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Kazuki Nanko - One of the best experts on this subject based on the ideXlab platform.
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[Dataset] Throughfall isotopic composition and drop size distributions Scots pine stand
2020Co-Authors: Juan Pinos, Kazuki Nanko, Jérôme Latron, Delphis F. Levia, Pilar LlorensAbstract:Data information Meteorological variables, rainfall amount, Throughfall amount, rainfall and Throughfall isotopic composition and rainfall and Throughfall drop size distributions. Open area and Pinus sylvestris L forest in Vallcebre research catchments. Study period: from May 2018 to July 2019. Data structure Date and time format • dd/mm/yyyy: day/month/year. • hh:mm:ss: hour/minutes/seconds Meteorological variables • Temp (°C): Air temperature (°C) • RH (%): Relative humidity (%) • Rn (W m-2): Net radiation (W m-2) • u (m s-1): Wind speed (m s-1) • Wind dir (°): Wind direction (°) Hydrometric variables • Rainfall (mm): Rainfall volume (mm) • Throughfall (mm): Throughfall volume (mm) Isotopic data • ISCO_sample: Sample number recorded by the ISCO sampler • RF_δ18O (‰): Rainfall oxygen-isotopic composition (‰) • RF_δ2H (‰): Rainfall deuterium-isotopic composition (‰) • TF_δ18O (‰): Throughfall oxygen-isotopic composition (‰) • TF_δ2H (‰): Throughfall deuterium-isotopic composition (‰) Drop size distribution data • RF_N drops: Number of recorded rainfall drops • RF_Vel mean: Mean velocity of rainfall drops (m s-1) • RF_nKE: Rainfall kinetic energy (J m-2) • RF-0.1 to RF-10.0: Rainfall volume (mm) for 0.1 mm drop size class to rainfall volume (mm) for 10 mm drop size class. • TF_N drops: Number of recorded Throughfall drops • TF_Vel mean: Mean velocity of Throughfall drops (m s-1) • TF_nKE: Throughfall kinetic energy (J m-2) • TF-0.1 to TF-10.0: Throughfall volume (mm) for 0.1 mm drop size class to Throughfall volume (mm) for 10 mm drop size class “N/D” indicated no available data and “Discarded samples” indicated the water isotope samples that have been discarded from the analysis because the (rainfall or Throughfall) water samples contained mixed water either from pre- or post-event, therefore, they corresponds to the first or last samples of certain events.
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Throughfall isotopic composition in relation to drop size at the intra-event scale in a Mediterranean Scots pine stand
Hydrology and Earth System Sciences, 2020Co-Authors: Juan Pinos, Kazuki Nanko, Jérôme Latron, Delphis F. Levia, Pilar LlorensAbstract:Abstract. The major fraction of water reaching the forest floor is Throughfall, which consists of free Throughfall, splash Throughfall and canopy drip. Research has shown that forest canopies modify the isotopic composition of Throughfall by means of evaporation, isotopic exchange, canopy selection and mixing of rainfall waters. However, the effects of these factors in relation to Throughfall isotopic composition and the Throughfall drop size reaching the soil surface are unclear. Based on research in a mountainous Scots pine stand in northeastern Spain, this study sought to fill this knowledge gap by examining the isotopic composition of Throughfall in relation to Throughfall drop size. In the experimental stand, Throughfall consisted on average of 65 % canopy drip, 19 % free Throughfall and 16 % splash Throughfall. The dynamics of the isotopic composition of Throughfall and rainfall showed complex behaviour throughout events. The isotopic shift showed no direct relationship with meteorological variables, number of drops, drop velocities, Throughfall and rainfall amount, or raindrop kinetic energy. However, the experiment did reveal that the isotopic shift was higher at the beginning of an event, decreasing as cumulative rainfall increased, and that it also increased when the median volume drop size of Throughfall (D50_TF) approached or was lower than the median volume drop size of rainfall (D50_RF). This finding indicates that the major contribution of splash Throughfall at the initial phase of rain events matched the highest vapour pressure deficit (VPD) and, at the same time, corresponded to higher isotopic enrichment, which implies that splash droplet evaporation occurred. Future applications of our approach will improve understanding of how Throughfall isotopic composition may vary with drop type and size during rainfall events across a range of forest types.
