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Zahra Thomas - One of the best experts on this subject based on the ideXlab platform.
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Hedgerows reduce nitrate flux at hillslope and catchment scales via root uptake and secondary effects
Journal of Contaminant Hydrology, 2018Co-Authors: Zahra Thomas, Albert AbbottAbstract:Agricultural contamination of groundwater with nitrate (NO3-) is one of the most widespread and pressing environmental issues. The preservation and planting of Hedgerows around agricultural fields can reduce NO3- flux, but the efficacy of Hedgerows depends on the amount of NO3- in soil and groundwater, hydrological flowpath and timing, and biogeochemical conditions surrounding and below roots. Quantifying these parameters is a major challenge, usually requiring involved and destructive fieldwork. Here, we present a new analytical method to characterize NO3- stratification using water chemistry sampled during piezometer slug tests. We tested this method with a network of wells in a hillslope intersected by an oak Hedgerow during high- and low-water conditions, respectively spring and autumn. We found that Hedgerows had a strong seasonal effect on near-surface NO3- dynamics in the proximity of the root system, reducing annual hillslope-level fluxes by 26 to 63%, comparable to NO3- removal from cover crop techniques. Hedgerow root uptake accounted for two-thirds of this reduction, with the remaining third attributable to secondary effects, potentially Hedgerow-induced microbial retention or denitrification due to increased organic carbon and heterogeneous redox conditions in the rooting zone. However, a simple scaling exercise suggested that at the catchment level, Hedgerow NO3- removal has a smaller effect (ca 1-10% reduction of annual flux), due to the large legacy of NO3- in the aquifer from past fertilizer application. These results suggest that while Hedgerows cannot immediately solve problems of past groundwater contamination, protection and reestablishment of Hedgerow networks could substantially accelerate recovery of groundwater quality on decadal timescales.
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Soil water movement under a bottomland Hedgerow during contrasting meteorological conditions
Hydrological Processes, 2011Co-Authors: Reza Ghazavi, Zahra Thomas, Y. Hamon, P. MerotAbstract:Linear vegetation structures such as hedge tree networks (Hedgerows), shelterbelts, and isolated trees play a major role on soil water transfer. Our objective is to evaluate the influence of a bottomland Hedgerow on water flux in the saturated and unsaturated zones. Soil water movement was investigated in a hillslope crossed by a Hedgerow using total water-potential gradients and shallow groundwater dynamics. Results of a dry year were presented by Ghazavi et al. (2008). In this study, we analyse a wet year and then compare the two contrasting years (dry and wet). During the 2 years, the soil located at the vicinity of the Hedgerow developed a drier status than the surrounding soils. Water flux in the unsaturated zone was directed towards the Hedgerow for a longer period during the dry year than the wet year. The duration of delayed rewetting of the soil decreased from 3 months for the dry year to 1 month for the wet year. Variation in water storage calculated over the study period was highest near the Hedgerow and lowest far from the Hedgerow. In the hillslope studied, Hedgerow and stream proximity controlled water transfer. It is clear that the Hedgerow controlled water transfer in the unsaturated zone throughout the year, except for the period when the soil profile was fully saturated. First, Hedgerows control water transfer by increasing lateral transfer, which is related to high soil water potential gradients in its vicinity. These processes may increase capillary rise and decrease groundwater recharge near the Hedgerow. Second, reverse hydraulic gradient (upward flux of water) occurred during the period of lowest groundwater level, mainly because of groundwater and stream connectivity. Processes related to Hedgerow presence, such as delayed soil rewetting and flow towards the Hedgerow need to be considered to quantify the impact of linear vegetation structures on water flux.
