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Delphis F Levia - One of the best experts on this subject based on the ideXlab platform.
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pairing geophysical techniques improves understanding of the near surface critical zone visualization of preferential routing of Stemflow along coarse roots
Geoderma, 2020Co-Authors: Li Guo, Gregory J Mount, Sean A Hudson, Henry Lin, Delphis F LeviaAbstract:Abstract There is compelling evidence from aboveground observations that trees considerably affect precipitation partitioning through the Critical Zone. However, due to the lack of appropriate methods, the role of root systems (the hidden half of trees) on redistributing precipitation and infiltration into and routing through the soil remains inadequately visualized and understood. Here, we designed a novel experiment to pair two non-invasive geophysical techniques, ground-penetrating radar (GPR) and electrical resistivity tomography (ERT), to trace Stemflow through the soil in a forested hillslope after water was released on the trunk of an American beech (Fagus grandifolia Ehrh.) to induce Stemflow. We used GPR to locate lateral coarse roots and GPR and ERT together to confirm the wetting areas in response to the non-uniform transport of Stemflow. Signal changes between time-lapse geophysical images were used to reveal both the response time and location of Stemflow infiltration into and redistribution through the soil. This first known study to investigate the subsurface routing of Stemflow by combining GPR and ERT revealed that the belowground funneling of Stemflow along laterally oriented coarse roots transported water 2.8 m downslope from the study tree in 30 min after Stemflow was initiated. In situ excavation validated the distribution of lateral roots and lateral root-derived preferential flow paths identified in geophysical images, confirming the utility of pairing GPR and ERT to gain insights into the temporal dynamics and spatial distribution of subsurface routing of Stemflow. The proposed method visualized and confirmed the funneling effect of roots on belowground water redistribution that contributed to subsurface lateral flow. Pairing GPR and ERT provides a useful combination of geophysical methods to advance our understanding of the complex interactions between plant and soil, such as the role of tree roots in soil hydrological process by revealing areas of funneling in the hidden part of the Critical Zone.
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effect of biotic and abiotic factors on inter and intra event variability in Stemflow rates in oak and pine stands in a mediterranean mountain area
Journal of Hydrology, 2018Co-Authors: Carles Cayuela, Delphis F Levia, Pilar Llorens, Elisenda Sanchezcosta, Jerome LatronAbstract:Abstract Stemflow, despite being a small proportion of gross rainfall, is an important and understudied flux of water in forested areas. Recent studies have highlighted its complexity and relative importance for understanding soil and groundwater recharge. Stemflow dynamics offer an insight into how rain water is stored and released from the stems of trees to the soil. Past attempts have been made to understand the variability of Stemflow under different types of vegetation, but rather few studies have focused on the combined influence of biotic and abiotic factors on inter and intra-storm Stemflow variability, and none in Mediterranean climates. This study presents Stemflow data collected at high temporal resolution for two species with contrasting canopies and bark characteristics: Quercus pubescens Willd. (downy oak) and Pinus sylvestris L. (Scots pine) in the Vallcebre research catchments (NE of Spain, 42° 12′N, 1° 49′E). The main objective was to understand how the interaction of biotic and abiotic factors affected Stemflow dynamics. Mean Stemflow production was low for both species (∼1% of incident rainfall) and increased with rainfall amount. However, the magnitude of the response depended on the combination of multiple biotic and abiotic factors. Both species produced similar Stemflow volumes and the largest differences were found among trees of the same species. The combined analysis of biotic and abiotic factors showed that funneling ratios and Stemflow dynamics were highly influenced by the interaction of rainfall intensity and tree size.
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Expressing Stemflow commensurate with its ecohydrological importance
Advances in Water Resources, 2018Co-Authors: Darryl E. Carlyle-moses, Sonja Germer, Pilar Llorens, Shin'ichi Iida, Beate Michalzik, Kazuki Nanko, Alexander Tischer, Delphis F LeviaAbstract:Abstract Despite some progress, the importance of Stemflow remains obscured partly due to computations emphasizing canopy interception loss. We advocate for two metrics—the stand-scale funneling ratio and the stand-scale infiltration funneling ratio—to more accurately portray Stemflow inputs and increase comparability across ecosystems. These metrics yield per unit area Stemflow inputs orders of magnitude greater than what would have been delivered by throughfall or precipitation alone. We recommend that future studies employ these stand-scale funnelling metrics to express Stemflow commensurate with its ecohydrological importance and better conceptualize the role of Stemflow in plant-soil interactions, permitting advances in critical zone science.
