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[Objective] The aims of this study are to investigate the soil infiltration patterns under different land uses in karst trough valley and to propose a suitable soil infiltration model for karst trough valley. [Methods] Four typical land uses (forest, grassland, cropland and orchard) in the karst trough valley were taken as the research objects to determine the differences in soil infiltration characteristics and influencing factors as affected by different land uses, and to evaluate the adaptability of three common infiltration models: Horton, Kostiakov and Philip, the in this area. [Results] (1) Soil bulk density, water content and electrical conductivity were markedly different among different land uses (p＜0.05). Soil bulk density (1.1 g/cm³), water content (26.9%) and electrical conductivity (75.43 mS/cm) in cropland were lower than those in other land uses. Soil bulk density (1.32 g/cm³) in orchard, water content in forest (35.02%) and electrical conductivity in grassland (164.6 mS/cm) were higher than those in other land uses, respectively. (2) The infiltration process of different land use types showed rapid decline, slow decline and stabilization. (3) There were differences in the fitting results of Horton model, Kostiakov model and Philip model for different land use modes in karst trough valley. Horton model had the best results, with the fit R² reaching 0.922～0.951, and Philip model had the worst results, with the fit R² ranging from 0.754 to 0.908. (4) The pH value was highly significantly positively correlated with initial infiltration rate and average infiltration rate (p＜0.01) and significantly positively correlated with stable infiltration rate (p＜0.05); 0.05～0.25 mm and ＜0.05 mm fractions of micro-aggregates were significantly positively and negatively correlated with stable infiltration rate and average infiltration rate, respectively (p＜0.05). The multiple linear regression model showed that soil bulk density, water content and ＜0.05 mm fraction of micro-aggregates were the main factors influencing infiltration rate, which had an inhibitory effect on infiltration. [Conclusion] Cropland has better infiltration performance among different land uses, and the Horton model is more suitable for modeling soil infiltration in karstic troughs and valleys. The results of the study can provide a scientific basis for the assessment of soil infiltration performance and vegetation allocation in karst trough valley areas. [ABSTRACT FROM AUTHOR]

Comprehending the impacts of land-use type on soil nutrition and stoichiometry in watersheds is crucial for effective regional ecosystem management. However, a deeper understanding of the influence of land-use type on soil stoichiometry in karst agricultural watersheds is still lacking. Here, we analyzed the contents, stoichiometries, and drivers of topsoil C, N, and P in a karst agricultural watershed in China, focusing on six land-use types: paddy fields, dry farmland, tussock land, shrubland, shrubby tussock land, and woodland. We found that woodland exhibited significantly higher soil organic carbon (SOC) content than other land-use types except shrubland. Moreover, woodland exhibited the highest total nitrogen (TN) and total phosphorus (TP) contents compared with other land-use types. C/N and N/P ratios did not vary significantly with land-use type, whereas dry farmland (18.68) showed a significantly lower C/P ratio than woodland (39), shrubland (39.92), and paddy fields (34.87). In addition, our results revealed that soil pH, catalase and invertase activity, and bacterial and actinomycetes abundance significantly influenced C, N, and P content and stoichiometry. These findings reveal that interactions between multiple biotic and abiotic factors drive variability in soil stoichiometry, offering valuable insight for land improvement and ecological management in karst agricultural watersheds. [ABSTRACT FROM AUTHOR]

There are various types of land use in the agricultural and pastoral areas of northern China, including natural grassland and artificial grassland, scrub land, forest land and farmland, may change the soil microbial community However, the soil microbial communities in these different land use types remain poorly understood. In this study, we compared soil microbial communities in these five land use types within the agro-pastoral ecotone of northern China. Our results showed that land use has had a considerable impact on soil bacterial and fungal community structures. Bacterial diversity was highest in shrubland and lowest in natural grassland; fungal diversity was highest in woodland. Microbial network structural complexity also differed significantly among land use types. The lower complexity of artificial grassland and farmland may be a result of the high intensity of anthropogenic activities in these two land-use types, while the higher structural complexity of the shrubland and woodland networks characterised by low-intensity management may be a result of low anthropogenic disturbance. Correlation analysis of soil properties (e.g., soil physicochemical properties, soil nutrients, and microbiomass carbon and nitrogen levels) and soil microbial communities demonstrated that although microbial taxa were correlated to some extent with soil environmental factors, these factors did not sufficiently explain the microbial community differences among land use types. Understanding variability among soil microbial communities within agropastoral areas of northern China is critical for determining the most effective land management strategies and conserving microbial diversity at the regional level. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibet Plateau, located at the Third Pole and known as the "Asian water tower," serves as a crucial ecological barrier for China. Grasping the soil quality on the Qinghai-Tibet Plateau holds paramount importance for the rational and scientific exploitation of soil resources within the region and is essential for vegetation restoration and ecological reconstruction. This study, conducted in Maqin County, Qinghai Province, collected 1647 soil samples (0–20 cm) within a study area of 6300 km2. Sixteen soil indicators were selected that were split into beneficial (N, P, S, and B), harmful (Cr, Hg, As, Pb, Ni, and Cd), and essential (Cu, Zn, Se, Ga, K, and Ca) elements. The Soil Quality Index (SQI) was computed to assess soil quality across diverse geological contexts, land cover classifications, and soil profiles. The results indicate that the overall SQI in the study area was comparatively high, with most regions having an SQI between 0.4 and 0.6, categorized as moderately to highly satisfactory. Among the different geological backgrounds, the highest SQI was found in the Quaternary alluvium (0.555) and the lowest in the Precambrian Jinshuikou Formation (0.481). Regarding different land-use types, the highest SQI was observed in glacier- and snow-covered areas (0.582) and the lowest in other types of grassland (0.461). The highest SQI was recorded in typical alpine meadow soil (0.521) and the lowest in leached brown soil (0.460). The evaluation results have significant reference value for the sustainable utilization and management of soil in Maqin County, Qinghai Province, China. [ABSTRACT FROM AUTHOR]

Using land use type data from four periods of 1990, 2000, 2010 and 2020 in the Bijie experimental area, the changes of different land use types in the experimental area over the past 30 years were studied. The InVEST model was used to estimate the carbon storage of different ecosystems in the experimental area, and the temporal and spatial changes of ecosystem carbon storage under the background of significant success in ecological construction were analyzed. The results showed that from 1990 to 2020, there were significant changes in land use types in the Bijie City, with an increase in the area of forest land and construction land, a decrease in the area of cultivated land and grassland, and the main conversion of cultivated land to forest land, grassland and construction land, while the main conversion of grassland to cultivated land and forest land. The total carbon storage of the ecosystem in Bijie City from 1990 to 2020 was 51.21×107-52.37×107t, the total carbon storage increased by 1.16×107t, with an average annual increase of 0. 04×107t. The carbon storage in Bijie City showed a spatial distribution trend of high in the west and low in the east. From 1990 to 2020, the carbon storage of forest land and construction land increased, while the carbon storage of cultivated land and grassland decreased. [ABSTRACT FROM AUTHOR]

Climate is one of the key factors driving changes in vegetation, and the response of the vegetation to climate often occurs with a time delay. However, research on the cumulative lagged response of the vegetation to meteorological factors in large-scale regions is limited. Therefore, this study first evaluated the performance of the Gross Primary Productivity (GPP) products provided by Moderate Resolution Imaging Spectroradiometer (MODIS) and Penman–Monteith–Leuning (PML) over the past 20 years in China and then determined the lagged relationships between the GPP and major meteorological factors in different regions and land-use types in China based on a partial correlation analysis. The results indicate that (1) GPP_PML outperforms GPP_MODIS products in the regional context of China; (2) China's regional GPP has shown a fluctuating upward trend over the past 20 years, with a stepwise increase in the multi-year average from the northwest inland to the southeast coastal regions, and a higher contribution from the southern regions than the northern ones; (3) unlike the recent upward trend in regional temperatures, both precipitation and radiation have decreased, with these two factors showing completely opposite multi-year trends in most regions; and (4) the proportion of regions with lagged effects of the GPP on meteorological factors is higher than those with cumulative effects in China. Among these, GPP exhibits a higher proportion of a 3-month lagged response to precipitation, which is particularly pronounced at altitudes between 500 and 2500 m and above 5500 m. the proportion of the areas with no lag cumulative response to temperature and radiation with GPP in China is the highest due to the influence of more barren land and grassland in the northwest interior. Simultaneously, grassland and barren land have a higher proportion of the non-lagged cumulative responses to temperature and precipitation. This study contributes to our understanding of vegetation dynamics in the context of global climate change and provides a theoretical foundation for regional ecological conservation and high-quality coordinated development. [ABSTRACT FROM AUTHOR]

