The Experts below are selected from a list of 3021 Experts worldwide ranked by ideXlab platform
T. Datry - One of the best experts on this subject based on the ideXlab platform.
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towards an improved understanding of biogeochemical processes across surface groundwater interactions in intermittent rivers and Ephemeral Streams
Earth-Science Reviews, 2021Co-Authors: Lluis Gomezgener, T. Datry, Maria Isabel Arce, Susana Bernal, Shai Arnon, Rossano Bolpagni, Giulia Gionchetta, Andre R SiebersAbstract:Abstract Surface-groundwater interactions in intermittent rivers and Ephemeral Streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES. We combine a review of theIRES biogeochemistry literature with concepts of IRES hydrogeomorphology to: (i) outline common distinctions among hydrological states in IRES; (ii) use these distinctions, together with considerations of carbon, nitrogen, and phosphorus cycles within IRES, to predict the relative potential for biogeochemical processing across different reach-scale processing zones (flowing water, fragmented pools, hyporheic zones, groundwater, and emerged sediments); and (iii) explore the potential spatial and temporal variability of carbon and nutrient biogeochemical processing across entire IRES networks. Our approach estimates the greatest reach-scale potential for biogeochemical processing when IRES reaches are fragmented into isolated surface water pools, and highlights the potential of relatively understudied processing zones, such as emerged sediments. Furthermore, biogeochemical processing in fluvial networks dominated by IRES is likely more temporally than spatially variable. We conclude that biogeochemical research in IRES would benefit from focusing on interactions between different nutrient cycles, surface-groundwater interactions in non-flowing states, and consideration of fluvial network architecture. Our conceptual framework outlines opportunities to advance studies and expand understanding of biogeochemistry in IRES.
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plant litter decomposition in intermittent rivers and Ephemeral Streams
2021Co-Authors: Ruben Del Campo, Arnaud Foulquier, Gabriel Singer, T. DatryAbstract:Intermittent rivers and Ephemeral Streams (hereafter IRES) are waterways that temporarily cease to flow and/or dry up. They represent half the length of the global river network and are expanding in time and space in response to global change. The hydrological regimes of IRES are characterized by alternating flowing, non-flowing and dry phases, which translate to varying importance of in-stream litter accumulation, processing and downstream transport. Decomposition agents, processes and rates dramatically change among these hydrological phases, leading to decomposition dynamics that differ markedly from perennial rivers and Streams. As a result, IRES have a specific “biogeochemical heartbeat” characterized by high temporal and spatial variability of leaf decomposition, and so they can be idealized as pulsed bioreactors. The ecological effects of flow cessation and drying are sometimes visible far beyond rewetting, generating “legacy effects” that become apparent even during later flowing phases. Rewetting events can represent “hot moments” of litter decomposition due to the intense biological and physical activities, generating pulses of transport and decomposition. Upscaling the abundant reach-scale knowledge to larger river-network scales is probably one of the most challenging but timely paths for future research.
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Towards an improved understanding of biogeochemical processes across surface-groundwater interactions in intermittent rivers and Ephemeral Streams
2021Co-Authors: Lluís Gómez-gener, T. Datry, Maria Isabel Arce, Susana Bernal, Andre Siebers, Shai Arnon, Rossano Bolpagni, Giulia Gionchetta, Hans-peter Grossart, Clara Mendoza-leraAbstract:Surface-groundwater interactions in intermittent rivers and Ephemeral Streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES
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sediment respiration pulses in intermittent rivers and Ephemeral Streams
Global Biogeochemical Cycles, 2019Co-Authors: T. Datry, D Von Schiller, Roland Corti, Arnaud Foulquier, Klement Tockner, Rafael Marce, Gonzalo Garciabaquero, Inaki Odriozola, Biel ObradorAbstract:Intermittent rivers and Ephemeral Streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32‐fold to 66‐fold upon sediment rewetting. Structural equation modeling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use, and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2–0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting‐drying cycles on respiration and CO2 emissions in stream networks.
