N values, with chemical group accounting for 36 % and lignin group for 48 % in topsoil, while physical group dominated 42 % in subsoil. Our findings underscore the shifts in SOM sources and distinct mechanisms of degradation/preservation of SOM following land use changes. [ABSTRACT FROM AUTHOR]

[Display omitted] Soils at 57 ancient Hindu temples in India are documented from field profiles as a basis for understanding livelihoods of the five cults of Puranic (Smarta) Hinduism during the first millennium CE. Similar soils were found at different temples of the same deity, but different kinds of soils at temples of different deities. Temples of Ganesha and Hanuman, for example, are alluvial Entisols and Vertisols, the principal cultivable soils of India. Temples of Vishnu and Lakshmi are well drained Alfisols and Aridisols suitable for grazing, housing and markets. Different soils supported different livelihoods, social classes and cults, such as servant (shudra) class for farmers Ganesha and Hanuman, and herder-merchant (vaishya) class for Vishnu and Lakshmi. This result matches accounts in the Matsya Purana (250–500 CE) specifying dark organic soils for shudras and red soil for vaishyas. Puranic Smarta polytheism may reflect amalgamation of different tribal traditions during expansion of Gupta and other Hindu empires. [ABSTRACT FROM AUTHOR]

• The agri-horticulture (AH) system exhibited the highest Carbon management index (CMI). • CMI increased at higher altitude in dry temperate Himalayas. • Passive carbon pool was higher under AH system than agriculture (A) by 16.2 %. • The highest Lability index was reported in A indicating lower stability than AH. Globally, land use management consistently changes the dynamics of labile and recalcitrant (non-labile) soil organic carbon (SOC) fractions. However, the effects vary depending on altitude, soils and management practices. The dry temperate north-western Himalayan region is characterized by the presence of diverse land use systems, however the comparison of these SOC fractions across various land use regimes is not well-documented in the area. This study reported the differences in labile and non-labile SOC fractions under the major land-use systems viz., Agriculture (A), Horticulture (H), Agri-horticulture (AH) and Grass fallow (OF) land in various soil-depth classes (0–20, 20–40 and 40–60 cm) along three altitudinal ranges i.e., 2200–2500, 2500–2800 and 2800–3100 m above mean sea level (m. a.m.s.l.) across the dry temperate region of north-western Himalayas. The lability index and carbon management index of the soils were determined using these fractions. The analysis affirmed the highest accumulation of active fractions viz., very-labile (2.66 mg g−1), and labile C fraction (2.55 mg g−1) under AH, while the highest recalcitrant fractions i.e., less-labile (3.34 mg g−1) and non-labile C fraction (7.46 mg g−1) was documented under H. Moreover, the Carbon Management Index (CMI) followed the order of AH > A > H > OF. All the SOC fractions, pools and CMI significantly increased with increase in altitude but declined at lower soil depths. The Pearson correlation analysis revealed that the CMI was positively correlated with the active C fractions i.e. C frac 1 (r = 0.96; p < 0.05) and C frac 2 (r = 0.9; p < 0.05). The higher active carbon pool and CMI (6.9–16 % and 4.1–15.7 % higher, respectively) under the AH may be due to the greater organic matter inputs to the soil under the agri-horticulture land use system. The findings of this study suggest that the soil can be managed sustainably by the adoption of stable land use systems such as agri-horticulture (owing to their higher CMI values) in the highly fragile dry temperate ecosystem of the north-western Himalayas. [ABSTRACT FROM AUTHOR]

• Determine soil zinc cycle using isotopic tracing from karst area. • Zinc behaviors strongly controlled by rock weathering and leaching processes. • Cultivation limits δ66Zn fractionation, grazing induces heavier δ66Zn compositions. Stable isotopes are increasingly employed to identify anthropogenic disturbances and geogenic processes of zinc (Zn) in terrestrial ecosystems. To reveal how land use affects the transformation of soil Zn, profile samples were collected from abandoned cropland (AC), grazing shrubland (GS), and natural land (secondary forest land, SF) in a typical karst area, and analyzed the Zn content and isotopic composition. Results exhibited that soil Zn contents in forest (SF: 72.50 ∼ 131.20 mg/kg) were more variable than those in agricultural lands (AC: 74.53 ∼ 112.20 mg/kg; GS: 48.26 ∼ 82.57 mg/kg). Rock weathering was the main contributor to soil Zn in each profile. Differences among profiles arose from partially assimilative Zn returning to the forest through plant debris, whereas leaching processes coupled with the consumption of crop production and livestock led to Zn loss. The δ66Zn varied in the largest range in SF (−0.26 ‰ to 0.04 ‰), and the extremums were both in the upper soil (0 to 80 cm). After the decomposition of plant debris, vegetation preferentially assimilated lighter δ66Zn, while retaining heavier δ66Zn in the surface soil. Moreover, the soil solution also had a lighter δ66Zn composition that leached downward. The narrowest range of δ66Zn composition was in AC (−0.14 ‰ to −0.02 ‰). The assimilation of crops exhausted the lighter δ66Zn fraction during cultivation, and the heavier δ66Zn fraction continued to be lost by leaching after stopping tillage. The δ66Zn composition ranged from −0.18 ‰ to 0.00 ‰ and decreased with depth in the GS. Animal excrement supplied unintentionally heavier δ66Zn compositions during grazing and obviously disturbed soil Zn behavior under the effects of vertical leaching. Both the content and isotopic composition showed that soil Zn dynamics were highly sensitive to agricultural activities. This study reveals a potential feedback mechanism for soil Zn behavior during agricultural disturbances, which is beneficial for optimizing land management in karst areas. [ABSTRACT FROM AUTHOR]

• Spatiotemporal DSL variation and associated forcings were explored at a semi-humid catchment. • Land use type was the dominant control on DSL variation at a catchment scale. • DSL response to meteorological factors differed between the semiarid and semi-humid catchments. • The mixed "forest/shrubland + grass" plantation type is recommended for the semi-humid catchment. The formation of dried soil layers (DSLs) is a broad consequence of climate change (i.e., through temperature increases and/or precipitation decreases) and poor land management practices, where these layers exist has severe negative effects (i.e., retardation of vegetation, negative water cycle balance) on the sustainability of restored ecosystems and health of agriculture. Because of the effort and time required, only sporadic in situ measurements on spatial and temporal DSL variation have been reported, particularly at a catchment scale. However, this information is essential for understanding mechanisms associated with evolutionary DSL processes as well as developing effective land management techniques. Accordingly, this study monitored soil water content to a 5 m depth over a 5-year period in a semi-humid catchment on the Loess Plateau while also investigating temporal DSL dynamics and dominant controls. In the semi-humid catchment, DSLs occurred at 90.7 % of all sampling sites. Spatially and temporally averaged DSL formation depth (DSLFD), DSL thickness (DSLT), and DSL soil water content (DSL-SWC) within the 0–5 m profile were 170 cm, 262 cm, and 9.52 %, respectively. Forest and shrubland DSL regimes were drier than those of grassland. These three DSL indices exhibited significant correlation with temperature variables, while only DSLFD variables significantly correlated to precipitation. Land use type was the predominant control of DSL variation at a catchment scale. A spatial DSLT variation comparison under different land use treatment positions determined the feasibility of planting grass at an upslope position and mixed forest/shrubland + grass at mid-slope and downslope positions in the semi-humid catchment, which provides a good case study for afforestation practices at a catchment scale. Findings from this study are intended to aid in catchment soil and water conservation, soil drought mitigation, and sustainable vegetation management practices on the Loess Plateau as well as other water-limited regions worldwide. [ABSTRACT FROM AUTHOR]

[Display omitted] • Soil properties and enzymatic activities varied across land use types and villages. • Agroforestry establishment accelerated soil enzymatic activities by 39.41–90.17%. • Cultivation caused massive decline in level and variability of enzymatic activities. • Climate, vegetation, and management practices determined the enzymatic activities. Soil microbial enzymatic activities, often used as indicators of soil health and fertility, are vulnerable to changes in climate and anthropogenic activities. This study analyses the responses of specific soil enzymatic activities– dehydrogenase (DHA), acid phosphatase (APH), β-glucosidase (BG) and urease (URE)– in Nitosols/Luvisols of the subtropical zone of the Central Himalaya, India. We investigated how these enzymatic activities vary with different land uses: arable land (AL), kitchen garden (KG) and peach orchard (PO), across four villages– Niglat, Kainchidham, Majhera and Syalikhet. Considering associated management practices, we quantified cumulative average soil enzymatic activities for the rabi season (2017–2018). In general, catalytic activity of the selected enzymes was highest in Syalikhet and lowest in Majhera. However, for land use types, enzymatic activities were lower in AL and KG (75.56–90.17% and 39.41–61.72%, respectively) compared to PO values. MANOVA analysis evaluated significant spatial differences (P < 0.001) in enzymatic activities. Soil enzymatic mean values were highest in the surface layer (0–10 cm) and decreased gradually with increasing depth. Parameters such as soil moisture content (SMC) and pH, along with vegetation, management practices, and nutrients such as SOC, TN, K, AP, and N forms (NH 4 +–N and NO 3 ––N) showed significant and strong correlations with all the soil enzyme activities (r = 0.40–0.97; P < 0.05). TN, SOC, K, SMC, pH, AP, NH 4 +- N, and clay content were key determining factors of soil enzymatic activities, explaining approximately 59% of the variation. These results suggest that using soil microbial enzymatic activities as soil quality indicators is a feasible approach to assess the impacts of vegetation, management practices, and soil profile depths in soils under different land use types/systems in selected impoverished villages of the fragile Central Himalaya, India. [ABSTRACT FROM AUTHOR]

