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Anthropogenic and climatic changes are continuously altering the freshwater plankton, necessitating an evaluation of the complex structure of plankton communities to understand and mitigate these impacts. In this context, the present study focuses on evaluating the structure of plankton communities, specifically Phytoplankton Functional Groups (FGs) for assessing the environmental sensitivity of wetlands under changing scenario. These FGs are defined by shared adaptive features rather than taxonomic traits. Over the period from 2016 to 2018, two ecologically distinct wetlands were examined, analysing their phytoplankton FGs and their relationship with water quality parameters. Ecohydrological data revealed significant seasonal variations (p ≤ 0.05) in key parameters such as water depth, temperature, pH, electrical conductivity, dissolved oxygen, total alkalinity, total hardness, NO3-N, and PO4-P. Notably, there were no significant differences observed among the sampling stations within each wetland. A total of 125 phytoplankton genera/species were classified into 23 FGs in the open wetland and 22 FGs in the closed wetland. Spatial and seasonal analyses of dominant FGs suggested both wetlands were experiencing pollution pressures. This study highlights the powerful role of phytoplankton functional groups (FGs) as bioindicators of wetland health, uncovering pollution pressures. In open wetlands, 15 phytoplankton FGs with 36 key taxa (Indicator Value ≥ 40%) emerged as critical indicators, while in closed wetlands, only 10 FGs with 17 taxa were identified. To assess eutrophication, the occurrence of these indicator species was evaluated using BVSTEP function analysis. The study recommends pollution reduction in catchment areas and restoration of riverine connectivity to enhance FG diversity. Phytoplankton FG methodologies are deemed effective for assessing the environmental sensitivity of wetlands significantly impacted by human activities. This research offers a scientific foundation for the evaluation and restoration of wetland ecosystems. Highlights: Phytoplankton functional groups (FGs) serve as precise bioindicators of wetland environmental sensitivity and pollution pressures. Seasonal and spatial assessments of water quality reveal insights into wetland ecological health. The response of phytoplankton FGs to environmental factors effectively indicates water quality. Key plankton species were identified as indicators of wetland ecological sensitivity. [ABSTRACT FROM AUTHOR]

Fog is an important water source that alleviates vegetation water stress, especially for dryland ecosystems. Comprehensive knowledge of fog and rainfall effects can help us better understand dryland vegetation responses to current and future climates. However, the differences between fog and rainfall effects on vegetation are poorly understood. This study compared the effects of fog and rainfall on vegetation greenness changes based on the ground‐level meteorological observations in the Namib Desert and the satellite vegetation index. The vegetation index and its first derivative were utilized to indicate vegetation greenness and its change rate, respectively. Results showed that fog played a more significant role than rainfall in explaining vegetation greenness change rates, while accumulated rainfall was more important than fog in determining vegetation greenness. Soil temperature was an important factor in explaining vegetation greenness changes. These findings offer key insights into how fog and rainfall differentially contribute to vegetation greenness changes. Plain Language Summary: Dryland plant significantly impacts the global carbon budget, making up about 40% of global net primary productivity. The importance of fog on dryland productivity is highlighted since plant growth in dry areas is strongly constrained by water resources. This study showed that fog consistently appeared among the top five most critical factors in explaining variations in plant greenness and its change rates for both herbaceous and woody areas. Notably, it was found that plant greenness change rates were more influenced by fog than rainfall, although plant greenness was more sensitive to accumulated rainfall than fog. Soil temperature consistently showed large effects on plant greenness changes, potentially limiting plant growth in the context of future global warming. Key Points: The first study to simultaneously quantify the effects of fog and rainfall on vegetation greenness changes in a dryland ecosystemFog was more important than rainfall in explaining vegetation greenness change ratesSoil temperature played an important role in vegetation greenness changes with a negative effect [ABSTRACT FROM AUTHOR]

The Pra River Basin in Ghana is a major source of ecological, cultural, and economic benefits. However, it has been experiencing degradation, and logistical constraints have limited the implementation of Integrated Water Resources Management. This study presents a GIS-based ecohydrological risk model that identifies ecohydrological units with the highest degradation risk. First, the PRB was divided into 25 eco-hydrological units. Second, seven drivers of degradation were identified and mapped. The drivers were reclassified into five categories with risk scores of 1–5, with 5 indicating higher risk scores. The variables were ranked using the Analytical Hierarchy Process, the degradation risk model was calculated using the weighted sum method, and the multi-criteria decision tool was used to identify the ecohydrological units with the highest degradation risk. Of the 25 ecohydrological units delineated, the Buama, Lower Offin, Ayensu, and Oda ecohydrological units were found to be at the highest risk of degradation due to high artisanal small-scale gold mining, high population density, low forest/vegetation cover, and high encroachment in waterways. The results can be used as a guide to prioritize management intervention, starting with the areas classified as high risk and moving down to those classified as moderate risk. [ABSTRACT FROM AUTHOR]

This study investigates the influence of bark properties on nutrient fluxes in urban environments, focusing on the relationship between bark wettability, chemical composition, and the concentrations of nutrients in stemflow and adjacent soil across eight urban tree species. Through a comprehensive analysis involving chemical assays and ecohydrological measurements, we explored how variations in bark characteristics affect water interaction and subsequent chemical dynamics within urban landscapes. Contrary to the initial hypothesis that bark properties would significantly influence nutrient flux, results revealed a complex scenario where environmental and anthropogenic factors in urban settings seemingly overshadow the direct impact of bark characteristics on nutrient dynamics. Our findings indicate that while bark properties such as wettability and chemical composition do vary among tree species, these variations do not directly correlate with significant differences in stemflow or soil nutrient concentrations. This suggests a homogenising effect of urban environments on ecohydrological processes, highlighting the need for a broader understanding of urban forest ecology that incorporates both biological traits and urban‐specific environmental influences. This research contributes to the field of urban ecohydrology by underscoring the complexity of nutrient fluxes in urban forests and suggesting that effective urban tree management requires an integrated approach that considers the interplay between tree physiological traits and urban environmental conditions. Our study calls for further research to unravel the intricate dynamics of urban ecosystems, aiming to enhance the sustainability and ecological benefits of urban forests. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms and patterns of runoff generation in watersheds is fundamental to building hydrological and soil erosion models. It also provides important guidance for watershed water resources management and rational utilization. In order to reveal the in- fluence of vegetation restoration on the runoff production mechanism and model of the Loess Plateau, the Dongzhuanggou watershed, which is dominated by natural grassland restoration, and the Yangjiagou watershed, which is dominated by afforestation restorationin in the gullied loess plateaus were taken as research areas. The flood process lines and regression curves of two contrasting small catchments under different rainfall types were analyzed, and the change of runoff production pattern in the gullied region of loess plateau under vegetation restoration was studied. The results indicate that with the restoration of the watershed's vegetation and its eco-hydrological functions in these small water- sheds, annual runoff generation capacity decreases, while water retention capacity increases. Vegetation restoration effectively reduces peak flow and prolongs flood duration, especially the recession period of the flood, thereby achieving the effect of flood mitigation. Under the influence of vegetation restoration, the runoff generation pattern tends to shift from the traditional infiltration-excess runoff pattern to a shallow sub- surface saturation runoff pattern. This change demonstrates that vegetation restoration can effectively mitigate floods and thus play a significant role in flood control and disaster reduction. Additionally, it can efficiently transform generalized precipitation resources into soil water and interflow, regulate the seasonal distribution of streamflow, increase ecological water use, and promote the healthy and stable development of vegetation ecosystems in semi-arid areas. [ABSTRACT FROM AUTHOR]

Terrestrial water fluxes are substantially mediated by vegetation, while the distribution, growth, health, and mortality of plants are strongly influenced by the availability of water. These interactions, playing out across multiple spatial and temporal scales, link the disciplines of plant ecophysiology and ecohydrology. Despite this connection, the disciplines have provided complementary, but largely independent, perspectives on the soil‐plant‐atmosphere continuum since their crystallization as modern scientific disciplines in the late 20th century. This review traces the development of the two disciplines, from their respective origins in engineering and ecology, their largely independent growth and maturation, and the eventual development of common conceptual and quantitative frameworks. This common ground has allowed explicit coupling of the disciplines to better understand plant function. Case studies both illuminate the limitations of the disciplines working in isolation, and reveal the exciting possibilities created by consilience between the disciplines. The histories of the two disciplines suggest opportunities for new advances will arise from sharing methodologies, working across multiple levels of complexity, and leveraging new observational technologies. Practically, these exchanges can be supported by creating shared scientific spaces. This review argues that consilience and collaboration are essential for robust and evidence‐based predictions and policy responses under global change. Summary statement: Ecophysiology and ecohydrology share an interest in plant–water interactions but have largely developed and operated along distinct paths. We review the development of these fields and difficulties that emerged and argue how greater consilience can address pressing challenges under global change. [ABSTRACT FROM AUTHOR]