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Throughfall erosivity in relation to drop size and crown position a case study from a teak plantation in thailand
2020Co-Authors: Kazuki Nanko, Nobuaki Tanaka, Michael Leuchner, Delphis F. LeviaAbstract:Throughfall erosivity is necessary for the prediction of soil erosion in some forests with little protective ground cover. Throughfall drops and erosivity were compared with open rainfall and at four different crown positions beneath the canopy in a teak plantation in Thailand. Throughfall was partitioned into free Throughfall, splash Throughfall, and canopy drip using drop size distributions of both open rainfall and Throughfall. Compared with open rainfall, (1) Throughfall drops were lower in number but larger in size due to the coalescence of raindrops on canopies; (2) Throughfall drops, especially canopy drip, had lower velocity due to insufficient fall distance from the canopy to the forest floor to reach terminal velocity, which partly depends on crown base height and the vertical distribution of foliage; and (3) Throughfall usually had higher kinetic energy due to larger drop size, which depends on the amount of canopy drip and the crown base height. Throughfall kinetic energy was higher in mid-crown positions than in the gap or near-stem positions. Compared to mid-crown positions, the gap position had smaller drops and less canopy drip, while the near-stem position had lower drop fall velocity. The erosivity of Throughfall with respect to crown position is useful to better understand canopy–water–soil interactions, develop high-resolution maps of potential soil erosion risk, and help maintain forest productivity.
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Throughfall partitioning by trees
Hydrological Processes, 2019Co-Authors: Delphis F. Levia, Kazuki Nanko, Norifumi Hotta, Hiromasa Amasaki, Thomas W. Giambelluca, Shin'ichi Iida, Ryan G. Mudd, Michael A. Nullet, Naoki Sakai, Yoshinori ShinoharaAbstract:Although we know that rainfall interception (the rain caught, stored, and evaporated from aboveground vegetative surfaces and ground litter) is affected by rain and Throughfall drop size, what was unknown until now is the relative proportion of each Throughfall type (free Throughfall, splash Throughfall, canopy drip) beneath coniferous and broadleaved trees. Based on a multinational data set of >120 million Throughfall drops, we found that the type, number, and volume of Throughfall drops are different between coniferous and broadleaved tree species, leaf states, and timing within rain events. Compared with leafed broadleaved trees, conifers had a lower percentage of canopy drip (51% vs. 69% with respect to total Throughfall volume) and slightly smaller diameter splash Throughfall and canopy drip. Canopy drip from leafless broadleaved trees consisted of fewer and smaller diameter drops (D₅₀_DR, 50th cumulative drop volume percentile for canopy drip, of 2.24 mm) than leafed broadleaved trees (D₅₀_DR of 4.32 mm). Canopy drip was much larger in diameter under woody drip points (D₅₀_DR of 5.92 mm) than leafed broadleaved trees. Based on Throughfall volume, the percentage of canopy drip was significantly different between conifers, leafed broadleaved trees, leafless broadleaved trees, and woody surface drip points (p ranged from <0.001 to 0.005). These findings are partly attributable to differences in canopy structure and plant surface characteristics between plant functional types and canopy state (leaf, leafless), among other factors. Hence, our results demonstrating the importance of drop‐size‐dependent partitioning between coniferous and broadleaved tree species could be useful to those requiring more detailed information on Throughfall fluxes to the forest floor.
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Throughfall partitioning by trees
Hydrological Processes, 2019Co-Authors: Delphis F. Levia, Kazuki Nanko, Norifumi Hotta, Hiromasa Amasaki, Thomas W. Giambelluca, Shin'ichi Iida, Ryan G. Mudd, Michael A. Nullet, Naoki Sakai, Yoshinori ShinoharaAbstract:Although we know that rainfall interception (the rain caught, stored, and evaporated from aboveground vegetative surfaces and ground litter) is affected by rain and Throughfall drop size, what was unknown until now is the relative proportion of each Throughfall type (free Throughfall, splash Throughfall, canopy drip) beneath coniferous and broadleaved trees. Based on a multinational data set of >120 million Throughfall drops, we found that the type, number, and volume of Throughfall drops are different between coniferous and broadleaved tree species, leaf states, and timing within rain events. Compared with leafed broadleaved trees, conifers had a lower percentage of canopy drip (51% vs. 69% with respect to total Throughfall volume) and slightly smaller diameter splash Throughfall and canopy drip. Canopy drip from leafless broadleaved trees consisted of fewer and smaller diameter drops (D₅₀_DR, 50th cumulative drop volume percentile for canopy drip, of 2.24 mm) than leafed broadleaved trees (D₅₀_DR of 4.32 mm). Canopy drip was much larger in diameter under woody drip points (D₅₀_DR of 5.92 mm) than leafed broadleaved trees. Based on Throughfall volume, the percentage of canopy drip was significantly different between conifers, leafed broadleaved trees, leafless broadleaved trees, and woody surface drip points (p ranged from
Jeffrey J Mcdonnell - One of the best experts on this subject based on the ideXlab platform.