• Channel dynamics of pseudomeandering rivers is poorly known. • The study river reacted very rapidly to sediment supply changes. • Deforestation resulted in an increase of sediment supply and in a braided channel. • Reforestation and gravel mining caused river incision and a low sinuosity channel. • Post mining sediment supply increase was a key factor in shaping channel morphology. Typically, pseudomeandering rivers are gravel-bed streams considered unstable and prone to turning into braided or meandering channels under the effect of external forcings. Channel changes of pseudomeandering rivers have not been investigated in detail so far. This paper analyses the response of a pseudomeandering river (the Cecina River in western central Italy) to variations of sediment supply resulting from streambed material mining and land use change throughout the last two centuries. Old maps and 11 sets of aerial images from 1954 to the present of four representative sites were used to measure the variation through time of bankfull width and channel sinuosity. The changes in the number of bends, chute channels, bank erosion, bend extension, migration and retraction were recorded and the main processes which favoured pseudomeandering river channel changes were investigated. The old maps indicate that in the first half of the XIX century, the study river had probably a braided morphology in response to the increase in sediment supply following the liberalization of deforestation. From the beginning of the XX century to the present, the river had a predominantly single thread, pseudomeandering morphology which did not change during about 20 years of intense gravel mining (the 1960s – mid-1980s) when the main response of the river was channel incision and narrowing. A few years after bed material extraction stopped the river started to widen, to increase channel sinuosity and consolidate its pseudomeandering morphology. The study confirms that marked variations in sediment supply are more effective than floods in triggering river channel changes. The study also shows that the pseudomeandering configuration is less unstable than previously highlighted in other scientific works. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rainfall and temperature both had a significant effect on forest land. • Annual rainfall and grassland area contributed the most to soil conservation. • Land use had a greater direct impact on soil conservation than climate factors. • Land use, rainfall, and temperature had threshold effects on soil conservation. In the Loess Plateau, enhancing the function of soil conservation (SC) is essential for maintaining ecological sustainability. Land use (LU), rainfall, and temperature might all have a big influence on SC. In this study, we applied the InVEST model to assess the SC of a typical city, Yan'an, in 1990, 2000, 2010, and 2020. Effects of LU, rainfall, and temperature changes on SC were examined using correlation analysis, redundancy analysis (RDA), regression analysis, and frequency ratio analysis. The findings indicated that farmland (FC), forest land (FL), and grassland (GL) were Yan'an City's main LU types. The expansion of FL and GL areas has come at the expense of the FC areas, partly due to the "Grain for Green" Project, and this change has accelerated considerably since 2000. The total amount of SC in 1990, 2000, 2010, and 2020 generally showed a decreasing and then increasing trend, which was 0.96, 0.87, 1.22, and 1.39 billion tons respectively. In the research region, temperature, rainfall, and LU changes occurred all at once. The FL region was quite consistent with the geographical distribution of areas with low temperatures and heavy rainfall. The results of correlation analysis and RDA indicated that GL area and annual rainfall (PY) were the main causes of SC (p < 0.01). A strong connection (r = 0.63, p < 0.01) was also seen between the daily temperature range (ΔT) and SC. Increased LU-type area, rainfall, and temperature improved SC with a threshold range. Calculated by regression analysis, it recommended the FL ≤ 11040 km2, GL ≥ 14720 km2, and FC ≤ 7360 km2 in Yan'an City. Rainfall and temperature showed no significant pattern and were difficult to regulate by human intervention. The improvement of SC should focus on adjusting the LU structure under the existing ecological planning. Accepting some degrees of uncertainty, our findings provide insights into how possible LU, rainfall, and temperature will affect SC. It's crucial both for future regional management and ecological sustainability development. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SAS around the Danjiangkou Reservoir shows a clear spatial distribution. • Landscape and environmental factors and soil properties synergistically influence SAS. • Orchards displayed higher SAS compared to paddy fields and uplands. • SAS can be enhanced by reducing LPI and increasing landscape heterogeneity. Soil aggregate stability (SAS) plays a crucial role in determining the soil's resistance to erosion. Conducting a spatial variability analysis of SAS in the reservoir area, which is highly susceptible to soil degradation and erosion, can yield valuable insights for agricultural practices, landscape planning, and environmental management in this region. Nevertheless, existing research remains constrained in its capacity to accurately map and forecast soil aggregates at a spatial level. This study aims to investigate the spatial distribution of SAS in the Danjiangkou reservoir area, as well as to explore the intrinsic linkage mechanisms between changes in soil properties, environmental factors and landscape patterns and SAS. Results revealed significant spatial variations in SAS within the vicinity of the Danjiangkou reservoir area. Notably, soil properties (including clay, available potassium, soil organic matter, and available phosphorus), environmental factors (such as digital elevation model, slope, land surface temperature difference between seasons (ΔLST)), and landscape pattern (largest patch index (LPI), shannon's diversity index (SHDI), edge density (ED)) significantly affected the spatial variability of SAS, explaining 18.91%, 8.22%, and 8.17% of the total variability of soil SAS, respectively. Structural equation modeling results indicated that altering soil properties serves as the primary approach to enhance SAS. Furthermore, interventions targeting landscape factors such as LPI, SHDI, and ED, alongside environmental factors like ΔLST and slope, exert direct influences on SAS, while also indirectly impacting it through their effects on soil properties. These findings contribute to the design of land planning and soil and water conservation measures in the reservoir watershed, promoting its protection of soil structure and its ecological service function. [ABSTRACT FROM AUTHOR]

[Display omitted] • Establishing exclosures aids in vegetation restoration of degraded lands. • Exclosures of studied watersheds were limited in restoring degraded lands. • The efficacy of <11 & >11-year exclosures was different in restoring degraded lands. Land degradation is a severe environmental problem in the northern and northwestern Ethiopian highlands. As a response to increasing land degradation, rehabilitation of degraded grazing lands through exclosures (exclusion of farmers and domestic animals) has been undertaken. This study aimed to evaluate the effectiveness of 11 and 8-year exclosures in improving degraded landscapes in the Karita-Wuha and Dengora watersheds. It was assumed that the conditions on communal grazing lands at the time of the investigation corresponded to those at the establishment of exclosures. Vegetation was inventoried, and soil samples were collected and analyzed in 14 and 21 sampling sites selected from exclosures and communal grazing lands in Dengora and Karita-Wuha watersheds, respectively. Sampling plots (20 × 20 m) were established for soil sampling. In the two land uses, 10x10 m and 5x5 m sub-plots were used to survey trees and bushes/shrubs, respectively. Richness, diversity, evenness, and aboveground biomass (AGB) were evaluated using measurements from the vegetation inventory. Organic carbon (OC), total nitrogen (TN), and available phosphorus (AP) and their stocks were used as soil nutrient indicators. The result showed that exclosures aided in restoring vegetation in both watersheds and soil nutrient parameters in the Dengora watershed compared with communal grazing lands. In the Karita-Wuha watershed, there was significantly higher OC, TN, and their stocks in communal grazing land than exclosures (t -test, p < 0.05). These results are generally attributed to the fact that communal grazing lands were significantly degraded before exclosure and have yet to recover. As a result, exclosures of Dengora and Karita-Wuha watersheds were limited in restoring degraded landscapes. There have been differences in the effectiveness of < 11- and > 11-year exclosures in restoring degraded landscapes in the literature. The effectiveness of various aged exclosures in restoring degraded landscapes is likely variable and dependent on local biophysical parameters and land use systems. [ABSTRACT FROM AUTHOR]

The area of Burdur Lake gradually decreased from 211 to 122 km2 between 1975 and 2021. In this study, we explored the effects of time, environmental factors, and land uses on the spatial distribution of soil chemical properties (SOC, CaCO 3 , EC, and pH). In total 240 soil samples were taken (0–20 cm depth) at a 400 × 400 m grid sampling in the former lakebed, pasture, and agricultural fields representing a chronosequence. We found a considerable temporal and topographic trend in SOC, CaCO 3 , EC, pH, and vegetation density. The SOC, EC, and pH were higher in younger soils. Land use significantly affected soil properties. Natural vegetation species mainly grew in the pasture but only sparsely in the former lakebed areas. Salt-affected and alkaline soils and exposure time affected the density and spatial distribution of vegetation in the former lakebed and pasture areas. We tested different models to spatially predict soil properties and found that random forest had higher prediction accuracy for SOC (r2 = 0.50) and CaCO 3 (r2 = 0.36), whereas the cubist model had higher prediction accuracy for EC (r2 = 0.60) and pH (r2 = 0.38). We conclude that the vegetation density and distribution of SOC, CaCO 3 , EC, and pH were controlled by topography, time, and land use. The time and space-for-time substitution approach can be used to study soil chronosequence and biosequence in areas with shrinking lakes. [ABSTRACT FROM AUTHOR]