Deep soil moisture is one of the primary factors restricting vegetation growth on the Loess Plateau (LP) of China. Investigating the spatial variations and influencing factors of shallow and deep soil moisture is of great significance for ecological restoration on the LP. In this study, we sampled disturbed soil up to a depth of 10 m with a soil drill. A 200 × 200 m grid was superimposed on a digital topographic map, and 78 sampling sites were selected across the Zhifanggou (ZFG) watershed. According to the results, the vertical profile of soil could be subdivided into four layers: the shallow active layer (SAL; 0–0.5 m), the shallow rainfall recharge layer (SRL; 0.5–2.2 m), the deep excessive layer (DEL; 2.2–4 m), and the deep stable layer (DSL; 4–10 m). The horizontal distribution characteristics of soil moisture in various soil layers were similar, with a generally high concentration in the south and a low concentration in the north. In addition, a relatively low soil moisture content (SMC) occurred in the center of the SRL. Soil moisture was negatively correlated with slope and slope aspect between 0 and 2.2 m (p < 0.05), whereas slope and slope aspect had no significant effects on deep soil moisture (>2.2 m). The SMCs of the four soil layers, from lowest to highest, were as follows: forestland, shrubland, and grassland. The SMC of forestland was negatively correlated with restoration age, whereas the SMC of grassland was positively correlated with restoration age. This study deepens our understanding of shallow and deep soil moisture distribution characteristics and the corresponding ecological restoration on the LP and provides a reference for the rational use of deep soil moisture. [ABSTRACT FROM AUTHOR]

Study region: The Dongzhi tableland on the loess plateau, China. Study focus: This study investigates how various land use types on the Loess Plateau affect groundwater recharge using the chloride mass balance method (CMB). By integrating data from Cl–, NO3/Cl–, and stable isotopes (δ18O and δ2H), the research develops a new approach to estimate the average ion concentration rates in soil profiles. This methodology provides a nuanced understanding of how precipitation infiltration recharges groundwater under different land use scenarios and the impact of land use changes on these processes. New hydrological insights for the region: The research findings highlight significant variations in groundwater recharge rates among different land uses. Grasslands show the highest recharge rate at 26 mm/yr, followed by forests at 23 mm/yr, while shrublands have the lowest at 5 mm/yr. Agricultural lands have moderate recharge rates ranging from 14 to 16 mm/yr. Transitioning from agricultural land to other land uses like shrublands and forests results in dramatic changes in recharge rates, with decreases and increases in recharge of 72% and 61%, respectively. These insights are crucial for developing strategic land-use planning to optimize groundwater recharge and enhance water security on the Loess Plateau. The study emphasizes the need for policies that balance hydrological science and land management to sustain both human livelihoods and ecological continuity.

The advance of deforestation impacts freshwater ecosystems and, consequently, the environmental heterogeneity and associated biodiversity. Our objective was to examine the effect of deforestation on environmental heterogeneity (EH), species richness (SR), and functional richness (FRic) and the role of EH in the abundance of species and functional groups of stream fish. We analyzed 71 streams of the Acará-Capim basin, eastern Amazon. We used path analysis to assess whether land-use types influence the predominant vegetation cover and channel characteristics, and their indirect effect on EH, SR, and FRic. Taxa indicator threshold analysis was used to assess whether fish species and functional groups act as bioindicators of EH and percentage of forest in total catchment (PFTC). The higher percentage of secondary forest in total catchment (PSFTC) favored herbaceous understory plants and SR. The largest amount of sediments and higher PSFTC negatively influenced EH. FRic was not influenced by any of the variables. Species with high swimming ability that belong to the trophic guilds piscivores and invertivores, are associated with high values of EH and PFTC. Our results may be useful for riparian forest restoration projects, as we show which variables increase or decrease EH and demonstrate how bioindicators respond to this. [ABSTRACT FROM AUTHOR]

Comprehending the impacts of land-use type on soil nutrition and stoichiometry in watersheds is crucial for effective regional ecosystem management. However, a deeper understanding of the influence of land-use type on soil stoichiometry in karst agricultural watersheds is still lacking. Here, we analyzed the contents, stoichiometries, and drivers of topsoil C, N, and P in a karst agricultural watershed in China, focusing on six land-use types: paddy fields, dry farmland, tussock land, shrubland, shrubby tussock land, and woodland. We found that woodland exhibited significantly higher soil organic carbon (SOC) content than other land-use types except shrubland. Moreover, woodland exhibited the highest total nitrogen (TN) and total phosphorus (TP) contents compared with other land-use types. C/N and N/P ratios did not vary significantly with land-use type, whereas dry farmland (18.68) showed a significantly lower C/P ratio than woodland (39), shrubland (39.92), and paddy fields (34.87). In addition, our results revealed that soil pH, catalase and invertase activity, and bacterial and actinomycetes abundance significantly influenced C, N, and P content and stoichiometry. These findings reveal that interactions between multiple biotic and abiotic factors drive variability in soil stoichiometry, offering valuable insight for land improvement and ecological management in karst agricultural watersheds.

In arid mountainous areas with stony soils in the Eastern Tibetan Plateau, intensively managed orchards (which include the need for plowing, irrigation, and soil stone removal), eco-forests, and grasslands, all converted from croplands, are becoming increasingly popular. We randomly collected soil samples at 0–15, 15–30, 30–45, and 45–60 cm depths from the four land-use types on the northern and southern slopes in the region. Differences in soil organic carbon (SOC) content/stock, soil water content (SWC), and rock fragment content (RFC) in land-use types and slopes were analyzed using two-way ANOVA. The factors' contributions to SOC variation were assessed using mixed-effect models. Results showed the following: (1) In topsoil (0–30 cm), SOC contents followed the order eco-forest > orchard > grassland ≈ cropland; in subsoil (30–60 cm), the order was orchard > eco-forest > cropland ≈ grassland. SOC stocks (0–60 cm) were higher in orchards (93.72 Mg ha−1) and eco-forests (92.44 Mg ha−1) than in grasslands (53.65 Mg ha−1) and croplands (53.05 Mg ha−1). Contributions of SOC stocks at the 0–15 cm depth level to total SOC were above 40% for GL and EF and between 27 and 35% for OL and CL; at the 45–60 cm level, OL contributed 16–20% and was higher than 10–15% for the other land-use types. (2) Eco-forests and grasslands showed increased SOC contents/stocks at all soil layers on the northern slope than on the southern one. Orchards and croplands, however, showed no differences in contents between slopes. (3) Land-use types, TN, SWC, RFC, slope aspect, and management practices significantly affected SOC variation. Our results suggest that forest plantations (orchards and eco-forests) in arid mountainous regions, through active management practices (e.g., irrigation and fertilization), are vital for improving soil carbon sinks and achieving peak carbon/carbon neutrality goals. [ABSTRACT FROM AUTHOR]

Tidal flats in eastern China have undergone various transformations into other land-use types. Understanding the impact of land-use conversion on soil properties and microbial communities is crucial for effective ecological conservation efforts. In this study, we compared soil chemical properties and the diversity, composition, and ecological functions of soil bacterial and fungal communities across four land-use types: natural bare land (BL), unused reclaimed tidal land (Phragmites, PL), agricultural land (maize, ML), and shelterbelt land (SL), utilizing next-generation sequencing technology. The results indicated that soil electrical conductivity decreased, while soil organic carbon (SOC) and nutrient contents increased in ML and SL compared to BL and PL. The bacterial Chao1 and fungal Chao1 and Shannon values vary across different land-use types. A higher relative abundance of Acidobacteriota, specifically RB41, was found in ML compared to BL. Principal coordinate and PerMANOVA analysis showed that the composition of bacterial and fungal communities differed significantly across the four land-use types. SOC explained the most variance in both bacterial and fungal communities. Carbon-related functional genes and fungal guilds exhibit greater diversity across the four land-use types compared to nitrogen-related functional genes. In conclusion, the transformation of natural land-use types to managed one greatly altered soil chemical and microbial properties. Our study offers foundational insights into the microbial communities in the typical land-use types of Eastern China's coastal area. Future studies should emphasize the quantification of human interventions and their impact on soil microbial communities and ecological functions. [ABSTRACT FROM AUTHOR]