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Spatial patterns of Throughfall isotopic composition at the event and seasonal timescales
Journal of Hydrology, 2015Co-Authors: Scott T Allen, Richard F. Keim, Jeffrey J McdonnellAbstract:Summary Spatial variability of Throughfall isotopic composition in forests is indicative of complex processes occurring in the canopy and remains insufficiently understood to properly characterize precipitation inputs to the catchment water balance. Here we investigate variability of Throughfall isotopic composition with the objectives: (1) to quantify the spatial variability in event-scale samples, (2) to determine if there are persistent controls over the variability and how these affect variability of seasonally accumulated Throughfall, and (3) to analyze the distribution of measured Throughfall isotopic composition associated with varying sampling regimes. We measured Throughfall over two, three-month periods in western Oregon, USA under a Douglas-fir canopy. The mean spatial range of δ18O for each event was 1.6‰ and 1.2‰ through Fall 2009 (11 events) and Spring 2010 (7 events), respectively. However, the spatial pattern of isotopic composition was not temporally stable causing season-total Throughfall to be less variable than event Throughfall (1.0‰; range of cumulative δ18O for Fall 2009). Isotopic composition was not spatially autocorrelated and not explained by location relative to tree stems. Sampling error analysis for both field measurements and Monte-Carlo simulated datasets representing different sampling schemes revealed the standard deviation of differences from the true mean as high as 0.45‰ (δ18O) and 1.29‰ (d-excess). The magnitude of this isotopic variation suggests that small sample sizes are a source of substantial experimental error.
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the role of pre event canopy storage in Throughfall and stemflow by using isotopic tracers
Ecohydrology, 2014Co-Authors: Scott T Allen, Richard F. Keim, J R Brooks, Barbara J Bond, Jeffrey J McdonnellAbstract:Stable isotopes can be a valuable tool for tracing the redistribution, storage, and evaporation of water associated with canopy interception of rainfall. Isotopic differences between Throughfall and rainfall have been attributed to three mechanisms: evaporative fractionation, isotopic exchange with ambient vapor, and temporal redistribution. We demonstrate the potential importance of a fourth mechanism: rainfall mixing with water retained within the canopy (in bark, epiphytes, etc.) from prior rain events. Amount and isotopic composition (18O and 2H) of rainfall and Throughfall were measured over a 3-month period in a Douglas-fir forest in the Cascade Range of Oregon, USA. The range of spatial variability of Throughfall isotopic composition exceeded the differences between event-mean isotopic compositions of rainfall and Throughfall. Inter-event isotopic variation of precipitation was high and correlated with the isotopic deviation of Throughfall from rainfall, likely related to a high canopy/bark storage capacity storage bridging events. Both spatial variability of Throughfall isotopic composition and Throughfall–precipitation isotopic differences appear to have been controlled by the temporally varying influence of residual precipitation from previous events. Therefore, isotopic heterogeneity could indicate local storage characteristics and the partitioning of flow-paths within the canopy. Copyright © 2013 John Wiley & Sons, Ltd.
