Riparian Research Articles

Submerge-emerge alternation promotes sediment per- and polyfluoroalkyl substance (PFAS) release and bioaccumulation

Understanding the sediment release and plant bioaccumulation of per- and polyfluoroalkyl substances (PFASs) under submerge-emerge alternation (SE) is crucial to predicting their transport and fate in the riparian zones. In the present study, a simulational device was firstly constructed to explore the effects of SE on the transport of PFASs in riparian sediment-plant systems and the underlying mechanisms. The submerge (CS) and emerge (CE) situations were compared. The results showed that SE significantly enhanced the transport and bioaccumulation of PFASs in sediments. Compared with the initial concentration, PFASs in sediments decreased by 81.84 %, 50.48 %, and 21.68 % in the SE, CS, and CE groups, respectively. The bioaccumulation of PFASs in plant roots in the SE group was 1.26 and 4.16 times higher than that in the CS and CE groups, respectively, and the bioaccumulation of PFASs in leaves in the SE group was 2.05 and 1.71 times higher than that in the other two groups. Dissolved organic matter (DOM) composition and molecular properties under SE were recognized as the dominant factors regulating the release of PFASs from sediments. Root morphology and low-molecular-weight organic acids (LMWOAs) in root exudates were closely associated with the bioaccumulation of PFASs in plants. Among the substitutes, hexafluoropropylene oxide trimer acid (HFPO-TA) demonstrated greater hydrophobicity, hexafluoropropylene oxide dimer acid (Gen-X) had greater mobility, and 6:2 fluorotelomer sulfonate (6:2 FTS) accumulated more in plants. This study has expanded the understanding of the geochemical cycling of PFASs in riparian sediment-plant systems under submerge-emerge alternation.

Assessment of predation on small semi-aquatic mammals by the Eurasian otter through genetic analysis of spraints

AbstractSmall semi-aquatic mammals play a critical role in the river ecosystem and can be used as bioindicators of environmental health. Many populations of these species are threatened by multiple factors, mainly habitat degradation, but also by other causes such as predation. Among potential predators, the Eurasian otter (Lutra lutra) is known to prey on some of these species, but the significance of the impact on their populations remains uncertain. To study the effect of the Eurasian otter on the small semi-aquatic mammal community, we collected feces containing hair remains from different rivers in the Iberian Peninsula and used genetic methods to identify the predator and prey species. We identified 83 Eurasian otter spraints containing 25 Iberian desmans (Galemys pyrenaicus), 21 Iberian water shrews (Neomys anomalus), and 28 Southern water voles (Arvicola sapidus). These prey species were recorded in different watersheds throughout the study area and over a long period of time, indicating their widespread presence in the otter diet. These findings are of particular concern for the Iberian desman, given its endangered status. Our results highlight the need to specifically investigate less abundant but ecologically significant groups consumed by the otter, such as semi-aquatic mammals, to better understand the influence of this predator on the riparian ecosystem. In addition, future efforts should address the genetic analysis of feces containing hair remains from different riparian carnivores to assess the impact of predation on the viability of semi-aquatic mammal populations.

Assessment of the Land Use/Land Cover Change in Koitobos River Catchment, Trans Nzoia County, Kenya