Benthic metabolism is an essential process which plays a critical role in the carbon and nutrient cycles and in the transfer of material and energy in stream ecosystems. Benthic algae are one of principal primary producers in stream food webs that converts dissolved inorganic carbon to organic matter, and algae are more palatable basal resources for aquatic consumers due to its higher unsaturated fatty acid content than terrestrial carbon. Despite the importance of algae, few studies have investigated how the benthic metabolism is influenced by distal factors, such as upland land use and landscape configuration, and proximal factors, such as stream temperature, nutrient availability, and light availability at various spatial scales. Here, we measured the benthic metabolism and proximal factors at the outlet of 14 selected sub-catchments in a subtropical river. Land use and landscape metrics at the catchment, riparian, and reach scales were processed as distal factors. Using stepwise regression models, we found that the proximal factors, such as water temperature (WT) and total phosphorus (TP), significantly increased primary production, and that nitrate-nitrogen ( N O 3 - -N), pH, and electrical conductivity (EC) decreased gross primary production (GPP). Also, TP was positively correlated with respiration (R) while N O 3 - -N negatively impacted R. Structural equation modeling demonstrated that the patch cohesion index negatively affected GPP by restraining WT and TP at the catchment scale while the increased shape index elevated the WT and TP to promote GPP. Our results suggested that stream metabolism is vulnerable to anthropogenic disturbances, such as upland land use and landscape patterns. Thus, land use planning and administration, particularly at catchment scale, should consider how to minimize the influence of human activities on ecosystem function in streams. [ABSTRACT FROM AUTHOR]

• Land use types determined deep soil water redistribution. • Soil moisture in abandoned land was strongly affected by rainfall. • Decreased rainfall and soil drying reduced the growth of forage and shrubs. • Farmland in terraces and abandoned land on slopes were the ideal use types. The land-use change affects soil hydrological processes in semi-arid areas. Investigating the impact of precipitation change on soil moisture in different land use types (LUTs) is conducive to water resource management and ecological restoration. The volumetric water content (VWC) at 0–300 cm soil profile, meteorology data, and vegetation aboveground biomass were continuously observed from 2018 to 2022 in five terraced and three sloped LUTs. The results showed that soil moisture was affected by precipitation, vegetation, antecedent soil water, soil properties, and artificial management measures. There were significant differences in soil moisture among these land use types (P < 0.05), with the priority order of multi-year profile average VWC at 0–300 cm depth was farmland in the slope (FAS) (0.22 ± 0.01 cm3 cm−3) > bare land in the terrace (BAT) and farmland in the terrace (FAT) (0.19 ± 0.01 cm3 cm−3) > abandoned land in the slope (ABS) (0.18 ± 0.02 cm3 cm−3) > abandoned land in the terrace (ABT) (0.13 ± 0.02 cm3 cm−3) > forage land in the slope (FOS) (0.12 ± 0.02 cm3 cm−3) > forage land in the terrace (FOT) and shrubland in the terrace (SHT) (0.10 ± 0.01 cm3 cm−3). Except for BAT, soil water storage (SWS) in other LUTs decreased in 0–300 cm soil profile from 2018 to 2022. There were no or slight soil desiccations in FAS, BAT, ABS, and FAT, moderate soil desiccation in ABT, and serious soil desiccation in FOS, FOT, and SHT. The VWC, SWS, and soil desiccation index (SDI) of all LUTs were positively correlated with precipitation, especially at 0–100 cm depth. Precipitation threshold response to soil desiccation alleviation was determined to be 98–116 mm month−1. Moreover, aboveground biomass of FOT, ABT, and SHT exhibited a significant correlation with both soil moisture and precipitation (P < 0.05). Therefore, forage lands and shrublands have adverse effects on the mitigation of deep soil desiccation with decreasing rainfall. This study recommended farmland in the terrace and abandoned land in the slope for soil and water conservation and sustainable ecological restoration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amino sugars are chosen as biomarkers of microbial necromass in aggregate soils. • NW conversion to FL or CL increases the contribution of aggregate MNC to SOC. • FNC are the main contributor to microbial necromass in estuarine soils. • Enhanced perturbation induces the enrichment of BNC to smaller-size aggregates. • pH and SMC affect the aggregate-associated MNC accumulation by mediating the MBC. Microbial necromass carbon (MNC), as an important component of the soil organic carbon (SOC) pool in natural environments, has increasingly gained significant attention in recent years. However, the redistribution pattern of microbial necromass in aggregate fractions of estuarine soils induced by human activity still remain unclear. In this study, we assessed the effect of land use conversion on the redistribution and accumulation patterns of aggregate-associated MNC in estuarine wetland soils on the Pearl River estuary of China. Typical soil samples in 0–30 cm profiles under different land uses [Natural Wetland (NW), Farmland (FL), and Construction Land (CL)] were analyzed. The results showed that the NW conversion to FL and then CL contributed to the continuous losses of SOC, however, the aggregate-associated MNC content was higher in FL and lower in CL compared to NW. The MNC contribution to total SOC in aggregate fractions gradually increased from NW (16.41 % − 23.62 %) to CL (23.87 % − 30.98 %) and then FL (34.62 % − 38.83 %) in profiles. Fungal necromass C was the primary contributor to the total MNC in each aggregate fraction. In NW, the MNC was mainly present in large aggregate size, however, the MNC was gradually enriched into smaller size aggregates, especially for the bacterial necromass C, after the conversion from NW to FL or CL. Microbial biomass carbon had a direct and positive effect on the MNC in soil aggregates under different land uses, except for in silt + clay fraction from NW. Moreover, pH and soil moisture content were two key variables affecting the MNC content and accumulation by mediating the microbial biomass of different land uses, while the dominate factors controlling the MNC accumulation varied with size fractions in aggregates. Our results emphasize the influence of land use conversion on the soil aggregate-associated MNC accumulation in estuarine wetland. [ABSTRACT FROM AUTHOR]

• Classification of flood events into typhoon and non-typhoon rainstorm floods. • Key parameters in HEC-HMS model were systematically different for the two types of floods. • Impact of land use change on typhoon floods was smaller than that of non-typhoon floods. • Frequency distribution of the mixture flood series with the effect of land use change. There are two major types of rainstorms in the Asia-Pacific region –typhoon induced rainstorm and non-typhoon rainstorm. This study investigated and separated the different flood responses to these two types of rainstorms, based on a scheme that combined the classification of typhoon and non-typhoon rainstorm floods, the simulation from a distributed hydrological model, and a method to forward restore the impact of land use change on flood frequency analysis. For flood events in a typical basin on the southeast coast of China, the flood characteristics in response to typhoon and non-typhoon rainstorms were significantly different in three aspects: (1) The key parameters in the HEC-HMS model were systematically different. The initial loss and wave velocity of the model were apparently larger for the typhoon rainstorm flood than for the non-typhoon rainstorm flood. (2) The impacts of land use change were different, with smaller effect on typhoon induced floods than on non-typhoon floods under the same magnitude of flood peak flow. (3) Classification of two types of floods resulted in more reasonable frequency analysis affected with the land use change because the annual maximum flood series is the mixture of typhoon and non-typhoon rainstorms. Frequency analysis for the forward-restored mixture flood series showed that the land use change with the decrease in the area of forest land and the increase of garden and construction land resulted in the increase of the mean maximum flow from 2266.6 to 2510.19 m3/s, but the values of coefficient of variation were slightly altered, the ratio of skewness coefficient to variation coefficient were unchanged. The results provide new ideas and methods for a deeper understanding of the impact of land use change on flooding in typhoon and non-typhoon co-action regions. [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]

• Spatial variations in soil erodibility was quantified by indicators in karst hillslope. • Identify the predominant factors affecting spatial variations in soil erodibility. • Land use and slope position had great effects on near-surface soil characteristics. • CSEI varied with land use and slope position, and affected by soil characteristics. Land use type and slope position have a considerable impact on soil properties and thus likely influence soil erodibility. Soil erosion on karst hillslopes in South China is still serious due to the high intensity of human activities and fragile ecological environment. Nevertheless, the potential effects of land use type and slope position on soil erodibility indicators in karst areas are still unclear. This study was conducted to investigate the spatial variations in soil erodibility indicators, namely, the saturated hydraulic conductivity (K S), mean weight diameter (MWD), soil structural stability (SSI), soil erodibility K factor, soil organic carbon content (SOC), and a comprehensive soil erodibility index (CSEI) for three typical land uses and three slope positions on a karst hillslope. The results showed that K S , MWD , SSI , K factor, SOC and CSEI varied significantly with land use type and slope position. The measured K S , MWD , SSI , K factor and SOC at the nine tested sites displayed a similar trend with soil depth. SOC , MWD and SSI contributed more to the CSEI , with contributions of 27.9%, 25.9% and 25.9%, respectively. K S and K factor contributed less to the CSEI , with contributions of 17.7% and 2.5%, respectively. Woodland is most susceptible to erosion on upper, cropland on middle and grassland on lower slope positions according to the values of CSEI. There were significant positive correlations among sand content, bulk density and CSEI , and there were significant negative correlations among clay content, silt content, root mass density, SOC and CSEI. The changes in soil properties and soil erodibility indicators with land use type and slope position led to the differences in the CSEI. The results provide valuable information for policymakers to select appropriate land use types to mitigate soil erosion and thus improve the healthy development of the ecological environment on karst slopes. Moreover, the results have crucial implications for understanding the mechanism of the spatial variation in soil erosion of karst hillslopes in Southwest China. [ABSTRACT FROM AUTHOR]

