Soil Retention Research Articles

Dynamical Identification of Urban-Rural Gradient and Ecosystem Service Response: A Case Study of Jinghong City, China

Understanding ecosystem service characteristics along urban-rural gradients is vital for enhancing the well-being of urban and rural residents. Despite this importance, prior research has neglected the dynamic evolution of urban-rural gradients during urbanization. This study investigates the spatiotemporal variations of four ecosystem services—habitat quality, carbon sequestration, water yield, and soil retention—along the urban-rural gradient in Jinghong City, China. We propose a method for identifying the gradient using the inverse S function of urban land density distribution and concentric analysis. From 2000 to 2020, ecosystem service supply capacity in Jinghong City continuously declined, indicating degradation over the two decades. The urban-rural gradient zone is classified as core area, inner urban area, suburban area, and urban periphery, each experiencing outward expansion, reflecting significant urbanization. Changes in ecosystem services along the gradient revealed consistently high losses in habitat quality, carbon sequestration, and overall services in the inner urban area, while water yield and soil retention suffered the greatest losses in the urban periphery. As urbanization expanded outward, the loss of these services shifted from the inner urban area to the suburban and urban periphery. These results support decision-making in urban planning and sustainable development for urban-rural regions.

ESTABLISHING THE FIRST DATABASE OF SOIL HYDRAULIC PROPERTIES IN TUNISIA BASED ON PEDOTRANSFER FUNCTIONS

Soil hydraulic properties play a crucial role in the unsaturated soil water supply process. Currently, Tunisia lacks a database containing essential values for soil retention properties and soil saturated hydraulic conductivity. The main objective of this study is to create the inaugural soil hydraulic properties database through the utilization of open-access data and pedotransfer functions (PTFs). To achieve this goal, the harmonized world soil database (FAO) was employed to identify 752 measurement points across Tunisia. Subsequently, the soil texture, organic carbon content, and bulk density were determined at each point. These acquired values were then entered into the CalcPTF software to estimate the van Genuchten soil retention parameters. The calculation of soil saturated hydraulic conductivity was accomplished using two widely recognized pedotransfer functions (Saxton and Rosetta). The outcomes facilitated the creation of a catalog containing soil hydraulic parameter value for each soil texture. Significance of discrepancies between values obtained from the PTFs was assessed using a Tukey test. The spatial variability of each soil hydraulic property was studied using the simple kriging. In conclusion, the establishment of this significant soil hydraulic properties database holds diverse applications in agricultural, hydrological, and environmental studies in Tunisia.

Constructing ecological security patterns with differentiated management intensity based on multifunctional landscape identification and multi-criteria decision-making

The trade-off of ecosystem services should be considered in ecological security pattern (ESP) construction, which can be reflected in landscape multifunctionality and comprehensive importance. Multi-intensity ESPs management is also required to achieve effective ecological planning. In this study, we proposed an approach of multi-intensity ESPs construction that integrated multifunctional landscape identification and multi-criteria decision-making into ecological source identification, and categorized ecological sources based on the “trend-status-risk” framework, with a case study in the city belt along the Yellow River in Ningxia. The results showed that the optimal weights of the four ecosystem services of habitat maintenance, water conservation, carbon sequestration and soil retention based on multi-criteria decision making were 0.5000, 0.2071, 0.1589 and 0.1340, respectively. The trade-off degree of the ecosystem services was 0.6612, and the overall conservation efficiency was 1.5212. Conservation priority areas based on multifunctional landscape identification and multi-criteria decision-making had an overlapping area of 2189.38 km2, accounting for 84.86% of that identified through landscape multifunctionality. The comprehensive ESP of the study area included 45 ecological sources covering a total area of 6067.14 km2 and 91 ecological corridors with a total area of 3331.62 km2. Multi-intensity ESPs aiming at conservation, prevention, restoration and reconstruction were established with corresponding management suggestions. The approach to constructing multi-intensity ESPs proposed in this study has application potential in ecological planning of ecologically vulnerable regions, facilitating differentiated ESP management.