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Soil water movement under a bottomland Hedgerow during contrasting meteorological conditions
Hydrological Processes, 2010Co-Authors: Reza Ghazavi, Zahra Thomas, Y. Hamon, P. MerotAbstract:Linear vegetation structures such as hedge tree networks (Hedgerows), shelterbelts, and isolated trees play a major role on soil water transfer. Our objective is to evaluate the influence of a bottomland Hedgerow on water flux in the saturated and unsaturated zones. Soil water movement was investigated in a hillslope crossed by a Hedgerow using total water-potential gradients and shallow groundwater dynamics. Results of a dry year were presented by Ghazavi et al. (2008). In this study, we analyse a wet year and then compare the two contrasting years (dry and wet). During the 2 years, the soil located at the vicinity of the Hedgerow developed a drier status than the surrounding soils. Water flux in the unsaturated zone was directed towards the Hedgerow for a longer period during the dry year than the wet year. The duration of delayed rewetting of the soil decreased from 3 months for the dry year to 1 month for the wet year. Variation in water storage calculated over the study period was highest near the Hedgerow and lowest far from the Hedgerow. In the hillslope studied, Hedgerow and stream proximity controlled water transfer. It is clear that the Hedgerow controlled water transfer in the unsaturated zone throughout the year, except for the period when the soil profile was fully saturated. First, Hedgerows control water transfer by increasing lateral transfer, which is related to high soil water potential gradients in its vicinity. These processes may increase capillary rise and decrease groundwater recharge near the Hedgerow. Second, reverse hydraulic gradient (upward flux of water) occurred during the period of lowest groundwater level, mainly because of groundwater and stream connectivity. Processes related to Hedgerow presence, such as delayed soil rewetting and flow towards the Hedgerow need to be considered to quantify the impact of linear vegetation structures on water flux. Copyright © 2010 John Wiley & Sons, Ltd.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake
Hydrological Processes, 2008Co-Authors: Gholamreza Ghazavi, Zahra Thomas, Y. Hamon, Jean-claude Marie, Michael S. Corson, Philippe MérotAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of Hedgerows is useful in many fields of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a Hedgerow on rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a Hedgerow perpendicular to the slope was monitored. To evaluate Hedgerow rainfall interception, rainfall was measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 m downslope perpendicularly away from the Hedgerow. The strongest correlation between rainfall next to the Hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the Hedgerow on spatial rainfall distribution was related to distance from the Hedgerow and rainfall amount. Annual distribution of soil-water potential showed that the Hedgerow influenced it up to 9 m upslope and 6 m downslope, the area in which most of the Hedgerow's roots were observed. The soil was driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the Hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the Hedgerow in summer and autumn. These results indicate that at the local scale Hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the Hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around Hedgerows should be integrated into relevant hydrological models, especially for catchments with a dense Hedgerow network.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake
Hydrological Processes, 2008Co-Authors: Gholamreza Ghazavi, Zahra Thomas, Yannick Hamon, Jean-claude Marie, Michael Corson, Philippe MérotAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of Hedgerows is useful ill many fields Of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a Hedgerow oil rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a Hedgerow perpendicular to the slope was monitored. To evaluate Hedgerow rainfall interception, rainfall was Measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 in downslope perpendicularly away from the Hedgerow. The strongest correlation between rainfall next to the Hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the Hedgerow on spatial rainfall distribution wits related to distance from the Hedgerow and rainfall amount. Annual distribution of soil-water potential showed that (lie Hedgerow influenced it up to 9 in upslope and 6 m downslope, the area in which most of the Hedgerow's roots were observed. The soil wits driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the Hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end Of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the Hedgerow in summer and autumn. These results indicate that at the local scale Hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the Hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around Hedgerows should be integrated into relevant hydrological models, especially For catchments with it dense Hedgerow network. Copyright (C) 2008 John Wiley & Sons, Ltd.
Philippe Mérot - One of the best experts on this subject based on the ideXlab platform.
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Chloride concentration distribution under oak Hedgerow: an indicator of the water-uptake zone of tree roots?