Globally, many countries are facing pressure to meet the livelihood needs of their fast-growing populations. This often leads to overuse of natural resources and consequent encroachment on fragile ecosystems such as river catchments and riparian areas mostly in developing countries. The objective of this study was to assess the implication of land use, land cover changes on surface water acreage in the Koitobos River catchment. Specifically, the study assessed the extent of land use/land cover changes with data being based on Landsat images pertaining to the period of study, 1992 - 2022. The research design used was correlations where the Google Earth Engine (GEE) and Remote sensing techniques were used for the analysis with in-depth review of journals and research reports. A sample size of 384 respondents, according to Krejcie, & Morgan as drawn from a target population of 203,821 residents within the study area. The survey data was analyzed using SPSS software version 25 and the Microsoft excel. The results were presented in form of frequencies, charts, maps, and tables. The findings of Land Use/Land Cover Change for the years 1995, 2009 and 2022, showed that Agricultural Land covered most of the study area with a cover of 26,853Ha, (58%), 32,438 Ha (70%), and 36,118Ha (77.68%) respectively. When transitioning through the years, thus shows drastic increased changes in area. This was followed by bare land area which covered an area of 14,915 Ha (32%), 8,093 Ha, (17%) and 6175 Ha (13.28%) for the years 1995, 2009, and 2022 respectively, of the entire catchment area which extremely decreased transitionally as the agricultural land increased due to the pressure exerted on the resource. The forest land showed a drastic decreasing trend through the transitional period from a cover of 2242 Ha (5%) to 1647 Ha (4%) and then 222 Ha (0.48%), due to an increasing demand for space by the growing population as depicted by the Kenya National Bureau of Statistics (KNBS) reports, which increasingly resulted to deforestation activities. The coverage for the agricultural land in the years 1995, 2009, and 2022 spread all over the area separated by patches of bare lands, water, and forests. The population of the study area in 2009, was 166,524 persons and 203,821 persons in 2019, within an area of 465.3 square Kilometers with residents’ density of 438.0 per square kilometer. The study found out that due to a 2% (percent) annual population change over the period 2009 to 2019, this resulted in an increased demand for food production and therefore concluded that environmental policies and laws needed to be adopted together with sustainable land management practices for healing and conserving biodiversity in Koitobos river catchment. The study therefore recommended the adoption of sustainable land use management practices that continually have the potential to heal the land and conserve biodiversity in Koitobos river catchment.

Temporal and spatial patterns of riparian vegetation in the Colastiné Basin (Argentina) and riparian ecological quality estimation as tools for water management

ABSTRACT Information on the riverbanks can improve our ability to monitor water quality and generate adequate management strategies. This research seeks insights into the riverbanks of eight Colastiné River Basin (Argentina) streams, which have been influenced by intensive agricultural land use for decades. We aim to (a) describe the temporal and spatial distribution patterns of riparian vegetation, (b) assess their current riparian quality through riverbank quality indices, and (c) estimate whether the riparian quality is linked to the water quality. Results of the Normalized Difference Vegetation Index (NDVI) showed an increasing trend in the vegetation cover with seasonal periodicities during the last 22 years in only 2 streams. Overall, 41% of plant species registered were exotic although native species dominated in most streams. The overall riverbank quality, based on the mean values of four riverbank quality indexes, was regular-to-bad. The overall water quality of the streams was low and significantly correlated to the Riparian Quality Index, suggesting a link between both compartments. More studies are needed to determine the main variables that establish this connection. Further effort is also needed to generate appropriate indices for this region, as no current ones are still developed.

Biomass yield potential, feedstock quality, and nutrient removal of perennial buffer strips under continuous zero fertilizer application

Abstract. Perennial-based buffer strips have been promoted as having the potential for improving ecosystem services from riparian areas while producing biomass as livestock feed or as a bioenergy feedstock. Both biomass production and nutrient removal of buffer strips are substantially influenced by the vegetation types for the multipurpose perennial buffers. In this 2016–2019 study in western Illinois, two perennial cropping systems, including forage crops composed of cool-season grass mixtures (forage system) and bioenergy crops made up of warm-season grass mixtures (bioenergy system), were used to establish buffer strips for assessing biomass production, feedstock quality, nutrient removal, and buffer longevity. Treatments for this study reflecting agronomic practices included (1) two harvests occurring in summer (at anthesis) and fall (after complete senescence) and (2) one harvest in fall for the forage system (two-cut vs. one-cut forage) and (3) one fall harvest for the bioenergy system (one-cut bioenergy). Successively harvesting without any fertilizer input resulted in a yield decline in forage biomass over 3 years by approximately 30 % (6.3 to 4.4 Mg DM ha−1 (dry matter) with a rate of 1.0 Mg ha−1 yr−1) in the two-cut forage and by 35 % (4.9 to 3.2 Mg DM ha−1 with a rate of 0.9 Mg ha−1 yr−1) in the one-cut forage systems. The feed quality also decreased over the years by showing declined rates of 12.9 (crucial protein), 0.9 (calcium), 0.7 (copper), and 1.3 g kg−1 DM yr−1 (zinc). Empirical models predicted enteric CH4 emissions from cattle ranged from 225.7 to 242.6 g per cow per day based on the feed nutritive values. In contrast, bioenergy biomass yield increased by 27 % from 4.9 to 6.7 Mg DM ha−1 with a consistent quality (cellulose of ∼ 397.9 g kg−1; hemicellulose of ∼ 299.4 g kg−1), corresponding to the increased total theoretical ethanol yield from 1.8 × 103 to 2.4 × 103 L ha−1 (∼ 33 % increase). Annual nutrient removals of N, P, K, Ca, and Mg were significantly higher in the forage systems (e.g., two-cut: 52.6–106.9 kg N ha−1; one-cut: 44.5–84.1 kg N ha−1) than those in the bioenergy system (e.g., 25.9–34.4 kg N ha−1); however, the removal rate declined rapidly over 3 years (e.g., ∼ 49 % reduction) as the annual biomass yield declined in the forage systems. This on-farm field study demonstrated the potential of the perennial crop used as buffer strip options for biomass production and buffer sustainability at the edge of the field.