The urban public transport network is closely related to urban construction and is susceptible to external influences, especially the bus network (BN). The measurement of the changes in the performance of BN under disruptions plays an important role in the development of bus systems. This paper takes the land-use type around each bus stop to modify the standard coverage range and then combines the attractive service area of the stop and the passenger flow as the opportunity coefficient to propose an improved accessibility model. Finally, the vulnerability of the BN based on the improved accessibility model in different time periods under four disruptions is analyzed. Taking BN in the central area of Xi'an as a case study, the results show that the BN is less vulnerable when stops are associated with high land-use type attractiveness, and regions with a single land-use type have high vulnerability levels. In addition, the land-use disruption causes larger-scale network vulnerability than topological disruptions. An interesting result, opposed to common sense, is found in stops within the top 10% of topological disruption failure probabilities, i.e., the BN is the most vulnerable during the off-peak night period. This study supplements the coordinated development of public transport and land use in future planning. [ABSTRACT FROM AUTHOR]

Dashan Village area is one of the representative areas in China with high selenium concentration in the natural environment. A total of 133 topsoil samples have been collected in the Dashan Village area to explore the potential toxic elements (PTEs) background concentrations in soils under different land-use types for a comprehensive PTEs risk assessment (arsenic, cadmium, chromium, copper, mercury, nickel, lead, selenium and zinc). The results show that the geometric mean concentrations of As, Cr, Cu, Hg, Ni, Pb, Se and Zn found in the soil of the Dashan Village area were lower than the control standard for soil contamination risk in agricultural land. However, the geometric mean concentrations of Cd exceeded their corresponding standard values. For different land-use types, geometric mean concentrations of As, Cd, Cu, Hg, Ni and Pb in the arable soils were higher than in woodland soils and tea garden soils. Based on the potential ecological risk assessment, the woodland, arable and tea garden were at low-risk levels. Cadmium posed the highest ecological risk, while the other PTEs were of low risk in soils. Multiple statistical analyses and geostatistical analysis indicated that the concentrations of Cr, Ni, Pb, Cu, Zn and Se originated mainly from natural sources, while the concentrations of Cd, As and Hg could be influenced by anthropogenic activities. These results provide scientific support for the safe utilization and ecological sustainability of selenium-rich land resources. [ABSTRACT FROM AUTHOR]

Urban soil organic carbon (SOC) plays an important role in urban ecosystem services. Rapid urbanization and anthropogenic disturbances have created complex and dynamic land-use patterns and heterogeneous urban landscapes, however, the impact of these patterns on the spatial distribution of soil organic carbon density (DSOC) remains unclear. This study investigated SOC using a spatial sampling method from 213 sites in Xi'an City Ring Expressway, China. The results showed that the DSOC ranged from 1.79 to 4.93 kg m−2, with a mean of 3.31 kg m−2, and the value of Dsoc was decreased from city center toward suburb with a significant spatial heterogeneity. The DSOC varied with land-use types, being higher in parks, transportation, commercial, and public lands than in industrial, agricultural, parking, and construction lands. The Dsoc was positively related to population density, normalized difference impervious surface index, road density, and landscape shape index, while negatively to aggregation index and patch richness density. Overall, the urbanization of Xi'an City has strongly affected the soil C stocks, and the capacity of urban soils to store C was sustainable. These findings lays a scientific foundation for future soil carbon management in urban development. [ABSTRACT FROM AUTHOR]

Knowledge of soil properties such as texture, bulk density, organic matter, soil reaction, soil electrical conductivity, and soil erodibility factor is fundamental to the sustainable management of soil resources. This study aimed to determine the changes in certain soil properties including texture, bulk density, organic matter, pH, electrical conductivity, and soil erodibility factor with different land uses, elevation zones and soil depths in the Arhavi Sub-basin, Artvin, Turkiye. For these purposes, a total of 618 soil samples (309 disturbed and 309 undisturbed) were taken from 155 sampling points located in areas with different land uses, including tea (33 sampling points), hazelnut (33 sampling points), forest (67 sampling points), and grassland (22 sampling points). The results of the statistical analysis revealed that the soils at depths of 0–15 cm and 15–30 cm showed significant differences according to the land use in terms of sand, clay, silt, bulk density, organic matter, and pH. There were significant positive correlations between elevation and soil bulk density (r = 0.495) at a soil depth of 0–15 cm in the tea areas. In the grassland areas, there were significant positive correlations between elevation and silt, bulk density, and the soil erodibility factor (r = 0.485, r = 0.794, and r = 0.442, respectively) at depths of 0–15 cm, and significant positive correlations between elevation and both silt and bulk density (r = 0.468 and r = 0.691, respectively) at depths of 15–30 cm. Similarly, there were significant positive correlations between elevation and both sand and organic matter at soil depths of 0–15 cm and 15–30 cm (sand: r = 0.351 and r = 0.638, respectively; organic matter: r = 0.277 and r = 0.587, respectively). On the other hand, significant negative correlations were found between elevation and silt, bulk density, pH, and the soil erodibility factor at depths of 0–15 cm and 15–30 cm (silt: r = −0.400 and r = −0.461, respectively; bulk density: r = −0.593 and r = −0.545, respectively; pH: r = −0.354 and r = −0.309, respectively; soil erodibility factor: r = −0.443 and r = −520, respectively). Soil acidity was found to be the most important problem threatening soil fertility in all land uses. The use of soil acidity-increasing fertilizers, such as ammonium sulfate, in tea gardens in the region should be eliminated to protect the fertility of soils in the future. The knowledge that this study provides might help farmers and foresters in the region in the proper management and fertilization of their lands. Moreover, this study will provide data to future studies related to soil acidification, soil erosion, and land use that are planned for the Arhavi Sub-basin. [ABSTRACT FROM AUTHOR]

Purpose: Long-term excessive application of nitrogen fertilizer under diverse land uses has caused serious environmental problems on the North China Plain. Current studies focus on denitrifiers and bacterial communities in topsoil under diverse land-use types; however, few studies have studied denitrifiers and microbial communities in subsoils. Materials and methods: The variations in soil bacterial communities and denitrifiers with soil profiles (0–300 cm) under crop, apple orchard, and vegetable fields were investigated through high-throughput sequencing and quantitative PCR technologies. Results and discussion: NO3−-N largely accumulated in the deeper soil layers (100–300 cm) in the apple orchard, resulting in a higher risk of NO3−-N leaching. The soil bacterial community structure at the 0–100 cm soil depth had a marketable difference from that at 100–300 cm under these three land-use types, and the C:N ratio was the main driving factor for their vertical distribution. The bacterial α-diversity decreased with soil depth; the crop field had the highest α-diversity across all horizons except 100–200 cm, and total carbon was the most important factor driving α-diversity. In addition, the absolute abundance of the nirK, nirS, and nosZ genes decreased with soil depth and varied with land-use type, which was deeply affected by multiple soil properties, such as soil organic matter and total nitrogen. Conclusion: Our findings highlighted that potentially important and unique functions remain to be revealed in subsoils, which may provide new insights into mitigating nitrate leaching in various land-use types. [ABSTRACT FROM AUTHOR]