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Examining the role of Throughfall patterns on subsurface stormflow generation
Journal of Hydrology, 2011Co-Authors: Luisa Hopp, Jeffrey J McdonnellAbstract:Summary The effect of Throughfall input patterns on the hydrological response of forested hillslopes is not well understood. While field studies have contributed to our understanding of subsurface stormflow generation at the hillslope scale, such work is still of limited value because of the small number of places and events that have been characterized to date and the uniqueness of each study hillslope. In recent years, virtual experiments have been used to investigate the role of topography, soil depth, bedrock permeability and storm size, on the generation of lateral subsurface flow. However, these studies have generally assumed spatially uniform rainfall, and the interaction between vegetation and its effect on the spatial structure of input (canopy interception, Throughfall) for hillslope hydrologic response has not yet been explored. Here we present a number of virtual experiments that explore the interplay among hydrological inputs (temporal and spatial distribution of rainfall) and hillslope properties (subsurface topography, soil depth), i.e. physical phenomena that are sources of space and/or time variability. We address specifically the relative importance of fine-scale Throughfall patterns for hillslope hydrologic response. Topography and hydrologic field observations from an existing study hillslope were used to calibrate and test a 3D Richards equation-based finite element model. Throughfall patterns were based on published Throughfall patterns in an even age stand of young conifers in the Pacific Northwest. These patterns were then varied across the hillslope during the virtual experiments. Our results showed that, surprisingly, the effect of spatial input variability of Throughfall on lateral subsurface stormflow generation was minimal. For our tested case, the bedrock topography control on flow generation was much greater than the fine-scale spatial variability of the input. Using a spatially uniform area-averaged “Throughfall” (i.e. open rainfall reduced by some assumed fraction, which is the simplest and most common form of Throughfall representations) yielded minimal differences in subsurface stormflow response. Nevertheless, using open rainfall as spatially uniform input strongly overestimated lateral subsurface stormflow, and thus, the average impact of Throughfall is important for input estimation at the hillslope-scale. Overall, the effects of fine-scale Throughfall patterns on subsurface stormflow generation appear to be of secondary importance compared to effects of temporal distribution of rainfall, subsurface topography and variable soil depths.
Delphis F. Levia - One of the best experts on this subject based on the ideXlab platform.
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[Dataset] Throughfall isotopic composition and drop size distributions Scots pine stand
2020Co-Authors: Juan Pinos, Kazuki Nanko, Jérôme Latron, Delphis F. Levia, Pilar LlorensAbstract:Data information Meteorological variables, rainfall amount, Throughfall amount, rainfall and Throughfall isotopic composition and rainfall and Throughfall drop size distributions. Open area and Pinus sylvestris L forest in Vallcebre research catchments. Study period: from May 2018 to July 2019. Data structure Date and time format • dd/mm/yyyy: day/month/year. • hh:mm:ss: hour/minutes/seconds Meteorological variables • Temp (°C): Air temperature (°C) • RH (%): Relative humidity (%) • Rn (W m-2): Net radiation (W m-2) • u (m s-1): Wind speed (m s-1) • Wind dir (°): Wind direction (°) Hydrometric variables • Rainfall (mm): Rainfall volume (mm) • Throughfall (mm): Throughfall volume (mm) Isotopic data • ISCO_sample: Sample number recorded by the ISCO sampler • RF_δ18O (‰): Rainfall oxygen-isotopic composition (‰) • RF_δ2H (‰): Rainfall deuterium-isotopic composition (‰) • TF_δ18O (‰): Throughfall oxygen-isotopic composition (‰) • TF_δ2H (‰): Throughfall deuterium-isotopic composition (‰) Drop size distribution data • RF_N drops: Number of recorded rainfall drops • RF_Vel mean: Mean velocity of rainfall drops (m s-1) • RF_nKE: Rainfall kinetic energy (J m-2) • RF-0.1 to RF-10.0: Rainfall volume (mm) for 0.1 mm drop size class to rainfall volume (mm) for 10 mm drop size class. • TF_N drops: Number of recorded Throughfall drops • TF_Vel mean: Mean velocity of Throughfall drops (m s-1) • TF_nKE: Throughfall kinetic energy (J m-2) • TF-0.1 to TF-10.0: Throughfall volume (mm) for 0.1 mm drop size class to Throughfall volume (mm) for 10 mm drop size class “N/D” indicated no available data and “Discarded samples” indicated the water isotope samples that have been discarded from the analysis because the (rainfall or Throughfall) water samples contained mixed water either from pre- or post-event, therefore, they corresponds to the first or last samples of certain events.