Analyzing Monterrey blue/green infrastructure for the mitigation of heat islands using Earth Observation and WUDAPT method

Abstract. The Metropolitan Area of Monterrey has grown excessively along with its population in recent decades, resulting in an urban area with problems of distribution of spaces and services. In addition to this, factors such as pollution resulting from industrial activities and the reduction of green areas are related to the increase in temperatures in the area and the creation of urban heat islands, which are mitigated by the cooling action provided by the green/blue infrastructure of urban rivers. Because the rivers in the study area do not have a continuous channel throughout the year and the water supply problems that have recently worsened due to the drought in the north of the country, the riparian vegetation of its 3 rivers (Pesqueria, Santa Catarina and La Silla) plays a crucial role in reducing temperatures by acting as a natural heat sink, so its conservation and restoration is essential. In this research, the influence of rapid urbanization on the deterioration of rivers during 2003, 2013 and 2021 was evaluated using Google Earth Engine and the WUDAPT scheme for local climatic zones, finding that there is a correspondence between local climatic zones and fluctuations in temperature. The results obtained over a period of approximately two decades indicate that natural climate zones register lower temperatures compared to impervious surfaces, and that there is also considerable variation between areas with dense green/blue infrastructure and natural covers with little or no vegetation, since the latter have temperatures similar to those of the built classes.

Extreme rainfall events eliminate the response of greenhouse gas fluxes to hydrological alterations and fertilization in a riparian ecosystem

Riparian ecosystems are essential carbon dioxide (CO2) sources, which considerably promotes climate warming. However, the other greenhouse gas fluxes (GHGs), such as methane (CH4) and nitrous oxide (N2O), in the riparian ecosystems have not been well studied, and it remains unclear whether and how these GHG fluxes respond to extreme weather, fertilization and hydrological alterations associated with reservoir management. Here, we assessed the impacts of hydrological alterations (i.e., flooding frequency) and fertilization (nitrogen and/or phosphorus) induced by human activities (hydroengineering construction and agricultural activities) on GHG fluxes, and further investigated the underlying mechanisms in two contrasting years (normal vs. extreme rainfall years) in a reservoir riparian zone dominated by grasses. The significant combined effects of extreme rainfall events and human activities (hydrological alterations and fertilization) on the GHGs were observed. Continuous flooding reduced CO2 emissions by 24% but increased CH4 emissions by ∼4 times in a normal rainfall year. In addition, nitrogen fertilization promoted CO2 emissions by 37%. However, these phenomena were not observed in the year with extreme rainfall events, which made the flooding levels homogeneous across the treatments. Furthermore, we found that CO2 fluxes were driven by the soil moisture, nutrient content, aboveground biomass, and root carbon content, while CH4 and N2O fluxes were merely driven by the soil properties (pH, moisture, and nutrient content). This study provides valuable insights into the crucial role of extreme rainfall events, hydrological alteration, and fertilization in regulating GHG fluxes in riparian ecosystems, as well as supports the integration of these changes in GHG emission models.