Accurate evapotranspiration (ET) estimation is crucial for sustainable water management in the diverse and water-scarce Mediterranean region. This study compares three prominent models (Simulator of Terrestrial Ecohydrological Processes and Systems (STEPS), Soil-Canopy-Observation of Photosynthesis and Energy fluxes (SCOPE), and Two-Source Energy Balance (TSEB)) with established global datasets (Moderate Resolution Imaging Spectroradiometer 8-day global terrestrial product (MOD16A2), Global Land Evaporation Amsterdam Model (GLEAM), and TerraClimate) at multiple spatial and temporal scales and validates model outcomes with eddy covariance based ground measurements. Insufficient ground-based observations limit comprehensive model validation in the eastern Mediterranean part (Turkey and Balkans). The results reveal significant discrepancies among models and datasets, highlighting the challenges of capturing ET variability in this complex region. Differences are attributed to variations in ecosystem type, energy balance calculations, and water availability constraints. Ground validation shows that STEPS performs well in some French and Italian forests and crops sites but struggles with seasonal ET patterns in some locations. SCOPE mostly overestimates ET due to detailed radiation flux calculations and lacks accurate water limitation representation. TSEB faces challenges in capturing ET variations across different ecosystems at a coarser 10 km resolution. No single model and global dataset accurately represent ET across the entire region. Model performance varies by region and ecosystem. As GLEAM and TSEB excel in semi-arid Savannahs, STEPS and SCOPE are better in grasslands, croplands, and forests in few locations (5 out of 18 sites) which indicates these models need calibration for other locations and ecosystem types. Thus, a region-specific model calibration and validation, sensitive to extremely humid and arid conditions can improve ET estimation across the diverse Mediterranean region. [ABSTRACT FROM AUTHOR]

The gradual accumulation of phosphorus from historical fertilization can contribute to the eutrophication of surface waters by increasing the potential for subsurface leaching losses. Grazing lands areas are a priority for concern, and phytoremediation efforts in grazing lands have prioritized grasses that may be used as forage for cattle. This study investigated the influence of three different forage species—Paspalum notatum, Hemarthria altissima, and Cynodon nlemfuensis—on the loss of phosphorus in leachate from surface soils. The experiment used a nested pot mesocosm design that allowed us to monitor leachate volume and concentration biweekly over the course of 3 months. Pots containing P. notatum plants leached significantly more phosphorus than pots containing C. nlemfuensis or empty pots with no plants growing in them, despite losing an equivalent amount of water. H. altissima lost equivalent amounts of phosphorus in leachate water, but each H. altissima plant removed approximately 33.6 mg of phosphorus, approximately 2.5× that removed by P. notatum (13.4 mg). C. nlemfuensis had lower average leachate phosphorus concentrations at each biweekly sampling than either plant species (C. nlemfuensis‐P. notatum, padj = 0.001; C. nlemfuensis‐H. altissima, padj = 0.02), averaging only 0.110 ppm in leachate relative to 0.175 ppm and 0.200 ppm in pots beneath H. altissima and P. notatum, respectively. This, combined with C. nlemfuensis' slightly higher‐than‐average aboveground P content and overall aboveground biomass expression suggest it is the best possible phytoremediation candidate. As even minor leachate P loads can be critically threatening to neighboring oligotrophic water bodies, if the conservation of downstream environments is the priority, the short‐term threat of increased leachate must be considered. Further research is needed to explore the underlying mechanisms and field‐scale implications of these findings. [ABSTRACT FROM AUTHOR]

This review meticulously examines the dynamics of river microbiomes, with an emphasis on the Ganges and Yamuna rivers of South Asia. These rivers are vital for both ecological and cultural landscapes and offer to understand the interaction between ecological and anthropogenic factors and their impact on microbial communities and activities. Ecological and hydrological factors such as seasonal changes, water flow and physico‐chemical properties of rivers influence microbial diversity and abundance. The effect of heavy metals from industrial and agricultural sources on the river microbiome and how these pollutants modify microbial community structures and ecosystem health are not understood well yet. This underscores the need for sustainable water treatment and remediations for practical engineering solutions. The study reveals how these interactions, whether symbiotic or competitive, affect the composition and functionality of riverine microbial communities. An innovative aspect of our research is the potential of river microbiomes as indicators of urban sewage contamination. We demonstrate how microbial patterns can signal pollution levels, proving valuable for environmental monitoring, management and mitigation. A special attention to the role of microbes in river ecosystems' biogeochemical cycles has been paid to how these microbes contribute to nutrient recycling, organic matter decomposition and overall ecosystem productivity, underlining their crucial role in maintaining the aesthetic value of the river. Additionally, study evaluates the latest methodologies for analysing microbiome metagenomic data, including functional annotation and microbial community analysis techniques. Findings highlight the key importance of understanding river microbiomes for hydrology, ecology and microbiology researchers. [ABSTRACT FROM AUTHOR]

Context: Published evidence suggests recruitment of floodplain trees is declining in the northern Murray–Darling Basin (MDB) and that this is linked to river flow. Aims: We investigated the reproductive phenology of Eucalyptus camaldulensis and Eucalyptus coolabah to better understand tree reproductive cycles and the influence of rainfall and flow on seed production. Methods: We surveyed phenological events (bud, flower and fruit production) over 6 years, at nine sites along the Condamine–Balonne River and examined correlations between these events and meteorological parameters. Key results: For both species, event timing was consistent across sites and years and event relative abundance scores were different between years. Bud abundance was correlated with rainfall, flooding and warming temperatures and E. coolabah produced additional bud crops after floods. Conclusions: The timing of events did not differ significantly from published results for the southern MDB. Rainfall, river flows and flooding in spring resulted in more abundant bud crops in E. camaldulensis and E. coolabah , and subsequently more abundant fruit crops. Fruit dehiscence coincided with summer–autumn flooding, which provides seed for germination. Genetic and physiological factors may also influence the observed pattern. Implications: These results will inform water planning in Queensland, Commonwealth Environmental Water Holder watering actions and long-term watering plans in the northern MDB. Eucalyptus camaldulensis and Eucalyptus coolabah are floodplain trees found in the Murray–Darling Basin (MDB). This long-term study observed the timing and abundance of buds, flowers and fruits at sites in the northern MDB and looked for patterns that would indicate the influence of river flows. Bud abundance, canopy seed storage and seed fall were influenced by moisture availability in both species. Image credit: J. L. Kerr. This article belongs to the collection Environmental flows in northern Murray–Darling Basin: what we know about the science and management after a decade of practice. [ABSTRACT FROM AUTHOR]

Climate warming and permafrost thaw induced land cover change are well documented in much of the circumpolar north. The extensive exposure of Precambrian continental crust in Canada's Taiga Shield ecoregion could mean impacts of land cover change documented in other regions without this feature are not transferable. This study examined energy partitioning with eddy covariance measurements, vegetation water use with stable isotopes and soil water state with time domain reflectometry sensors in conifer stands in the Taiga Shield ecoregion. The goal was to determine how changes in forest density with climate warming could influence water budget response and soil water state. Paired measurements of sensible and latent heat imply evaporative processes in denser canopies are controlled more by radiative than the aerodynamic factors predominant in sparser canopies. As denser canopies become more prevalent on the landscape, this switch in relative importance of evapotranspirative processes will lead to a reduction in inter‐annual variability of evapotranspiration. The dominant tree species (black spruce, tamarack and jack pine) were all quick to draw water from shallow soils after spring thaw and rainfall. Stand structural changes resulted in older, more evaporatively enriched water prevalent in soils below dense canopies. While there is evidence for forest infilling, widespread lakes and exposed bedrock restricts extensive expansion of forested land covers. The insufficient difference between sparse and dense canopy evapotranspiration suggest a fundamental change in how water cycles in Taiga Shield catchments is unlikely, which is notably different than previously investigated landscapes in Alaska and the Canadian Taiga Plains. Key Points: Evapotranspiration becomes less sensitive to precipitation variability as canopy density increases in Taiga Shield forestsTaiga vegetation tends to draw younger less evaporatively enriched soil water, and denser forests tend to have older more evaporatively enriched water in soils by the end of the growing seasonIncreased forest cover is not expected to change catchment water cycles because open water and exposed bedrock restrict tree expansion [ABSTRACT FROM AUTHOR]