• Bacterial communities, networks, and functions significantly differed in land use. • Paddy fields had the most bacterial diversity and complex network structure. • The abundance of predictive functional genes was the highest in the garden plot. • pH was the main influencing factor, followed by soil nutrients. Soil microorganisms participate in almost all soil ecological processes and are essential in maintaining ecosystem functions and terrestrial carbon, nitrogen, and sulfur cycles. Soil bacterial communities, networks, biogeochemical cycles, and land use types influence it. However, there are few studies on the changes in these indicators and their influencing factors under different land use types. Taking Dongting Lake watershed as an example, high-throughput sequencing technology combined with FAPROTAX were used to analyze the characteristics and influencing factors of soil bacterial community, network structure, and C, N, and S cycle function genes under different land use conditions. Land use types include paddy fields (PF), garden plots (GP), woodland (WL), and sloped arable land (SAL). PLS-PM model and redundancy analysis method were used to study the mechanism of soil bacterial community, network structure, functional genes, and environmental variables. The results showed that the relative abundance of dominant phylum and dominant fungi changed significantly in different land use types. The first three dominant gates in WL had the most considerable abundance and the most extensive diversity index of PF. The symbiotic network of PF has the most effective connectivity and average degree, the minor network diameter, the most complex network structure, and fierce competition among species within the same ecological niche. The results of functional genes showed that different land use types significantly changed the abundance of soil C, N, and S cycle functional genes, and soil bacteria predicted the highest abundance of functional genes in GP. C, N, and S circulating function genes were significantly correlated with pH, soil nutrients, and soil texture (P < 0.05). PLS-PM model and redundancy analysis showed that soil pH was the main factor affecting the bacterial community, network structure, and functional genes, followed by soil nutrients. [ABSTRACT FROM AUTHOR]

• The mean soil organic carbon (SOC) content in agroecosystem of Eastern China was 18.24 g kg−1. • The SOC content of planted forest > cropland > grassland in the total study area. • The SOC value of grassland was higher than cropland in North China due to excessive mechanized operation. • The random forest hybrid model exhibited higher comprehensive performance in SOC prediction. • Our predictions were much more detailed and accurate than the existing SOC content maps. Soil organic carbon (SOC) plays a key role in soil function, ecosystem services, and the global carbon cycle. Large SOC stocks accumulate in agroecosystems, but the estimates of SOC distribution and magnitude in agroecosystems still have large uncertainties in global products. Based on multiple high-resolution environmental variables (terrain derived from digital elevation model, climate and organism from Landsat 8 OLI) and 369 observed soil samples from 2019 to 2021, two machine learning methods, random forest (RF) and support vector machine (SVM) models, were used to estimate the content and spatial distribution of SOC in agroecosystems of Eastern China. We proposed a hybrid model in which the optimal predictors of SOC were selected for different land use types (cropland, planted forest and grassland), and it aimed to improve the performance of machine learning. Our results showed that (1) the hybrid models performed better than the global models, and the Random forest-Hybrid (RF-Hybrid) model led to the highest prediction accuracy, with a validation R2 of 0.65 and RMSE of 5.76 g kg−1. (2) The SOC content in the agroecosystems of Eastern China among different land use types ranked in the following order: planted forest (19.92 g kg−1) > cropland (17.51 g kg−1) > grassland (17.30 g kg−1). However, in North China, the SOC content in cropland (14.04 g kg−1) was much lower than that in planted forest (17.21 g kg−1) and grassland (17.07 g kg−1), which was caused by excessive mechanized operation. (3) The agroecosystem in Northeast China presented the highest mean SOC content (26.55 g kg−1) due to low temperature. (4) Our estimations (R2 = 0.53, RMSE = 6.74 g kg−1, 30-m resolution) were more detailed and precise than the existing global SOC maps (Soil Grids: R2 = 0.26, RMSE = 12.44 g kg−1, 250-m resolution; HWSD: R2 = 0.06, RMSE = 41.07 g kg−1, 1000-m resolution). The results may improve the accuracy of agroecosystem carbon mapping and contribute to SOC assessments in agricultural ecosystems. [ABSTRACT FROM AUTHOR]

summarizing the synthesis of minimum dataset for soil quality indexing across different land use types in semi-arid Ethiopia. [Display omitted] • Land use effects on soil quality were analyzed. • SQI was significantly impacted by land use type. • Shrub land showed higher SQI than grass land and cultivated land. • Compared with PCA and EO, DA was found to be an effective indicator selection approach. • Soil functions related to varying land uses were best explained by SQI _NLS_DA. Knowledge on the influence of land use practices on soil quality is crucial to develop soil-specific management practices. In order to quantify soil quality index of different land use types in Hintalo Wajerat district of northern Ethiopia, twenty-three biochemical and physical soil attributes were measured at 0–30 cm depth from cultivated land (CL), grass land (GL) and shrub land (SL). Principal component analysis (PCA), discriminant analysis (DA) and expert opinion (EO) were used for minimum data sets (MDS) selection, and six soil quality indices were generated using linear (LS) and non-linear (NLS) scoring methods. One-way analysis of variance (ANOVA) was used to identify members of total data set. Results indicated a significant (p < 0.05) difference in soil quality index among the land use types with a definite trend in the following increasing order of SL > GL > CL, reflecting the need for improved managements in CL soils. The estimated soil quality index using NLS indicator transformation and DA indicator selection approach (SQI _NLS_DA) best distinguished soil functions related to varying land use types. The findings of this study indicated the significant influence of land use practices on soil quality and SQI _NLS_DA is suggested for future soil quality studies in semi-arid tropical soils. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cocoa system in semiarid region increases soil organic matter C. • Growing cocoa promotes greater accumulation of nutrients in the litter. • K release occurs more rapidly and differs between systems. Climate and litter quality change the dynamics of soil organic matter (SOM) in agricultural systems, directly influencing the soil biological activity and, consequently, energy and nutrient cycling. This work evaluated the dynamics of organic carbon decomposition and nutrient release in litter in three land use management systems. The study was carried out under semi-arid conditions in Minas Gerais State, Brazil, using decomposition bags arranged in a randomized block design and four replications. The treatments consisted of three land use systems (native forest, corn, and cocoa) and seven evaluation times: 0, 30, 90, 150, 210, 270, and 330 days. Was evaluated dry matter production, litter decomposition in polyamide bags, and nutrient release (N, P, K, S, Ca, and Mg). Systems with native forest, cocoa and maize had similar average monthly litter production, a fact linked to the climate conditions. While in the semi-arid climate, the full-sun cocoa system showed a sudden oscillation in relation to the organic carbon content up to 330 days, the native forest and corn systems were more balanced, whitout significant changes. The higher litter C/N ratio in relation to the native and corn systems favors the maintenance of organic C levels in the soil. K release has a similar behavior in cultivated soils and occurs more quickly when compared to the native system. Regarding the other macronutrients, the soil in the cocoa production system showed the highest mineralization. Periods of accumulated precipitation accelerate litter decomposition and macronutrient release. The results of this study give more insight into the carbon dynamics and nutrient release from litter as a function of land use systems in a semi-arid region. [ABSTRACT FROM AUTHOR]

• Facility lands were considered to be greater carbon sinks compared to other land uses. • The most stable type of organic carbon is in facility land, and the most unstable is in grasslands. • Changes in land use have a significant impact on organic carbon fractions and carbon mineralization. Soil carbon is an essential component that influences soil health and agronomic productivity, and land-use practices significantly impact soil carbon stocks. In this study, the researchers investigated the impact of various land-use types (farmland, orchards, grasslands, and facility lands) on soil organic carbon (SOC) fractions in the Qaidam Basin of China's Qinghai-Tibet Plateau. The soil samples were taken from the 0–10 and 10–20 cm depths. The particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) fractions of various land uses have been measured. The results revealed that grasslands had the greatest POC/SOC ratio (0.59), with POC accounting for the majority of the SOC fraction. In contrast, all other land-use types (facility land, orchards, and farmland) had greater MAOC/SOC ratios than POC/SOC. The facility land had the highest SOC content (17.75 g kg−1), and orchard had the lowest (8.51 g kg−1). The grassland had the highest POC content (9.82 g kg−1) at a depth of 0–10 cm. The trend for MAOC content among the various land-use types was facility lands > farmlands > grasslands > orchards. The soil pH was also observed to be moderately alkaline, with an average of 8. The orchard has the highest bulk density (BD), measuring 1.38 g cm−3. The grasslands contained the highest amount of total nitrogen (TN) (2.2 g kg−1) while the agricultural fields contained the highest amount of total phosphorus (TP) (1.16 g kg−1). In addition, facility lands showed the highest level of microbial activity compared to other land-use types. According to the findings, SOC, POC, and MAOC fractions had considerably positive associations with TN and microbial biomass carbon (MBC), but were significantly negatively associated with metabolic CO 2. The findings imply that different land-use types can have a considerable impact on the quality and amount of soil organic carbon, which has consequences for soil health and ecosystem processes. The findings also highlight the significance of long-term land management practices that promote the preservation and enhancement of soil organic carbon in various land-use systems. [ABSTRACT FROM AUTHOR]