Freeze-thaw effects on pore space and hydraulic properties of compacted soil and potential consequences with climate change

Freezing and thawing affect the pore-space structure in agricultural soils with implications for soil hydraulic properties and water flow. Previous studies have focused on the upper few centimeters of the tilled topsoil, where most freeze-thaw (FT) cycles occur, even though deeper soil layers are also subject to freezing and thawing in cold climates. Thus, little is known about how freezing and thawing affect untilled soil layers, which often show high bulk densities that restrict vertical water movement. Furthermore, it remains unclear how shifts in FT patterns with climate change may change the pore-space structure and water flow through these soil layers. Here we investigated the effects of freezing and thawing on X-ray imaged pore-space characteristics, water retention and near-saturated hydraulic conductivity (K) in untilled soil directly below plough depth. Intact cores were sampled at two sites in central Sweden under the same long-term reduced tillage management. The two soils, a silt loam and a silty clay loam, were subjected to three FT scenarios in a laboratory environment intended to represent FT patterns that are considered likely under current and future winter conditions for this region. The latter scenario was characterised by more FT cycles and a lower freezing temperature. Freezing and thawing increased K in the near-saturated range in both soils, which we attribute to observed small (<0.01 mm3 mm−3) increases in the volume of pores of diameters close to the X-ray resolution limit. Concomitant increases in pore network connectivity and critical pore diameter, especially in the denser silty clay loam soil, probably contributed to this increase in K. The water retention data suggested that changes in pore-space characteristics below X-ray resolution also occurred in both soils. Furthermore, our results indicate that both soils may show higher drainage rates due to shifts in FT patterns in the future, although longer-term changes in pore-space structure with an increasing number of FT cycles would mostly be limited to soils with relatively high clay contents. These soils are often more compacted below plough depth and, thus, benefits from improvements in soil structure such as improved root growth and plant water supply are also expected to be larger.

Identifying the effects of landscape pattern on soil conservation services on the Qinghai-Tibet Plateau

Land use patterns affect soil erosion processes and soil conservation services. Identifying key landscape pattern affecting soil conservation services is critical for improving soil conservation services and optimizing land use patterns. In this study, the Qinghai-Tibet Plateau (QTP), where ecosystem services are important, was selected as research area. Based on land use, meteorological, soil and vegetation data, the RUSLE model was used to estimate soil conservation quantitatively from 2000 to 2020. The temporal changes in landscape metrics were analyzed using Fragstats, and the response of soil conservation services to landscape metrics was analyzed by correlation analysis. The landscape pattern showed an obvious temporal change trend. In general, the overall landscape of the QTP became more diversified and fragmented, and the landscape shape tended to become more complicated. Patch density (PD), edge density (ED), landscape shape index (LSI), splitting index (SPLIT), Shannon's diversity index (SHDI), and Shannon's evenness index (SHEI) showed increasing trends, while largest patch index (LPI), mean patch area (AREA_MN), aggregation index (AI), and contagion index (CONTAG) showed decreasing trends. At the class level, the variations of landscape pattern metrics of different land use types were big difference. In the 20-year period, soil conservation services were generally on the rise. The spatial heterogeneity of soil conservation services decreased from the south-east to the north-west. PD and ED were positively correlated with soil conservation function, while AREA_MN and AI had a negative correlation with soil conservation function. The effect of landscape pattern metric variation on soil conservation capacity significantly differed among different land use types. Results of the research offer reasonable evidence for landscape management, water and soil retention function improvement and regional ecological protection on the QTP.

Estimation of Water Yield and Soil Erosion in Samanalawewa Watershed in Sri Lanka using GIS-based InVEST Model

Ecosystem services (ES) are a group of tasks performed by the earth's ecosystems that are required to support life and offer benefits to humanity. Thus, this study explores two of the water-related ecosystem services, water yield, and soil retention that were distributed in the Samanalawewa Watershed (SW) and its eight sub-watersheds in Sri Lanka, over 20 years (2000-2020) with five- year time intervals. Soil and water conservation and water yield play an important role in ecosystem management. Hydrological balance is a crucial component of the hydrological ecosystem services. Assessing water yield and soil erosion are pivotal for watershed management. Thus, this study estimated and mapped the water yield and soil erosion, using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST 3.9.2) Annual Water Yield (AWY) and Sediment Delivery Ratio (SDR) model respectively. According to the obtained results, in 2000, 2005, 2010, 2015 and 2020, the estimated mean annual water yield was 2.62x105, 2.6x105, 3.5x105, 3.58x105 and 2.75x105 m3 ha-1year-1, respectively. Furthermore, the estimated mean annual soil erosion rates for the above- mentioned years were 53.2, 52.9, 69.7, 87.7 and 70.2 t ha-1 year-1. The estimated soil loss values of the SW are 10 to 18 times greater than the soil erosion tolerance (5 t ha-1 year-1) in Sri Lanka. The results show that the years 2015 and 2005 have the highest and the lowest water yield and total soil loss values, respectively. The upper part of the watershed has relatively moderate water yield and soil loss values than the lower part. These findings would be beneficial in developing watershed management strategies and in the implementation of suitable soil and water conservation techniques within the watershed. &#x0D; Keywords: Ecosystem services, InVEST, Samanalawewa watershed, Soil erosion, Water yield