The critical role of macrophytes in aquatic environments cannot be overstated, but little attention has been paid to macrophytes in Moroccan rivers. This study aims to investigate the environmental factors that affect the presence and distribution of macrophytes in the Hydrological Basin of Sebou (HBS) in Morocco. The study focused on 39 hydrological stations, distributed across the five hydro‐ecoregions of the basin. The results show that the number of aquatic species is limited and significantly lower than that of riparian species, which are more diverse. Analysis of similarity (ANOSIM) revealed that there is a significant difference in the riparian species communities between the various hydro‐ecoregions (R = 0.1853, Bonferroni corrected α = 0.0022). However, when only aquatic species were considered, ANOSIM showed no significant difference (R = 0.05524, Bonferroni corrected α = 0.1453), and the results were confirmed by the PERMANOVA test. Furthermore, ANOSIM did not reveal a clear difference in the composition of aquatic species between stations with low and high nutrients (R = 0.01348, p = 0.4245). The Student's t‐test also showed no significant difference in the variation of riparian and aquatic species numbers between the two groups (all species combined: t = 0.1639, p = 0.8723; riparian species: t = 0.4740, p = 0.6434; aquatic species: t = 0.9869, p = 0.3417). These findings highlight the need for further research into environmental factors limiting aquatic species diversity and nutrient thresholds affecting macrophyte abundance. Understanding these elements is crucial for addressing species distribution constraints and elucidating nutrient dynamics that influence macrophyte populations, enriching ecosystem management and conservation strategies. [ABSTRACT FROM AUTHOR]

Because of the confluence of human activities and climate change, the hydrological regime in the Han River basin has substantially evolved, necessitating a multi‐faceted, quantitative analysis of the causative factors. Employing cross‐wavelet analysis, we examined nonlinear relationships between runoff and meteorological variables. Additionally, we assessed hydrological indicators via the IHA index and RVA, then quantified the drivers of runoff variations across different time scales using the Budyko hypothesis and a Generalized Regression Neural Network (GRNN) model. The findings reveal the presence of sustained resonance periods within the climate‐runoff system, notably concentrated in 9‐ to 15‐month intervals during the years 1985–1994, 1995–2012, and 2014–2018, with a confidence level of 95%. Overall, the basin exhibited moderate change (41.66%), with 15 indicators displaying varying degrees of moderate to high transformation. These shifts underscore significant ecosystem transformations. The influence of driving factors on runoff varies across temporal scales. On an annual scale, human activities predominantly shape runoff changes (52.35%), while meteorological factors contribute significantly (47.65%). Conversely, at the monthly scale, climate change emerges as the dominant influence on runoff patterns in June and September, with human activities maintaining a principal role in other months, notably exceeding 90% even in November. [ABSTRACT FROM AUTHOR]

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The Hailar River is located in the Inner Mongolia Autonomous Region of Northeast China. It is a connecting hub of the agricultural pastoral transitional zone on the Hulunbuir grassland, with abundant water and biodiversity resources, and important ecological conservation significance. This study takes the Hailar River as the research area to evaluate the impact and main influencing factors of soil C, N, and P ecological measurement from the upstream to downstream concave convex riverbanks of the Hailar River. The research results show that: (1) The average soil particle size shows differences in the upstream and downstream: the average soil particle size in Section 1 is 31.6–192.3 µm, Section 2 is 21–213 µm, Section 3 is 21–288 µm, and Section 4 is 42–206 µm; the pH value in the upstream area is generally low, while the pH value in the downstream area increases. The reason for this is that the convex bank area has sufficient water, which plays a role in inhibiting salt content; (2) the nutrient content in the concave bank is generally higher in the upstream region than in the downstream region, while the difference in nutrient content between the upstream and downstream regions is relatively small in the convex bank; (3) the nutrient content of concave banks is mostly positively correlated with soil moisture content, while convex banks are positively and negatively correlated with soil moisture content and soil particle size. Research has shown that different cross-sections upstream and downstream, as well as uneven riverbanks, significantly affect soil physicochemical properties and soil C, N, and P ecological measurements. Studying the content of soil C, N, and P in different riparian zones under typical cross-sections can provide new ideas for regional ecological protection and even global C, N, and P cycling. [ABSTRACT FROM AUTHOR]

Peatland restoration and rehabilitation action has become more widely acknowledged as a necessary response to mitigating climate change risks and improving global carbon storage. Peatland ecosystems require restoration time spans of the order of decades and, thus, cannot be dependent upon the shorter-term monitoring often carried out in research projects. Hydrological assessments using geospatial tools provide the basis for planning restoration works as well as analysing associated environmental influences. "Restoration" encompasses applications to pre-restoration and post-restoration scenarios for both bogs and fens, across a range of environmental impact fields. The aim of this scoping review is to identify, describe, and categorize current process-based modelling uses in peatlands in order to investigate the applicability and appropriateness of ecohydrological and/or hydrological models for northern peatland restoration. Two literature searches were conducted using the entire Web of Science database in September 2022 and August 2023. Of the final 211 papers included in the review, models and their applications were categorized according to this review's research interests in seven distinct categories aggregating the papers' research themes and model outputs. Restoration site context was added by identifying 229 unique study site locations from the full database, which were catalogued and analysed against raster data for the Köppen–Geiger climate classification scheme. A majority of northern peatland sites were in temperate oceanic zones or humid continental zones that experienced snow. Over one in five models from the full database of papers were unnamed and likely intended for single use. Key themes emerging from topics covered by papers in the database included the following: modelling restoration development from a bog growth perspective, the prioritization of modelling greenhouse gas (GHG) emissions dynamics as a part of policymaking, the importance of spatial connectivity within or alongside process-based models to represent heterogeneous systems, and the increased prevalence of remote sensing and machine learning techniques to predict restoration progress with little physical site intervention. Models are presented according to their application to peatlands or broader ecosystem and organized from most to least complex. This review provides valuable context for the application of ecohydrological models in determining strategies for peatland restoration and evaluating post-intervention development over time. [ABSTRACT FROM AUTHOR]

The eco-hydrological process related to vegetation on the Qinghai–Tibet Plateau is special, and the impact of snow cover on the growth of vegetation is unique and important. In this study, we analyzed the multi-year variations in the normalized difference vegetation index (NDVI) and snow cover on the Qinghai–Tibet Plateau from spatial and temporal perspectives and determined the relationship between the changes in the NDVI and snow cover. Results showed that in the last 40 years, the rate of change in the snow depth on the plateau was −0.016 mm/a, and the NDVI changed by 0.0005/a. The correlations (|R| values) between the different factors and the NDVI followed the order of precipitation (0.77) > snow depth (0.76) > temperature (0.67) > solar radiation (0.21). The responses of the NDVI to changes in meteorological elements were synchronous, whereas the opposite was found for the snow cover. The snow cover had more significant impacts on vegetation at higher elevations. The NDVI had a lag of about 2 months from the onset of the snow cover, and heavy snow events had negative impacts on the NDVI for more than 3 years. Our findings will facilitate studies of ecological vulnerability and the predictions of changes in vegetation on the plateau. [ABSTRACT FROM AUTHOR]

Determining the sources of water inside plants using its isotopic composition is a long‐standing research challenge in ecohydrology. A better understanding of water sources can help improve models and ultimately contribute to more accurate forecasts of water availability, food production, carbon sequestration or ecosystem status. Over the years, several methods have been developed and applied to water source partitioning, and Gai et al. (2023, https://doi.org/10.1029/2022wr033849) provide a systematic assessment of the uncertainty of different isotopic tracers (2H, 3H, 17O, 18O) and mixing models (IsoSource, SIAR, MixSIR, MixSIAR) for an apple tree orchard on the Loess Plateau in north‐central China. For that study area, the combination of 2H and 18O with the MixSIAR mixing model is recommended. Importantly, the systematic assessment provides a framework that can be applied to select a suitable combination of tracers and mixing models for different ecosystems and climate zones. This commentary aims to provide a wider context for a selection of key results from Gai et al. (2023, https://doi.org/10.1029/2022wr033849) and highlight potential future research directions. Plain Language Summary: Plants use water from the soil to survive, reproduce and grow. Plants can access water sources in shallow soil layers or from greater depth. The source of water can be determined by extracting water from a plant and measuring it precisely. This involves sophisticated machines and the use of models. Knowing where water is coming from, helps researchers to predict how plants respond to a changing climate or extreme weather. There exist several methods to estimate water sources and Gai et al. (2023, https://doi.org/10.1029/2022wr033849) test which of these methods works best for an apple tree orchard in China. This same procedure can be used for selecting the most appropriate method for other ecosystems and climate zones. Key Points: The source of water inside plants, which can vary with season and across the field, can be traced using isotopes in waterGai et al. (2023, https://doi.org/10.1029/2022wr033849) present a systematic assessment of tracers and mixing models to partition water sources in vegetationUnderstanding water use strategies in vegetation can support modeling the response to extreme environmental conditions, such as droughts [ABSTRACT FROM AUTHOR]