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Throughfall isotopic composition in relation to drop size at the intra-event scale in a Mediterranean Scots pine stand
Hydrology and Earth System Sciences, 2020Co-Authors: Juan Pinos, Kazuki Nanko, Jérôme Latron, Delphis F. Levia, Pilar LlorensAbstract:Abstract. The major fraction of water reaching the forest floor is Throughfall, which consists of free Throughfall, splash Throughfall and canopy drip. Research has shown that forest canopies modify the isotopic composition of Throughfall by means of evaporation, isotopic exchange, canopy selection and mixing of rainfall waters. However, the effects of these factors in relation to Throughfall isotopic composition and the Throughfall drop size reaching the soil surface are unclear. Based on research in a mountainous Scots pine stand in northeastern Spain, this study sought to fill this knowledge gap by examining the isotopic composition of Throughfall in relation to Throughfall drop size. In the experimental stand, Throughfall consisted on average of 65 % canopy drip, 19 % free Throughfall and 16 % splash Throughfall. The dynamics of the isotopic composition of Throughfall and rainfall showed complex behaviour throughout events. The isotopic shift showed no direct relationship with meteorological variables, number of drops, drop velocities, Throughfall and rainfall amount, or raindrop kinetic energy. However, the experiment did reveal that the isotopic shift was higher at the beginning of an event, decreasing as cumulative rainfall increased, and that it also increased when the median volume drop size of Throughfall (D50_TF) approached or was lower than the median volume drop size of rainfall (D50_RF). This finding indicates that the major contribution of splash Throughfall at the initial phase of rain events matched the highest vapour pressure deficit (VPD) and, at the same time, corresponded to higher isotopic enrichment, which implies that splash droplet evaporation occurred. Future applications of our approach will improve understanding of how Throughfall isotopic composition may vary with drop type and size during rainfall events across a range of forest types.
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Throughfall erosivity in relation to drop size and crown position a case study from a teak plantation in thailand
2020Co-Authors: Kazuki Nanko, Nobuaki Tanaka, Michael Leuchner, Delphis F. LeviaAbstract:Throughfall erosivity is necessary for the prediction of soil erosion in some forests with little protective ground cover. Throughfall drops and erosivity were compared with open rainfall and at four different crown positions beneath the canopy in a teak plantation in Thailand. Throughfall was partitioned into free Throughfall, splash Throughfall, and canopy drip using drop size distributions of both open rainfall and Throughfall. Compared with open rainfall, (1) Throughfall drops were lower in number but larger in size due to the coalescence of raindrops on canopies; (2) Throughfall drops, especially canopy drip, had lower velocity due to insufficient fall distance from the canopy to the forest floor to reach terminal velocity, which partly depends on crown base height and the vertical distribution of foliage; and (3) Throughfall usually had higher kinetic energy due to larger drop size, which depends on the amount of canopy drip and the crown base height. Throughfall kinetic energy was higher in mid-crown positions than in the gap or near-stem positions. Compared to mid-crown positions, the gap position had smaller drops and less canopy drip, while the near-stem position had lower drop fall velocity. The erosivity of Throughfall with respect to crown position is useful to better understand canopy–water–soil interactions, develop high-resolution maps of potential soil erosion risk, and help maintain forest productivity.
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Throughfall partitioning by trees
Hydrological Processes, 2019Co-Authors: Delphis F. Levia, Kazuki Nanko, Norifumi Hotta, Hiromasa Amasaki, Thomas W. Giambelluca, Shin'ichi Iida, Ryan G. Mudd, Michael A. Nullet, Naoki Sakai, Yoshinori ShinoharaAbstract:Although we know that rainfall interception (the rain caught, stored, and evaporated from aboveground vegetative surfaces and ground litter) is affected by rain and Throughfall drop size, what was unknown until now is the relative proportion of each Throughfall type (free Throughfall, splash Throughfall, canopy drip) beneath coniferous and broadleaved trees. Based on a multinational data set of >120 million Throughfall drops, we found that the type, number, and volume of Throughfall drops are different between coniferous and broadleaved tree species, leaf states, and timing within rain events. Compared with leafed broadleaved trees, conifers had a lower percentage of canopy drip (51% vs. 69% with respect to total Throughfall volume) and slightly smaller diameter splash Throughfall and canopy drip. Canopy drip from leafless broadleaved trees consisted of fewer and smaller diameter drops (D₅₀_DR, 50th cumulative drop volume percentile for canopy drip, of 2.24 mm) than leafed broadleaved trees (D₅₀_DR of 4.32 mm). Canopy drip was much larger in diameter under woody drip points (D₅₀_DR of 5.92 mm) than leafed broadleaved trees. Based on Throughfall volume, the percentage of canopy drip was significantly different between conifers, leafed broadleaved trees, leafless broadleaved trees, and woody surface drip points (p ranged from <0.001 to 0.005). These findings are partly attributable to differences in canopy structure and plant surface characteristics between plant functional types and canopy state (leaf, leafless), among other factors. Hence, our results demonstrating the importance of drop‐size‐dependent partitioning between coniferous and broadleaved tree species could be useful to those requiring more detailed information on Throughfall fluxes to the forest floor.