As natural selenium (Se)-rich soil in China is generally characterized by a high geological background of cadmium (Cd), the safe utilization of such seleniferous soil remains a challenge. The accumulating evidence shows that the threshold value of the Se:Cd ratio is a determinant of regulating Cd accumulation in plants. However, the factors modulating the soil's Se:Cd ratio in selenium-enriched regions are not well understood. Here, a comprehensive study aimed at quantitatively analyzing the effects of land-use types, parent-material types, and soil properties on the distribution and influencing factors of Se, Cd, and the Se:Cd ratios. According to land use and parent-material types, 77 soil samples were collected in Yuanzhou District, a typical naturally seleniferous area in the subtropical hilly area. The results suggested that, compared with quaternary red clays (qrc), the Se content of soils derived from river and lake sediments (rls) and weathered acidic crystalline rocks (wacr) decreased by 5.81%–19.75%, while the weathered quartzite (wq)-derived soils was increased significantly. The soil Cd content in an orchard was significantly reduced compared with that in a paddy field. A redundancy analysis (RDA) revealed that SOM, Total K, and Total P significantly affected the changes in Se and Cd contents. In addition, the land-use type had the most significant effect on the Se:Cd ratio, with a regression coefficient of −0.6999 analyzed by the binary logistic regression model (p < 0.05). Furthermore, pH and Total K were the critical soil properties in controlling the Se:Cd ratio. The study indicated that the Se:Cd ratio in natural selenium-rich soil was mainly regulated by land-use types. Therefore, it is a feasible measure to regulate the Se:Cd ratio by using agronomic practices, mainly regulating soil pH, for the safe utilization of selenium-rich soil with a high Cd background. [ABSTRACT FROM AUTHOR]

This study explores the soil biodiversity and distribution of earthworms in Yunnan Province. Employing a quadrat survey method, the province was divided into six climate types, among which four representative land-use types (arable land, wasteland, grassland, and garden) were selected for sampling of earthworms and soil. In total, 1984 earthworm individuals were gathered from 148 plots, representing 27 species occurrences across four families, with Moniligastridae being dominant. The present study emphasized that different land use modes can affect the distribution of earthworm communities; there are differences in soil physical and chemical properties under different land use types; therefore, various land use modes can further affect the density and biomass of earthworms by influencing soil physical and chemical properties. Soil properties such as SOM, TN, TK, and OP significantly affect earthworm communities. For example, SOM had a significant positive correlation with earthworm density in Wasteland and Arable land and a significant positive correlation with earthworm biomass in Grassland and Garden; in addition, soil temperature and TK content had a significant negative correlation with earthworm density in Garden. This study provides data support for understanding earthworm species diversity and its spatial distribution characteristics in Yunnan Province. It gives a scientific basis for further discussion of the influence of land use on soil fauna conservation and its ecological functions. [Display omitted] • Different land use types affect the distribution of earthworms by affecting soil physicochemical properties. • The wasteland that is least affected by human interference has the highest number and density of earthworms. • SOM, TN, TK, and OP have a significant impact on the distribution of earthworms. [ABSTRACT FROM AUTHOR]

This study investigated geospatial distributions of endocrine-disrupting chemicals (EDCs) in the waters of the Dongjiang River and their associations with anthropogenic activities. Fifteen EDCs, with total concentrations in the river water of 149–2525 ng/L were detected, with bisphenol-A, 4-nonylphenol, 4- tert -octylphenol, p -hydroxybenzoic acid, and methylparaben being the five predominant EDCs. The total estrogen concentration was high downstream and significantly correlated with the spatial distribution of urban land use, wastewater discharge, population, and gross domestic product, indicating human activities have increased estrogen levels and threatened ecological health. The total risk quotient indicated a high ecological risk of estrogens to fish and a moderate to high ecological risk of personal care products to algae. Estrone, triclosan, bisphenol-A, 4-nonylphenol, and 4- tert -octylphenol were categorized as priority pollutants, which required special concern. Triclosan and triclocarban can serve as reliable chemical indicators for predicting EDC levels based on correlation analysis. The crucial factors affecting EDC levels were identified through the Mantel test and predictor importance was quantified using a multiple regression model, which can help predict occurrences and geospatial distributions of EDCs. Total phosphorus and electrical conductivity were the major predictors of EDC levels, providing promising indicators for monitoring EDCs in river water. Urban land proportion significantly affected phenolic environmental estrogens, natural estrogens, and disinfectants. In the main stream, urban population, urbanization rate, and gross domestic product influenced phenolic environmental estrogen levels. A mini-review of the global distribution of EDCs in river water revealed that income and population differences among countries affect their occurrence, suggesting socioeconomic factors should be considered to mitigate EDC pollution. [Display omitted] • Triclosan and triclocarban can serve as reliable surrogates for target EDCs. • Total phosphorus and electrical conductivity were major predictors of EDC levels. • EDC contamination was positively associated with the urban land percentage. • Priority EDCs posing potential environmental risks were identified. [ABSTRACT FROM AUTHOR]

Applying biochar and 3,4-dimethylpyrazole phosphate (DMPP) is considered to be effective means of mitigating soil nitrous oxide (N2O) emissions. However, their N2O abatement efficiency can be affected by soil properties and associated functional microorganisms. In this study, we investigated the effects of biochar and/or DMPP application on N2O emissions from different agricultural soils (i.e., vegetable, tea, and peach orchards grown for 1 and 7 years) through an incubation experiment. Biochar application significantly reduced N2O emissions from vegetable and tea soils by inhibiting ammonia oxidation. In contrast, in peach orchard soils, adding biochar promoted N2O emissions due to the positive effect of biochar on ammonia-oxidizing bacteria (AOB), which accelerated ammonia oxidation and the inhibition of N2O reduction. DMPP application mitigated 57–74% of soil N2O emissions due to its inhibitory effect on AOB. When biochar and DMPP were co-applied, biochar reduced the efficiency of DMPP in mitigating N2O emissions from tea and peach soils as biochar addition weakened the inhibitory effect of DMPP on AOB. However, N2O emissions from vegetable soils could be further reduced by the synergistic inhibition of ammonia oxidation by biochar and DMPP. Our results suggest that DMPP had a stable mitigation effect on N2O emissions in different soils, while biochar addition could potentially weaken the efficiency of DMPP. The mitigation effect of the co-application of biochar and nitrification inhibitors needs to be explored in future studies under field conditions. [ABSTRACT FROM AUTHOR]

Microbiota play essential roles in nitrogen (N) cycling in freshwater river ecosystems. However, our understanding of microbial functional groups associated with N cycling (especially denitrification) in freshwater rivers under anthropogenic disturbance is still poor. Here, we studied the impacts of different land‐use types on denitrification‐related microbiota in the Weihe River, Hanjiang River, and their tributaries, in the Qinling Mountains, China. The major land‐use types in the three river areas were divided into natural (forest, shrub, grassland, and open water) and anthropogenic (agricultural and urbanized land) types. A landscape survey of microbiota in the river water and sediment was carried out with extensive sample sources based on deep 16S rRNA gene sequencing, which yielded operational taxonomic units for predicting functional groups. With increases in proportions of agricultural and urbanized land areas, electrical conductivity, total N, ammonium‐N, and nitrate‐N all increased in water samples. Conversely, microbial diversity exhibited a decreasing trend in water samples, whereas the relative abundance of denitrification‐related functional groups increased, with increases in the proportions of agricultural and urbanized land areas. The relative abundances of denitrification‐ and human‐related microbial functional groups in sediment samples were distinctively higher in Weihe River (mainly under agriculture and urbanization), when compared with those of Hanjiang River and Qinling tributaries (dominated by forests). The results indicate that anthropogenic land‐use types, such as agricultural and urbanized land, result in simple microbial community structure and stimulate microbe‐mediated denitrification in freshwater rivers. [ABSTRACT FROM AUTHOR]