This research quantifies streamflow temporal configuration and demonstrates the advantages of examining the hydrologic record on a day‐to‐day basis, heretofore unavailable with statistical‐based index parameters. The streamflow chronological structure represents a previously untapped wealth of information that would benefit ecohydrology allowing alternate lines of investigation, re‐evaluating past research in a new light and expanding analysis options for ecohydrologists. Innovative approaches are introduced to quantify this important but overlooked hydrologic property. To accomplish this, a non‐index calculus‐based differential approach has been developed using the lag(1) temporal autocorrelation signature of streamflow. The techniques for quantifying discharge (Q), day‐to‐day discharge change (dQ/dt), rate of day‐to‐day discharge change (d2Q/dt2) and sequential discharge summations are explained and presented using updated data visualization methods. A dam release river impact case study for the Colorado River at Lees Ferry, Arizona, demonstrates this novel way of analyzing and comparing discharge datasets. A set of highly customizable tools for this new approach can be used as a stand‐alone analysis or to complement other existing techniques. The result is a better understanding of the hydrologic regime, permitting more focused research and more effective management planning. [ABSTRACT FROM AUTHOR]

Twenty first century faces unprecedented challenges for the management of global waterways. The Himalayan waterways in Asia are exposed to unpredictable climatic warming together with anthropogenic perturbations caused by population growth, land use change and socio‐economic development. Given the increased public concerns on the Himalayan Mountain development programmes including the hydropower and tourism, there has been a growing need of the use of interdisciplinary scientific approaches to address water resources challenges that the Himalayan region has faced during the 21st century. Ecohydrology is an emerging scientific tool that explores key hydrological processes regulating structure and function of ecosystems, as well as assessing the impact of biological processes on water cycle variables under rapidly changing environment. The International Geosphere‐Biosphere Programme and the International Hydrological Programme hosted by the United Nations Educational, Scientific and Cultural Organization have adopted ecohydrology as a sustainable development tool by linking water resources and poverty eradication and ecosystem restoration, irrigation, energy and sanitation. However, ecohydrology tool needs to be reconfigured for sustainable development of rapidly changing Himalayan waterways. Here we propose the advancement of ecohydrology by developing various integrated frameworks of ecology, hydrology, hydraulics and sociology for resilient waterways in the Asian Himalayas. [ABSTRACT FROM AUTHOR]

Abstract Fog is an important water source that alleviates vegetation water stress, especially for dryland ecosystems. Comprehensive knowledge of fog and rainfall effects can help us better understand dryland vegetation responses to current and future climates. However, the differences between fog and rainfall effects on vegetation are poorly understood. This study compared the effects of fog and rainfall on vegetation greenness changes based on the ground‐level meteorological observations in the Namib Desert and the satellite vegetation index. The vegetation index and its first derivative were utilized to indicate vegetation greenness and its change rate, respectively. Results showed that fog played a more significant role than rainfall in explaining vegetation greenness change rates, while accumulated rainfall was more important than fog in determining vegetation greenness. Soil temperature was an important factor in explaining vegetation greenness changes. These findings offer key insights into how fog and rainfall differentially contribute to vegetation greenness changes.

Abstract The gradual accumulation of phosphorus from historical fertilization can contribute to the eutrophication of surface waters by increasing the potential for subsurface leaching losses. Grazing lands areas are a priority for concern, and phytoremediation efforts in grazing lands have prioritized grasses that may be used as forage for cattle. This study investigated the influence of three different forage species—Paspalum notatum, Hemarthria altissima, and Cynodon nlemfuensis—on the loss of phosphorus in leachate from surface soils. The experiment used a nested pot mesocosm design that allowed us to monitor leachate volume and concentration biweekly over the course of 3 months. Pots containing P. notatum plants leached significantly more phosphorus than pots containing C. nlemfuensis or empty pots with no plants growing in them, despite losing an equivalent amount of water. H. altissima lost equivalent amounts of phosphorus in leachate water, but each H. altissima plant removed approximately 33.6 mg of phosphorus, approximately 2.5× that removed by P. notatum (13.4 mg). C. nlemfuensis had lower average leachate phosphorus concentrations at each biweekly sampling than either plant species (C. nlemfuensis‐P. notatum, padj = 0.001; C. nlemfuensis‐H. altissima, padj = 0.02), averaging only 0.110 ppm in leachate relative to 0.175 ppm and 0.200 ppm in pots beneath H. altissima and P. notatum, respectively. This, combined with C. nlemfuensis' slightly higher‐than‐average aboveground P content and overall aboveground biomass expression suggest it is the best possible phytoremediation candidate. As even minor leachate P loads can be critically threatening to neighboring oligotrophic water bodies, if the conservation of downstream environments is the priority, the short‐term threat of increased leachate must be considered. Further research is needed to explore the underlying mechanisms and field‐scale implications of these findings.

Abstract Ecological and ecosystem monitoring is rapidly shifting towards using environmental DNA (eDNA) data, particularly in aquatic systems. This approach enables a combined coverage of biodiversity across all major organismal groups and the assessment of ecological indices. Yet, most current approaches are not exploiting the full potential of eDNA data, largely interpreting results in a localized perspective. In riverine networks, by explicitly modelling hydrological transport and associated DNA decay, hydrology‐based models enable upscaling eDNA‐based diversity information, providing spatially integrated inference. To capitalize on these unprecedented biodiversity data and translate it into space‐filling biodiversity projections, a streamlined implementation is needed. Here, we introduce the eDITH R‐package, implementing the eDITH model to project biodiversity across riverine networks with minimal prior information. eDITH couples a species distribution model relating a local taxon's eDNA shedding rate in streamwater to environmental covariates, a mass balance expressing the eDNA concentration at a river's cross‐section as a weighted sum of upstream contributions, and an observational model accounting for uncertainties in eDNA measurements. By leveraging on spatially replicated eDNA measurements and minimal hydro‐morphological data, eDITH enables disentangling the various upstream eDNA sources, and produces space‐filling maps of a taxon's spatial distribution at any chosen resolution. eDITH is applicable to both eDNA concentration and metabarcoding data, and to any taxon whose DNA can be retrieved in streamwater. The eDITH package provides user‐friendly functions for single‐run execution and fitting of eDITH to eDNA data with both Bayesian methods (via the BayesianTools package) and non‐linear optimization. An interface to the DHARMa package allows model validation via posterior predictive checks. Necessary preliminary steps such as watershed delineation and hydrological characterization are implemented via the rivnet package. We illustrate eDITH's workflow and functionalities with two case studies from published fish eDNA data. The eDITH package provides a user‐friendly implementation of eDITH, specifically intended for ecologists and conservation biologists. It can be used without previous modelling knowledge but also allows customization for experienced users. Ultimately, eDITH allows upscaling eDNA biodiversity data for any river globally, transforming how state and change in biodiversity in riverine systems can be tracked at high resolution in a highly versatile manner.

Peatlands play a significant role in global carbon and nitrogen cycles due to their carbon storage capabilities. However, there are key knowledge gaps in our understanding of how peatland hydrology influences the biogeochemical properties that drive peatland functioning and health. This study examines peatland hydrology and biogeochemical dynamics by exploring the variations in carbon chemistry, total amino acid ('protein') content and amino acid composition in the ecohydrologic layers: acrotelm, mesotelm and catotelm. The dynamic movement of the water table recorded half‐hourly over 4 years was used to assist in identifying the boundaries between these layers. Peat amino acids were measured using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Carbon chemistry was analysed by solid state Cross Polarization Magic Angle Spinning (CPMAS) 13C Nuclear Magnetic Resonance (NMR) spectroscopy, with the alkyl:O‐alkyl ratio used to quantify the extent of decomposition. Our result revealed a strong positive correlation between the extent of decomposition and total protein content, indicating selective preservation of proteinaceous materials during peat decomposition. Each ecohydrologic layer displayed a distinct amino acid composition and carbon functional group composition. The acrotelm was relatively enriched in seven amino acids and two carbon functional groups. The mesotelm was relatively enriched in four amino acids, while the catotelm was relatively enriched in three amino acids and four carbon functional groups. The variations in amino acid composition reflect differences in microbial function and efficiency, while variations in carbon functional groups provide insights into long‐term carbon sequestration in peatland. Collectively, these results provide more insights into nutrient cycling and changes in organic matter composition during peat decomposition. These findings demonstrate that peatland biogeochemistry is closely linked to ecohydrology and suggest that changes to water table dynamics could affect the ability of peatlands to sequester and store carbon in the future. [ABSTRACT FROM AUTHOR]