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Throughfall partitioning by trees
Hydrological Processes, 2019Co-Authors: Delphis F. Levia, Kazuki Nanko, Norifumi Hotta, Hiromasa Amasaki, Thomas W. Giambelluca, Shin'ichi Iida, Ryan G. Mudd, Michael A. Nullet, Naoki Sakai, Yoshinori ShinoharaAbstract:Although we know that rainfall interception (the rain caught, stored, and evaporated from aboveground vegetative surfaces and ground litter) is affected by rain and Throughfall drop size, what was unknown until now is the relative proportion of each Throughfall type (free Throughfall, splash Throughfall, canopy drip) beneath coniferous and broadleaved trees. Based on a multinational data set of >120 million Throughfall drops, we found that the type, number, and volume of Throughfall drops are different between coniferous and broadleaved tree species, leaf states, and timing within rain events. Compared with leafed broadleaved trees, conifers had a lower percentage of canopy drip (51% vs. 69% with respect to total Throughfall volume) and slightly smaller diameter splash Throughfall and canopy drip. Canopy drip from leafless broadleaved trees consisted of fewer and smaller diameter drops (D₅₀_DR, 50th cumulative drop volume percentile for canopy drip, of 2.24 mm) than leafed broadleaved trees (D₅₀_DR of 4.32 mm). Canopy drip was much larger in diameter under woody drip points (D₅₀_DR of 5.92 mm) than leafed broadleaved trees. Based on Throughfall volume, the percentage of canopy drip was significantly different between conifers, leafed broadleaved trees, leafless broadleaved trees, and woody surface drip points (p ranged from
Alexander Zimmermann - One of the best experts on this subject based on the ideXlab platform.
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capturing heterogeneity the role of a study area s extent for estimating mean Throughfall
Journal of Hydrology, 2016Co-Authors: Alexander Zimmermann, Sebastian Voss, Johanna Clara Metzger, Anke Hildebrandt, Beate ZimmermannAbstract:Abstract The selection of an appropriate spatial extent of a sampling plot is one among several important decisions involved in planning a Throughfall sampling scheme. In fact, the choice of the extent may determine whether or not a study can adequately characterize the hydrological fluxes of the studied ecosystem. Previous attempts to optimize Throughfall sampling schemes focused on the selection of an appropriate sample size, support, and sampling design, while comparatively little attention has been given to the role of the extent. In this contribution, we investigated the influence of the extent on the representativeness of mean Throughfall estimates for three forest ecosystems of varying stand structure. Our study is based on virtual sampling of simulated Throughfall fields. We derived these fields from Throughfall data sampled in a simply structured forest (young tropical forest) and two heterogeneous forests (old tropical forest, unmanaged mixed European beech forest). We then sampled the simulated Throughfall fields with three common extents and various sample sizes for a range of events and for accumulated data. Our findings suggest that the size of the study area should be carefully adapted to the complexity of the system under study and to the required temporal resolution of the Throughfall data (i.e. event-based versus accumulated). Generally, event-based sampling in complex structured forests (conditions that favor comparatively long autocorrelations in Throughfall) requires the largest extents. For event-based sampling, the choice of an appropriate extent can be as important as using an adequate sample size.
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Capturing heterogeneity: The role of a study area’s extent for estimating mean Throughfall
Journal of Hydrology, 2016Co-Authors: Alexander Zimmermann, Sebastian Voss, Johanna Clara Metzger, Anke Hildebrandt, Beate ZimmermannAbstract:Abstract The selection of an appropriate spatial extent of a sampling plot is one among several important decisions involved in planning a Throughfall sampling scheme. In fact, the choice of the extent may determine whether or not a study can adequately characterize the hydrological fluxes of the studied ecosystem. Previous attempts to optimize Throughfall sampling schemes focused on the selection of an appropriate sample size, support, and sampling design, while comparatively little attention has been given to the role of the extent. In this contribution, we investigated the influence of the extent on the representativeness of mean Throughfall estimates for three forest ecosystems of varying stand structure. Our study is based on virtual sampling of simulated Throughfall fields. We derived these fields from Throughfall data sampled in a simply structured forest (young tropical forest) and two heterogeneous forests (old tropical forest, unmanaged mixed European beech forest). We then sampled the simulated Throughfall fields with three common extents and various sample sizes for a range of events and for accumulated data. Our findings suggest that the size of the study area should be carefully adapted to the complexity of the system under study and to the required temporal resolution of the Throughfall data (i.e. event-based versus accumulated). Generally, event-based sampling in complex structured forests (conditions that favor comparatively long autocorrelations in Throughfall) requires the largest extents. For event-based sampling, the choice of an appropriate extent can be as important as using an adequate sample size.
