Riparian Research Articles

Numerical investigation on the evolutionary characteristics of landslide dam-break flow in a wet-bed channel with riparian vegetation

Riparian vegetation always grows on both sides of a natural river during a dam-break event, while the river typically retains some water instead of completely drying out. The RNG k-ϵ turbulence model is employed to examine the evolutionary characteristics of the dam-break flow in the downstream vegetated channel. This model facilitates the analysis of water-level fluctuations, velocity distributions, and the retardation effects of vegetation on the dam-break flow by varying the initial water depth (IWD) in the downstream channel. Results indicates that as the water depth in the downstream channel increases, the dam-break wave tends to form more readily, possesses a larger amplitude, and the duration of rapid congestion in the dam-break current decreases. Hence, the surface velocity gradually declines and shows an intermittent distribution. Vegetation impedes the flow evolution in the vegetated area, an effect that diminishes progressively with increasing IWD. In contrast, vegetation hastens the evolution of water flow in the main channel, which remains minimally affected by the IWD.

Cynodon dactylon and Sediment Interaction in the Three Gorges Reservoir: Insights from a Three-Year Study

Sediment deposition is critical in maintaining riparian plant communities by providing essential nutrients and posing growth challenges. This study focuses on Cynodon dactylon, a dominant clonal species in the riparian zones of the Three Gorges Reservoir, and its interaction with sediment deposition over three years. Results indicated an average sediment deposition depth of 2.85 cm in the lower riparian regions. Observations revealed that C. dactylon coverage increased progressively at lower elevations despite its dominance diminishing with rising elevation levels. Additionally, positive linear correlations between C. dactylon coverage and sediment deposition depths were identified during flood periods, underscoring the species’ role in enhancing sediment deposition. These findings suggest that C. dactylon plays a significant role in sediment accumulation, which may bolster its growth and survival prospects during subsequent growing cycles. The study highlights the importance of riparian vegetation, mainly perennial clonal species like C. dactylon, in promoting sediment accumulation and contributing to the stability and functionality of riparian ecosystems.

Mechanism underlying revetment effects on the spatial distribution of nitrogen removal and N2O emissions in riparian zones at summer

Study Region, Shanghai, China, Study FocusUrban riparian zones can mitigate or even control nitrogen pollution in rivers through nitrification and denitrification processes. However, these processes also produce N2O, a potent greenhouse gas. During urbanization, various types of revetments have been constructed in riparian zones. These revetments alter the exchange of materials and energy between the riparian zone and the river, which in turn affects the nitrification and denitrification processes in the riparian zone. However, the mechanisms by which revetments impact nitrogen removal and N2O emissions in riparian zones are not yet clear, and the ways in which revetments balance nitrogen removal and N2O emissions remain unknown. Therefore, in a single river section, natural (NR), permeable (PR), and impervious revetment (IR) types were replicated. Measurements are taken of nitrogen removal, N2O emissions, and related environmental indicators in both the river-riparian interface (RRI) and the riparian zone area outside the RRI (RZ). The study analyzes the differences in environmental factors, nitrification and denitrification potentials, and N2O emission rates among the different revetments to identify the main factors affecting nitrogen removal and N2O emissions in the riparian zone. It also explores the potential mechanisms by which revetments influence the spatial distribution of nitrogen removal and N2O emissions in the summer riparian zone.New Hydrological Insights for the Region: PR exhibit greater denitrification potential and lower N2O emission rates. The denitrification potential is higher in the RRI compared to RZ, while the N2O emission rate is lower than in RZ. nirK is the primary factor influencing denitrification potential, whereas nosZII predominantly affects N2O emissions. The lower soil carbon-to-nitrogen ratio in PR increases the abundance of nirK, thereby enhancing the riparian zone's denitrification potential. Moreover, greater aboveground vegetation biomass increases the abundance of nosZII, reducing the N2O emission rate. The study results could provide guidance for urban ecological restoration and greenhouse gas emission reduction.