Vegetation canopies intercept and redistribute rainfall into throughfall and stemflow, which transfer substantial amounts of elements into the soil, influencing soil microbial community, plant survival, and plant community succession. Despite advancements in ecohydrological research, the implication of nutrient enrichment resulting from this redistribution of rainfall by canopies remains largely unexplored. To address this gap, we conducted a systematic review of 1020 papers published between 2000 and 2022, gathering data on nutrient concentration and enrichment for critical ions (including K+, Na+, Ca2+, Mg2+, NH4+, Cl−, NO3− and SO42−) from the Web of Science and Chinese Knowledge Infrastructure databases. We aimed to synthesize the mechanisms, quantify the enrichments, and identify global patterns of nutrient enrichment in stemflow and throughfall across climate zones, and vegetation types and ecosystems. The results of this study indicate that stemflow exhibits, on average, 2.1 times greater ion concentration (6.13 mg L−1) compared to throughfall. In particular, among the investigated ions, SO42− (12.45 and 6.32 mg L−1) for stemflow and throughfall, respectively, and Cl− (9.21 and 4.81 mg L−1) exhibit the highest concentrations in both rainfall redistribution components, while K+ (13.7 and 5.8) and Mg2+ (5.6 and 2.8) have the highest enrichment factors. Across climate zones, throughfall and stemflow show the lowest ion concentrations but the highest enrichment factors in extremely humid regions. Along the temperature gradient, ion concentrations are the highest in cold climates with no clear patterns observed for enrichment factors with increasing temperature. In addition, shrubs, conifers, mixed forests, and artificial ecosystems demonstrate enrichment factors 1.1 to 3.0 times greater than those of trees, broad- leaved plants, pure forests, and natural ecosystems. These findings emphasize the need for increased attentions to artificial ecosystems, such as urban and agricultural ecosystems, which often received limited research focus, especially regarding shrubs and conifers exhibiting stronger nutrients enrichment capabilities. Future investigations should integrate soil moisture analysis to better understand the impact of rainfall redistribution on the nutrient enrichment processes, patterns, and nutrient balance in global terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Ecological and ecosystem monitoring is rapidly shifting towards using environmental DNA (eDNA) data, particularly in aquatic systems. This approach enables a combined coverage of biodiversity across all major organismal groups and the assessment of ecological indices. Yet, most current approaches are not exploiting the full potential of eDNA data, largely interpreting results in a localized perspective. In riverine networks, by explicitly modelling hydrological transport and associated DNA decay, hydrology‐based models enable upscaling eDNA‐based diversity information, providing spatially integrated inference. To capitalize on these unprecedented biodiversity data and translate it into space‐filling biodiversity projections, a streamlined implementation is needed.Here, we introduce the eDITH R‐package, implementing the eDITH model to project biodiversity across riverine networks with minimal prior information. eDITH couples a species distribution model relating a local taxon's eDNA shedding rate in streamwater to environmental covariates, a mass balance expressing the eDNA concentration at a river's cross‐section as a weighted sum of upstream contributions, and an observational model accounting for uncertainties in eDNA measurements. By leveraging on spatially replicated eDNA measurements and minimal hydro‐morphological data, eDITH enables disentangling the various upstream eDNA sources, and produces space‐filling maps of a taxon's spatial distribution at any chosen resolution. eDITH is applicable to both eDNA concentration and metabarcoding data, and to any taxon whose DNA can be retrieved in streamwater.The eDITH package provides user‐friendly functions for single‐run execution and fitting of eDITH to eDNA data with both Bayesian methods (via the BayesianTools package) and non‐linear optimization. An interface to the DHARMa package allows model validation via posterior predictive checks. Necessary preliminary steps such as watershed delineation and hydrological characterization are implemented via the rivnet package. We illustrate eDITH's workflow and functionalities with two case studies from published fish eDNA data.The eDITH package provides a user‐friendly implementation of eDITH, specifically intended for ecologists and conservation biologists. It can be used without previous modelling knowledge but also allows customization for experienced users. Ultimately, eDITH allows upscaling eDNA biodiversity data for any river globally, transforming how state and change in biodiversity in riverine systems can be tracked at high resolution in a highly versatile manner. [ABSTRACT FROM AUTHOR]

Numerous models had been developed to predict the annual evapotranspiration (ET) in vegetated lands across various spatial scales. Fu's (Scientia Atmospherica Sinica, 5, 23–31) and Zhang's (Water Resources Research, 37, 701–708) ET simulation models have emerged as highly effective and have been widely used. However, both formulas have the non‐quantitative parameters (m in Fu's model and w in Zhang's model). Based on the collected 1789 samples from global long‐term hydrological studies, this study discovered significant relations between m (or w) and vegetation coverage or greenness in collected catchments. Then, we used these relations to qualify the parameters in both Zhang's and Fu's models. Results show that the ET estimation accuracies of Fu's (or Zhang's) model are significantly improved by about 13.49 mm (or 6.74 mm) for grassland and cropland, 38.52 mm (or 29.84 mm) for forest and shrub land (coverage<40%), 19.74 mm (or 16.17 mm) for mixed land (coverage<40%), respectively. However, Zhang's model shows higher errors compared with Fu's model, especially in regions with high m (or w) values, such as those with dense vegetations or P/E0 (annual precipitation to annual potential ET) smaller than 1.0. Additionally, this study also reveals that for regions with vegetation cover less than 40%, the annual ET is not only determined by vegetation types, but also relates to the sizes of vegetation‐covered areas. Conversely, for regions with vegetation cover more than 40%, the annual ET is mainly determined by the vegetation density rather than vegetation types or vegetation coverage. Thus, linking m (or w) parameters with vegetation greenness allows leveraging remote sensing for forest management in data‐scarce areas, safeguarding regional water resources. This study pioneers integrating vegetation‐related indices with basin parameters, advocating for their crucial role in more effective hydrological modelling. [ABSTRACT FROM AUTHOR]

Recent interest in landscape re‐wilding and ecological restoration has resulted in a proliferation of large‐scale projects in many countries that have the potential to cause significant ecohydrological change. In Scotland an increasing number of watershed "restoration" schemes are motivated by declining Atlantic salmon populations and the threat of climate change. These usually involve riparian planting to shade salmon streams and re‐engineering of river channels to "enhance" salmon habitat. However, the need for, and objectives of, these schemes are often highly uncertain and there is no compelling scientific evidence to suggest that they are likely to be successful in halting salmon declines. Remarkably, these schemes ‐ which affect can affect rivers with the highest conservation designations in protected landscapes ‐ have been subject to limited environmental assessment. In some cases, engineering activities pose significant potential risk to juvenile salmon, and existing high quality salmon habitat may be degraded in the re‐engineering of streams. This commentary highlights the urgent need for more evidence‐based approaches in the management of complex ecohydrological systems. [ABSTRACT FROM AUTHOR]

Trees in residential environments are affected by a unique combination of environmental and anthropogenic factors, including occasional insect outbreaks that are increasing in frequency and severity due to climate change. We studied loblolly pine trees infested by bark beetles in a residential backyard in a southeastern US city. We investigated the responses of tree and stand‐level transpiration to environmental factors (solar radiation, atmospheric vapor pressure deficit, and soil moisture), severe weather events (strong winds and heavy storms), bark beetle infestation, and human actions (insecticide treatments and tree removals). We used constant heat dissipation probes to make continuous sap flux measurements (J0) in tree boles. Over 22 months of the study, J0 of trees with confirmed infestation decreased from ~90 to ~60 g cm−2 day−1 and J0 of the rest of the trees increased from ~60 to ~80 g cm−2 day−1. One infested tree died, as its J0 steadily declined from 110 g cm−2 day−1 to zero over the course of 2 months, followed by a loss of foliage and visible signs of severe infestation 6 months later. J0 was sensitive to variations in incoming solar radiation and atmospheric vapor pressure deficit. In most trees, J0 linearly responded to soil water content during drought periods. Yet despite complex dynamics of J0 variations, plot‐level transpiration at the end of the study was the same as at the beginning due to compensatory increases in tree transpiration rates. This study highlights the intrinsic interplay of environmental, biotic, and anthropogenic factors in residential environments where human actions may directly mediate ecosystem responses to climate. [ABSTRACT FROM AUTHOR]