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Requirements for Throughfall monitoring: The roles of temporal scale and canopy complexity
Agricultural and Forest Meteorology, 2014Co-Authors: Alexander Zimmermann, Beate ZimmermannAbstract:Abstract A wide range of basic and applied problems in water resources research requires high-quality estimates of the spatial mean of Throughfall. Many Throughfall sampling schemes, however, are not optimally adapted to the system under study. The application of inappropriate sampling schemes may partly reflect the lack of generally applicable guidelines on Throughfall sampling strategies. In this study we conducted virtual sampling experiments using simulated fields which are based on empirical Throughfall data from three structurally distinct forests (a 12-year old teak plantation, a 5-year old young secondary forest, and a 130-year old secondary forest). In the virtual sampling experiments we assessed the relative error of mean Throughfall estimates for 38 different Throughfall sampling schemes comprising a variety of funnel- and trough-type collectors and a large range of sample sizes. Moreover, we tested the performance of each scheme for both event-based and accumulated Throughfall data. The key findings of our study are threefold. First, as errors of mean Throughfall estimates vary as a function of Throughfall depth, the decision on which temporal scale (i.e. event-based versus accumulated data) to sample strongly influences the required sampling effort. Second, given a chosen temporal scale Throughfall estimates can vary considerably as a function of canopy complexity. Accordingly, Throughfall sampling in simply structured forests requires a comparatively modest effort, whereas heterogeneous forests can be extreme in terms of sampling requirements, particularly if the focus is on reliable data of small events. Third, the efficiency of trough-type collectors depends on the spatial structure of Throughfall. Strong, long-ranging Throughfall patterns decrease the efficiency of troughs substantially. Based on the results of our virtual sampling experiments, which we evaluated by applying two contrasting sampling approaches simultaneously, we derive readily applicable guidelines for Throughfall monitoring.
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Sampling procedures for Throughfall monitoring: A simulation study
Water Resources Research, 2010Co-Authors: Beate Zimmermann, Alexander Zimmermann, R. M. Lark, Helmut ElsenbeerAbstract:What is the most appropriate sampling scheme to estimate event-based average Throughfall? A satisfactory answer to this seemingly simple question has yet to be found, a failure which we attribute to previous efforts' dependence on empirical studies. Here we try to answer this question by simulating stochastic Throughfall fields based on parameters for statistical models of large monitoring data sets. We subsequently sampled these fields with different sampling designs and variable sample supports. We evaluated the performance of a particular sampling scheme with respect to the uncertainty of possible estimated means of Throughfall volumes. Even for a relative error limit of 20%, an impractically large number of small, funnel-type collectors would be required to estimate mean Throughfall, particularly for small events. While stratification of the target area is not superior to simple random sampling, cluster random sampling involves the risk of being less efficient. A larger sample support, e.g., the use of trough-type collectors, considerably reduces the necessary sample sizes and eliminates the sensitivity of the mean to outliers. Since the gain in time associated with the manual handling of troughs versus funnels depends on the local precipitation regime, the employment of automatically recording clusters of long troughs emerges as the most promising sampling scheme. Even so, a relative error of less than 5% appears out of reach for Throughfall under heterogeneous canopies. We therefore suspect a considerable uncertainty of input parameters for interception models derived from measured Throughfall, in particular, for those requiring data of small Throughfall events.