A novel chitosan/biochar-modified eco-concrete with balanced mechanical, planting, and water purification performance for riparian restoration

The blocking between terrestrial and riverine ecosystems by impermeable concrete can cause negative impacts on plant growth, water quality, and biodiversity in riparian zones. Herein, pursuing a balance among mechanical, planting, and water purification property, chitosan/biochar-modified eco-concrete (CBEC) was prepared as a new sustainable alternative for riparian protection, ecological restoration and water quality improvement. Compressive strength of CBEC with an optimized chitosan/biochar content of 6% could reach up to 14.05 MPa, meeting the requirements for stabilizing riparian slopes. Micromorphology characterization and porosity measurement (29.63%) confirmed the abundantly porous structure of CBEC, facilitating the soil-water nutrient exchange, plant growth and microbial attachment. The 30-d water tank cultivation observed that the physiological parameters of T. orientalis planted in CBEC, including biomass, chlorophyll, protein and starch, were greatly improved compared to unmodified eco-concrete (EC). Moreover, compared to EC, biochar-modified EC and chitosan-modified EC, the planting CBEC could most effectively decrease the levels of TN, NH4+-N, TP, and COD by 53.82%, 62.50%, 88.31%, and 57.95%, respectively. Specially, the planting CBEC could degrade a common but recalcitrant pesticide nitenpyram (NTP) by 32.83% into low-toxic substances, recognized by LC-MS analysis. Microbiological analysis revealed that CBEC greatly promoted the proliferation of both nutrient-transforming bacteria (e.g., Nitrospira and Pseudomonas) and some specific species dominating NTP degradation (e.g., Rhodococcus and Bacillus). Also, PICRUSt2 prediction results identified the enrichment of functional genes related to nitrogen and phosphorus transformation. Our findings can not only develop a superior multi-performance eco-concrete material but also provide a promising strategy for sustainable riparian restoration.

Gut microbiota and antibiotic resistance genes in endangered migratory Scaly-sided merganser (Mergus squamatus) in northeast China

Studying the diversity of gut microbiota and antibiotic resistance genes (ARGs) in endangered migratory birds, as well as their responses to different environments, can reflect the health status of migratory birds and the ecological risk of ARG transmission. The globally endangered Scaly-sided merganser (Mergus squamatus) is a typical migratory bird, yet the diversity of its intestinal microbiota and ARGs has not been reported. In this study, fecal samples were collected from two major riparian foraging areas utilized by M. squamatus in the Changbai Mountains of China: the Lushui River and the Manjiang River. The gut microbiota and ARG composition were characterized using 16S rRNA amplicon and metagenomic sequencing. The results indicated that the relative abundance of gut microbiota in the two habitats differed significantly, but the core flora was similar. Moreover, the relative abundance of pathogenic bacteria was high, suggesting that M. squamatus faces a high risk of disease. A total of 382 ARGs were identified, which were primarily resistant to multidrug, tetracycline, macrolides-lincosamides-streptogramins, and mupirocin. MsbA, abcA, rpoB2, and tetT were the most abundant shared ARGs between the two sites. The findings demonstrate that habitat influences the diversity of gut microbiota and ARGs in the endangered migratory M. squamatus. This species could serve as a reservoir for pathogenic bacteria and ARGs. Therefore, monitoring the diversity of gut microbiota and ARGs in M. squamatus across different habitats is essential for a comprehensive assessment of its health status and the ecological risk of ARG transmission in the future.

Water Temperature Model to Assess Impact of Riparian Vegetation on Jucar River and Spain

Water temperature is a critical factor for aquatic ecosystems, influencing both chemical and biological processes, such as fish growth and mortality; consequently, river and lake ecosystems are sensitive to climate change (CC). Currently proposed CC scenarios indicate that air temperature for the Mediterranean Jucar River will increase higher in summer, 4.7 °C (SSP5-8.5), resulting in a river water temperature increase in the hotter month; July, 2.8 °C (SSP5-8.5). This will have an impact on ecosystems, significantly reducing, fragmenting, or even eliminating natural cold-water species habitats, such as common trout. This study consists of developing a simulated model that relates the temperature of the river with the shadow generated by the riverside vegetation. The model input data are air temperature, solar radiation, and river depth. The model proposed only has one parameter, the shadow river percentage. The model was calibrated in a representative stretch of the Mediterranean river, obtaining a 0.93 Nash–Sutcliffe efficiency coefficient (NSE) that indicates a very good model fit, a 0.90 Kling–Gupta efficiency index (KGE), and a relative bias of 0.04. The model was also validated on two other stretches of the same river. The results show that each 10% increase in the number of shadows can reduce the river water temperature by 1.2 °C and, in the stretch applied, increasing shadows from the current status of 62% to 76–87% can compensate for the air temperature increase by CC. Generating shaded areas in river restorations will be one of the main measures to compensate for the rise in water temperature due to climate change.