Intensification of Human Land Use Decreases Taxonomic, Functional, and Phylogenetic Diversity of Macroinvertebrate Community in Weihe River Basin, China

Recent anthropogenic activities have escalated human exploitation of riparian zones of river ecosystems, consequently diminishing aquatic biodiversity. This intensification of land use is also causing water quality degradation and changes in water environmental factors, evidenced by increased nutrient levels and adversely impacting the community structure and diversity of aquatic organisms. Notably, the Weihe River Basin, the largest tributary of the Yellow River, has demonstrated signs of significant anthropogenic pressure. Despite this, comprehensive investigations examining the effects of land-use intensity on aquatic organism diversity in this watershed remain limited. In this study, the environmental impacts and macroinvertebrate diversity under high-intensity and low-intensity land-use scenarios within the Weihe River Basin were investigated through field surveys conducted during the spring and autumn seasons. Our results demonstrated that areas under high-intensity land use exhibited elevated nutrient concentrations (e.g., total nitrogen) compared to those under low-intensity land use. These environmental changes significantly influenced the macroinvertebrate community structure, reducing functional and phylogenetic diversities in high-intensity land-use watersheds. Hydrological factors (water depth, river width, and discharge) have a significant impact on macroinvertebrate taxonomic diversity. Thus, understanding the effects of land-use intensity on aquatic biodiversity is essential for ecological assessments of impacted watersheds and developing management strategies for the sustainable use and planning of riparian lands in the Weihe River Basin.

Morphological Traits and Biomass Allocation of Leymus secalinus along Habitat Gradient in a Floodplain Wetland of the Heihe River, China

Plant organ biomass allocation and morphological characteristics are important functional traits. The responses of plant root, stem, and leaf traits to heterogeneous habitats in floodplain wetlands are highly important for understanding the ecological adaptation strategies of riparian plants. However, the patterns of these responses remain unclear. In a floodplain wetland in the middle reaches of the Heihe River, we studied the responses of the root, stem, and leaf morphological traits and biomass allocation of Leymus secalinus to varying habitat conditions. We measured these traits in three sample plots, delineated based on distance from the riverbank: plot I (near the riparian zone, 50–150 m from the riverbank), plot II (middle riparian zone, 200–300 m from the riverbank), and plot III (far riparian zone, 350–450 m from the riverbank). The results showed that in plot I, L. secalinus tended to have slender roots and stems and small leaves, with a biomass allocation strategy that maximized the root–shoot ratio (RSR). In plot II, L. secalinus had thick stems and moderate leaf and root patterns, and the RSR values were between those of plot I and plot III. In plot III, L. secalinus had thin and short stems and large leaves; furthermore, among the root morphological structures, plot III had the shortest Rhizome length (RL) and longest Rhizome diameter (RD), and the RSR was the lowest. Moreover, there was a significant correlation between organ biomass and leaf thickness, stem length, RD, and RL in the three habitats (p < 0.05). By balancing the biomass allocation among organs, wetland plants in floodplains balance changes in root, stem, and leaf morphological characteristics to improve their environmental adaptation.

Numerical Analysis of Stability of Plant-Animal Interactions in Riparian Zones

Numerical Analysis of Stability of Plant-Animal Interactions in Riparian Zones

Effects of Taxon and Body Size on Mercury Concentrations in Spiders from Two Rivers with Different Levels of Mercury Contamination: Implications for the Use of Riparian Spiders as Sentinels.

Due to widespread atmospheric deposition of mercury (Hg), all aquatic food webs are contaminated with toxic methyl mercury (MeHg). At high concentrations, MeHg poses a health hazard to wildlife and humans. Spiders feeding in riparian habitats (hereafter referred to as riparian spiders) have been proposed as sentinels of MeHg contamination of aquatic systems. Riparian spiders are exposed to MeHg through their diets, and the concentration of MeHg in spiders is positively related to the proportion of MeHg-contaminated emergent aquatic insects in their diets. The use of spiders as sentinels is complex because their MeHg concentrations can vary, not only among ecosystems but also between different spider taxa and as a function of spider body size. The objective of the present study was to examine how the level of ecosystem contamination, spider taxon, and spider body size interact to influence MeHg concentrations in four genera of riparian spiders from two rivers with different levels of Hg contamination. We collected four genera of riparian spiders (Tetragnatha sp., Larinioides sp., Pardosa sp., and Rabidosa sp.) from two sites along both the Clear Fork of the Trinity River and the West Fork of the Trinity River (Fort Worth, TX, USA). We analyzed concentrations of MeHg in different body sizes of spiders from each genus. We found that MeHg contamination of the river ecosystem, spider taxon, and spider body size were important determinants of MeHg concentration in riparian spiders. The results suggest that any of the four taxa of riparian spiders from the present study could be used as sentinels of aquatic MeHg contamination, but they should not be used interchangeably because of the interdependence between the effects of ecosystem contamination level, spider taxon, and body size. Future studies utilizing riparian spiders as sentinels of biomagnifying aquatic contaminants (e.g., MeHg, polychlorinated biphenyls) should consider the potentially complex interaction effects between ecosystem contamination level, spider taxon, and spider body size. Environ Toxicol Chem 2024;00:1-7. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Cutthroat trout responses to increased light via conventional and alternative riparian buffers