While vascular plants in drylands can spatially self-organize and persist under climatic stress through gradual changes in patch attributes, dryland patch dynamics largely assumes bare soil between plants. Biological soil crusts (BSCs) are communities living in the soil surface of drylands and mediate water redistribution in space. BSCs often occur in patches of light cyanobacteria and dark-mixed aggregates; however, little is known about their spatial patterns and dynamics. Here, we investigate spatial attributes of BSC patches, their spatial interactions with vascular plants, and factors that drive variation in these attributes using ultra-high-resolution (1 cm) maps from UAV imagery across three ecoregions of the southwest United States. Our analysis showed that light cyanobacteria BSCs varied most in patch shape complexity with aridity, while dark-mixed BSCs varied most in abundance. The distribution of dark-mixed BSCs was strongly affected by the soil template (texture and calcareousness) and vascular plants. Light cyanobacteria BSCs and woody plants spatially aggregated with aridity, while slope enhanced the spatial association between BSC functional groups. We conclude that light cyanobacteria BSCs can likely persist under stress through patch shape alterations, while dark-mixed BSC patches may have a lower capacity to do so—corroborating that dark-mixed BSC abundance may decline under altered climatic regimes. Light cyanobacteria BSCs may also buffer the effects of aridity for other biota by promoting runoff. BSCs and vascular plants coordinate in space in response to resource availability, suggesting the need to consider self-organization of multiple unique assemblages to better predict dryland response to climate change. [ABSTRACT FROM AUTHOR]

Soil temperature is an important index of climate change, and the analysis of soil temperature change is of great significance for understanding climate change and ecohydrological processes. This study was based on the measured meteorological data of a meteorological station, combined with the soil temperature data of 0–10, 10–40, 40–100 and 100–200 cm from the Global Land Data Assimilation System (GLDAS-NOAH). The Mann–Kendall test, wavelet analysis, linear tendency estimation and other methods were used to analyze the variability, periodicity and trend of soil temperature in Lhasa from 2006 to 2022. The results showed that the soil temperature of different soil layers had abrupt changes in annual and seasonal time series, and all showed a warming phenomenon after abrupt changes. In terms of periodicity, the average annual soil temperature of different soil layers has similar periodic changes, and the periodic oscillation is strong around 10a, which is the main cycle of soil temperature change. The soil temperature in Lhasa showed a significant rising trend in the interannual and seasonal time series, and the average annual rising trend of soil temperature was greater than that of air temperature. The correlation between soil temperature and mean air temperature (MAT), maximum air temperature (Tmax), minimum air temperature (Tmin) and snow depth (SD) was investigated by Pearson correlation analysis. Soil temperature in spring, autumn and winter had a strong correlation with MAT, Tmax and Tmin, showing a significant positive correlation. The negative correlation between soil temperature and SD in 0–40 cm soil in spring and winter was more severe. The research results show that Lhasa has experienced a rise in air temperature and soil temperature in the past 17 years, and reveal the specific changes in soil temperature in Lhasa against the background of climate change. These findings have reference significance for understanding the impact of climate change on the natural environment. [ABSTRACT FROM AUTHOR]

Urban trees play a pivotal role in mediating the hydrological and nutrient cycles within urban ecosystems, yet the mechanisms by which bark characteristics influence these processes remain underexplored. This study aimed to investigate the impact of the bark morphology—specifically texture, depth, and number of furrows—on the water absorption capacity and to determine the relationship between this capacity and ion concentration in stemflow across various urban tree species. Our findings reveal significant variations in water absorption and ion concentration related to the morphological traits of bark among tree species, highlighting the intricate relationship between bark physical and chemical characteristics and stemflow nutrient composition. Notably, species with furrowed textures, greater depth, and a higher number of furrows demonstrated pronounced differences in ion enrichment in their stemflow. However, a canonical redundancy analysis suggested a low association between bark absorption capacity and ion concentration, indicating the influence of other, possibly external, environmental factors on ion leaching. The results underscore the complexity of nutrient transport mechanisms in urban trees and show a new understanding of tree bark's ecohydrological roles. This study contributes valuable insights into ecohydrology science and emphasizes the need for further research to unravel the multifaceted influences on nutrient dynamics in urban landscapes. [ABSTRACT FROM AUTHOR]

Sap flow offers key insights about transpiration dynamics and forest‐climate interactions. Accurately simulating sap flow remains challenging due to measurement uncertainties and interactions between global and local environmental controls. Addressing these complexities, this study leveraged Long Short‐Term Memory networks (LSTMs) with SAPFLUXNET to predict hourly tree‐level sap flow across Europe. We built models with diverse training sets to assess performance under previously unseen conditions. The average Kling‐Gupta Efficiency was 0.77 for models trained on 50% of time series across all forest stands, and 0.52 for models trained on 50% of the forest stands. Continental models not only matched but surpassed the performance of specialized and baselines for all genera and forest types, showcasing the capacity of LSTMs to effectively generalize across tree genera, climates, and forest ecosystems given minimal inputs. This study underscores the potential of LSTMs in generalizing state‐dependent ecohydrological processes and bridging tree level measurements to continental scales. Plain Language Summary: Transpiration is the dominant flux of water from the land surface to the atmosphere, yet it remains challenging to measure and estimate especially given different climates and tree types. This study shows how large‐scale deep learning models can simulate sap flow, the movement of water within trees, with high precision, even in forests and conditions not previously studied. We show that these models excel when they learn from large and diverse data sets. The flexible design of our model training means that every new sap flow measurement can potentially be used to further optimize our networks. Our findings indicate that this approach of continuously updating the model with new information greatly improves its performance to simulate and predict tree‐level sap flow. This work thus highlights the potential of deep learning models to generalize sap flow, thereby enhancing ecohydrological investigations from the tree to the continental scale. Key Points: Long Short‐Term Memory networks (LSTMs) can predict hourly sap flow for diverse trees and climates across Europe bridging tree level measurements to continental scalesTraining on the extensive SAPFLUXNET data set enhances the ability of the LSTMs to simulate sap flow accurately in time and spaceThe study underscores the value of large‐scale deep learning models and advocates for the expansion of data sets like SAPFLUXNET [ABSTRACT FROM AUTHOR]

The potential implementation of future geoengineering projects alters solar radiation to counteract global warming trends. These changes could have effects on ecohydrological systems with impacts which are still poorly quantified. Here, we compute how changes in solar radiation affect global and local near surface meteorological variables by using CMIP6 scenario results and we compute climate sensitivities to solar radiation. These sensitivities are used to construct two sets of numerical experiments: the first focuses on solar radiation changes only, and the second systematically modifies precipitation, air temperature, specific humidity, and wind speed using the CMIP6 derived sensitivities to radiation changes, i.e., including its climate feedback. We use those scenarios as input to a mechanistic ecohydrological model to quantify the responses of the energy and water budget as well as vegetation productivity spanning different biomes and climates. In the absence of climate feedback, changes in solar radiation tend to reflect mostly in sensible heat changes, with minor effects on the hydrological cycle and vegetation productivity correlates linearly with changes in solar radiation. When climate feedback is included, changes in latent heat and hydrological variables are much more pronounced, mostly because of the temperature and vapor pressure deficit changes associated with solar radiation changes. Vegetation productivity tends to have an asymmetric response with a considerable decrease in gross primary production to a radiation reduction not accompanied by a similar increase with a radiation increase. These results provide important insights on how ecosystems could respond to potential future solar geoengineering programs. [ABSTRACT FROM AUTHOR]

Summary: A fundamental assumption when using hydrogen and oxygen stable isotopes to understand ecohydrological processes is that no isotope fractionation occurs during plant water uptake/transport/redistribution. A growing body of evidence has indicated that hydrogen isotope fractionation occurs in certain environments or for certain plant species. However, whether the plant water source hydrogen isotope offset (δ2H offset) is a common phenomenon and how it varies among different climates and plant functional types remains unclear.Here, we demonstrated the presence of positive, negative, and zero offsets based on extensive observations of 12 plant species of 635 paired stable isotopic compositions along a strong climate gradient within an inland river basin.Both temperature and relative humidity affected δ2H offsets. In cool and moist environments, temperature mainly affected δ2H offsets negatively due to its role in physiological activity. In warm and dry environments, relative humidity mainly affected δ2H offsets, likely by impacting plant leaf stomatal conductance. These δ2H offsets also showed substantial linkages with leaf water 18O enrichment, an indicator of transpiration and evaporative demand.Further studies focusing on the ecophysiological and biochemical understanding of plant δ2H dynamics under specific environments are essential for understanding regional ecohydrological processes and for conducting paleoclimate reconstructions. [ABSTRACT FROM AUTHOR]