Identifying priority areas for conservation: using ecosystem services hotspot mapping for land-use/land-cover planning in central of Iran.

The modeling and mapping of hotspots and coldspots ecosystem services (ESs) is an essential factor in the decision-making process for ESs conservation. Moreover, spatial prioritization is a serious stage in conservation planning. In the present research, based on the InVEST software, Getis-Ord statistics (Gi*), and a set of GIS methods, we quantified and mapped the variation and overlapping among three ESs (carbon storage, soil retention, and habitat quality). Furthermore, an approach was proffered for detecting priority areas to protect multiple ecosystem services. Hotspots recognized via the Gi* statistics technique contain a higher capacity for supplying ESs than other areas. This means that protecting these areas with a bigger number of overlapped hotspots can provide more services. Results indicated that population growth accompanied by the increase in construction sites and low-yield agricultural lands in the Zayanderood dam watershed basin has resulted in ES losses. This situation is represented by increasing soil erosion, reduced carbon storage, reduced biodiversity, and fragmented habitat distribution due to land-use change. The statistically significant carbon storage, soil retention, and habitat quality hotspots with above 95% confidence level account for 21.5%, 39.3%, and 16.9% of the study area, respectively. Therefore, a clear framework was presented in this study for setting ES-based conservation priority. Decision makers and land-use planners can also combine this technique into their framework to identify and conserve ES hotspots to support their targeted ecosystem policies.

Is marginalised cultivated land on the Tibetan Plateau suitable for production or ecology? An example from the northeastern Tibetan Plateau

AbstractIn the ecologically fragile alpine area of the Tibetan Plateau, some marginalised cultivated lands have more serious conflicts related to agricultural production and ecological protection than others; thus, it is of practical significance to explore the rational use of marginalised cultivated lands. In this study, Xining City and Haidong City in the northeastern part of the Tibetan Plateau were taken as the study area. Marginalised cultivated land was identified, and the vegetation photosynthesis model was used to evaluate its production function. Ecological function was evaluated in terms of soil retention, landscape connectivity and habitat maintenance. The rational use pathways of marginalised cultivated land were derived through statistical analysis and aggregation model analysis. The results showed that there were 183,489.19 ha of marginalised cultivated land in the study area; the average value of production function of marginalised cultivated land was approximately 70% of that of nonmarginalised cultivated land, and its various ecological functions reached 93.64%–117.98% of that of nonmarginalised cultivated land. In general, the distribution of production functions decreases from northwest to southeast, and the ecological functions are high in the middle and low in the surroundings. A comprehensive analysis of the production and ecological functions of marginalised cultivated land can provide a reference basis for the rational formulation of cultivated land protection policies and ecological protection policies.

Biochar produced at high temperature mitigates N2O emission and promotes nitrogen retention in subtropical forest soils

AbstractBiochar is produced by burning biomass under oxygen‐limited conditions, and it has been widely used as a soil amendment to improve soil functions such as nutrient retention. However, whether the impact of biochar application on soil nitrogen (N) transformation and N2O emission varies with the pyrolysis temperature remains unclear, especially in different forest types in subtropical regions. In this study, a 60‐day laboratory incubation experiment was conducted to evaluate the impact of biochar with different pyrolysis temperatures (300°C [BC300], 500°C [BC500], and 800°C [BC800]) on net N transformation rates and N2O emission in soils collected from Castanopsis kawakamii dominated natural forest (NF) and Chinese fir (Cunninghamia lanceolate, CF) plantation in subtropical China. The results showed that the application of biochar significantly increased soil ammonium (NH4+) content (p &lt; 0.001) but reduced nitrate (NO3−) content (p &lt; 0.001) compared with the control. The soil NH4+ content of the BC800 treatment was significantly higher than that of other treatments (p &lt; 0.001). Biochar application significantly reduced soil net N mineralization (NRmin) and nitrification (NRnit) rate (p &lt; 0.001), but increased net ammonification (NRamm) rate (p &lt; 0.001). The application of biochar led to a remarkable decrease in cumulative N2O emission compared to the control (p &lt; 0.001). In particular, soils treated with high‐temperature biochar emitted significantly lower N2O compared to other treatments (p &lt; 0.001). The partial least squares path model demonstrated that biochar influenced N2O emission through a direct effect in NF soil and an indirect effect in CF soil. This study highlights the distinct role of biochar, particularly that produced under high pyrolysis temperatures as a soil amendment to mitigate N2O emission and promote N retention in both subtropical natural and planted forests.