Soil salinity poses a threat to the sustainable management of agricultural landscapes and has an effect on soil carbon storage. This study investigated land use-land cover (LULC) relations with soil organic carbon (C) in a salinity-infested landscape with inter-spun vegetated and non-vegetated land area. A sodicity infested command area (~100 ha) along Sharda Sahayak canal in Uttar Pradesh, India was selected for studying LULC effects on soil organic carbon (C) and soil properties to 60 cm soil depth. The area was divided in a grid of 100 m × 100 m, and soils were sampled and analyzed at 140 geo-referenced points representing five LULC classes. The LULC dominant in the representative area were barren-coverless (BC), barren-grass cover (BG), rice-fallow (RF), rice-wheat (RW), and rice-okra-mentha (ROM). Soil organic C decreased with depth, decreased with increase in soil pH, and decreased with an increase in exchangeable sodium percentage (ESP). The effects were highly significant in surface layers (0–0.3 m). Similarly with electrical conductivity (EC) too, soil organic C had a negative correlation. Soil organic C varied significantly with LULC. The soil organic C content decreased in the order: ROM > RW > RF > BG > BC. As the intensity of crop/plant cover increased, the soil salinity (ESP, pH and EC) decreased. The average soil ESP was maximum in BC (44%) followed by BG (30%), RF (15%), RW (8.5%), and ROM (7.0%). The cumulative probability trends indicated the probability of lesser ESP with increased vegetative cover/primary productivity. A strong (p < 0.001), a negative relationship was observed between soil organic C and pH in rice-based systems. Analysis of soil organic C stock with depth for the studied LULCs indicated 4–70% (grass cover to rice-wheat cropping sequence) increase in total soil organic C stock just by supporting vegetative cover on barren sodic land. The study was indicative of scope for soil C sequestration and reclamative effects in salt-affected areas of Indo-Gangetic region by adopting appropriate land use strategies, which may include the adoption of rice-based and grass-based cropping systems, to check the development of sodicity in soils. • Soil ESP, pH and EC have negative relationship with soil organic carbon. • Intensified land use-land cover shows ameliorative effects on salinity. • Intensive management relates to increased soil C and decreased pH, EC, ESP. • Land use management could be frontline strategy against soil salinity development. [ABSTRACT FROM AUTHOR]

Identifying the soil water response processes to rainfall events can provide scientific guidance to sustain and enhance ecosystem services of the terrestrial ecosystem. This study presents the results of soil water content and isotopic compositions response to a typical rainfall in the subtropical zone in east China. The response of soil water (including soil water content, hydrogen and oxygen isotope ratios) to rainfall event at three soil layers (0–10, 10–20, 20–30 cm) in two croplands, two orchards (tea and peach), and two forests were analyzed. The results showed that soil water recharge processes were varied in different land uses. The variation in the isotopic composition of soil water showed a hysteresis pattern, and this pattern was affected by land use types. The extents of isotopes depletion in topsoil (0–10 cm) were along the sequence of forest (9.90%) < orchard (10.86%) < cropland (13.70%), in contrast to the reduction of soil water content (17.46% in cropland, 32.06% in forest, and 41.78% in orchard). Little depletion in isotopes indicated limited evaporation effect on soil water, and the corresponding large reduction in water content suggested large infiltration or water recharge into deep soil, these implying a good water buffer for forest soils compared with crop soils. Soil texture and antecedent soil water were the main factors influencing the variations of both soil water content and isotopic compositions. The identification of different soil water changing processes may be important for water management and plant-available water evaluation. [ABSTRACT FROM AUTHOR]

Tropical mountain ecosystems cover a broad variety of climatic and vegetation zones and are global hotspots of biodiversity. These ecosystems are severely threatened by climate and land-use change, which also strongly affect soil properties. Mt. Kilimanjaro, with its large elevation gradient and relatively homogeneous geology of volcanic rocks and ashes, provides a unique opportunity to study and interpret soil organic matter (SOM) responses to climatic changes. Our objectives were to identify key SOM compounds in six elevation zones (covering ecosystems from tropical dry-lowland, through montane forest, up to alpine heathlands) that are affected by the climatic changes along a 3400 m transect, and to relate these SOM changes to ecosystem specific characteristics. The SOM composition in four topsoils (0–10 cm) samples per ecosystem was characterized by analytical double-shot pyrolysis-gas chromatography–mass spectrometry (Py-GC/MS). Evolving-gas analysis-mass spectrometry (EGA-MS) was used to quantitatively compare the thermal desorption (first shot: <280 °C) and pyrolysis step (second shot: 280–600 °C). The percentage of thermally desorbed compounds increased 10 fold from lowland (<900 m) to mountain forest soils (>2000 m), followed by a 40% decrease in alpine ecosystems (>4000 m). Alkanes/-enes/-ols contributed between 4% and 30% to the identified SOM composition, with a maximum at mid elevation (2120 m). Fatty acids and fatty acid esters contributed with <3% to SOM composition and decreased to a minimum of <1% at Podocarpus forest soils (2900 m), followed by a re-increase at higher elevation. The percentage of lignin-derived compounds followed a similar pattern but also responded to reduced woody inputs above the tree line. Two main factors that seem to affect SOM quality and composition at Mt. Kilimanjaro were: 1) the rate and composition of organic matter inputs that in turn are controlled by climatic characteristics and the vegetation type and 2) the decomposition rate and efficiency, mainly controlled by soil pH, temperature and water availability. High forest productivity at mid elevations (2200 m) leads to high amounts of volatile compounds and increases stable SOM pools. The overall carbon accumulation in Andosols of Mt. Kilimanjaro is linked to the percentage of bound lipids (mainly alkanes, alkenes and alcohols), while site specific input patterns (e.g. vegetation or wild fires) are strongly reflected by sterols, lignin derived compounds or polycyclic aromatic compounds in SOM. Unlabelled Image • Vegetation and climatic characteristics controls SOM composition at Mt. Kilimanjaro. • High forest productivity at mid elevations increases both; volatile compounds and stable SOM pools. • Carbon accumulation in Mt. Kilimanjaro soil is linked to increased percentage of alkanes and alkenes. • Sterols, lignin derived and polyaromatic compounds define ecosystem SOM fingerprints. [ABSTRACT FROM AUTHOR]

Land use assessment is among the practical purposes of soil classification. Several researches has been specifically focused on the use of conventional surveys in the evaluation of soil suitability for agriculture products whose quality is influenced by the interactions between soil, plants and the biological stock of the rhizosphere. Our aim was to expand the application of the soil suitability protocol by relating soil types with biodiversity and the ecological equilibria of biological communities. This goal can be pursued by combining the approaches to soil type delineation with the techniques of quantitative ecology that are based on the similarity theory. Given the qualitative scale of several field-recorded attributes make their numerical processing difficult, we focused on numerical techniques for multivariate sets of data to combine with geostatistics. We thought these techniques would originate local soil classes meaningful in terms of both soil processes and soil suitability evaluation. Since auger boring data are formally comparable to vegetation data, we tested Goodall's and Burnaby's pairwise similarity indexes: the former assumes that pairs of observations sharing an infrequent value are more similar than pairs which share more frequent values; the latter considers associations among attributes, giving higher weights to independent ones. We did an intensive soil survey in a 1200-ha flood plain of the Istria region, Croatia. The morphological characteristics of soil cores were recorded and analysed to produce pairwise similarities that were partitioned by hierarchical clustering into similarity vectors. Such vectors were in the end submitted to geostatistical analysis for the drawing up of similarity maps. Both similarity measures originated five partially overlapping clusters that were consistent with the main soil forming processes present in the investigated area. Goodall's index gave the most meaningful results, fulfilling three compulsory requirements for soil mapping: i) similarity vectors were meaningful in terms of fluvial dynamics; ii) similarities displayed a structured spatial variability; and, iii) similarity maps were consistent with the soil forming factors acting in the investigated area. The results obtained indicate that Goodall's similarity index could be currently used in soil suitability evaluation, allowing to better exploit field-recorded data and to extend its application to the relations existing between soil types and the ecological equilibria of biological communities. • Goodall's and Burnaby's similarity measures were highly correlated. • Clusters from Goodall's index were better separated than those from Burnaby's measure. • Goodall's clusters were also more meaningful in terms of fluvial dynamics. • Similarity maps from Goodall's index were consistent with local soil forming factors. • Maps helped delineating the part of Čepić Polje suitable for T. magnatum truffle. [ABSTRACT FROM AUTHOR]

Among the several environmental problems that affect the soil system, causing severe losses to agricultural production, there is the salinization process. Salinization is the accumulation of soluble salts in the agricultural layers of the soil, an environmental problem in several Brazilian semiarid environments. The objective of this study is to map the different degrees of susceptibility to soil salinization in the Quilombola de Cupira community in the municipality of Santa Maria da Boa Vista, Pernambuco. We provide a methodology that uses physical-natural and socio-environmental attributes cross-referenced from geoprocessing tools. Mappings of characteristics such as geology, relief, soils, potential evapotranspiration and land use (vegetation cover) were carried out to carry out this study. All procedures were performed using geoprocessing tools. More than half of the study area presents a medium susceptibility to salinization. Although the greatest susceptibilities occupy no >30% of the community's land, attention should be high since the most significant dangers are concentrated on areas of agricultural production. Unlabelled Image • 21.84% of the soils of the community has very high susceptibility to salinization. • Areas for irrigated agriculture need adequate planning. • The proposed methodology met the study objective. [ABSTRACT FROM AUTHOR]