Plant and Soil, 2015Co-Authors: Hongtao Hao, Catherine Grimaldi, Christian Walter, Gilles Dutin, Béatrice Trinkler, Philippe MérotAbstract:In agroforestry systems, root activity of trees may either reduce nutrient leaching beneath neighboring crops or compete with them. A previous study reveals high chloride (Cl) accumulation in the soil under a bottomland oak Hedgerow in western France. Our study tests whether Cl can be used as an indicator of the spatial extent of tree root activity. Cl was analyzed in soil profiles up to 2 m deep along transects perpendicular to Hedgerows. One site was explored in detail to examine the role of Hedgerow position on the slope, supplemented with multi-annual and multi-site studies on bottomland Hedgerows. Upslope Cl accumulation was highest near the tree line (and up to 6 m away) and around 1 m deep. Downslope it extended up to 18 m from the tree line and near the surface. This difference was caused by differences in water availability or physical soil constraints. Cl accumulation was found in both temporal (multi-annual) and spatial (multi-site) studies. Cl accumulation under oak Hedgerows can be used to identify the lateral extent and depth of water uptake by roots. It results from root activity over many years. The method is more suitable for poorly drained soils.
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Modeling the interaction between fields and a surrounding Hedgerow network and its impact on water and nitrogen flows of a small watershed
Agricultural Water Management, 2013Co-Authors: Cyril Benhamou, Catherine Grimaldi, Jordy Salmon-monviola, Patrick Durand, Philippe MérotAbstract:The rural landscape in Western Europe, as in many regions of the world, is structured by networks of woody Hedgerows that surround agricultural fields. Although many studies at local scale have shown the strong impact of Hedgerows on soil water and nitrogen balances, few have quantified the impact of Hedgerows at the watershed scale. This study estimated via modeling the impact of Hedgerow networks on soil water and nitrogen balances of a small watershed in a temperate climate. The spatially explicit model TNT2 (topography-based nitrogen transfer and transformation), to which a new sub-model of Hedgerow functioning was added, was used to perform the study. The unique character of this sub-model is to consider "double-cover" cells (crop plus hedge) to take into account competition for light, water, and nitrogen. The effect of hedge management by branch pruning was also studied. The model was used to simulate a small experimental watershed in western Europe over 17 years with the Hedgerow network that existed in 1999 (48 m ha(-1)), or without Hedgerows. On average, predictions of hedge transpiration and hedge N uptake were consistent with observations from the bibliography. On double-cover cells, the hydro-chemical impact of the hedge resulted from the complex combination of processes, which can have opposite effects. At the watershed scale, the Hedgerow network decreased predicted water flow at the outlet by 4.5% and nitrogen flow by 3.3%, respectively, compared to those flows when the watershed had no Hedgerows. Finally, Hedgerow pruning has a low effect on water and nitrogen flow at the outlet of watershed. (c) 2013 Elsevier B.V. All rights reserved.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake
Hydrological Processes, 2008Co-Authors: Gholamreza Ghazavi, Zahra Thomas, Y. Hamon, Jean-claude Marie, Michael S. Corson, Philippe MérotAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of Hedgerows is useful in many fields of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a Hedgerow on rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a Hedgerow perpendicular to the slope was monitored. To evaluate Hedgerow rainfall interception, rainfall was measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 m downslope perpendicularly away from the Hedgerow. The strongest correlation between rainfall next to the Hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the Hedgerow on spatial rainfall distribution was related to distance from the Hedgerow and rainfall amount. Annual distribution of soil-water potential showed that the Hedgerow influenced it up to 9 m upslope and 6 m downslope, the area in which most of the Hedgerow's roots were observed. The soil was driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the Hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the Hedgerow in summer and autumn. These results indicate that at the local scale Hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the Hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around Hedgerows should be integrated into relevant hydrological models, especially for catchments with a dense Hedgerow network.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake
Hydrological Processes, 2008Co-Authors: Gholamreza Ghazavi, Zahra Thomas, Yannick Hamon, Jean-claude Marie, Michael Corson, Philippe MérotAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of Hedgerows is useful ill many fields Of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a Hedgerow oil rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a Hedgerow perpendicular to the slope was monitored. To evaluate Hedgerow rainfall interception, rainfall was Measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 in downslope perpendicularly away from the Hedgerow. The strongest correlation between rainfall next to the Hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the Hedgerow on spatial rainfall distribution wits related to distance from the Hedgerow and rainfall amount. Annual distribution of soil-water potential showed that (lie Hedgerow influenced it up to 9 in upslope and 6 m downslope, the area in which most of the Hedgerow's roots were observed. The soil wits driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the Hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end Of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the Hedgerow in summer and autumn. These results indicate that at the local scale Hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the Hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around Hedgerows should be integrated into relevant hydrological models, especially For catchments with it dense Hedgerow network. Copyright (C) 2008 John Wiley & Sons, Ltd.