Few studies have been conducted on the factors and distribution of soil organic carbon (SOC) in plantation forests in arid mountainous regions, especially in orchards. We aimed to unravel the SOC distribution among land‐use types and the effects of altitude gradients and rock fragment content (RFC) on SOC accumulation and sequestration in the Upper Min River Arid Valley, China. The differences in SOC distribution among land‐use types were quantified. The correlation analysis of SOC with various factors, such as altitude and RFC, was conducted. The variation percentage in SOC content and stocks was explained by the factors' contribution using mixed‐effects models. SOC distribution was characterized by high content and low stocks in native forests and shrubs, high content and high stocks in eco‐forest, and low content and high stocks in orchards. At the surface (0–30 cm), SOC content and stocks in orchards (cherry, plum, and apple) were significantly lower than those in eco‐forests. There was a significant positive correlation between altitude and SOC content at the surface but not at the subsoil (30–60 cm). With RFC increased, the surface SOC content decreased in native forests, shrubs, and eco‐forests, while it increased in orchards. Our results suggest that land management is the main factor controlling the variation in SOC distribution. Enhancing the surface SOC stability in orchards by land management is a priority for soil carbon pool management in the Arid Valleys. [ABSTRACT FROM AUTHOR]

As a transitional boundary between terrestrial and aquatic ecosystems, the riparian zone is considered a hotspot for N2O production because of the active nitrogen processes. Ammoxidation is an important microbial pathway for N2O production, but the distribution of ammonia oxidizers under different land‐use types in the reservoir riparian zone and what role they played in N2O emissions are still not clear. We investigated spatiotemporal distributions of ammonia‐oxidizing archaea (AOA) and bacteria (AOB) and their role in N2O emissions in different land‐use types along the riparian zone of Miyun Reservoir: grassland, sparse woods, and woodland. We found significant differences in both AOA abundance and AOB diversity indices among land‐use types. AOA and AOB communities were significantly separated by different land‐use types. The main drivers to determine the distribution of ammonia‐oxidizing microbial community were soil water content, NH4+, NO3−, and total organic carbon (TOC). In situ N2O flux was highest in woodland with a mean value of 12.28 μg/m2·h, and it was substantially decreased by 121% and 123% in sparse woods and grassland. TOC content was decreased by 20% and 40% in sparse woods and grassland compared with woodland, and it was significantly positively correlated with in situ N2O flux. Meanwhile, AOB diversity indices were significantly correlated with in situ N2O flux. These results showed that the heterogeneity of physicochemical properties among different land‐use types affected the community of AOA and AOB in riparian zones. AOB not AOA, and community diversity rather than abundance, played a role in N2O emissions. [ABSTRACT FROM AUTHOR]

Tibet has a unique ecosystem and unique species resources and is an important ecological protection area in China and surrounding countries. Ecological protection in Tibet needs to be strengthened and targeted regionally. Therefore, it is necessary to evaluate the importance of ecological protection and its spatial difference for policy formulation. In this study, the importance of biodiversity conservation, water retention, soil retention, and sand prevention, as well as the vulnerability of soil erosion and land desertification, was assessed, and the importance of ecological protection was classified. The extremely important ecological protection areas covered an area of 615,000 km2, mainly located in the Northern Tibet Plateau, the southern foot of the Himalayas, the Hengduan Mountains, and the Gangdise-Nyainqentanglha Mountains. The relationship between land-use type, elevation, and ecological protection importance was studied. The results showed that the most important ecological protection area consisted of forest and grassland in low-altitude areas or uninhabited areas 5000 m above sea level. The spatial characteristics of dominant ecological functions in different regions were identified by comparing the importance of different factors. The study found that there are significant differences in the dominant factors of important ecological protection areas in Southeast Tibet, Northern Tibetan Plateau, and Central Tibet. The results provide an effective reference for ecological function zoning and ecological protection policy formulation in Tibet, as a scientific basis for promoting ecological protection and restoration in Tibet. [ABSTRACT FROM AUTHOR]

Land uses have a large impact on the magnetic properties of soil. Understanding the changes in such properties caused by different land uses will help to correctly explain and apply magnetic parameters. In this study, the magnetic susceptibility, magnetic mineral types, and magnetic domain state of iron oxide particles in soil after the transformation of a forest into a tea garden and cornfield in a tropical area were compared. 1)The vertical distribution characteristics of soil magnetism under the three land uses in tropical red soil area were similar. The magnetic properties of soil in the 0–20 cm surface layer was significantly different, but there were no significant differences below 20 cm. The low-frequency mass magnetic susceptibility and anhysteretic susceptibility of topsoil were largest in the cornfield, followed by the forest and tea garden, and the magnetic susceptibility of the topsoil in the cornfield was significantly higher than in the tea garden and forest. 2)The magnetic minerals in tropical red soil area were mainly ferrimagnetic minerals (maghemite and magnetite). The content of ferrimagnetic minerals decreased with depth, while the content of antiferromagnetic minerals (hematite) increased. 3)The magnetic particles were mainly composed of superparamagnetic (SP), single domain (SD), and pseudo single domain (PSD) particles. The magnetic differences in the topsoil were mainly caused by changes in the ferrimagnetic mineral concentration of SD particles. Tea garden and cornfield are the two main agricultural land in the study area. Through the correct application of magnetic parameters, it is helpful to monitor the influence of land use change on soil properties, so as to provide the necessary reference for the rational use of soil. • Soil magnetism changes after forest-to-cultivation conversion were investigated. • The transformation of land leads to changes in surface soil magnetic properties. • Magnetic characteristics across soil profiles under three land uses were similar. • Magnetism changes were due to changes in SD grains ferrimagnetic mineral content. [ABSTRACT FROM AUTHOR]

Gully erosion is an important sediment source in small watershed, and causes severe land degradation, particularly in semi-arid regions. Accurately measuring gully morphological characteristics, and determining its topographic threshold, are vital for gully erosion simulation and control. In this study, 910 gullies were visually interpreted by unmanned aerial vehicle (UAV) technology combined with field measurement. Ten gully morphological characteristics were extracted from the digital orthophoto map (DOM) and digital elevation model (DEM) generated by UAV images, including gully length (L), circumference (C), plane area (PA), surface area (SA), volume (V), depth (D), top width (TW), mean width (MW), cross-sectional area (CSA), and ratio of top width to depth (TW/D). The morphological characteristics of 30 reachable gullies were measured by a real time kinematic (RTK) to validate the parameters extracted from the UAV images. The topographic thresholds were determined based on the local slope gradient (S) and upland drainage area (A), using a dataset of 365 gully heads and their corresponding land-use types. The results show that the mean absolute percentage errors (MAPE) of the 2D and 3D gully characteristics are less than 10% and 20%, respectively, demonstrating a high accuracy of gully characteristic extraction from UAV images. Gully V is significantly related to the other nine parameters. Significant power functions were fitted between V, and L, C, PA, and SA. The gully volume could be well-estimated by SA (V = 0.212 SA0.982), with a R2 of 0.99. For all land-use types, the topographic threshold could be described as S = 0.61 A0.48, implying that water erosion is the dominant process controlling gully erosion in this region. The topographic threshold is land-use-dependent, and shrubland is hardest for gully incision, followed by grassland and cropland. The results are helpful to rapidly estimate gully erosion, and identify the areas for gully erosion mitigation in small watershed. [ABSTRACT FROM AUTHOR]

Aiming to solve the problem of the low efficiency and single objective of low impact development (LID) layout, the objectives of stormwater control, water quality purification, and economic cost are selected to present the performance of LID practices. A novel method of evaluating urban runoff and pollutant concentration is put forward based on the land-use type of each catchment. Shenzhen City is selected as the study area, and three LID scenarios are designed and contrasted for an ideal solution according to their land-use type. The results show that the multiobjective optimization model based on runoff evaluation, pollutant simulation, and investment calculation can be more efficient and can be applied in other areas. [ABSTRACT FROM AUTHOR]

ABSTRACT Due to large-scale wetland reclamation, the typical wetland had been conversed to different wetland use types (upland field, paddy field, and artificial forest) in the Sanjiang Plain. However, there are scarce data regarding soil aggregates and active organic carbons during land-use transition. Here, soil aggregates and the changes in content and storage of active organic carbon [total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), and readily oxidized carbon (ROC)] were studied under three land-uses reclaiming wetlands as an upland field, paddy field, and artificial forest in Heilongjiang Province, China. The results showed that soil aggregate structure changed significantly under the three land-uses, of which the largest decrease of mean weight diameter (MWD) occurred in the upland field. Under the three land-use types, the content and storage of TOC and each active organic carbon in soil aggregates with different size fractions significantly decreased compared with that in the wetland. In addition, the proportion of the 1–2 mm soil aggregate was significantly lower than that of other particle sizes, which resulted in the lowest storage of TOC and active organic carbon at 1-2 mm and was found in the wetland, and different land-use types; small aggregates (