Forested headwaters, particularly in the Pacific Northwest, USA, are typically heavily shaded by dense stands of riparian vegetation. Reduced riparian cover can occur from natural or anthropogenic events, resulting in increased light which can increase fish biomass by promoting in-stream food resources. We conducted a 5 y before-after-control-impact (BACI) study on 10 small streams in the Oregon Coast Range, USA, and investigated how changes to the magnitude of stream light, mediated by conventional and alternative riparian buffer configurations adjacent to upland timber harvest, changed Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) abundance, biomass, bioenergetics, diet composition, and the availability of aquatic food resources. Riparian buffer treatments reduced canopy cover as much as 34 % cover (98–99 % pre; 64–98 % post-treatment) and enhanced total available sunlight reaching the stream surface by 8–31 % relative to unharvested references that only changed by 3–4 %. In the first year following the treatments, young-of-year trout (YOY, age 0) densities changed by between +0.1 and +0.78 #/m2 in treatment streams while densities changed by –0.001 and +0.02 #/m2 at reference streams. Although change in YOY densities was positively correlated with change in stream light (rs=0.81, p=0.02), changes in basal resources (periphyton and macroinvertebrates) were both positive and negative and did not increase with change in stream light. Adult (age 1+) trout responses were mixed in the first year post-treatment, but changed by –0.14 to +0.24 #/m2 at treatment sites (–0.02 to –0.05 at reference sites) in the second year post-treatment, likely due to increased recruitment from the strong cohort of YOY in the first year. Bioenergetics analysis in one post-treatment year showed that adult trout did not experience greater summer growth (–0.003 to +0.0005 g g−1 d−1) or proportions of maximum consumption (0.18–0.25) in streams with more light than at reference streams (–0.001 and +0.001 g g−1 d−1, 0.19 and 0.23). Overall, while standing stock assessments suggest that fish showed some increases after experimental treatments that increased light, our data did not provide the clear mechanistic evidence for bottom-up drivers that was expected. The relationship between canopy removal and fish production is not always predictable in small headwater streams, and even though fish populations were generally resilient to riparian manipulation, evaluations of terrestrial food resources, the dynamic between canopy cover and light reaching the stream, and changes to temperature may lend valuable insight on the impacts to fish populations.

Riparian Landscape Change: A Spatial Approach for Quantifying Change and Development of a River Network Restoration Model

Natural river landscapes can be biodiversity hotspots but are one of the most human altered ecosystems with habitats significantly damaged around the world, and a third of fish populations threatened with extinction. While riparian ecosystems have been negatively altered by anthropogenic activities, effective planning and restoration strategies can reverse negative impacts by improving habitat quality. However, restoring rivers requires appropriate data on current riparian health while also considering priorities for different stakeholders. To address this, a Geographic Information System (GIS) was used to create a new and transferable restoration priority model based on a section of the river Linth in Switzerland as a case study. The restoration priority model is founded on connectivity, river condition, national priority species and species hotspots. Landscape change of the riparian zone was analyzed using aerial imagery and landscape metrics. Almost a quarter of rivers within the study area were considered high or very high restoration priority, with many aquatic species set to benefit from restoration. From 1946 to 2019, the riparian landscape became highly fragmented due to significant growth in impervious surfaces and a concomitant loss of agricultural land. The GIS model provides a tool by which environmental agencies can manage natural features over large scales, while also planning priorities and targeting conservation strategies to the areas of greatest need.