P. Merot - One of the best experts on this subject based on the ideXlab platform.
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Soil water movement under a bottomland Hedgerow during contrasting meteorological conditions
Hydrological Processes, 2011Co-Authors: Reza Ghazavi, Zahra Thomas, Y. Hamon, P. MerotAbstract:Linear vegetation structures such as hedge tree networks (Hedgerows), shelterbelts, and isolated trees play a major role on soil water transfer. Our objective is to evaluate the influence of a bottomland Hedgerow on water flux in the saturated and unsaturated zones. Soil water movement was investigated in a hillslope crossed by a Hedgerow using total water-potential gradients and shallow groundwater dynamics. Results of a dry year were presented by Ghazavi et al. (2008). In this study, we analyse a wet year and then compare the two contrasting years (dry and wet). During the 2 years, the soil located at the vicinity of the Hedgerow developed a drier status than the surrounding soils. Water flux in the unsaturated zone was directed towards the Hedgerow for a longer period during the dry year than the wet year. The duration of delayed rewetting of the soil decreased from 3 months for the dry year to 1 month for the wet year. Variation in water storage calculated over the study period was highest near the Hedgerow and lowest far from the Hedgerow. In the hillslope studied, Hedgerow and stream proximity controlled water transfer. It is clear that the Hedgerow controlled water transfer in the unsaturated zone throughout the year, except for the period when the soil profile was fully saturated. First, Hedgerows control water transfer by increasing lateral transfer, which is related to high soil water potential gradients in its vicinity. These processes may increase capillary rise and decrease groundwater recharge near the Hedgerow. Second, reverse hydraulic gradient (upward flux of water) occurred during the period of lowest groundwater level, mainly because of groundwater and stream connectivity. Processes related to Hedgerow presence, such as delayed soil rewetting and flow towards the Hedgerow need to be considered to quantify the impact of linear vegetation structures on water flux.
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Soil water movement under a bottomland Hedgerow during contrasting meteorological conditions
Hydrological Processes, 2010Co-Authors: Reza Ghazavi, Zahra Thomas, Y. Hamon, P. MerotAbstract:Linear vegetation structures such as hedge tree networks (Hedgerows), shelterbelts, and isolated trees play a major role on soil water transfer. Our objective is to evaluate the influence of a bottomland Hedgerow on water flux in the saturated and unsaturated zones. Soil water movement was investigated in a hillslope crossed by a Hedgerow using total water-potential gradients and shallow groundwater dynamics. Results of a dry year were presented by Ghazavi et al. (2008). In this study, we analyse a wet year and then compare the two contrasting years (dry and wet). During the 2 years, the soil located at the vicinity of the Hedgerow developed a drier status than the surrounding soils. Water flux in the unsaturated zone was directed towards the Hedgerow for a longer period during the dry year than the wet year. The duration of delayed rewetting of the soil decreased from 3 months for the dry year to 1 month for the wet year. Variation in water storage calculated over the study period was highest near the Hedgerow and lowest far from the Hedgerow. In the hillslope studied, Hedgerow and stream proximity controlled water transfer. It is clear that the Hedgerow controlled water transfer in the unsaturated zone throughout the year, except for the period when the soil profile was fully saturated. First, Hedgerows control water transfer by increasing lateral transfer, which is related to high soil water potential gradients in its vicinity. These processes may increase capillary rise and decrease groundwater recharge near the Hedgerow. Second, reverse hydraulic gradient (upward flux of water) occurred during the period of lowest groundwater level, mainly because of groundwater and stream connectivity. Processes related to Hedgerow presence, such as delayed soil rewetting and flow towards the Hedgerow need to be considered to quantify the impact of linear vegetation structures on water flux. Copyright © 2010 John Wiley & Sons, Ltd.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake.