Co‐production of a vulnerability assessment for aquatic and riparian ecosystems in the southwestern United States

AbstractTo address impacts of climate change and other stressors on stream ecosystems, managers must prioritize resources and locations for conservation actions to facilitate effective cross‐boundary solutions. Through a science management partnership, we co‐produced a spatially explicit landscape assessment framework for cold‐water fish habitat and riparian corridors in three large watersheds of the southwestern United States. Using literature review and stakeholder workshops, we developed indicators of vulnerability and built spatial datasets depicting areas of low to high vulnerability based on exposure, sensitivity, and adaptive capacity for each resource. We found that, in general, vulnerability was greater for cold‐water fish habitat than for riparian corridors. The Little Colorado River and San Juan River watersheds had the highest percentages of subwatersheds with high vulnerability of cold‐water fish habitat. Conversely, the Upper Rio Grande watershed had the highest percentage with high vulnerability of riparian corridors. Assessments like ours facilitate the management of water resources at the scale of watersheds or river basins and incorporate physical characteristics, land‐use history, current management practices, and status of imperiled species into actionable management plans.

The RARCrec: A rapid riparian vegetation assessment method for use in river systems undergoing vegetative and geomorphic recovery

SummaryMonitoring the condition of returning vegetation over time is essential for effectively managing riparian vegetation. Rapid riparian assessment methods are standard tools for capturing a suite of variables relevant to river health and are accessible to a range of users with different levels of experience. Monitoring efforts are particularly important for rivers undergoing degrading impacts and subsequent management interventions. In coastal catchments of New South Wales, Australia, vegetation is returning to rivers that were historically cleared for agriculture and are now experiencing geomorphic recovery. We present a rapid riparian assessment method for rivers undergoing vegetative and geomorphic recovery in this region. It addresses a gap in available rapid assessments by providing a methodology that can be used at sites with no historical analogue. Our assessment method adapts and extends a widely used method called the Rapid Assessment of Riparian Condition (RARC) to capture the quality of returning riparian vegetation along recovering rivers (rec), including native species diversity and vegetation structure (hence the name RARCrec). The RARCrec incorporates four sub‐indices – vegetation cover, native species richness, proportion of native to exotic species, and features of vegetation health – to produce an overall vegetation condition score that classifies sites as poor, moderate, or good condition. Scores for each sub‐index are assessed for the vegetation strata (groundcover, graminoids, midstorey, vines, and canopy) on the landform units of river bars, benches, and floodplains. The RARCrec has been designed to be sufficiently general for use in the main Vegetation Formations in coastal New South Wales and has been trialled at 36 sites across this region. Assessments can be conducted within half a day by two technically competent users and can be used to monitor vegetation condition over time to inform where to prioritise implementation of management activities. Field methodology and data sheets, including a scoring system, are provided to support the implementation of the RARCrec.

Relative potential for stand persistence of riparian and upland aspen stands of a semi-arid montane landscape of the Southern Rocky Mountains

Several studies have predicted a loss of quaking aspen (Populus tremuloides) from many western landscapes, but other studies have suggested that aspen persistence is driven by local site factors. Increased frequency of acute drought has been implicated as an important factor driving overstory mortality and reduced regeneration densities in the region. We investigated the relationship between aspen regeneration and site moisture availability potential using ecosystem type as a proxy. We hypothesized that aspen stands growing along perennial-flowing streams would support higher aspen regeneration densities than upland aspen stands. We compared stand structure, groundcover composition, and regeneration densities of nine riparian aspen stands with nine paired upland aspen stands in the Caribou-Targhee National Forest. Aspen regeneration densities were significantly higher in the riparian aspen stands (845. 3 + 318.7 stems ha-1) compared to the upland aspen stands (249.1 + 74.1 stems ha-1) for regeneration shorter than one meter (p = 0.0391). Riparian stands also exhibited significantly higher forb (p< 0.001) and graminoid (p < 0.001) cover compared to upland aspen stands, suggesting that riparian sites provided higher site moisture availability. We suggest that riparian areas may provide refugia for aspen in the future considering projections of increased incidence of acute drought.