The effect of redox fluctuation on carbon mineralization in riparian soil: An analysis of the hotspot zone of reactive oxygen species production

Riparian zones are important depositional environments at the catchment scale and provide environmental services such as carbon sequestration. This zone is a highly dynamic interface for oxygen and electron exchange, which confers the basis for reactive oxygen species (ROS) production. However, the differences in soil ROS production and their impact on carbon turnover across various redox locations within the riparian zone remain to be fully elucidated. In this study, we investigated the distribution characteristics and generation mechanism of ROS in riparian soil based on soil samples collected in a three-month field monitoring experiment, with additional incubation experiments conducted to examine the effect of hydroxyl radical (•OH) on soil organic carbon (SOC) mineralization. The obtained results demonstrated that the riverine wetland was the hotspot zone for •OH production, with the production flux of 13.05 μmol kg−1 d−1, which was significantly higher than that in floodplain (7.29 μmol kg−1 d−1) and riverbank soils (8.61 μmol kg−1 d−1). Moreover, •OH levels displayed distinct rhythmic fluctuations, with significantly higher concentrations at low water levels compared to those at high water levels, and remained essentially flat over three cycles. The statistic analysis revealed that the ROS production was highly dependent on reduced species and microbial community structure, which function as biogeochemical batteries and electron shuttles under redox fluctuations. Furthermore, the generated •OH involved in the abiotic mineralization of SOC, contributing to 13.1‒21.8 % of total CO2 efflux. Compared to particulate organic carbon (POC), mineral-associated organic carbon (MAOC) fractions of SOC were more susceptible to •OH attacks. The findings provide a novel insight to comprehensively assess the redox process on riparian carbon turnover.

Effect of intensive seasonal pumping and recharge on sulfur biogeochemistry in groundwater of agricultural riparian zones

Physico-chemical characteristics of groundwater are often impacted by agricultural practices such as land use, fertilizer types, and groundwater pumping. This study aimed to identify contaminant sources and redox processes controlling the hydrogeochemistry of groundwater in riparian zones influenced by intensive agricultural activities, focusing on sulfur species. Groundwater samples were collected bimonthly from March 2014 to March 2015 from groundwater wells in two zones in South Korea with different agricultural systems. The water isotopic compositions of the groundwater indicated that all groundwater originated from the same meteoric water. Groundwater samples affected by periodic groundwater pumping exhibited wide variations in Mn2+ (47.8 ± 18.2 μM) and Fe2+ (123 ± 61.0 μM) and elevated SO42−, while NO3− was below the detection limit. Groundwater chemistry was affected by fertilizer and manure, and denitrification. The oxidation of reduced sulfur compounds by oxygen and nitrate did not fully account for the elevated SO42− concentrations and isotopic composition of sulfate (δ34S and δ18O) in the investigated aquifers. Therefore, we postulate that water level change due to periodic groundwater pumping and recharge enabled oxidants (MnO2 and Fe3+) to also contribute to oxidation of reduced sulfur. Additionally, fertilizers with distinct δ34S values and bacterial sulfate reduction (BSR) affected groundwater chemistry and its sulfur species, including δ34SSO4 and δ18OSO4. Removal of sulfate from the aquifer during pumping limited BSR. Consequently, the agricultural practices may further increase sulfate concentrations in the groundwater. This environmental impact should be thoroughly managed because high sulfate concentrations in drinking water cause ingestion problems in humans.

Restoration measures of the riparian vegetation of the Black Volta Basin in Ghana: Experiences from the Lawra Municipality

The study is focused on measures put in place to restore the degraded riparian vegetation of the Black Volta Basin in the Lawra Municipality. The study is necessitated by the fact that much attention has not been given to rehabilitation of degraded riparian flora species in the Upper West Region by scholars and researchers. The current study aims at filling the knowledge gaps on restoration measures of degraded riparian flora species in the Lawra Municipality in particular and Upper West Region in general. Going by pragmatism as a research philosophy, the study employed the mixed methods research approach in data collection, analysis, and presentation. Computed values of the Shannon Wiener Index (0.686) and Simpson's Index (1.5328) show that the riparian vegetation of the Black Volta Basin in the Lawra Municipality has dwindled due to livelihood activities as compared to the Shannon Index (1.6406) and Simpson's Index (3.5511) of the riparian vegetation of the Burkina Faso site across the Black Volta Basin. The reduction in vegetative cover of the Black Volta Basin in the Lawra Municipality is confirmed by satellite images which demonstrate dwindling riparian vegetation in the years 2020 and 2021 as compared to the years 2000 and 2001. The current study also discloses that restoration of the riparian vegetation of the Black Volta Basin in the Lawra Municipality is a collaborative effort of local and external stakeholders using measures such as complete ban on farming activities within the riparian zone, creating a buffer zone, promoting natural regeneration and a total ban on logging in the riparian zone. The study concludes that restoration of the degraded riparian vegetation of the Black Volta Basin of the study area is a panacea for sustainable development. It is recommended that by-laws to prevent logging of riparian tree species should be enforced by local and external stakeholders of the riparian vegetation of the study area.