Abstract Termite mounds influence ecosystem heterogeneity and contribute to the stabilization of the system under global change. A number of environmental factors influence the distribution, height, diameter and designs of termite mounds but these factors are not only poorly understood, they cannot be extrapolated for everywhere. In this study, we employed a ground based survey and Geographical Information System (GIS) technique to map 156 km2 study area in Keffi, Nigeria. The aims were to (1) estimate the density and area covered by termite mounds, (2) sample and identify species types and how they are distributed, and (3) use five environmental factors (elevation, geology, surface water drainage, land use/land cover and static water level) to model suitable sites for mounds construction. A total of 361 mounds were mapped representing a density of about 0.8 mounds ha−1 and covering only about 0.31% of the studied area. Next, the effect of the five chosen environmental factors on the geographic distribution, life status, height and diameter of mounds and species diversity were analysed and their relationships plotted in pairwise comparison matrices using the Saaty's Analytical Hierarchy Process. Normalized rates for classes in each factor and corresponding weights were computed and aggregated using the Weighted Linear Combination method. The result depicted that moderate to low elevation (270–330 m amsl), rock cover types that are more susceptible to weathering (schist), cultivated areas and shallow water table zones are most favourable for termites to build mounds. The result obtained in this study shows a promising correlation between the environmental factors and termite mounds distribution. The proposed model can easily be replicated in a different but similar multi-land use and rock cover types. Graphical abstract Unlabelled Image Highlights • Water table is a major mechanism controlling termite mounds distribution. • Distance between termite mounds and drainage was assessed with respect to stream size. • Relation between mound height and water table depth was assessed. • Floodplains and build-up environments were assessed for termite settlement. • We found Macrotermes species is more resistant to environmental perturbation. [ABSTRACT FROM AUTHOR]

Abstract Topography is one of the key factors controlling soil erosion and redistribution of pedogenic material along slope. Land cover change can have an accelerating or retarding impact on topographically-controlled soil erosion rates, depending on the type and intensity of land use and management. In this study, we investigated the combined effect of hillslope gradient and land cover change on soil redistribution and rejuvenation in a subtropical region where Atlantic rain forest was converted to agricultural land. We used a two versus two factorial design, and evaluated the effect of hillslope gradient (steep vs. gentle) and land cover (forest vs. cropland) on the spatial pattern of soil weathering degree along slope. In four soil toposequences, soil weathering indices (Total Reserve in Bases, Chemical Index of Alteration, clay content, iron oxide content) and mineralogical assemblages were used to express genetic and morphological differences among soil profiles. Our data showed that the spatial differentiation in chemical weathering degree along slope is strongly dependent on the hillslope gradient: while the gentle slopes show negligible differences in chemical weathering degree along slope, the steep slopes show clear spatial differences. Besides, there is an interaction effect between hillslope gradient and land cover. Forest conversion to cropland enhances erosion-driven soil redistribution with a marked effect on soil rejuvenation along steep slopes but no clear effect along gentle slopes. The comparative study based on four toposequences highlights that accelerated soil erosion after conversion of forests to cropland has further enhanced lateral soil fluxes and redistribution of topsoil material along steep slopes, and led to soil rejuvenation and exposure of less weathered soil material at the eroding sites. Highlights • Spatial differentiation in weathering degree along slope is slope-dependent. • Erosion-driven differentiation in weathering degree observed for steep slopes • Anthropogenic accelerated erosion enhances rejuvenation of weathered-derived soil nutrients. [ABSTRACT FROM AUTHOR]

Abstract Land inundation is a common occurrence in Bangladesh, mainly due to the presence of two major river systems – the Brahmaputra and the Ganges. Inundation influences land use and cropping intensity. However, there is little information on the influences of the extent of flooding and cropping intensity has on soil organic carbon (SOC), particularly at the landscape level. To investigate these influences, we collected 268 surface (0–30 cm) soil samples from 4 large sites within the two alluviums deposits (the Brahmaputra river and the Ganges river), on a regular grid (1600 m). The findings show that SOC levels are generally low, reflecting the intensity of agriculture and land management practices. SOC variability was higher across the medium high land (MHL) and medium low land (MLL) sites than in the high land (HL) and low land (LL) sites. The relatively low SOC levels and variability in the HL sites indicate soils here might have reached to equilibrium levels due to higher land use intensity. Topographically higher lands (HL and MHL), due to less of inundation, had higher cropping intensities and lower SOC's than lower lands (MLL and LL), which had lower cropping intensities, as they remain inundated for longer periods of time. The findings clearly demonstrate the intrinsic influence of land inundation in driving cropping intensity, land management practices and SOC levels. Highlights • Land inundation determines cropping intensity. • Cropping intensity is higher in less inundated land than lower lands. • SOC is dependent on inundation land types and cropping intensity. • High cropping intensity sites had considerably lower levels of SOC. [ABSTRACT FROM AUTHOR]

Abstract There are many controversies about the effect of forest cover on basin streamflows. The objective of this paper was to use the Soil and Water Assessment Tool (SWAT) to provide hydrological modeling of streamflows of a Brazilian Atlantic Rainforest watershed, simulating land use change scenarios with increasing and decreasing forest cover. Regarding the afforestation scenarios, the influence of the geographic location on the afforestation was also evaluated through two approaches: a) a "random" approach (RA), in which the location of reforested areas does not matter; and b) an "imposed" approach (IA), in which the geographical positions of the afforestation are precisely defined. The RA results showed little tendency of reduction in the simulated average and minimum flows with the afforestation. The IA approach showed that the geographic position of afforestation did not significantly interfere in the average flows, but interfered in the simulated minimum flows. Afforestation concentrated in areas close to streams caused a reduction in minimum flows, while its concentration in the upper parts of the basin managed to increase them. Highlights • SWAT was used to provide hydrological modeling of Atlantic Forest watershed. • Afforestation and deforestation scenarios were simulated. • Random and imposed approaches to afforestation scenarios were evaluated. • Afforestation concentrated close to streams reduced minimum flows. • Afforestation in the upper parts of the basin managed minimum flows to increase. [ABSTRACT FROM AUTHOR]

Abstract Assessing soil quality indicators is essential for ecosystem function evaluation. This study aimed to compare soil quality indicators of semi-arid forests and rangelands with different condition classes using direct soil quality indicators and landscape function analysis (LFA). Vegetation and soil properties were studied in three forest sites with different densities and 16 rangeland sites. A total of 72 soil samples were collected from various land use/cover types and their physical and chemical properties were measured. Eleven soil quality indicators were assessed from each patch and inter-patch zone along the established transects in each land use/cover type to obtain three functional indices including soil stability, infiltration, and nutrient cycling. The accuracy of the stability and infiltration indices of the LFA was verified by their correlations with some soil quality indicators. The results revealed a similar trend in soil quality indicators among the land use/cover types indicating that soil organic carbon (SOC), particulate soil organic matters (POM), mean weight diameter (MWD), soil stability index (SSI), and macronutrients had more appropriate conditions in rangelands with good conditions and dense forest sites compared to other land uses/covers. The soils in rangelands with poor conditions and sparse forests required substantial input of organic carbon to achieve an appropriate level of soil quality. The results highlighted the importance of SOC, POM, and soil texture for the prediction of aggregate stability in the region. The regression model showed a significant relationship between MWD and SSI. Moreover, nitrogen and SOC had significant relations with nutrient cycling and the relation between water dispersible clay and infiltration index was also significant (p < 0.01). The methods used in this study underscored the importance of conserving natural ecosystems. These methods can be implemented for assessing other semi-arid ecosystems. Holistic land management is required to conserve natural and productive ecosystems and to prevent soil degradation. Highlights • Soil quality indicators were considerably affected by land use and land cover types. • Soil organic matter and texture are important for predicting aggregate stability. • Indirect LFA assessment approach was effective in soil quality assessment. • Land use and land cover type conversation influenced soil quality in natural ecosystems. [ABSTRACT FROM AUTHOR]

Abstract Land-use changes can alter soil carbon (C) contents, and in particular deforestation has been responsible for a large part of the cumulative human-induced greenhouse gas (GHG) emissions. This study aimed to determine the influence of land-use and land cover change on soil organic carbon (SOC) content, microbial biomass C (MBC) and microbial respiration (MR) in the Hyrcanian forests, north of Iran. We compared an agricultural field (AF), plantations of Alnus subcordata (AS), Acer velutinum (AV), Quercus castaneifolia (QC) and Cupressus sempervirens (CS), and a natural forest (NF). Soil samples were collected at three different depths (0–20, 20–40 and 40–60 cm). Results showed that different land covers significantly affected soil characteristics, and SOC increased by 25% and 1.11% after the conversion of NF to CS and AS plantations respectively, and decreased by 4%, 12.11% and 53% when NF was converted to QC, AV and AF respectively. In all treatments, MBC and MR were significantly higher (p < 0.05) in the 0–20 cm depth, and MR was also correlated positively with MBC and SOC. Microbial biomass was near the half in the agriculture field than in plantations and natural forest in the upper layer, but the effects of land use on microbial biomass C decreased with soil depth. However, we observed considerable amounts microbial biomass C in 40–60 cm depth. Also, results showed that topographical feature, altitude and slope, will affect SOC content. Our results indicated that forest plantation is a key measure to enhance SOC content and mitigate global CO 2 emission, especially when soils are degraded and have low soil C content. In particular, afforestation had a crucial effect on elevating SOC content in the Hyrcanian forest, but plantations of oak (QC) and maple (AV) were less effective in terms of soil C increase. Graphical abstract Unlabelled Image Highlights • SOC increased after the conversion of NF to CS and AS plantations. • SOC stock of the agricultural field was about 50% lower compared to the NF. • Half of SOC content in agriculture field is concentrated in 0–20 cm of soil. • MBC decrease with depth, but there was a considerable MBC in the 40–60 cm depth. • The effects of land use on microbial biomass C decrease with depth. [ABSTRACT FROM AUTHOR]