Drivers of Spatiotemporal Patterns of Riparian Forest NDVI Along a Hydroclimatic Gradient

ABSTRACTIn the context of rising global temperatures and their impact on weather patterns and water cycles, understanding the relationship between vegetation and hydroclimatic forcing is critical. Riparian forests are highly vulnerable to hydroclimatic variability, which can significantly affect water availability in the soil on which they primarily depend. Along large rivers, hydroclimatic forcings can vary, resulting in different vegetative responses depending on the local climatic context and site conditions. To explore this, we studied riparian forest greenness along a 512‐km river corridor with a 3° latitudinal gradient, analysing the relative contributions of climate (latitude, season, temperature, precipitation) and local hydrological conditions (groundwater). Here, we show that riparian forests along a latitudinal gradient respond differently to hydroclimatic controls, with vegetative dynamics that can be attenuated or accentuated by local site conditions. We combined Sentinel‐2 satellite Normalised Difference Vegetation Index (NDVI) data over seven years (2016–2022) with hydroclimatic data to examine riparian forest greenness responses to latitudinal, seasonal and interannual hydroclimatic variability. We found contrasting hydroclimatic controls across the latitudinal gradient, with the northernmost sites predominantly controlled by temperature, while those further south are limited by water availability. In addition, we identified temperature as the primary driver of NDVI throughout the growing season, either positively or negatively. Late season precipitation and high phreatic water availability positively influenced NDVI, emphasising the role of local conditions in governing riparian forest resilience. This study enhances understanding of climate controls on riparian tree greenness, which is critical for designing effective landscape‐scale riparian ecosystem management and restoration strategies.

Habitat Utilization of Endemic Green Pit Viper (<i>Peltopelor trigonocephalus</i>) in the Wet Zone, Sri Lanka

The endemic arboreal pit viper Peltopelor trigonocephalus is restricted to three climatic zones of Sri Lanka. In this study, the habitat utilization of P. trigonocephalus was investigated by active search and the quadrate method between April 2021 and March 2022. Data on 49 individuals of P. trigonocephalus were collected from riparian, forest, and open habitats. A high encounter rate was recorded in riparian habitats which included areas with thick vegetation. Based on Principal Component Analysis, some habitat variables were key determining factors of microhabitat preference of this species. Ambient temperature, distance to stream, canopy cover and light intensity were significantly affecting the occupied microhabitat structure. Ambushing behavior was more prominent and time-consuming than other behaviors, with 42.59% of recorded sit-and-wait hunting activity. The results of this research indicate that P. trigonocephalus actively selects and utilizes the most suitable macro and microhabitats in wet zones, providing crucial insights for the conservation and management of the species as well as its natural habitat.

Local heterogenisation and regional homogenisation linked to habitat loss induced by dams in riparian forests of the Brazilian Atlantic Forest

Riparian forests are crucial for biodiversity, but dam construction for hydroelectric power disrupts these ecosystems, causing habitat loss and altering river dynamics. Our study investigates the impacts of dams on tree diversity in the southern Brazilian Atlantic Forest. We sampled trees along riverbanks and uplands across 15 dam-affected fragments, analysing the relationship between habitat loss (i.e. loss of riparian zones by permanent flooding due to dam filling), elevation difference, fragment size, and dam implementation time with alpha and beta diversity using mixed models and redundancy analyses. Habitat loss had a more significant impact on beta diversity, leading to shifts in species composition and reduced uniqueness of communities as the impact’s intensity, spatial extent, and duration increased. Alpha diversity only increased in response to local elevation differences between plots located on uplands and riverbanks. Our sampling design can be applied to other inadequately monitored systems to provide insights into beta diversity, a component often neglected in dam licensing and mitigation processes. Our findings reveal a transient local heterogenisation, transitioning into regional homogenisation due to dam-induced habitat loss in riparian forests of the Brazilian Atlantic Forest.