Diversity, stand and population structure of riparian woody species in two contrasting land use types in the distal Okavango Delta, Northwestern Botswana

AbstractLand use change threatens the integrity of riparian woodland vegetation. The aim of this study was to investigate the diversity and population structure of riparian plant species in protected and communal areas. A total of 71 transects were sampled from each of the protected and communal areas. Total species richness recorded was 36 and 38 in communal and protected areas, respectively. Species diversity was significantly (p < 0.05) higher in the protected than communal areas. Vachellia tortilis (communal areas) and Croton megalobotrys (both areas) showed a reverse J shaped pattern with more individuals in the lower diameter size classes than in the large ones. Dichrostachys cinerea (both areas), Ziziphus mucronata (communal areas), Combretum imberbe (protected areas), C. hereroense (protected areas), Berchemia discolor (protected areas) and Vachellia erioloba (communal areas) showed a reverse-J distribution pattern, but with missing size classes. Philenoptera violacea (protected areas) was characterized by a bell-shaped distribution with more individuals in the middle size classes than in the lower and upper ones while Combretum hereroense, C. imberbe and B. discolor were characterized by irregular population structure in communal areas. Croton megalobotrys, D. cinerea, C. imberbe, C. hereroense, Z. mucronata, B. discolor and S. erubescens had higher Important Value Indices (IVIs) in protected than communal areas. Comparatively, Vachellia tortilis, P. violacea and V. erioloba had higher IVIs in communal than protected areas. We recommended that species with J-shaped population structure and those with only one size class be protected to enable them to attain healthy population structures.

Size-dependent effects of dams on river ecosystems and implications for dam removal outcomes.

Understanding the relationship between a dam's size and its ecological effects is important for prioritization of river restoration efforts based on dam removal. Although much is known about the effects of large storage dams, this information may not be applicable to small dams, which represent the vast majority of dams being considered for removal. To better understand how dam effects vary with size, we conducted a multidisciplinary study of the downstream effect of dams on a range of ecological characteristics including geomorphology, water chemistry, periphyton, riparian vegetation, benthic macroinvertebrates, and fish. We related dam size variables to the downstream-upstream fractional difference in measured ecological characteristics for 16 dams in the mid-Atlantic region ranging from 0.9 to 57 m high, with hydraulic residence times (HRTs) ranging from 30 min to 1.5 years. For a range of physical attributes, larger dams had larger effects. For example, the water surface width below dams was greater below large dams. By contrast, there was no effect of dam size on sediment grain size, though the fraction of fine-grained bed material was lower below dams independently of dam size. Larger dams tended to reduce water quality more, with decreased downstream dissolved oxygen and increased temperature. Larger dams decreased inorganic nutrients (N, P, Si), but increased particulate nutrients (N, P) in downstream reaches. Aquatic organisms tended to have greater dissimilarity in species composition below larger dams (for fish and periphyton), lower taxonomic diversity (for macroinvertebrates), and greater pollution tolerance (for periphyton and macroinvertebrates). Plants responded differently below large and small dams, with fewer invasive species below large dams, but more below small dams. Overall, these results demonstrate that larger dams have much greater impact on the ecosystem components we measured, and hence their removal has the greatest potential for restoring river ecosystems.

Dry season assessment of carbon storage and emission from upland and riparian soils in the Ganga River basin

Soil organic carbon (C) and nitrogen (N) are profoundly affected by changes in land use and land cover (LULC), especially by farming in riparian zones. The five LULC classes were selected in contiguous order, i.e., undisturbed forest (CALref), conventional agriculture lands (CAL), reservoir riparian zones (RSRZ), river riparian zones (RRZ), and undisturbed riparian zones (RZref) in the Ganga River basin to study the C storage and emission trends at a landscape scale. The riparian soils showed higher moisture, temperature, and bulk density than the upland soils, strongly determining the spatial variations in the CO2 equivalent (CO2e), C:N ratio, and CO2 efflux. Riparian CO2e was more bulk density-dependent, while upland CO2e showed greater dependence on TOC. The C:N ratio showed a higher mean value in the reference soils (CALref and RZref) than in the other soils (P < 0.05). The total nitrogen (TN), total protein (TP), and NH4-N (ammonium‑nitrogen) showed the following trend: RSRZ > CAL > RRZ > RZref > CALref. The stepwise multiple regression models illustrated that soil moisture was the primary regulator of the C:N ratio and CO2 efflux in the upland soils while the temperature in the riparian soils. These intrinsic soil variables resulted in 1.15 to 2.26 times higher CO2 efflux from the cultivated soils (CAL, RSRZ, and RRZ) than from the reference soils. Hence, the present study revealed how agricultural practices tangibly increase the riparian system's carbon footprint while offering unsustainable livelihood options to farmers.