Impacts of multi-scenario land use change on ecosystem services and ecological security pattern: A case study of the Yellow River Delta

The Yellow River Delta (YRD), a critical economic zone along China's eastern coast, also functions as a vital ecological reserve in the lower Yellow River. Amidst rapid industrialization and urbanization, the region has witnessed significant land use/cover changes (LUCC), impacting ecosystem services (ES) and ecological security patterns (ESP). Investigating LUCC's effects on ES and ESP in the YRD is crucial for ecological security and sustainable development. This study utilized the PLUS model to simulate 2030 land use scenarios, including natural development (NDS), economic development (EDS), and ecological protection scenarios (EPS). Subsequently, the InVEST model and circuit theory were applied to assess ES and ESP under varying LUCC scenarios from 2010 to 2030. Findings indicate: (1) Notable LUCC from 2010 to 2030, marked by decreasing cropland and increasing construction land and water bodies. (2) From 2010 to 2020, improvements were observed in carbon storage, water yield, soil retention, and habitat quality, whereas 2020–2030 saw increases in water yield and soil retention but declines in habitat quality and carbon storage. Among the scenarios, EPS showed superior performance in all four ES. (3) Between 2010 and 2030, ecological sources, corridors, and pinchpoints expanded, displaying significant spatial heterogeneity. The EPS scenario yielded the most substantial increases in ecological sources, corridors, and pinchpoints, totaling 582.89 km2, 645.03 km2, and 64.43 km2, respectively. This study highlights the importance of EPS, offering insightful scientific guidance for the YRD's sustainable development.

Effects of soil heterogeneity and preferential flow on the water flow and isotope transport in an experimental hillslope

Soil water movement plays vital roles in hillslope runoff generation and groundwater and surface water interaction. However, there are still knowledge gaps about the impacts of soil heterogeneity and preferential flow on the internal water flow and transport process. In this study, the vertical soil heterogeneity focused on the variations in soil retention capacity, and the consideration of lateral preferential flow emphasized the higher hydraulic conductivity. We combined isotopic tracing and numerical modeling in an artificial hillslope, focusing on monitored processes of the artificial rainfall and isotopic tracing experiment. The results showed that the soil moisture quickly accumulated at the bottom of the hillslope during rainfall events, while the 2H enrichment occurred in the topsoil derived from enriched isotope injection in the second artificial rainfall. The evaporation process slowed down the mixing of new water in the topsoil and old water in the lower layer. We found that the vertical soil heterogeneity had significant influences on the internal water and isotope transport paths within the hillslope. The lateral preferential flow played an important role in the water flux and transport time to the seepage face. The coupling of isotopic tracing, which reflects the water transport and mixing with the hillslope, effectively improved the model simulation and mechanism analysis of hillslope water flow. Our findings provide new insights into the mechanisms governing soil water flow and transport dynamics in hillslopes, taking into account vertical soil heterogeneity and lateral preferential flow.

Potential of Irrigated Agricultural Production of Corn (Zea mays L.) in Semi-Arid Region using Geoprocessing

This work aimed to evaluate and map the potential of irrigated agricultural production for corn for the watershed of the region of the middle course of the Paraíba River. Using SPRING, a map of soil irrigation potential and soil retention capacity was prepared and a partial map was generated through matrix crossing. Using average annual rainfall data, the climate condition map was prepared. After using LEGAL, the agricultural production potential map was generated through the matrix crossing between the partial map and the climate scenario. For maize, a Full climatic condition (C1) was identified in 2.02% of the basin's total; the full climatic condition with prolonged rainy season (C2) and the climatic condition moderated by excess water (C3) were not identified; the climatic condition Moderate by water deficiency (C4) in 0.86%; the unfit condition due to severe water deficit (C5) in 97.12% of the basin. The potential of irrigated agricultural production for maize did not show Very High (MA), High (A), Medium (M) and Low (B) potential, only the Very Low (MB) potential in 100% of the basin.