Hydrological Processes, 2008Co-Authors: Michael S. Corson, P. Merot, Y. Hamon, Gholamreza Ghazavi, Jean-claude Marie, Zahra ThomasAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe.Knowledge about the hydrological role of Hedgerows is useful ill many fields Of study, such as hydrological modelling
Y. Hamon - One of the best experts on this subject based on the ideXlab platform.
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Soil water movement under a bottomland Hedgerow during contrasting meteorological conditions
Hydrological Processes, 2011Co-Authors: Reza Ghazavi, Zahra Thomas, Y. Hamon, P. MerotAbstract:Linear vegetation structures such as hedge tree networks (Hedgerows), shelterbelts, and isolated trees play a major role on soil water transfer. Our objective is to evaluate the influence of a bottomland Hedgerow on water flux in the saturated and unsaturated zones. Soil water movement was investigated in a hillslope crossed by a Hedgerow using total water-potential gradients and shallow groundwater dynamics. Results of a dry year were presented by Ghazavi et al. (2008). In this study, we analyse a wet year and then compare the two contrasting years (dry and wet). During the 2 years, the soil located at the vicinity of the Hedgerow developed a drier status than the surrounding soils. Water flux in the unsaturated zone was directed towards the Hedgerow for a longer period during the dry year than the wet year. The duration of delayed rewetting of the soil decreased from 3 months for the dry year to 1 month for the wet year. Variation in water storage calculated over the study period was highest near the Hedgerow and lowest far from the Hedgerow. In the hillslope studied, Hedgerow and stream proximity controlled water transfer. It is clear that the Hedgerow controlled water transfer in the unsaturated zone throughout the year, except for the period when the soil profile was fully saturated. First, Hedgerows control water transfer by increasing lateral transfer, which is related to high soil water potential gradients in its vicinity. These processes may increase capillary rise and decrease groundwater recharge near the Hedgerow. Second, reverse hydraulic gradient (upward flux of water) occurred during the period of lowest groundwater level, mainly because of groundwater and stream connectivity. Processes related to Hedgerow presence, such as delayed soil rewetting and flow towards the Hedgerow need to be considered to quantify the impact of linear vegetation structures on water flux.
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Soil water movement under a bottomland Hedgerow during contrasting meteorological conditions
Hydrological Processes, 2010Co-Authors: Reza Ghazavi, Zahra Thomas, Y. Hamon, P. MerotAbstract:Linear vegetation structures such as hedge tree networks (Hedgerows), shelterbelts, and isolated trees play a major role on soil water transfer. Our objective is to evaluate the influence of a bottomland Hedgerow on water flux in the saturated and unsaturated zones. Soil water movement was investigated in a hillslope crossed by a Hedgerow using total water-potential gradients and shallow groundwater dynamics. Results of a dry year were presented by Ghazavi et al. (2008). In this study, we analyse a wet year and then compare the two contrasting years (dry and wet). During the 2 years, the soil located at the vicinity of the Hedgerow developed a drier status than the surrounding soils. Water flux in the unsaturated zone was directed towards the Hedgerow for a longer period during the dry year than the wet year. The duration of delayed rewetting of the soil decreased from 3 months for the dry year to 1 month for the wet year. Variation in water storage calculated over the study period was highest near the Hedgerow and lowest far from the Hedgerow. In the hillslope studied, Hedgerow and stream proximity controlled water transfer. It is clear that the Hedgerow controlled water transfer in the unsaturated zone throughout the year, except for the period when the soil profile was fully saturated. First, Hedgerows control water transfer by increasing lateral transfer, which is related to high soil water potential gradients in its vicinity. These processes may increase capillary rise and decrease groundwater recharge near the Hedgerow. Second, reverse hydraulic gradient (upward flux of water) occurred during the period of lowest groundwater level, mainly because of groundwater and stream connectivity. Processes related to Hedgerow presence, such as delayed soil rewetting and flow towards the Hedgerow need to be considered to quantify the impact of linear vegetation structures on water flux. Copyright © 2010 John Wiley & Sons, Ltd.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake
Hydrological Processes, 2008Co-Authors: Gholamreza Ghazavi, Zahra Thomas, Y. Hamon, Jean-claude Marie, Michael S. Corson, Philippe MérotAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe. Knowledge about the hydrological role of Hedgerows is useful in many fields of study, such as hydrological modelling and rural landscape management. The aim of this study was to investigate the impact of a Hedgerow on rainfall distribution, soil-water potential gradient, lateral water transfer and water balance. A hillslope with a Hedgerow perpendicular to the slope was monitored. To evaluate Hedgerow rainfall interception, rainfall was measured (hourly, daily, and by rainfall event) both next to and up to 16 m upslope and 12 m downslope perpendicularly away from the Hedgerow. The strongest correlation between rainfall next to the Hedgerow and rainfall at more distant points was obtained using data measured per rainfall event. The average percentage of rainfall intercepted equalled 28% for the leafed period and 12% for the leafless period. The impact of the Hedgerow on spatial rainfall distribution was related to distance from the Hedgerow and rainfall amount. Annual distribution of soil-water potential showed that the Hedgerow influenced it up to 9 m upslope and 6 m downslope, the area in which most of the Hedgerow's roots were observed. The soil was driest at the end of summer, which delayed soil rewetting during autumn in areas surrounding the Hedgerow. Annual groundwater dynamics exhibited three distinct periods due to temporal rainfall distribution and, especially at the end of summer, root-water uptake. In addition, the total potential gradient showed that unsaturated flow was directed towards the Hedgerow in summer and autumn. These results indicate that at the local scale Hedgerows influences (1) spatial rainfall distribution, (2) soil rewetting, and (3) groundwater recharge, often at distances well beyond the Hedgerow's drip line. Consequently, the processes involved in soil-water dynamics around Hedgerows should be integrated into relevant hydrological models, especially for catchments with a dense Hedgerow network.
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Hedgerow impacts on soil-water transfer due to rainfall interception and root-water uptake.
Hydrological Processes, 2008Co-Authors: Michael S. Corson, P. Merot, Y. Hamon, Gholamreza Ghazavi, Jean-claude Marie, Zahra ThomasAbstract:Hedgerow is one of the most important rural landscapes in the world, especially in Europe.Knowledge about the hydrological role of Hedgerows is useful ill many fields Of study, such as hydrological modelling
Martin Diekmann - One of the best experts on this subject based on the ideXlab platform.
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Contrasting microclimates among Hedgerows and woodlands across temperate Europe
Agricultural and Forest Meteorology, 2020Co-Authors: Thomas Vanneste, Sanne Govaert, Fabien Spicher, Jorg Brunet, Sara A.o. Cousins, Guillaume Decocq, Martin Diekmann, Bente Graae, Per-ola Hedwall, Rozália KapásAbstract:Hedgerows have the potential to facilitate the persistence and migration of species across landscapes, mostly due to benign microclimatic conditions. This thermal buffering function may become even more important in the future for species migration under climate change. Unfortunately, there is a lack of empirical studies quantifying the microclimate of Hedgerows, particularly at broad geographical scales. Here we monitored sub-canopy temperatures using 168 miniature temperature sensors distributed along woodland-Hedgerow transects, and spanning a 1600-km macroclimatic gradient across Europe. First, we assessed the variation in the temperature offset (that is, the difference between sub-canopy and corresponding macroclimate temperatures) for minimum, mean and maximum temperatures along the woodland-Hedgerow transects. Next, we linked the observed patterns to macroclimate temperatures as well as canopy structure, overstorey composition and Hedgerow characteristics. The sub-canopy versus macroclimate temperature offset was on average 0.10 °C lower in Hedgerows than in woodlands. Minimum winter temperatures were consistently lower by 0.10 °C in Hedgerows than in woodlands, while maximum summer temperatures were 0.80 °C higher, albeit mainly around the woodland-Hedgerow ecotone. The temperature offset was often negatively correlated with macroclimate temperatures. The slope of this relationship was lower for maximum temperatures in Hedgerows than in woodlands. During summer, canopy cover, tree height and Hedgerow width had strong cooling effects on maximum mid-day temperatures in Hedgerows. The effects of shrub height, shrub cover and shade-casting ability, however, were not significant. To our knowledge, this is the first study to quantify Hedgerow microclimates along a continental-scale environmental gradient. We show that Hedgerows are less efficient thermal insulators than woodlands, especially at high ambient temperatures (e.g. on warm summer days). This knowledge will not only result in better predictions of species distribution across fragmented landscapes, but will also help to elaborate efficient strategies for biodiversity conservation and landscape planning.