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spatial and temporal patterns of Throughfall quantity and quality in a tropical montane forest in ecuador
Journal of Hydrology, 2007Co-Authors: Alexander Zimmermann, Wolfgang Wilcke, Helmut ElsenbeerAbstract:Summary In forests, complex canopy processes control the change in volume and chemical composition of rain water. We hypothesize that (i) spatial patterns, (ii) the temporal stability of spatial patterns, and (iii) the temporal course of solute concentrations can be used to explore these processes. The study area at 1950 m above sea level in the south Ecuadorian Andes is far away from anthropogenic emission sources and marine influences. It received ca. 2200 mm of rain annually. We collected rain and Throughfall on an event and within-event basis for five precipitation periods between August and October 2005 at up to 25 sites and analyzed the samples for pH and concentrations of K, Na, Ca, Mg, NH 4 + , Cl−, NO 3 - , PO 4 3 - , and total N (TN), P (TP), and organic C (TOC). Cumulative Throughfall amounted to 79% of rainfall. Compared with other tropical forests, rainfall solute concentrations were low and Throughfall solute concentrations similar. Volumes and solute concentrations of rainfall were spatially and temporally little variable. The spatial coefficient of variation for Throughfall volumes was 53%, for solute concentrations 28–292%, and for deposition 33–252%. Temporal persistence of spatial patterns was high for Throughfall volumes and varied among solutes. Spatial patterns of K, Mg and TOC concentrations in Throughfall were highly persistent. The spatial patterns of Throughfall fluxes were less stable than those of concentrations. During a monitoring time of 72 h, solute concentrations in Throughfall of selected rain events remained at a similar level indicating that the leachable element pool in the canopy was not exhausted. Our results demonstrate that the passage of rain through the canopy of a tropical montane forest in Ecuador results in a spatially heterogeneous Throughfall pattern with a considerable stability during three months. There is a large leachable element pool in the canopy, which is not depleted by the typical light rain within 72 h.
Elina N M Inkilainen - One of the best experts on this subject based on the ideXlab platform.
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the role of the residential urban forest in regulating Throughfall a case study in raleigh north carolina usa
Landscape and Urban Planning, 2013Co-Authors: Elina N M Inkilainen, Melissa R Mchale, Gary Blank, April L James, Eero NikinmaaAbstract:Overwhelming stormwater volumes, associated with deteriorating water quality and severe flooding in urbanizing cities, have become a great environmental and financial concern globally. Urban forests are capable of reducing the amount of stormwater runoff, in part, by regulating Throughfall via canopy rainfall interception; however, the lack of stand-scale studies of urban Throughfall hinders realistic estimates of the benefits of urban vegetation for stormwater regulation. Furthermore, urban forest characteristics that may be influencing rainfall interception are difficult to establish as these environments are extremely heterogeneous and managed, to a large extent, by private residents with varying landscape preferences. To quantify the amount of rainfall interception by vegetation in a residential urban forest we measured Throughfall in Raleigh, NC, USA between July and November 2010. We analyzed 16 residential yards with varying vegetation structure to evaluate the relative importance of different descriptive measures of vegetation in influencing Throughfall in an urban watershed. Throughfall comprised 78.1–88.9% of gross precipitation, indicating 9.1–21.4% rainfall interception. Canopy cover (p < 0.0001) and coniferous trees (p = 0.017) were the most influential vegetation variables explaining Throughfall whereas variables such as leaf area index were not found significant in our models. Throughfall and vegetation characteristics varied significantly among yards (p < 0.0001), between front and back yards (p < 0.0001), and between rented and privately-owned yards (p = 0.001), suggesting a potentially significant role in stormwater regulation for urban residents.
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the role of the residential urban forest in regulating Throughfall a case study in raleigh north carolina usa
Landscape and Urban Planning, 2013Co-Authors: Elina N M Inkilainen, Melissa R Mchale, Gary Blank, April L James, Eero NikinmaaAbstract:Abstract Overwhelming stormwater volumes, associated with deteriorating water quality and severe flooding in urbanizing cities, have become a great environmental and financial concern globally. Urban forests are capable of reducing the amount of stormwater runoff, in part, by regulating Throughfall via canopy rainfall interception; however, the lack of stand-scale studies of urban Throughfall hinders realistic estimates of the benefits of urban vegetation for stormwater regulation. Furthermore, urban forest characteristics that may be influencing rainfall interception are difficult to establish as these environments are extremely heterogeneous and managed, to a large extent, by private residents with varying landscape preferences. To quantify the amount of rainfall interception by vegetation in a residential urban forest we measured Throughfall in Raleigh, NC, USA between July and November 2010. We analyzed 16 residential yards with varying vegetation structure to evaluate the relative importance of different descriptive measures of vegetation in influencing Throughfall in an urban watershed. Throughfall comprised 78.1–88.9% of gross precipitation, indicating 9.1–21.4% rainfall interception. Canopy cover (p