Plant transpiration is a key component of the hydrological cycle that moves water from the soil through plants to the atmosphere and is largely determined by environmental conditions. The challenges of highly variable climatic conditions and water scarcity in the semi‐arid savannas of southern Africa drive trees to exhibit different water use strategies.An additional challenge for savanna trees arises from the browsing of large mammals, and its potential impact on transpiration has largely been overlooked.To assess water use strategies and the impact of browsing on transpiration in three common savanna woody species (Colophospermum mopane, Catophractes alexandri, Senegalia mellifera), we conducted an extensive field experiment in a wildlife reserve in Namibia. We established a browsing gradient ranging from 0% to 100% leaf removal to disentangle complex relationships, and we measured sap flow representing whole‐tree transpiration, stomatal conductance as a proxy for leaf level transpiration, and environmental factors including soil moisture, solar radiation, air temperature and air humidity.We discovered a unimodal relationship between browsing intensity and sap flow, consistent across all species, and peaking at low to moderate browsing levels equivalent to approximately 30% leaf removal. This universal pattern is remarkable since we found water use strategies to differ among species: Colophospermum mopane and C. alexandri exhibit a water‐saving behaviour to reduce water loss under unfavourable conditions while S. mellifera demonstrates water‐spending characteristics.The deviation from a negative linear effect of browsing does not meet the functional expectation when browsing is translated into a simple leaf area reduction. Instead, it can be attributed to stomatal adjustments that partially compensate for transpiratory surface loss. We propose that this conceptual mechanism can be generalised to other woody species and various ecosystems. In addition, common transpiration models relying solely on leaf area indices and abiotic factors can be improved by including a non‐linear relationship to reproduce the effect of browsing accurately.Our findings highlight the role of herbivores in shaping the connection between the Earth's spheres and improve our understanding of ecohydrological and vegetation dynamics in Southern African savannas. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The important progress in research on the application of urban ecological hydrology in the past 40 years, especially the optimization and control of regional water cycle elements, has effectively supported the construction of urban safety resilience. Under the guidance of the concept of urban ecohydrological system, low impact development (LID), Water Framework Directive, sponge city and climate-resilient city construction have successively emerged in North America, Europe and China. The interaction of global change and human activities has produced complex urban ecohydrological processes, and the natural water cycle model has been transformed into a dual water cycle model of “naturesociety” interaction. In the face of global change, the construction of resilient and safe cities pays more attention to the mitigation and adaptation of climate change, especially the ability to adapt to extreme weather and climate events. China’s long-term continuous large-scale urban development and construction has strongly affected and changed the key elements of regional water cycle, and the development and utilization of urban underground space and land subsidence are faced with disaster risks under extreme weather and climate situations. Therefore, the geological basic conditions and their toughness constitute the basis of urban resilience safety base. Mitigation and adaptation strategies based on the control design of the key elements of the dual water cycle play an important role in the construction of a new round of climate-resilient cities. “Climate change - regional dual water cycle - water balance regulation - disaster risk” and “Remote sensing big data - small data of station network - transfer function - cloud twin” can be used as a combination of technical frameworks and methods for Earth big data to support resilient city construction and sustainable development. Shanghai, as the leader of the Yangtze River Basin and a sensitive area of sea-land interaction, is also facing the test of sea level rise. Under the climate change scenario, the regulation of key elements of regional dual water cycle can be used as a strategy to serve the safety of underground space and urban resilience in Shanghai. [ABSTRACT FROM AUTHOR]

Although urbanization fundamentally alters water and energy cycles, contemporary land surface models (LSMs) often do not include key urban vegetation processes that serve to transfer water and energy laterally across heterogeneous urban land types. Urban water/energy transfers occur when rainfall landing on rooftops, sidewalks, and driveways is redirected to lawns or pervious pavement and when transpiration occurs from branches overhanging impervious surfaces with the corresponding root water uptake takes place in nearby portions of yards. We introduce Noah‐MP for Heterogenous Urban Environments (Noah‐MP HUE), which adds sub‐grid water transfers to the widely used Noah‐MP LSM. We examine how sub‐grid water transfers change surface water and energy balances by systematically increasing the amount of simulated water transfer for four scenarios: tree canopy expanding over pavement (Urban Tree Expansion), tree canopy shifting over pavement (Urban Tree Shift), and directing impermeable runoff onto surrounding vegetation (Downspout Disconnection) or into an engineered pavement (Permeable Pavement). Even small percentages of sub‐grid water transfer can reduce runoff and enhance evapotranspiration and deep drainage. Event‐scale runoff reduction depends on storm depth, rainfall intensity, and antecedent soil moisture. Sub‐grid water transfers also tend to enhance (reduce) latent (sensible) heat. Results highlight the importance not only of fine‐scale heterogeneity on larger scale surface processes, but also the importance of urban management practices that enhance lateral water transfers and water storage–so‐called green infrastructure–as they change land surface fluxes and, potentially, atmospheric processes. This work opens a pathway to directly integrate those practices in regional climate simulations. Key Points: We develop an urban land surface model representation of impervious to pervious runon and canopy overhanging impervious surfacesUsing idealized land use, we systematically examine the effects of lateral transfers on water and energy budgets over warm seasonsWe found large changes in runoff generation, water balances, and energy partitioning when lateral transfers are simulated [ABSTRACT FROM AUTHOR]

Climate change and nitrogen (N) pollution are altering biogeochemical and ecohydrological processes in dryland watersheds, increasing N export, and threatening water quality. While simulation models are useful for projecting how N export will change in the future, most models ignore biogeochemical "hotspots" that develop in drylands as moist microsites in the soil become hydrologically disconnected from plant roots when soils dry out. These hotspots enable N to accumulate over dry periods and rapidly flush to streams when soils wet up. To better project future N export, we developed a framework for representing hotspots using the ecohydrological model RHESSys. We then conducted a series of virtual experiments to understand how uncertainties in model structure and parameters influence N export to streams. Modeled N export was sensitive to three major factors (a) the abundance of hotspots in a watershed: N export increased linearly and then reached an asymptote with increasing hotspot abundance; this occurred because carbon and N inputs eventually became limiting as hotspots displaced vegetation cover, (b) the soil moisture threshold required for subsurface flow from hotspots to reestablish: peak streamflow N export increased and then decreased with an increasing threshold due to tradeoffs between N accumulation and export that occur with increasingly disconnected hotspots, and (c) the rate at which water diffused out of hotspots as soils dried down: N export was generally higher when the rate was slow because more N could accumulate in hotspots over dry periods, and then be flushed more rapidly to streams at the onset of rain. In a case study, we found that when hotspots were modeled explicitly, peak streamflow nitrate export increased by 29%, enabling us to better capture the timing and magnitude of N losses observed in the field. N export further increased in response to interannual precipitation variability, particularly when multiple dry years were followed by a wet year. This modeling framework can improve projections of N export in watersheds where hotspots play an increasingly important role in water quality. Key Points: We developed a model framework to represent biogeochemical hotspots in dryland ecosystemsNitrogen export was sensitive to parameters controlling hotspot abundance, subsurface hydrologic connectivity, and soil moisture dynamicsThe abundance and physical characteristics of hotspots can affect the timing of hot moments [ABSTRACT FROM AUTHOR]

Simulation models are valuable tools for estimating ecosystem response to environmental conditions and are particularly relevant for investigating climate change impacts. However, because of high computational requirements, models are often applied over a coarse grid of points or for representative locations. Spatial interpolation of model output can be necessary to guide decision‐making, yet interpolation is not straightforward because the interpolated values must maintain the covariance structure among variables. We present methods for two key steps for utilizing limited simulations to generate detailed maps of multivariate and time series output. First, we present a method to select an optimal set of simulation sites that maximize the area represented for a given number of sites. Then, we introduce a multivariate matching approach to interpolate simulation results to detailed maps for the represented area. This approach links simulation output to environmentally analogous matched sites according to user‐defined criteria. We demonstrate the methods with case studies using output from (1) an individual‐based plant simulation model to illustrate site selection, and (2) an ecosystem water balance simulation model to illustrate interpolation. For the site selection case study, we identified 200 simulation sites that represented 96% of a large study area (1.12 × 106 km2) at a ~1‐km resolution. For the interpolation case study, we generated ~1‐km resolution maps across 4.38 × 106 km2 of drylands in North America from a 10 × 10 km grid of simulated sites. Estimates of interpolation errors using cross validation were low (<10% of the range of each variable). Our point selection and interpolation methods, which are available as an easy‐to‐use R package, provide a means of cost‐effectively generating detailed maps of expensive, complex simulation output (e.g., multivariate and time series) at scales relevant for local conservation planning. Our methods are flexible and allow the user to identify relevant matching criteria to balance interpolation uncertainty with areal coverage to enhance inference and decision‐making at management‐relevant scales across large areas. [ABSTRACT FROM AUTHOR]

Abstract Despite much interest in relationships among carbon and water in forests, few studies assess how carbon accumulation scales with water use in forested watersheds with varied histories. This study quantified tree growth, water use efficiency, and carbon‐water tradeoffs of young versus mature/old‐growth forest in three small (13–22 ha) watersheds in the H.J. Andrews Experimental Forest, Oregon, USA. To quantify and scale carbon‐water tradeoffs from trees to watersheds, tree‐ring records and greenness and wetness indices from remote sensing were combined with long‐term vegetation, climate, and streamflow data from young forest watersheds (trees ∼45 years of age) and from a mature/old‐growth forest watershed (trees 150–500 years of age). Biomass production was closely related to water use; water use efficiency (basal area increment per unit of evapotranspiration) was lower; and carbon‐water tradeoffs were steeper in young forest plantations compared with old‐growth forest for which the tree growth record begins in the 1850s. Greenness and wetness indices from Landsat imagery were not significant predictors of streamflow or tree growth over the period 1984 to 2017, and soil C and N did not differ significantly among watersheds. Multiple lines of evidence show that mature and old‐growth forest watersheds store and accumulate more carbon, are more drought resistant, and better sustain water availability compared to young forests. These results provide a basis for reconstructions and predictions that are potentially broadly applicable, because first‐order watersheds occupy 80%–90% of large river basins and study watersheds are representative of forest history in the Pacific Northwest region.