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simulating rewetting events in intermittent rivers and Ephemeral Streams a global analysis of leached nutrients and organic matter
Global Change Biology, 2019Co-Authors: T. Datry, Roland Corti, Arnaud Foulquier, Klement Tockner, Biel Obrador, O Shumilova, Daniel Von SchillerAbstract:Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and Ephemeral Streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.
Klement Tockner - One of the best experts on this subject based on the ideXlab platform.
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sediment respiration pulses in intermittent rivers and Ephemeral Streams
Global Biogeochemical Cycles, 2019Co-Authors: T. Datry, D Von Schiller, Roland Corti, Arnaud Foulquier, Klement Tockner, Rafael Marce, Gonzalo Garciabaquero, Inaki Odriozola, Biel ObradorAbstract:Intermittent rivers and Ephemeral Streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32‐fold to 66‐fold upon sediment rewetting. Structural equation modeling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use, and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2–0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting‐drying cycles on respiration and CO2 emissions in stream networks.
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simulating rewetting events in intermittent rivers and Ephemeral Streams a global analysis of leached nutrients and organic matter
Global Change Biology, 2019Co-Authors: T. Datry, Roland Corti, Arnaud Foulquier, Klement Tockner, Biel Obrador, O Shumilova, Daniel Von SchillerAbstract:Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and Ephemeral Streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.
Jeffery L Larkin - One of the best experts on this subject based on the ideXlab platform.
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effects of timber harvest within Streamside management zones on salamander populations in Ephemeral Streams of southeastern kentucky
Forest Ecology and Management, 2014Co-Authors: Thomas A Maigret, Steven J. Price, Dylan R Schneider, Christopher D Barton, Jeffery L LarkinAbstract:Abstract Timber harvest is an important extractive, economic activity to many human economies, but it can be detrimental to ecosystem function and species viability therein by degrading and fragmenting forest habitat. Salamanders comprise a significant amount of forest community biomass, and given their sensitivity to environmental stressors, including those caused by timber harvest, they often serve as important indicators of declines in forest ecosystem function. Several studies have focused on the impacts of timber harvest on salamanders inhabiting perennial and intermittent Streams, the findings of which have helped inform best management practices for timber harvest in the U.S. Ephemeral headwater Streams and associated riparia account for a small fraction of the total landscape, yet these features are critical to the functioning of forested ecosystems; however, few studies have examined how timber harvest impacts salamanders in or near these areas. Our objective was to investigate the effects of three different silvicultural treatments, each involving different Streamside management zone (SMZ) characteristics, on salamander communities in southeastern Kentucky hardwood forest Ephemeral Streams. Data were collected by regular checks of pitfall traps, coverboards, and transect searches. Using both pre- and post-harvest data, abundance estimates were acquired using binomial mixture models. Declines in some species of terrestrial and stream-breeding salamanders were detected, and were shown to be likely related to characteristics of the corresponding silvicultural treatment. We suggest that application of modest SMZ regulations to Ephemeral Streams would likely reduce or alleviate salamander declines in these important headwater areas.