Nitrite-dependent anaerobic methane oxidation (N-DAMO) is an important biological process that combines microbial nitrogen and carbon cycling and is mainly carried out by nitrite-dependent anaerobic methane-oxidizing bacteria. The discovery of this microbial process has changed the conventional view of methane oxidation and nitrogen loss. In this study, the abundance, diversity, and community structure of N-DAMO bacteria were investigated based on high-throughput sequencing and fluorescence quantitative PCR measurements. We examined environmental factors driving the variations of CH4 fluxes and N-DAMO bacterial using correlation analysis and redundancy analysis. We found low CH4 fluxes and abundant N-DAMO bacteria in the riparian zone. After decomposing the effects of single variables and exploring them, NO3− was the only significant factor that significantly correlated with the abundance and richness of the N-DAMO community and gas fluxes (p < 0.05). Under the influence of three different land use types, the increase in NO3− (grassland vs. woodland and sparse woods, + 132.81% and + 106.25%) caused structural changes in the composition of the N-DAMO bacterial community, increasing its abundance (− 9.58% and + 21.19%), thus promoting the oxidation of CH4 and reduced CH4 emissions (+ 4.78% and + 35.63%) from the riparian zone. Appropriate NO3− input helps maintain the existing low methane emission fluxes in the riparian zone of the reservoir. [ABSTRACT FROM AUTHOR]

Abstract Background Land degradation through soil erosion by water is severe in the highlands of Ethiopia. In order to curb this problem, the government initiated sustainable land management interventions in different parts of the country since 2008, and in Geda watershed since 2012. However, the impacts of the interventions on soil properties were not assessed so far. Thus, this study investigated the impacts of sustainable land management interventions on selected soil properties in Geda watershed. Soil samples were collected from treated and untreated sub-watersheds at the upper and lower landscape positions, from cropland and grazing lands at two soil depths (0–15 cm and 15–30 cm). Selected soil physicochemical properties were assessed with respect to landscape position, land-use type, and soil depth in both treated and untreated sub-watersheds. Results Generally, most of the soil physicochemical properties differed greatly across sub-watersheds, land-use types, and soil depths. Clay, electrical conductivity, total N, available P, exchangeable K, and organic carbon were higher in the treated sub-watershed, whereas sand, silt, bulk density, and pH were higher in the untreated sub-watershed. The higher sand, silt, and bulk density could be attributed to erosion, while the higher pH could be due to the higher exchangeable Na in the untreated sub-watershed. Most of the selected soil chemical properties were not affected by landscape position, but land-use type affected available P and organic carbon with higher mean values at croplands than at grazing lands, which could be ascribed to the conservation structure and tillage of the soils in that conservation structures trap and accumulate transported organic materials from the upper slope, while tillage facilitates aeration and decomposition processes. Conclusion Sustainable land management interventions improved soil physicochemical properties and brought a positive restoration of the soil ecosystem. Maintaining the soil conservation measures and enhancing community awareness about the benefits, coupled with management of livestock grazing are required to sustain best practices.

Much effort has been devoted to better understanding the effects of land-use and climate changes on biodiversity and ecosystem functions (BEF); however, the mechanistic pathways behind the observed changes remain largely unexplored, especially for grassland arthropod community. Using a 7-year grassland experiment in Inner Mongolian steppe, we examined the relative importance of direct versus indirect (through mediating plant and arthropod biodiversity) effects of four land-use types (growing-season grazing, spring & summer grazing, mowing and enclosure) and precipitation variation in two climatically contrasting years on plant and arthropod productivity. Our results showed that: (1) the variation patterns of species and functional diversity and productivity across land use types were significantly different between plant and arthropod communities, though both plants and arthropods had their community-weighted mean size (i.e., plant height and arthropod body size) decreased under grazing or mowing; (2) moderate grazing and plant growing-season precipitation enhanced plant productivity mainly via indirectly increasing plant functional dispersion and decreasing plant nitrogen concentration associated with the shift in dominant species, but reduced arthropod productivity majorly by direct grazing damage and less importantly by indirect mediation of arthropod body size; (3) grassland management and precipitation-induced variations in plant and arthropod productivity could be well explained by the changes in their functional traits and diversity, but not species richness. Our results indicate the importance of trait-based method in understanding the mechanisms of management and precipitation affecting plant and arthropod productivity, and suggest that biological traits in multiple trophic groups can be used as efficient indicators in the assessment of grassland ecosystem health.

Background Urbanization and global warming are generating ecological degradation and land pattern alteration problems in natural wetlands. These changes are greatly affecting the ecological services of wetlands. Therefore, there is an urgent need to explore the relationship between pollutants and land-use type for wetland restoration purposes. Zaozhadian Lake is a freshwater wetland in the North China Plain, which is facing degradation and land-use types changes. An experiment for analyzing soil pollutants was conducted in three land-use types of farmland, lake, and ditch in the Zaozhadian Lake. The aims of this study were to identify the distribution, pollution degree, and sources of pollutants in different land-use types, and to explore the influence of land-use type changes on contamination. Methods In this study, surface sediments (0–10 cm) of three land types (farmland, lake, and ditch) in Zaozhadian Lake were collected, and heavy metals (Cu, Ni, Zn, Pb, Cd, Cr, Hg), As, total nitrogen (TN), total phosphorus (TP) and organic matter (OM) were determined. Kriging interpolation was used to visualize the pollutants distribution. The pollution degree of TN and TP was evaluated by the Nemerow pollution index. The pollution of heavy metals and As was evaluated by the geological accumulation index (Igeo) and the potential ecological risk index (RI). Then, dual hierarchical clustering analysis and the principal component analysis were performed to further analyze the impact of land type changes on pollutants. Results The heavy metal contents in the farmland were higher than other areas, while the TN (3.71 ± 1.03 g kg-1) and OM (57.17 ± 15.16 g kg−1) in lake sediments were higher than that in other regions. Farmland, lake, and ditches had low ecological risks, with RI values of 84.21, 71.34, and 50.78, respectively. The primary heavy metal pollutants are Pb, Cu, and Ni. Furthermore, Cu, As, Ni, Pb, and Zn were primarily derived from agriculture pollution, the source of Cd was the industrial pollution, and Cr mainly originated from natural sources. Nutrients primarily came from the decomposition of aquatic animals, plants, and human-related activities. When the lake area was converted into farmland, the heavy metal concentrations in the soils increased and the TN and OM decreased. Based on the results, this study put forward key strategies including the adjustment of the land-use type and restriction of the entry of pollutants into the wetland ecosystems in the Zaozhadian Lake. More attention should be paid to the impact of land-use type change on pollutants in wetlands.

To explore the geochemical effects of land-use patterns on potentially toxic metals in agricultural soils in tropical areas, soil samples were collected in Hainan Island, China. Total concentrations of chromium, copper, lead and zinc were analyzed by inductively coupled plasma mass spectrometry. The sequential extraction procedure was applied to determine the fractions of these potentially toxic metals. The results showed that the concentrations of potentially toxic metals differed among different landuse types. The concentrations of Cr, Pb and Zn revealed the following order: abandoned cropland> paddy field>vegetable land, while Cu was ordered as abandoned cropland>vegetable land>paddy field. Fractionation analysis showed that the carbonate-bound fraction was present in high proportion in abandoned croplands, the Fe-Mn oxide-bound fraction and the organic matter-bound fraction were present in high proportion in paddy fields, and the exchangeable fraction and residual fraction were present in high proportion in vegetable lands. The chemical fractionations of potentially toxic metals were correlated with pH and organic matter, resulting in the transformation of different fractions. The results of this study contribute to a better understanding of the effects of land-use patterns on potentially toxic metals in tropical areas. [ABSTRACT FROM AUTHOR]