Streamflow diurnal fluctuation and driving mechanism of headwater stream in a semi-humid mountainous region

Diurnal fluctuation in streamflow during rainless periods provides valuable signals for the calibration of hydrological models and comprehension of hydrological processes. Previous research has primarily focused on this phenomenon in the context of single-factor analysis in the Mediterranean, Maritime, and Alpine climates of Middle Europe and Western US. This study is based on the Xitaizi Experimental Watershed (XEW), a typical mountainous headwater watershed situated in the semi-humid monsoon North China Plain. Seven years of high-frequency observation data were used to investigate the characteristics of streamflow diurnal fluctuation, its driving mechanisms, and the propagation pathways of these fluctuation signals through hillslope-riparian-stream. The results are as follows: (1) Streamflow exhibits diurnal fluctuation during rainless periods throughout the year, with variations up to 36% of the daily mean and distinct patterns in rainy (peak at night) and dry seasons (peak in the afternoon). Choosing the proper timing for daily discharge observation can reduce bias due to fluctuations. (2) In rainy seasons, the impact of discharge fluctuation is significant, particularly in years with lower discharge. Meanwhile, the soil moisture in both the hillslope and the riparian zone, and the groundwater level in the riparian zone exhibit a daytime decline and a nighttime rise. The groundwater level in the hillslope fluctuates with a lag time of approximately 6 to 9 hours. (3) Numerical simulations and cross-correlation analysis demonstrate that the dominant driving mechanism of diurnal fluctuations in rainy seasons is the diurnal evapotranspiration variation in the riparian zone, while the influence of aquifer hydraulic conductivity is insignificant.

Identifying factors influencing reservoir eutrophication using interpretable machine learning combined with shoreline morphology and landscape hydrological features: A case study of Danjiangkou Reservoir, China

Reservoir nearshore areas are influenced by both terrestrial and aquatic ecosystems, making them sensitive regions to water quality changes. The analysis of basin landscape hydrological features provides limited insight into the spatial heterogeneity of eutrophication in these areas. The complex characteristics of shoreline morphology and their impact on eutrophication are often overlooked. To comprehensively analyze the complex relationships between shoreline morphology and landscape hydrological features, with eutrophication, this study uses Danjiangkou Reservoir as a case study. Utilizing Landsat 8 OLI remote sensing data from 2013 to 2022, combined with a semi-analytical approach, the spatial distribution of the Trophic State Index (TSI) during flood discharge periods (FDPs) and water storage periods (WSPs) was obtained. Using Extreme Gradient Boosting (XGBoost) and SHapley Additive exPlanations (SHAP), explained the relationships between landscape composition, landscape configuration, hydrological topography, shoreline morphology, and TSI, identified key factors at different spatial scales and validated their reliability. The results showed that: (1) There is significant spatial heterogeneity in the TSI distribution of Danjiangkou Reservoir. The eutrophication levels are significant in the shoreline and bay areas, with a tendency to extend inward only during the WSPs. (2) The importance of landscape composition, landscape configuration, hydrological topography, and shoreline morphology to TSI variations during the FDPs are 25.12 %, 29.6 %, 23.09 %, and 22.19 % respectively. Besides shoreline distance, the Landscape Shape Index (LSI) and Hypsometric Integral (HI) are the two most significant environmental variables overall during the FDPs. Forest and grassland areas become the most influential factors during the WSPs. The influence of landscape patterns and hydrological topography on TSI varies at different spatial scales. At the 200 m riparian buffer zone, the increase in cropland and impervious areas significantly elevates eutrophication levels. (3) Morphology complexity, shows a noticeable threshold effect on TSI, with complex shoreline morphology increasing the risk of eutrophication.