Spatial flows of ecosystem services under future climate and land-use changes

Increasing global pressure on natural capital requires sustainable solutions to ensure long-term provision of ecosystem services (ES) which have complex flow dynamics. Although the importance of ES flows has been increasingly recognized during the past years, little is known about how they will be affected by future climate and land-use changes. Here, we integrated ES flows into a scenario-based assessment framework, and evaluated it by clarifying the local and distant effects of ES flows in the Black River basin, China. The spatiotemporal variations of ES flows were investigated by considering different land policies and climate scenarios, and the drivers of ES flow variations were explored. We found increasing inter-regional ES flows toward 2100. Compared to land-use change, the intra-regional flows were more sensitive to climate change, with greater shifts of flow size and synergistic areas identified under a moderate climatic forcing scenario with sustainable management strategies. Precipitation directly affected water retention flow, yet affected flood mitigation flow both directly and indirectly through changing vegetation cover, which was the major driver of soil retention flow. Biodiversity mediated the positive effects of precipitation and vegetation cover on soil retention flow. Our study highlights the importance of embracing the spatiotemporal features of ES flows in sustainable transboundary management and adaptation strategies.

A new framework for multi-level territorial spatial zoning management: Integrating ecosystem services supply-demand balance and land use structure

The supply-demand balance of ecosystem services (ESs balance) is a research hotspot. Previous studies have explored spatio-temporal patterns of ESs supply, demand, and balance, but have neglected the inherent relationship between ESs balance and land use structure, which impedes the development of direct and effective land use regulatory strategies. This study assessed the balance of six ESs (i.e., timber production (TP), food production (FP), water retention (WR), carbon sequestration (CS), soil retention (SR), and habitat quality (HQ)) by the index of ecological relative surplus ratio (ERSR) at 30 m × 30 m pixel scale, and identified ESs balance bundles (ESBBs) in Lancang County, a typical mountainous region in China. It also defined the land use proportion thresholds for achieving different objectives of ESs balance, and proposed land use regulatory strategies accordingly. The results showed that: (1) From 2010 to 2020, the supply of six ESs exceeded the demand in Lancang County, and the surplus of different ESs changed over time. ESs balance also exhibited spatial heterogeneity, and ESs imbalance aggravated in some areas. Three ESBBs were divided as FP-WR-SR integrated bundle, TP–CS–HQ integrated bundle, and Integrated promotion bundle at the township scale. (2) Cropland, built-up land, and forest were the key land use types that affected the balance of the six ESs. Moreover, the land use proportion thresholds under the objectives of “ERSR ≥0″ and “ERSR ≥1″ were determined, and they differed by ES type and objective. (3) For each ESBB, ESs comprehensive management zones were delineated at the multi-scales of the township and 1 km × 1 km grid. Regulatory strategies oriented by “reducing/increasing/maintaining the proportion of certain land use types” were suggested under different objectives. This study developed a framework for “multi-level zoning management of ‘county – ESs balance bundle – township – grid’ for promoting ESs balance by land use structure regulation” that aligned with China's territorial spatial planning hierarchy at the county and township levels. It could inform the design of a scientific and orderly territorial spatial pattern with a high-level ESs balance at various scales (e.g., counties, agglomerations, provinces, and cities) and regions. However, this framework could not be directly applied to land use spatial optimization at pixel scale. Further research is needed to integrate land use simulation models, such as the mixed-cell cellular automata (MCCA) model, to achieve ESs balance objectives at finer scales.

Potential and risks of water reuse in Brandenburg (Germany) – an interdisciplinary case study

Abstract For Brandenburg, a region in Germany with increasing water shortage and drought events, water reuse can counteract competition scenarios between drinking water supply, agricultural irrigation, and industrial use. Centralized and decentralized sources for reclaimed water are found to potentially substitute 245 or 28% of irrigation water, respectively, in agriculture production in Brandenburg. For such a reuse scenario, the fate of organic micro-pollutants is examined for diatrizoate (DZA) and carbamazepine (CBZ). Retention in local sandy soil and transfer into roots and leaves of arugula are analyzed in lysimeter studies and greenhouse pot experiments. Vertical transport was found for DZA and accumulation in or on arugula roots with a root concentration factor of 1,925 ± 34% but a low bioconcentration factor due to intrinsic molecule properties. CBZ was not found to be mobile in the sandy soil but accumulates in arugula roots and leaves by factors of 70 ± 7% and 155 ± 12%, respectively. Further research on potential plant uptake and groundwater enrichment for more substances is highly recommended as well as tertiary wastewater treatment prior to water reuse.