Purpose: Polycyclic aromatic hydrocarbons (PAHs) in the environment are strongly influenced by anthropogenic activities and negatively impact human health. Identifying the sources and potential risks of PAHs in soils will help to prevent soil pollution and utilize land more effectively. Materials and methods: In this study, soils under different land-use types in the northern Taihu Basin were investigated. The PAHs in soils were measured by gas chromatography-mass spectrometry. The toxicity of PAHs from different sources was quantitatively evaluated based on the positive matrix factorization-toxic equivalent quantity (PMF-TEQ) model. The incremental lifetime cancer risk (ILCR) method was used to assess the health risk of PAHs. Results and discussion: The results showed that the Σ16PAHs concentrations varied between 142.26 and 9278.51 ng g-1, with a mean value of 1640.43 ng g-1. High molecular weight PAHs were found to account for the largest fractions (87%) of the Σ16PAHs. Significant variation of the PAHs concentrations in soils was observed under different land-use types. The mean concentration of Σ16PAHs in different areas was in the order of industrial area > traffic area > commercial area > residential area > park > farmland. Vehicle emissions and coal/coke combustion were the predominant sources, accounting for 54% and 37% of the Σ16PAHs loading, respectively. The total predicted TEQ of PAHs ranged from 15.71 to 867.35 ng g-1 (mean 189.29 ng g-1), and benzo(a)pyrene was the major species. The total ILCR value for soil PAHs exposure was in a range of (0.13 ~ 9.13) × 10-6. Conclusions: Source identification showed that the dominant source of soil PAHs was vehicle emissions in commercial (89%) and traffic (85%) area, while coal/coke combustion was the main source of soil PAHs in industrial area (43%). The total TEQ indicated a potential carcinogenic risk in the study area, with vehicle emissions and coal/coke combustion making the primary contribution to the total TEQ (95%). The total ILCR value was in a range of 10-7 ~ 10-5, which indicated a low health risk. Children experienced a higher cancer risk than adults due to their sensitivity to the carcinogenic effects of PAHs. [ABSTRACT FROM AUTHOR]

An increasing number of studies have focused on the response and adaptation of plants to urbanization by comparing differences in leaf functional traits between urban and rural sites. However, considerable uncertainties remain because differences in land-use type have not frequently been taken into account when assessing the effect of urbanization on leaf traits. In this study, we sampled the needles of Chinese pine (Pinus tabuliformis Carr.) in areas with three land-use types (roadsides, parks, and neighborhoods) along an urban–rural gradient in Beijing, China to determine the effect of urbanization on leaf functional traits. There were significant differences in the values of leaf functional traits between the needles of the current and previous year and across land-use types. Pines growing on roadsides had leaves with smaller length, width, and area, as well as lower stomatal density, compared with those growing in parks and neighborhoods. This implies that on roadsides, plant capacity to acquire resources (e.g., light and carbon dioxide) was degraded. Stomatal density, leaf width, and leaf P concentration increased with increasing distance from the city center, while leaf K concentration decreased with increasing distance from the city center. Importantly, there were significant differences in the urban–rural gradient of leaf functional traits between leaves of different ages, and across land-use types. Leaf age was the most important factor influencing leaf nutrient traits, while land-use type was the most important factor influencing leaf morphological traits in urban environments. Thus, considering the effects of the plant characteristic and land-use type on traits is important for assessing the urban–rural gradients of plant functional traits.

Many previous studies have investigated BTEX concentrations in urban areas; however, the available evidence on the association of different land-use types and BTEX concentrations is still scarce. In this study, the BTEX concentrations were measured and compared in different land-use types and traffic volumes of Mashhad metropolis, Iran. Sampling was conducted in summer and winter of 2018 based on NIOSH 1501 method in six land-use types, including Residential, Commercial/official, Industrial, Greenspace, Transportation, and Tourism. The spatial autocorrelation model was used to investigate the emission pattern. The Monte Carlo simulation technique and sensitivity analysis were used to assess the health risk of exposure to BTEX compounds. The median [interquartile range (IQR)] of benzene, toluene, ethylbenzene m-xylene, o-xylene and total BTEX concentrations based on overall mean were 4 (2.23), 8.37 (4.48), 1.2 (1.46), 0.89 (2.59), 0.8 (1.73) and 17.7 (8.19) µg/m3, respectively. Benzene and toluene had clustered emission patterns (z-score > 1.96). Exposure to benzene in the study area had a carcinogenic risk for inhabitants. The concentration of BTEX compounds was significantly different based on land-use type. The maximum and minimum concentrations of BTEX were observed in Transportation and Greenspace land uses, respectively. The BTEX concentrations in summer were significantly higher than in winter, and traffic had a significant effect on BTEX concentrations. Overall, our results supported a significant relationship between land-use type and BTEX concentrations in the urban area. Moreover, ambient benzene concentration had a carcinogenic risk potential for inhabitants of study area. [ABSTRACT FROM AUTHOR]

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The increase in habitat destruction due to anthropogenic activities necessitates the study of bird species diversity and distribution for the purpose of conservation of wild bird species. This study was conducted on three selected sites (agricultural site, forested site, and developed site) in Nnamdi Azikiwe University Awka, using the line transect method. Eighteen bird species belonging to 7 orders and 10 families were recorded during the study. The highest mean number of birds was recorded in the developed site (7.17±0.77) followed by agricultural site (6.83±1.01) and forested sites (4.33±0.80). The developed site also recorded the least bird diversity index and species richness (H’= 1.82, r=2.13) compared to the forested site (H’= 2.09, r=2.46) and the agricultural site (H’= 2.34, r=3.32). The highest Simpson index of birds dominance (D=0.15) was recorded in developed site compared to the forested site (D=0.14) and agricultural site (D=0.12).The agricultural site recorded the least evenness (E=0.48) compared to the agricultural site (E=0.63) and forested site (E=0.64). The highest number of carnivorous and insectivorous bird species was recorded in the forest, while no granivore was recorded in the forest. The agricultural site recorded the highest number of granivore while the major birds recorded in the developed site were granivores and carnivores. The study showed that while some birds were well adapted to habitat modification, others were drastically affected by the change in their natural environment. It was therefore recommended that regular monitoring of various sites be conducted to check changes in the state of the environment for conservation.

Assessment of water infiltration of the urban surface is the prerequisite and basis when we study the impact of urbanization on the urban ecological environment such as stormwater runoff and the heat island effect. However, few studies have been done on how to make such an assessment. In this paper, a detailed assessment of water infiltration of urban surface for Wuhan, China was conducted based on remote sensing. Classification of land-use types and their water infiltration criterion was proposed by the V-I-S (Vegetation-Impervious Surface-Soil) model. The Landsat-8 remote sensing data were used to classify various land-use types in Wuhan. The water infiltration capacity distribution in Wuhan was then obtained and classified into five levels. These results will also be helpful to provide a basis for establishing a comprehensive water infiltration model of the urban surface in the future. [ABSTRACT FROM AUTHOR]

The rapid conversion of native forests to farmland in Ethiopia, the cradle of biodiversity, threatens the diversity of the arbuscular mycorrhizal fungi (AMF) pivotal to plant nutrition and carbon sequestration. This study aimed to investigate the impact of this land-use change on the AMF species composition and diversity in southern Ethiopia. Soil samples were collected from nine plots in each of three land-use types: native forest, agroforestry, and khat monocropping. The plots of the three land-use types were located adjacent to each other for each of the nine replicates. Three 10 × 10m subplots per plot were sampled. AMF spores were extracted from the soil samples, spore densities were determined, and species composition and diversity were evaluated through morphological analysis. Both spore density and species richness were statistically significantly higher in the native forest than in the agroforestry plots with no clear difference to khat, whereas the true diversity (exponential of Shannon–Wiener diversity index) did not differ among the three land-use types due to high evenness among the species in agroforestry. In total, 37 AMF morphotypes belonging to 12 genera in Glomeromycota were found, dominated by members of the genera Acaulospora and Glomus. The highest isolation frequency index (78%) was recorded for Acaulospora koskei from native forest. Consequently, the agroforestry system did not appear to aid in preserving the AMF species richness of native forests relative to perennial monocropping, such as khat cultivation. In contrast, the native forest areas can serve as in situ genetic reserves of mycorrhizal symbionts adapted to the local vegetative, edaphic, and microbial conditions. [ABSTRACT FROM AUTHOR]