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effects of timber harvest within Streamside management zones on salamander populations in Ephemeral Streams of southeastern kentucky
Forest Ecology and Management, 2014Co-Authors: Thomas A Maigret, Steven J. Price, Dylan R Schneider, Christopher D Barton, John J Cox, Jeffery L LarkinAbstract:Abstract Timber harvest is an important extractive, economic activity to many human economies, but it can be detrimental to ecosystem function and species viability therein by degrading and fragmenting forest habitat. Salamanders comprise a significant amount of forest community biomass, and given their sensitivity to environmental stressors, including those caused by timber harvest, they often serve as important indicators of declines in forest ecosystem function. Several studies have focused on the impacts of timber harvest on salamanders inhabiting perennial and intermittent Streams, the findings of which have helped inform best management practices for timber harvest in the U.S. Ephemeral headwater Streams and associated riparia account for a small fraction of the total landscape, yet these features are critical to the functioning of forested ecosystems; however, few studies have examined how timber harvest impacts salamanders in or near these areas. Our objective was to investigate the effects of three different silvicultural treatments, each involving different Streamside management zone (SMZ) characteristics, on salamander communities in southeastern Kentucky hardwood forest Ephemeral Streams. Data were collected by regular checks of pitfall traps, coverboards, and transect searches. Using both pre- and post-harvest data, abundance estimates were acquired using binomial mixture models. Declines in some species of terrestrial and stream-breeding salamanders were detected, and were shown to be likely related to characteristics of the corresponding silvicultural treatment. We suggest that application of modest SMZ regulations to Ephemeral Streams would likely reduce or alleviate salamander declines in these important headwater areas.
Giulia Gionchetta - One of the best experts on this subject based on the ideXlab platform.
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towards an improved understanding of biogeochemical processes across surface groundwater interactions in intermittent rivers and Ephemeral Streams
Earth-Science Reviews, 2021Co-Authors: Lluis Gomezgener, T. Datry, Maria Isabel Arce, Susana Bernal, Shai Arnon, Rossano Bolpagni, Giulia Gionchetta, Andre R SiebersAbstract:Abstract Surface-groundwater interactions in intermittent rivers and Ephemeral Streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES. We combine a review of theIRES biogeochemistry literature with concepts of IRES hydrogeomorphology to: (i) outline common distinctions among hydrological states in IRES; (ii) use these distinctions, together with considerations of carbon, nitrogen, and phosphorus cycles within IRES, to predict the relative potential for biogeochemical processing across different reach-scale processing zones (flowing water, fragmented pools, hyporheic zones, groundwater, and emerged sediments); and (iii) explore the potential spatial and temporal variability of carbon and nutrient biogeochemical processing across entire IRES networks. Our approach estimates the greatest reach-scale potential for biogeochemical processing when IRES reaches are fragmented into isolated surface water pools, and highlights the potential of relatively understudied processing zones, such as emerged sediments. Furthermore, biogeochemical processing in fluvial networks dominated by IRES is likely more temporally than spatially variable. We conclude that biogeochemical research in IRES would benefit from focusing on interactions between different nutrient cycles, surface-groundwater interactions in non-flowing states, and consideration of fluvial network architecture. Our conceptual framework outlines opportunities to advance studies and expand understanding of biogeochemistry in IRES.
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Towards an improved understanding of biogeochemical processes across surface-groundwater interactions in intermittent rivers and Ephemeral Streams
2021Co-Authors: Lluís Gómez-gener, T. Datry, Maria Isabel Arce, Susana Bernal, Andre Siebers, Shai Arnon, Rossano Bolpagni, Giulia Gionchetta, Hans-peter Grossart, Clara Mendoza-leraAbstract:Surface-groundwater interactions in intermittent rivers and Ephemeral Streams (IRES), waterways which do not flow year-round, are spatially and temporally dynamic because of alternations between flowing, non-flowing and dry hydrological states. Interactions between surface and groundwater often create mixing zones with distinct redox gradients, potentially driving high rates of carbon and nutrient cycling. Yet a complete understanding of how underlying biogeochemical processes across surface-groundwater flowpaths in IRES differ among various hydrological states remains elusive. Here, we present a conceptual framework relating spatial and temporal hydrological variability in surface water-groundwater interactions to biogeochemical processing hotspots in IRES
O Shumilova - One of the best experts on this subject based on the ideXlab platform.
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simulating rewetting events in intermittent rivers and Ephemeral Streams a global analysis of leached nutrients and organic matter
Global Change Biology, 2019Co-Authors: T. Datry, Roland Corti, Arnaud Foulquier, Klement Tockner, Biel Obrador, O Shumilova, Daniel Von SchillerAbstract:Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and Ephemeral Streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.