Ecological Environment Assessment System in River–Riparian Areas Based on a Protocol for Hydromorphological Quality Evaluation

This paper aims to propose a method for the evaluation of the hydromorphological quality of a river and its riparian areas using three essential components: morphological characterization, river connectivity, and vegetation coverage. The method has been applied to the Tordera river in Catalonia, Spain. The general goal is to establish a riparian environment assessment tool by proposing parameters for each of the three mentioned aspects. This approach relies on data collection and evaluation with a simple computational procedure for eliminating subjectivity in the weighting and classification of evaluation levels. In the proposed methodology, the weights of the indicators are determined by the Distance Correlation-Based CRITIC (D-CRITIC) method, and the results are integrated using the Coupling Coordination Degree Model (CCDM). The proposed methodology quantifies assessment parameters and analyzes the environmental problems faced by riparian zones and rivers through the parameters and the results of the CCDM and thus can be used as a basis for proposing methods to improve the ecological situation. The results can be used for the enhancement of the coordination between the development of riparian resources and the requirements of ecosystem protection and utilization, and they can be used to promote the healthy development of ecological environments and the effective use of riparian resources.

Groundwater-surface interaction amplified post-seismic streamflow fluctuation

Following the 2014 South Napa earthquake near the end of a long drought in Central California, streamflow in Sonoma Creek increased and showed amplified daily fluctuation. However, no such changes occurred in the shallow groundwater. Here we show that the amplified fluctuation reflected increased interaction between the post-seismic rising water table and plant roots in the riparian zone, according to results from numerical simulation constrained by streamflow data and hydraulic properties of riparian sediments. Evapotranspiration during the day kept the water table low beneath the riparian zone, lowering the discharge to the stream. At night, the water table rose and increased discharge to the stream. The study also show substantial spatial difference in earthquake-induced interactions between groundwater and the surface, which may influence our understanding of the spatial scale of earthquake impacts on vegetation and ecosystems.

Revisiting the epidemiological role of a native vector in Northern California vineyards

Abstract Effective disease management hinges on an accurate understanding of the ecological and epidemiological underpinnings of the pathosystem. New epidemics may prompt consideration of whether knowledge gaps or changes to the pathosystem warrant revision of management strategies. Pierce’s disease of grapevines is highly episodic in coastal Northern California vineyards, with modest incidence in most years punctuated by occasionally severe epidemics. To better understand what was driving a developing epidemic in the region, we revaluated what is known about the ecology and epidemiological role of the dominant vector, the blue-green sharpshooter Graphocephala atropunctata. We monitored vector spatiotemporal dynamics at 32 vineyards over three years, surveyed plant community composition in the adjacent habitat to understand its link to vector recruitment, and quantified patterns of natural infectivity for the pathogen Xylella fastidiosa. Overall, the results were consistent with past studies of G. atropunctata ecology. For example, the scale of dispersal from source habitat and seasonal patterns in activity were generally similar to those documented in prior studies. The results also confirmed the influence of adjacent plant community composition on G. atropunctata activity in vineyards, and the role of riparian habitat and select plant taxa as vector sources. Nonetheless, further consideration of the epidemiological significance of certain features of the pathosystem may be warranted, especially those related to seasonality in X. fastidiosa infection in vectors. A marked increase in infected G. atropunctata late in the season likely reflects pathogen acquisition from infected grapevines, which may have implications for disease management strategies.

The role of nitrogen and iron biogeochemical cycles in the production and export of dissolved organic matter in agricultural headwater catchments

Abstract. To better understand the seasonal variations in environmental conditions regulating dissolved organic matter (DOM) export in agricultural headwater catchments, we combined the monitoring of nitrate, iron, soluble phosphorus, and DOM concentration (as dissolved organic carbon; DOC) and composition (3D fluorescence) in soil and stream waters at regular intervals during 1 hydrological year. We installed 17 zero-tension lysimeters in organic-rich top soil horizons (15 cm below the surface) in the riparian area of a well-monitored agricultural catchment in French Brittany and collected them at a fortnightly frequency from October 2022 to June 2023. We observed a large increase in DOC concentrations in soil waters during the high-flow period linked to the establishment of Fe-reducing conditions and the subsequent release of DOM. We also noted that the timing and the spatial variability in Fe(II) biodissolution in soils was regulated by nitrate from agricultural origin and the heterogeneity of water flow paths at the hillslope scale. Contrary to our current understanding of DOM export in headwater catchments, these results lead us to consider the winter high-flow period as an active phase of both DOM production and export.