Aim: Agroforestry is a globally practised system of land use for achieving greater and more diverse biomass production, but it has other ecological benefits, such as mitigation of climate change. Despite this, long‐term carbon (C) accumulation in different components of agroforestry systems, the drivers for C accumulation and the linkages between tree biomass and soil C stocks remain unclear. Location: Global. Time period: From 1989 to 2019. Major taxa studied: Trees. Methods: Here, we report on a global meta‐analysis based on 141 studies to identify patterns of C accumulation in tree‐based agroforestry systems compared with sole cropland and pasture. Results: We found that agroforestry systems had, on average, 46.1 Mg/ha (95% confidence interval, 36.4–55.8 Mg/ha) more C in tree biomass compared with sole cropland‐ or pasture‐based land uses without trees. Furthermore, agroforestry systems with multiple tree species contained greater biomass C stocks and accumulated biomass C faster than systems with a single tree species. The effect of agroforestry practices on soil C stock increased with tree age, although such increases varied among climatic zones. Agroforestry systems in tropical zones had the ability to increase soil C to peak levels quickly, whereas soil C in temperate zones increased at a slower rate but peaked at a greater overall soil C level. Our structural equation model did not detect a direct linkage between biomass C and changes in total soil C stock in agroforestry systems. Main conclusions: Our results demonstrate that planting multiple tree species in agroforestry systems is an important strategy to increase biomass C sequestration, with regional climate affecting the temporal change of soil C in response to agroforestry practices. [ABSTRACT FROM AUTHOR]

Sewage irrigation has been widespread in the water shortage area of eastern China and inevitably tends to result in heavy metal accumulation in soils. A total of 148 surface soil samples from five land-use types were collected in Longkou, a typical sewage irrigation area of China, and As, Cd, Cu, Pb, and Zn concentrations were determined. The Nemerow index method and improved fuzzy comprehensive evaluation method were used to examine the pollution status of heavy metals. The potential ecological risk was evaluated by the Hakanson model by adjusting the assessment threshold, and its spatial distribution was interpolated using geostatistical techniques. As, Cd, Cu, Pb, and Zn accumulated in different amounts in the five land-use types. Urban industrial land and mining land were moderately polluted, irrigated land was slightly polluted, orchards were minimally polluted, and bare land was at a safe level of pollution. Cd exhibited high percentages of strong and severe levels of potential ecological risks. For Cd, irrigated land, orchard, and bare land mainly presented moderate risks, whereas urban industrial land and mining land mainly presented high risks. The comprehensive ecological risk of the five heavy metals was at a severe level for all tested land-use classes except for bare land. [ABSTRACT FROM AUTHOR]

Background: Land degradation through soil erosion by water is severe in the highlands of Ethiopia. In order to curb this problem, the government initiated sustainable land management interventions in different parts of the country since 2008, and in Geda watershed since 2012. However, the impacts of the interventions on soil properties were not assessed so far. Thus, this study investigated the impacts of sustainable land management interventions on selected soil properties in Geda watershed. Soil samples were collected from treated and untreated sub-watersheds at the upper and lower landscape positions, from cropland and grazing lands at two soil depths (0–15 cm and 15–30 cm). Selected soil physicochemical properties were assessed with respect to landscape position, land-use type, and soil depth in both treated and untreated sub-watersheds. Results: Generally, most of the soil physicochemical properties differed greatly across sub-watersheds, land-use types, and soil depths. Clay, electrical conductivity, total N, available P, exchangeable K, and organic carbon were higher in the treated sub-watershed, whereas sand, silt, bulk density, and pH were higher in the untreated sub-watershed. The higher sand, silt, and bulk density could be attributed to erosion, while the higher pH could be due to the higher exchangeable Na in the untreated sub-watershed. Most of the selected soil chemical properties were not affected by landscape position, but land-use type affected available P and organic carbon with higher mean values at croplands than at grazing lands, which could be ascribed to the conservation structure and tillage of the soils in that conservation structures trap and accumulate transported organic materials from the upper slope, while tillage facilitates aeration and decomposition processes. Conclusion: Sustainable land management interventions improved soil physicochemical properties and brought a positive restoration of the soil ecosystem. Maintaining the soil conservation measures and enhancing community awareness about the benefits, coupled with management of livestock grazing are required to sustain best practices. [ABSTRACT FROM AUTHOR]

The heat island effect, as the thermodynamic performance of the artificial ecosystem established by human modification of the natural environment matrix, should be studied from the comprehensive perspective of the regional thermal environment. Jianshui-Kaiyuan-Gejiu-Mengzi of Honghe Prefecture, as one of the regions with the most concentrated and complex ecological problem in Yunnan karst rocky desertification areas, can be coupled with urban heat island, dry-hot valley and karst rocky desertification for the comprehensive study, which has practical significance for the construction and restoration of the regional ecological environment. Based on the overall analysis of the karst rocky desertification and regional thermal environment in Southern Yunnan, it used the spatial interaction supported by a long time series of remote sensing images to study the influence of impervious surface, land use, vegetation coverage and rocky desertification degree on the regional thermal environment, so as to support the construction of human settlements in the karst rocky desertification areas, especially the construction of thermal comfort. The results showed the following: While the heat island was mainly distributed in the dam areas, but scattered in the surrounding mountain areas, the area was basically maintained at about 3000.00 km2, accounting for 1/4–1/3 of the whole study area. The total net increase of impervious surface in the past 30 years was 204.98 km2, while the proportion of impervious surface forming heat island showed an overall rising trend, from 44.17% in 1990 to 62.63% in 2020. The land use covered by the heat island was mainly cropland, as it showed an increasing trend, maintaining above 50.00% from 1990 to 2005 and above 60.00% from 2010 to 2020. The vegetation coverage covered by the heat island was mainly medium to low/medium vegetation coverage, as the total net increase in the past 30 years was 1801.72 km2, with the proportion above 60.00%. The rocky desertification covered by the heat island was mainly extremely severe rocky desertification (Fr > 0.90), as the total net increase in the past 30 years was 1526.60 km2, with the proportion above 40.00% gradually. Based on the regional thermal environment, the finding not only focuses on urban heat island and karst rocky desertification, but also provides theoretical support for the interpretation of the dry-hot valley's formation. • Comprehensive studies coupled with urban heat island, dry-hot valley and karst rocky desertification. • The land use was mainly cropland (50.00–60.00%), while vegetation coverage was medium to low/medium vegetation coverage (above 60.00%). • The rocky desertification was extremely severe rocky desertification (Fr > 0.90) with a proportion above 40.00%. [ABSTRACT FROM AUTHOR]

Vehicle collisions with animals pose serious issues in countries with well-developed highway networks. Both expanding wildlife populations and the development of urbanised areas reduce the potential contact distance between wildlife species and vehicles. Many recent studies have been conducted to better understand the factors that influence wildlife–vehicle collisions (WVCs) and provide mitigation methods. Most of these studies examined road density, traffic volume, seasonal fluctuations, etc. However, in analysing the distribution of WVC, few studies have considered a spatial and significant distance geostatistical analysis approach that includes how different land-use categories are associated with the distance to WVCs. Our study investigated the spatial distribution of agricultural land, meadows and pastures, forests, built-up areas, rivers, lakes, and ponds, to highlight the most dangerous sections of roadways where WVCs occur. We examined six potential ‘hot spot’ distances (5–10–25–50–100–200 m) to evaluate the role different landscape elements play in the occurrence of WVC. The near analysis tool showed that a distance of 10–25 m to different landscape elements provided the most sensitive results. Hot spots associated with agricultural land, forests, as well as meadows and pastures, peaked on roadways in close proximity (10 m), while hot spots associated with built-up areas, rivers, lakes, and ponds peaked on roadways farther (200 m) from these land-use types. We found that the order of habitat importance in WVC hot spots was agricultural land < forests < meadows and pastures < built-up areas < rivers < lakes and ponds. This methodological approach includes general hot-spot analysis as well as differentiated distance analysis which helps to better reveal the influence of landscape structure on WVCs.