Response characteristics of soil microorganisms under strong disturbance conditions in the riparian zone of the three Gorges reservoir Area

The normal operation of the Three Gorges Reservoir, which involves periodic water storage and discharge, has led to strong disturbances in environmental conditions that alter soil microbial habitats in the riparian zones. Riparian zones are an important part of controlling pollution in the Three Gorges Reservoir area, since they act as a final ecological barrier that intercepts pollutants. Meanwhile, monitoring the health of microbial communities in the riparian zone is crucial for maintaining the ecological security of the reservoir area. We specifically investigate the Daning River, which are tributaries of the Three Gorges Reservoir and have typical riparian zones. Soil samples from these areas were subjected to high-throughput sequencing of 16S rRNA genes and 18S rRNA genes, in order to obtain the characteristics of the present microbial communities under strong disturbances in the riparian zones. We studied the characteristics and distribution patterns of microbial communities and their relationship with soil physicochemical properties. The study results indicate that microbial communities exhibit high diversity and evenness, and spatial heterogeneity is present. The ASV dataset contains many sequences not assigned to known genera, suggesting the presence of new fungal genera in the riparian zone. Redundancy analysis (RDA) revealed that pH and NH4+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${NH}_{4}^{+}$$\\end{document}-N were the primary environmental factors driving bacterial community variation in the riparian zone, while pH, total carbon (TC) content, and NO3-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${NO}_{3}^{-}$$\\end{document}-N were identified as the main drivers of soil archaeal community variation.

Combining ecosystem service value and landscape ecological risk to subdivide the riparian buffer zone of the Weihe River in Shaanxi

Riparian buffer zones are transitional and ecological intersections between land and water. These areas play a major role in advancing ecosystem protection and restoration. Here, we investigated the spatial and temporal evolution of land use, ecosystem service value (ESV), and landscape ecological risk (LER) in riparian buffer zones between 1990 and 2020 using the Shaanxi section of the Weihe River as a case study using a GIS grid, the unit-area-equivalent-factor method, the landscape ecological risk index, and the natural breakpoint method. We also established four ecological zones using standardized Z-scores. The predominant land categories in the study area comprised cultivated, construction, and grassland, which together accounted for more than 80 % of the total area. The construction land demonstrated the most significant increase of 4,062.33 hm2 area, and cultivated land showed most significant decrease of 13,048.56 hm2 area, between 1990 and 2020. Next, study-site ESV increased from 28.30 × 108 CNY in 1990 to 28.94 × 108 CNY in 2020, reflecting 2.26 % growth. High-value areas were principally bodies of water and primarily situated along the Weihe River, extending from west to east along the main channel. The LER of the study area was dominated by the lowest ecological risk, low ecological risk, and medium ecological risk classes, which collectively accounted for more than 70 % of the total area. The main land types in the areas with high ecological risk were forest land and cultivated land. The study area’s LER demonstrated a decreasing trend from 1990 to 2020, and the area with the lowest ecological risk and low ecological risk zones increased by 9.97 %. The riparian buffer zone was divided into ecological restoration, reconstruction, conservation, and protection zones based on two factors, namely, ESV and LER. The most dominant of these was the ecological reconstruction zone, which showed a 13.75 % decrease in area share between 1990 and 2020. The ecological restoration zone occupied the smallest area with the largest increase of 56.63 % during this period. In conclusion, this study contributes to ecological zoning and management of the riparian buffer zone along the main channel of the Weihe River. Appropriate zoning is integral to protecting this valuable ecosystem and achieving sustainable development of surrounding human communities.

Urban Green Infrastructure Connectivity: The Role of Private Semi-Natural Areas

Green spaces and blue spaces in cities provide a wealth of benefits to the urban social–ecological system. Unfortunately, urban development fragments natural habitats, reducing connectivity and biodiversity. Urban green–blue infrastructure (UGI) networks can mitigate these effects by providing ecological corridors that enhance habitat connectivity. This study examined UGI connectivity for two indicator species in a rapidly developing city in the southern United States. We mapped and analyzed UGI at a high resolution (0.6 m) across the entire city, with a focus on semi-natural areas in private land and residential neighborhoods. Integrating graph theory and a gravity model, we assessed structural UGI networks and ranked them based on their ability to support functional connectivity. Most of the potential habitat corridors we mapped in this project traversed private lands, including 58% of the priority habitat for the Golden-cheeked Warbler and 69% of the priority habitat for the Rio Grande Wild Turkey. Riparian zones and other areas with dense tree cover were critical linkages in these habitat corridors. Our findings illustrate the important role that private semi-natural areas play in UGI, habitat connectivity, and essential ecosystem services.