Abstract The expansion of agriculture in the Brazilian Cerrado biome occurs at the expense of replacing native forest with pasture and/or crops. Negative environmental impacts, such as soil degradation, have been observed during this process. We aimed to evaluate the effect of different agricultural management systems on chemical attributes and soil organic matter fractions of a Ferralsol in an area of Cerrado, in the municipality of Hidrolândia, Goiás, Brazil. The following management systems were evaluated: (a) pasture (PAST), (b) no-tillage system (NT), organic cultivation (ORG) systems with different years of cultivation (2, 6, 8, and 10 years), and (c) a conventional management system (CS). Further, an area under native Cerrado forest (NF) was selected and used as a reference for steady state. Soil cores were collected at 0.0–0.10, 0.10–0.20, and 0.20–0.40 m depths. Macronutrients, total organic C (TOC), particulate organic C (POC), humic substances, and labile-C (Lab-C) were analyzed. The land-use change effect, driven by deforestation with subsequent pasture and/or crop, was evident by principal component (PC) analysis. In the 0.0–0.10 m soil layer, PC2 showed the isolation of NF from agricultural systems, whereas PC1 exhibited similar phenomena for the 0.10–0.20 and 0.20–0.40 m layers. In all cases, the agricultural systems showed weak correlation to TOC, POC, Lab-C and base saturation, suggesting loss of soil chemical fertility compared to NF. The ORG-8 area differed from other managed systems mainly due to high pH, P content, and base saturation. Soil cation exchange capacity was highly correlated to variables associated with soil organic matter, such as TOC, POC, and Lab-C. This result demonstrates that Cerrado soils are highly dependent on soil organic C dynamics. Conversion of Cerrado into agricultural land decreases soil chemical fertility. However, agroecosystems that reduce soil tillage and increase organic inputs, such as organic cultivation and no-tillage, seem to be suitable options for agricultural activity in Brazilian Cerrado. Highlights • We examined soil nutrients and C fractions status after land-use change in Cerrado. • Decrease of soil nutrients and labile-C was greater in conventional system. • No-tillage did not recover soil nutrients status after conversion from pasture. • Organic cultivation had a greater impact on recovering of soil chemical fertility. [ABSTRACT FROM AUTHOR]

Abstract In the Sahel, wind erosion increases the vulnerability of sandy soil through the removal of the finest and most fertile fraction of the soil, including nutrients, potentially limiting vegetation development. To provide experimental evidence of the role of different land uses on wind erosion, measurements of horizontal sand fluxes and associated meteorological parameters were taken for four years in Kilakina (southeast of Niger), where large rangeland surfaces coexist with cultivated surfaces and moving dunes in a typical Sahelian semiarid regime (average annual precipitation in the order of ±300 mm yr−1). The horizontal sand fluxes were monitored using BSNE sediment traps on the three sandy surfaces representative of the main land uses in the region: a cultivated field, a pastured land and a mobile dune. In addition, a meteorological station was installed to monitor the wind speed and direction and rainfall. Saltation flux on the bare mobile dune appeared to be an excellent proxy for wind erosivity in this region. The mobile dune produced saltation fluxes 2 to 40 times higher than the cultivated field and the rangeland. The annual fluxes on the dune varied from 2000 to 6000 kg m−1 due to the variability of the winds from year to year. The sediment fluxes are higher in the millet field than those on the pastured land due to a larger fraction of bare surface compared to the relatively homogeneous grass cover that exists on pastured surfaces. The vegetation produced in a given year affects the wind erosion of the following year through the effect of dry vegetation and litter cover. These results highlight the sensitivity of wind erosion to dry vegetation, even for low cover rates. This outcome suggests that any agricultural practice that decreases dry vegetation cover, such as the uptake of vegetation residues from the fields and the pastured land, has a strong impact on wind erosion. Wind erosion in East Niger can be higher during the Harmattan season than during the monsoon season, while similar measurements in West Niger showed that saltation fluxes were higher during the monsoon season. This outcome suggests that the intensity of the Harmattan surface winds could decrease from east to west. In addition to land use changes, the regional pattern of the surface winds and its future evolution clearly deserve further investigation based on relevant long-term in situ measurements. Highlights • For 300 mm annual rainfall in Niger, saltation is observed whatever the land uses. • Saltation fluxes measurements on mobile dune are good proxy of the wind erosivity. • Saltation fluxes in Harmattan and monsoon seasons are comparable on mobile dune. • Saltation flux on dune is 2 to 40 times higher than on the field and the pasture. • Saltation fluxes on rangeland are much lower than on the cultivated fields. [ABSTRACT FROM AUTHOR]

Abstract Slash and burn cultivation (jhum), a major form of traditional agriculture in the hills of north eastern Himalaya has now slowly shifted towards more stable forms of land use. This land use change in the region may have direct effect on soil quality which is an important concern for sustainable land use system. Our aim was to elucidate the impact of different land use from jhum cultivation on soil biological and biochemical properties. We have assessed the impact of such changes by comparing current jhum with replacement by plantations and forests for lengths of time varying from 15 to 30 years. The conversion to plantations (teak, arecanut and rubber) and secondary forests significantly increased the soil's water holding capacity (WHC) and soil organic carbon (SOC) contents. The SOC accumulation improved the moisture storage and increased soil microbiological processes such as microbial biomass C and N (MBC and MBN), percent of MBC to SOC, basal respiration and soil enzymes (acid and alkaline phosphatase, arylsulphatase, β–glucosidase, dehydrogenase and urease). The substrate use efficiency (metabolic quotient: q CO 2) under jhum (J) was 21.5%, 25.8%, 27.8%, 39.9% higher than secondary forest (F), arecanut (A), rubber (R) and teak (T) respectively in the surface soil layer (0–15 cm) indicating microbial stress due to recent disturbances. The soil quality as defined by the geometric mean (G) over the soil depths followed the order F > R > A > T > J. Principal component analysis (PCA) was useful in discriminating the importance of soil microbiological and biochemical properties for land use change. In conclusion, land use change from jhum to forest and plantations (rubber and arecanut) conserved and improved soil quality. Highlights • SOC and WHC increased from jhum to rubber, arecanut and forest. • MBC and MBN were higher under forest, rubber and arecanut than teak and jhum. • The q CO 2 was highest under jhum for the surface soil layer. • PCA analysis was helpful in determining the higher soil quality under forest, rubber and arecanut than teak and jhum land use. [ABSTRACT FROM AUTHOR]

Abstract Increasing land developments, unreasonable utilization of land, earthquakes, typhoons, and torrential rain often cause hillside disasters. Soil depth is a crucial parameter influencing the scale of shallow landslides and sustainable land use in hillside areas. This paper presents a statistical model, integrated with environmental factors, for estimating soil depth in a catchment area with complex topography. The study area selected was upstream of the Houlong River in Taiwan. The model was developed using multinomial logistic regression and environmental factors such as hill slope, hill aspect, elevation, topographical curvature, and the normalized difference vegetation index. The results were then compared with those obtained from previous models applying Ordinary Kriging, Regression Kriging, and topographical wetness index methods. A classification error matrix and the Kappa index were then employed to assess the various models. The results showed that, for the data set used for model establishment, the overall accuracy and Kappa index were 76.6% and 0.65, respectively, whereas for the data set used for verification, they were 70.5% and 0.57, respectively. By contrast, the Ordinary Kriging method yielded an overall accuracy and a Kappa index of 45.7% and 0.15, respectively; the Regression Kriging method yielded results of 46.7% and 0.16, respectively; and the topographical wetness index method yielded results of 30.5% and −0.05, respectively. The proposed model was therefore determined to be superior to the others in terms of soil depth estimation accuracy. The proposed model can predict soil depth on a regional scale and serve as a reliable tool that provides reference data for future research on land use and shallow landslides. Graphical abstract Unlabelled Image Highlights • Soil depth was modelled in a regional scale with complex topography. • Predictive performance of four statistical techniques was compared. • Multinomial logistic regression proved in soil depth estimation. • Soil depth conditioned by the topographical and geomorphological characteristics. [ABSTRACT FROM AUTHOR]

Abstract Nitrate dependent Fe-oxidizing bacteria (NFeOB) are important to study soil C and N cycle. Although several studies have isolated and identified NFeOB communities in different environments, their diversity in paddy soils and forest soils is still not well studied. Four different soils (rice-fallow rotation and forest soil, from Qianjiang, referred as QR and QF soil, respectively, and rice-fallow rotation and forest soil, from Xianning, referred as XR and XF soil, respectively) were used to study NFeOB diversity. The anaerobic enrichment incubations were conducted three times. The dominant groups of four soils among NFeOB were Proteobacteria , Firmicutes , Actinobacteria and Bacteroidetes. At the genus level, the compositions of the NFeOB communities in four soils were Bacillus , Magnetospirillum , Clostridium , Massilia , Paucimonas , Cellulomonas and Kluyvera. The diversity of NFeOB communities was highly influenced by land use and soil properties, such as pH, parent material, SOM, CEC and Fe. The results demonstrated that NFeOB are key mediators in C and N cycling under anaerobic environments. Highlights • NFeOB are important to study soil C and N cycle. • NFeOB are widely distributed among several subtropical soils of China. • The diversity of NFeOB communities was highly influenced by land use and soil properties. • NFeOB are key mediators in C and N cycling under anaerobic environments. [ABSTRACT FROM AUTHOR]