Exploring the complex trade-offs and synergies of global ecosystem services

The trade-off and synergy relationship of ecosystem services is an important topic in the current assessment. The value of each service provided by the ecosystem is substantially affected by human activities, and conversely, its changes will also affect the relevant human decisions. Due to varying trade-offs among ecosystem services and synergies between them that can either increase or decrease, it is difficult to optimize multiple ecosystem services simultaneously, making it a huge challenge for ecosystem management. This study firstly develops a global Gross Ecosystem Product (GEP) accounting framework. It uses remote sensing data with a spatial resolution of 1 km to estimate the ecosystem services of forests, wetlands, grasslands, deserts, and farmlands in 179 major countries in 2018. The results show that the range of global GEP values is USD 112–197 trillion, with an average value of USD 155 trillion (the constant price), and the ratio of GEP to gross domestic product (GDP) is 1.85. The trade-offs and the synergies among different ecosystem services in each continent and income group have been further explored. We found a correspondence between the income levels and the synergy among ecosystem services within each nation. Among specific ecosystem services, there are strong synergies between oxygen release, climate regulation, and carbon sequestration services. A trade-off relationship has been observed between flood regulation and other services, such as water conservation and soil retention services in low-income countries. The results will help clarify the roles and the feedback mechanisms between different stakeholders and provide a scientific basis for optimizing ecosystem management and implementing ecological compensation schemes to enhance human well-being.

Water-related ecosystem services interactions and their natural-human activity drivers: Implications for ecological protection and restoration

Sustainable development faces the crucial challenge of safeguarding water-related ecosystem services, particularly in arid regions. However, scale-dependent interactions and their influencing factors remain unclear. This study addresses this local gap on the regional level by focusing on ecologically vulnerable mountain areas, employing a comprehensive quantitative and spatial analysis approach, utilizing Spearman coefficient, trade-off/synergy index, and trade-off/synergy criterion, to examine water-related ecosystem services interactions across scales in arid area. Additionally, a Geographical detector was used to identify dominant natural and human activity factors. Finally, we determined ecologically optimal and worst areas and proposed spatial planning and management recommendations for ecological protection and restoration. Key results indicate that: (1) From 1995 to 2015, water yield and nutrient delivery ratio exhibited a declining trend, while soil retention showed an increasing trend, with the weakest nutrient delivery ratio function in the reserve. (2) At the grid scale, there were 2 trade-offs among water-related ecosystem services in 1995, which decreased to 1 trade-off in 2005 and 2015. The synergistic was most prominent near Qinghai Lake, while the trade-off was most obvious in the western mountainous areas. Conversely, the county scale demonstrated synergy. (3) NDVI, slope, and precipitation dominantly influence the spatial heterogeneity patterns of soil retention_water yield, soil retention_nutrient delivery ratio, and water yield_nutrient delivery ratio, respectively, with natural factors outweighing human activities in impacting water-related ecosystem services. This study contributes to the improvement and optimization of ecological environment management decisions.

Projecting the response of ecological risk to land use/land cover change in ecologically fragile regions

Anthropogenic activities have dramatically altered land use/land cover (LULC), leading to ecosystem service (ES) degradation and further ecological risks. Ecological risks are particularly serious in ecologically fragile regions because trade-offs between economic development and ecological protection are prominent. Thus, ways in which to assess the response of ecological risks to LULC change under each development scenario in ecologically fragile regions remain challenging. In this study, future LUCC and its impact on ESs under four development scenarios in 2040 in western Jilin Province were predicted using a patch-generating land use simulation model and the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model. Ecological risk was assessed based on future LUCC possibilities, and potential ES degradation and potential drivers of ecological risks were explored using a geographic detector. The results showed that the cropland development scenario (CDS) would experience large-scale urbanization and cropland expansion. Carbon storage (CS), habitat quality (HQ), and water purification (WP) degraded the most under the CDS, and grain yield (GY) and water yield (WY) degraded the most under the ecological protection scenario (EPS). The LUCC probability under the CDS (14.37 %) was the highest, while the LUCC probability under the comprehensive development scenario (CPDS) (8.68 %) was the lowest. The risk of WP degradation was greatest under the CDS, but the risk of soil retention (SR) degradation was greatest under the natural development scenario (NDS), EPS, and CPDS. Ecological risk coverage was the largest (98.04 %), and ecological risks were the highest (0.21) under the CDS, while those under the EPS were the opposite. Distance to roads and population density had a higher impact on ecological risks than other drivers. Further attention should be given to the ecological networks and pattern establishment in urbanized regions. This study will contribute to risk prevention and sustainable urban and agricultural development.