Stable isotopes of hydrogen and oxygen are used in agriculture to investigate the water sources used by crops. Yet, isotopic research on irrigated orchards is still scarce. We investigated the isotopic variability in an apple tree plantation in the Eastern Italian Alps (South Tyrol) during the growing seasons 2020 and 2021. The orchard was subject to an irrigation trial, whereby a drip system was triggered at different soil water potential thresholds at two treatment types: full irrigation (FI, −30 kPa) and deficit irrigation (DI, −60 kPa). On a bi-weekly basis, we sampled precipitation, river water, and groundwater used for irrigation. At both FI and DI, we sampled soil at different depths and bark-devoid branches, and cryogenically extracted their water. Isotopic analyses revealed large differences in δ18O values of soil water belonging to the two irrigation treatments, particularly during the irrigation period (up to 8.9‰). In xylem water, the differences were much smaller (up to 1.6‰). Mixing models (EEMMA) estimated a larger groundwater (vs. rainwater) fraction in the shallow soil (5–10 cm) at FI (25–55%) than at DI (0–5%), compatible with a larger presence of irrigation water in the former. DI plants had a deeper root water uptake (32.0 ± 11.9 cm) than FI ones (19.3 ± 14.5 cm) during the irrigation period. This agreed with the results of mixing models (IsoSource) that estimated a larger use of deeper (60–65 cm) soil water (42 ± 18%) and a lower use of shallow soil water (13 ± 6%) for DI than for FI (34 ± 26% and 27 ± 26%) during the same period. This root water uptake plasticity explains the lacking evidence of physiological stress in sap flux records at DI and supports the potential for further improvements of precision irrigation in similar climatic and edaphic settings.

Abstract The exchange of carbon dioxide and water vapor between terrestrial ecosystems and the atmosphere is regulated by stomata (small pores in the leaves of plants). Unsurprisingly, environmental factors controlling the opening and closure of stomata has been sought as early as 1800. One approach, popularized in the early 1970s, is a stomatal optimization framework. This framework is based on the hypothesis that plants optimize carbon gain subject to water loss or water availability constraints. This constraint optimization problem was solved in various forms assuming instantaneous adjustments of stomatal aperture to maximize a reward function with no future foresight or legacy effects. Holtzman et al. (2024, https://doi.org/10.1029/2023av001113) offers a novel approach that can diagnose the effective timescale over which the reward function maximization must be time‐integrated. The developed method thus optimizes an integrated carbon gain function but adjusted by a discount factor subject to water availability in the root zone. The discount factor considers how the plant values carbon gain to save water and its timescale can be inferred from observations because the model is analytically tractable. The results suggest that the most important climate factor that determines this discount timescale is multi‐annual mean of the longest dry period during the growing season. The findings highlight how local climate traits influence the spatial variation in ecosystem‐level water use strategies. This sets the stage for expanding such a framework to cases where multiple constraints act in concert while operating at distinct time scales.

This article discusses the metabolic activity of deep living cyanobacteria, specifically focusing on the species Planktothrix rubescens. While most cyanobacteria thrive in warm surface waters, P. rubescens is unique in its ability to develop in low temperatures and low light intensities. The article highlights the environmental adaptations and ecological plasticity of cyanobacteria, as well as the potential threats they pose to animal and human health. The research conducted by Dordoni et al. explores the relationship between photosynthesis and respiration in P. rubescens, using oxygen isotopes to measure metabolic activity. The findings have implications for the management of drinking water reservoirs and the study of cyanobacterial blooms in aquatic ecosystems. [Extracted from the article]

This article discusses the integration of ecohydrology and ecohydraulics as interdisciplinary sciences for managing freshwater ecosystems. It highlights the challenges faced by global freshwater systems due to human disturbances and climate warming. The article emphasizes the need for the integration of these disciplines to address ecological, hydrological, and societal challenges in river basins worldwide. The special issue includes papers that explore the roles of hydrology and hydraulics in setting up flow regimes, habitat extent, and ecosystem functioning in natural and regulated river systems. It also discusses the importance of ecohydrologic and ecohydraulic modeling in biogeochemical cycling in hydropower dams and groundwater. Overall, the article calls for further research to promote the sustainability of freshwater resources globally. [Extracted from the article]

Peatlands are sources of bioaccumulating neurotoxin methylmercury (MeHg) that is linked to adverse health outcomes. Yet, the compounding impacts of climate change and reductions in atmospheric pollutants on mercury (Hg) export from peatlands are highly uncertain. We investigated the response in annual flow‐weighted concentrations (FWC) and yields of total‐Hg (THg) and MeHg to cleaner air and climate change using an unprecedented hydroclimatic (55‐year; streamflow, air temperature, precipitation, and peatland water tables), depositional chemistry (21‐year; Hg and major ions), and streamwater chemistry (∼17‐year; THg, MeHg, major ions, total organic carbon, and pH) data sets from a reference peatland catchment in Minnesota, USA. Over the hydroclimatic record, annual mean air temperature increased by ∼1.8°C, while baseflow and the efficiency that precipitation was converted to runoff (runoff ratio) decreased. Concurrently, precipitation‐based deposition of sulfate and Hg declined, where wet Hg deposition declined by ∼3–4 μg Hg m−2. Despite declines in wet Hg deposition over the study period, the catchment accumulated on average 0.04 ± 0.01 g Hg ha−1 yr−1 based on wet Hg deposition minus THg yield alone. Annual MeHg FWC was positively correlated with mean annual air temperatures (p = 0.03, r = 0.51), runoff ratio (p < 0.0001, r = 0.76), and wet Hg deposition concentration (p < 0.0001, r = 0.79). Decreasing wet Hg deposition and annual runoff ratios counterbalanced increased peatland MeHg production due to higher air temperatures, leading to an overall decline in streamwater MeHg FWC. Streamwater MeHg export may continue to decrease only as long as declines in runoff ratio and wet Hg deposition persistently outpace effects of increased air temperature. Plain Language Summary: Climate change and cleaner air are unequivocally altering the movement of toxic mercury and methylmercury. Using long‐term and broad environmental measurements, a stream fed by a peatland exhibited decreased methylmercury levels that correlated with lower wet mercury deposition concentration and lower net water yields from the catchment (runoff ratio), which offsets potential increases of methylmercury due to elevated air temperatures. As such, methylmercury export from peatland catchments will likely continue to decrease over time if climate change continues to accelerate the reduction of runoff ratios and atmospheric wet mercury deposition further decreases. Adaptation to future climate and environmental changes would greatly benefit from additional and longer‐integrated multidisciplinary data sets. Without such long‐term and integrated measures critical insights, such as those gained from this study, would not be possible. Key Points: Lower streamwater methylmercury concentrations and yields due to compounding effects of climate change and cleaner airLower wet atmospheric mercury deposition and runoff ratios offset higher air temperatures, resulting in lower methylmercury concentrationsHeadwater peatland catchments will continue to be net sinks of total mercury; thus, we may not see a net flushing of anthropogenic mercury [ABSTRACT FROM AUTHOR]

Measurements of oxygen and hydrogen isotopes in plant xylem water (2H, 18O) have helped to redefine conceptual and numerical models of the hydrological cycle and understand how plants compete for subsurface water. Recent experiments have shown that Cryogenic Vacuum Extraction (CVE) of plant xylem water can result in a δ2H bias. We tested if CVE δ2H‐biases varied significantly across seven foundational northeastern US forest trees with a series of tree core rehydration experiments. Our analysis demonstrated that CVE δ2H‐biases were well predicted by sample gravimetric water content and varied significantly with tree species identity. We show that species‐level δ2H‐bias corrections can result in substantially different understandings of plant water uptake and transpiration versus uncorrected data or generic bias corrections. This research demonstrates an urgent need for the critical evaluation of CVE for plant water extraction. In the absence of a stronger understanding of CVE δ2H‐biases, we recommend that xylem water δ2H observations should not be used in plant water uptake studies. [ABSTRACT FROM AUTHOR]