Abstract Development and protection are both vital human demands in ecologically vulnerable areas. An estimation of the land use/cover changes and their ecological responses could help to understand the regional ecosystem dynamics under various human demands and provide the scientific basis for managing and regulating ecosystems. In this paper, we analysed the spatial-temporal variations in land use/cover types and systematically quantified the relationships between these changes and environmental variables in the Three Gorges Reservoir area. Our results revealed that forestland coverage increased linearly to 53.48%, and that of construction land increased exponentially from 0.25% to 2.75% during 1990–2015. The land use/cover changes exhibited two distinct transformation phases: before and after impoundment. The mutual transformations among vegetation types were significant before 2000, while the forest, water and construction land coverages increased continuously by occupying cropland after 2000. The land use/cover changes were significantly correlated with environmental variables and were sensitive to three topographic variables namely, elevation, surface-height-fluctuation and slope. The vegetation dynamics were easily affected by the complex and rugged topography. Moreover, the responses of land use/cover changes varied among topographic variables. The two parameters estimated in the multiple linear regression, elevation and slope, were −0.164 and −0.268 for forestland change, −0.391 and 0.378 for water area change, and −0.068 and −0.061 for construction land change. Forest cover was so larger in the regions of higher elevation and steeper slope that afforestation occurred in the regions of moderate elevation and slope. Urbanization and impoundment mainly occurred in the regions of lower elevation, and the regions of steeper slope were more easily submerged, while urbanization mainly occurred in the regions of gentler slope. Therefore, the land use/cover changes due to ecological protection and economic development responded to the interactions among environmental variables and was targeted to different regions to reconcile the land use conflicts, providing a reference for ecosystem management in ecologically vulnerable areas. Highlights • Land use/cover exhibited two transformation phases before and after impoundment in the study area. • Land use/cover changes were affected by environmental variables, especially topography. • Forest restoration and urbanization occurred in different regions and periods to reconcile the land use conflicts. [ABSTRACT FROM AUTHOR]

Abstract Soil carbon (C), nitrogen (N), and phosphorus (P) are some of the most important indicators of soil quality, especially in fragile ecological environments with shallow soils. However, the differences in their variations and influencing factors related to scale in karst areas remain unclear. Therefore, variations in surface soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) distributions and their determinant factors were quantitatively analyzed at different scales (i.e., region, sub-region, and catchment) in a typical karst area, southwest China. Overall, both soil nutrient variations and the determinant factors involved varied with scale. The coefficients of variation for SOC, TN, and TP increased significantly from catchment to sub-region scales but changed only slightly between sub-region and region scales. At region and sub-region scales, lithology only affected TP significantly, while land use affected all soil nutrients significantly. However, the explanations for TP variation by lithology and for SOC, TN, and TP variations by land use increased by 12.2, 7.0, 11.0, and 12.8% at sub-region scale over the values observed at region scale, respectively. When lithology and land use were controlled, soil depth was observed playing an important role in soil nutrients at the three studied scales. At region and sub-region scales, other factors related to soil texture (clay, silt, or sand content), topography (elevation or TWI), and climate (MAT or MAP) were selected as significant variables and accounted for a larger proportion of nutrient variation. However, at catchment scale, bare rock rate and micro-topography (e.g., slope) explained soil nutrient variation to a larger proportion. Therefore, elucidation of the role of factors influencing soil nutrients at different scales can provide a guide for soil quality assessment in karst areas. Highlights • Both soil nutrient variation and its determinant factors varied with scale. • Lithology explained 12.2% more of TP variation at sub-region than at region scale. • Land use explained soil nutrient variation best at the sub-region scale. • Bare rock rate affected cropland soil nutrients significantly at the three scales. [ABSTRACT FROM AUTHOR]

Abstract Regime analysis suggests that temperate alluvial watercourses overtop their banks on average once every 1.5 years transferring water and sediment across the valley floor to form floodplains helping maintain a strong hydrological connection between in-channel and overbank form and process. Flooding also causes erosion, sediment transfer and deposition creating a variety of floodplain morphologic units and functional connectivity with the main river. The result is a morphologically and ecologically varied wetland dominated ecotone where diversity is sustained by the action and flooding and shallow groundwater processes. Floodplains are, however, sensitive to disruption and many have been significantly degraded since the Bronze Age as a result of activities that alter flooding and groundwater processes and manage vegetation communities. The current (2015) floodplain condition and trends of change since 1990, for England are presented here using land use data for 1990, 2000, 2007 and 2015. Floodplain system degradation has been found to be both widespread and severe across the whole of the country. The 1990 data set showed that intensive agriculture occupied around 38% of floodplain zones expanding to 53% by 2000 before slowing slightly to covering 62% in 2007. Between 2007 and 2015 the coverage remained relatively static (64%) with some suggestion that arable areas were being transformed to pasture. Wetland areas in the form of fen, marsh, swamp and bog have been devastated with the data sets indicating that these fundamental floodplain units have been all but lost. Upland and lowland areas are both severely impacted with a near ubiquitous loss of natural floodplain functioning. Despite this some 31% of rivers in England are classified as good or better under the European Water Framework Directive classification system calling into question the UK WFD status classification process. Highlights • Floodplain condition and trends of change since 1990 • Changing impact of practices on English floodplain character using land use data • Floodplain system degradation found to be widespread and severe across the country. • Wetland areas devastated with these fundamental floodplains units all but lost. [ABSTRACT FROM AUTHOR]

Abstract In the context of the circular economy, the use of animal excrements as fertilizers is encouraged, but the addition of such organic materials can develop soil water repellency (SWR) or hydrophobicity. There is a lack of consensus about how to assess SWR in agricultural soils. This work evaluated SWR when pig slurries were applied onto soil using the two most common testing methods: the water drop penetration time (WDPT) and the molarity of ethanol droplet (MED) tests. The experiment consisted of five different slurry treatments plus a control (no slurry added). At sowing, slurry from fattening pigs (SF) or no slurry application was combined with a second application at the cereal tillering stage, in which SF, slurry from sows (SS) or no-slurry were the treatments. Soil water repellency was tested at cereal tillering before slurry application and then during the following 47 days. At each sampling date, hydrophobicity was tested in undisturbed samples at field-moist and after 25 °C, 65 °C, and 105 °C oven drying. Disturbed samples were tested after 40 °C oven drying. Soil disturbance removed SWR. Under field conditions, undisturbed samples attained the maximum SWR expression 7d from pig slurry application; moderate and very severe scores using WDPT and MED were respectively attained. From 14d to the end of the experiment, the highest SWR was observed after 105 °C oven drying and when SF applications at sowing (900 kg TOC ha−1) had been combined with SS applications at cereal tillering (1894 kg TOC ha−1). Slurry hydrophobic compounds rather than slurry dry matter influenced SWR expression which is enhanced as the soil dries. The persistence of repellency (WDPT test) was more sensitive to detecting changes in SWR between treatments than the changes in its severity (MED test). The importance of the SWR described hereafter slurry application will depend on plant cover over the soil and the effects in slaking prevention in order to avoid superficial water runoff. Highlights • Pig slurry develops transitory soil water repellency (SWR) lasting for 47 days. • The strongest SWR is recorded seven days after pig slurry addition. • Hydrophobic compounds in solid and liquid slurry fractions explain SWR persistence. • Soil sample management and moisture content influenced SWR expression. [ABSTRACT FROM AUTHOR]

Abstract Soil respiration is a biological process in microbes that convert organic carbon to atmospheric CO 2. This process is considered to be one of the largest global carbon fluxes and is affected by different physicochemical and biological properties of soil, land use, vegetation types and climate patterns. Soil respiration recently received much attention, and it could be measured in two states basal respiration (BR) and substrate induced respiration (SIR) which together gives a good representation of the general soil microbial activity. The aim of this study was to estimate the BR and SIR of 150 data points obtained from soil samples collected from the surface to 20 cm of depth under different land use categories using the Artificial Neural Network (ANN) and Linear Regression Methodology (LRM). This study is bringing data from an arid area, and there is little information on this issue. Soil samples were chosen from three provinces of Iran, with humid subtropical and semi-arid climate patterns. In each soil sample a variety of characteristics were measured: soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon (OC), OC fractionation data e.g. light fraction OC (LOC), heavy fraction OC (HOC), cold water extractable OC (COC) and warm water extractable OC (WOC), population of fungi, bacteria, actinomycete, BR and SIR. Our goal was to use the most efficient ANN-model to predict soil respiration with simple soil data and annual precipitation (AP) and mean annual temperature (MAT) and compare it with LRM. Our results indicated that for an ANN model containing all the measured soil parameters (14 variables), the R2 and RMSE values for BR prediction were 0.64 and 0.05 while these statistical indicators for SIR obtained 0.58 and 0.15, respectively; whereas the addition of AP and MAT data to this model (16 variables) caused a decrease in statistical indicators. When the R2 and RMSE values of the BR-ANN and SIR-ANN predicted using an ANN model with only 7 variables (including OC, pH, EC, CCE and soil texture) they were estimated to be 0.66, 0.043 and 0.52, 0.16, respectively. Overall, LRM in comparison to ANN had a lower R2. Therefore, the results show that ANN modeling is a reliable method for predicting soil respiration, even when based on easy to measure data. Our results revealed that highest and lowest BR and SIR were recorded in rice paddy soils and saline lands, respectively. In total, soil respiration (BR: 0.09 vs 0.06 and SIR: 0.46 vs 0.32 mg CO 2 g−1 day−1) was higher in agricultural land compared to natural covered land. Highlights • Significant relationships exist between soil physicochemical/biological parameters and BR/SIR. • ANN models can predict soil respiration using easy to measure soil properties. • Soil properties (soil texture, soil salinity, soil acidity, TOC, CCE) can predict soil respiration. • ANN models are an alternative for measuring soil respiration. • ANN models can predict soil respiration over large areas [ABSTRACT FROM AUTHOR]