Soil, climate, and landscape drivers of base cation concentrations in green stormwater infrastructure soils

Deicing practices and infrastructure weathering can impact plants, soil, and water quality through the input and transport of base cations. Base cation accumulation in green stormwater infrastructure (GSI) soils has the potential to decrease soil infiltration rates and plant water uptake or to promote leaching of metals and nutrients. To understand base cation retention in GSI soils and its drivers, we sampled 14 GSI soils of different age, contributing areas, and infiltration areas, across 3 years. We hypothesized that soil, climate, and landscape drivers explain the spatial and temporal variability of GSI soil base cation concentrations. Sodium (Na), Calcium (Ca), and Magnesium (Mg) concentrations in GSI soils were higher than in reference soils, while Ca and Mg were similar to an urban floodplain soil. Neither the contributing area, contributing impervious area, nor their ratios to infiltration area predicted base cation concentrations. Age predicted the spatial variability of Potassium (K) concentrations. Ca and Mg were moderately predicted by sand and silt, while clay predicted Mg, and sand predicted K. However, no soil characteristics predicted Na concentrations. A subset of sites had elevated Na in Fall 2019, which followed a winter with many freezing events and higher-than-average deicer salt application. K in sites with elevated Na was lower than in non-elevated sites, suggesting that transient spikes of Na driven by deicer salt decreased the ability of GSI soils to accumulate K. These findings demonstrate the large variability of GSI soil base cation concentrations and the relative importance of soil, climate, and landscape drivers of base cation dynamics. High variability in GSI soil data is commonly observed and further research is needed to reduce uncertainties for modeling studies and design. Improved understanding of how GSI soil properties evolve over time, and their relation to GSI performance, will benefit GSI design and maintenance practices.

Biodegradable microplastics boost dissimilatory nitrate reduction to ammonium (DNRA) process contributing to ammonium nitrogen retention in farmland soils

Microplastics (MPs) pollution in agriculture ecosystems profoundly affects biogeochemical cycles. However, the impacts of MPs, particularly biodegradable MPs, on dissimilatory nitrate reduction to ammonium (DNRA) process remain unclear. Herein, the alterations in denitrification and DNRA pathways and underlying mechanism by different MPs exposures (including conventional nonbiodegradable MPs (polyethylene (PE) and polypropylene (PP)) and biodegradable MPs (polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT)) were explored via soil microcosm experiments accompanied with 15N isotope tracer technology and 16S rRNA high-throughput sequencing. Compared with control, PE and PP increased the rates of denitrification by 117–126% but significantly decreased DNRA rates by 39.3–63.4%, whereas DNRA activities in PLA and PBAT treatments were remarkably boosted by 163–242% and dominated soil nitrate bioreduction (6.67–8.69 μg N g−1 d −1). This differentiation was attributed to the nutrient imbalance induced by MPs and distinctly selective effects of MPs on functional microbes. Microbial interaction mechanism further suggested that limited bioavailable carbon intensified the competition between heterotrophic denitrifiers (e.g., Bacillus, Sphingomonas and Microvirga) and DNRA bacteria (e.g., Luteitalea and Streptomyces) for electron donor in nonbiodegradable MPs treatments, reducing the abundances of DNRA bacteria. However, the high bioavailable C/NOx– ratio resulting from biodegradable MPs degradation released such competition and more greatly promoted the activities of DNRA bacteria than denitrifiers, facilitating ammonium retention in soils. Collectively, this study highlights the promotion of biodegradable MPs on soil ammonium recycle via DNRA process in farmland ecosystems and can shed some light on current plastic mulch-film management toward a sustainable and cleaner agricultural industry.