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Hedgerow age affects the species richness of herbaceous forest plants
Journal of Vegetation Science, 2019Co-Authors: Kathrin Litza, Martin DiekmannAbstract:QUESTIONS: Are recent Hedgerows less rich in forest vascular plants than ancient Hedgerows? Does the proximity to potential source populations influence the forest species richness in recent Hedgerows? Is there a difference in the dispersal potential of forest specialists found in recent and ancient Hedgerows? How similar is the species composition between Hedgerows of different ages? LOCATION: Southeastern Schleswig‐Holstein, Northern Germany. METHODS: We investigated 30 Hedgerows in a pairwise design to compare the species composition of ancient and recent Hedgerows. RESULTS: While recent Hedgerows already function as habitats for herbaceous forest specialists, they contain significantly fewer forest species than ancient Hedgerows. Besides Hedgerow age proximity to ancient forests, a wide shrub layer, high pH values and a low phosphorus content are also positively associated with the number of forest specialists. The similarity in species composition between recent and ancient Hedgerows increases with the age of the recent Hedgerow. Epizoochorous dispersal and reproduction by seed favour the colonisation of recent Hedgerows by forest species. Most environmental and Hedgerow structural parameters do not differ between the age categories except for pH, which is significantly higher in recent Hedgerows. CONCLUSIONS: Ancient Hedgerows are important for regional biodiversity, especially as source populations for recent Hedgerows, and therefore need to be protected. If the recent Hedgerows are managed traditionally, they can over time transform into valuable habitats similar to ancient Hedgerows.
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Importance of Hedgerows as habitat corridors for forest plants in agricultural landscapes
Biological Conservation, 2009Co-Authors: Stephan Wehling, Martin DiekmannAbstract:Abstract Hedgerows have been proposed as habitat and conservation corridor for forest plant species, but their importance for the survival of these species is still not clear. The objective of our study was to examine the frequency of occurrence of forest species and total forest species richness in different parts of the Hedgerows, and to relate these patterns of occurrence to the species’ habitat requirements and life history traits. We surveyed in total 130 forest-Hedgerow transects in North-western Germany, including three age classes. About 77% of all forest plant species (including some endangered taxa) occurring in the neighbouring forests were also found in the adjacent Hedgerows. In all age classes, there was a negative relationship between distance from the forest-Hedgerow ecotone and the number of species. Ancient Hedgerows were not significantly more species-rich than more recent ones. Within 100 m distance from the forest edge, forest species richness increased with an increasing number of species in the nearby forest and with an increasing cover of the tree canopy as well as a decreasing cover of the shrub layer. Species with high frequency had comparatively high Ellenberg indicator values for light, and were mostly associated with anemochorous and epizoochorous seed dispersal. The frequency of occurrence in Hedgerows of species with common attributes was partly in agreement, partly in disagreement with the results obtained in previous studies. We conclude that patterns are difficult to generalize, probably due to a strong regional variation in the pool of forest species and in the specific environments of both forests and Hedgerows.