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seasonal dynamics of the soil microbial community structure within the proximal area of tree boles possible influence of Stemflow
European Journal of Soil Biology, 2016Co-Authors: Carl L Rosier, Delphis F Levia, J.t. Van Stan, A Aufdenkampe, Jinjun KanAbstract:Abstract Soil microbial community (SMC) structure affects several ecosystem services (soil-carbon mineralization and stabilization), yet responds to edaphic conditions. Stemflow, water that drains over the exterior surface of trees, concentrates precipitation to soils near the trunk, thereby altering edaphic conditions. While recognizing that a suite of factors can affect soils, our research investigates the potential linkages between soil moisture, chemistry, and SMC structure within near-trunk soils from two species of contrasting Stemflow production ( Fagus grandifolia Ehrh. [American beech, AB] and Liriodendron tulipifera L. [yellow poplar, YP]) across seasons. Variations in SMC structure were determined by Nonmetric MultiDimensional Scaling (NMDS) analysis of Denaturing Gradient Gel Electrophoresis (DGGE) banding patterns. Sequencing/BLAST analysis of dominant DGGE-bands were conducted for shared and unique bands occurring in both AB and YP Stemflow-influenced soils. Findings suggest species-specific differences in Stemflow potentially alter moisture dynamics, pH, mineral nutrients, and soil-C near-trunk soils. SMC structure also increases in variability under low Stemflow flux (i.e., for YP). However, SMC structural variability decreases for near-stem soils across individual trees and seasons when Stemflow flux is consistently high (i.e., for AB). Differences in canopy structure that govern Stemflow production may be a plant trait capable of altering SMC structure. Variation in SMC structure may be related to tree species Stemflow input fluctuation response to seasonal change. Future investigations should consider intricate interrelationships among Stemflow and species composition of the SMC in near-trunk soils in order to better contextualize the effect of Stemflow on SMC vis-a-vis other factors, such as litter quality.
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A review of Stemflow generation dynamics and Stemflow-environment interactions in forests and shrublands
Reviews of Geophysics, 2015Co-Authors: Delphis F Levia, Sonja GermerAbstract:Many geoscientists now recognize Stemflow as an important phenomenon which can exert considerable effects on the hydrology, biogeochemistry, and ecology of wooded ecosystems and shrublands. Despite the explosive growth of Stemflow research, until this review there has been no comprehensive attempt to summarize and synthesize this literature since 2003. Topical areas of substantive new knowledge in Stemflow research include the following: (1) the interrelationships among Stemflow and meteorological conditions, especially within individual rain events; (2) the dynamic interplay between Stemflow and canopy structure; (3) Stemflow and the cycling of solutes and transport of particulate matter; (4) Stemflow and its interactions with canopy fungi and corticolous lichens; and (5) Stemflow-soil interactions. Each of these five topical areas of substantive new Stemflow research is summarized and synthesized, with areas of future research opportunities discussed. In addition, we have reviewed the parameters which can be used to describe Stemflow and critically evaluate their utility for different purposes. This review makes a call for scientists studying Stemflow to utilize common metrics in an effort to increase the cross-site comparability of Stemflow studies. Capitalizing on the insights of prior research, exciting research opportunities await hydrologists, biogeoscientists, and forest ecologists who will conduct studies to deepen our knowledge of Stemflow which will enable a better and more accurate framing of Stemflow in the larger context of watershed hydrology and biogeochemistry.
Chuan Yuan - One of the best experts on this subject based on the ideXlab platform.
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temporally dependent effects of rainfall characteristics on inter and intra event branch scale Stemflow variability in two xerophytic shrubs
Hydrology and Earth System Sciences, 2019Co-Authors: Chuan Yuan, Guangyao Gao, Xingwu Duan, Xiaohua WeiAbstract:Abstract. Stemflow is important for recharging root-zone soil moisture in arid regions. Previous studies have generally focused on Stemflow volume, efficiency and influential factors but have failed to depict Stemflow processes and quantify their relations with rainfall characteristics within events, particularly for xerophytic shrubs. Here, we measured the Stemflow volume, intensity, funneling ratio and time lags to rain at two dominant shrub species (Caragana korshinskii and Salix psammophila) and rainfall characteristics during 54 events at the semiarid Liudaogou catchment of the Loess Plateau, China, during the 2014–2015 rainy seasons. The funneling ratio was calculated as the ratio between Stemflow and rainfall intensities at the inter- and intra-event scales. Our results indicated that the Stemflow of C. korshinskii and S. psammophila, on average, started at 66.2 and 54.8 min, maximized 109.4 and 120.5 min after rain began, and ended 20.0 and 13.5 min after rain ceased. The two shrubs had shorter Stemflow duration (3.8 and 3.4 h) and significantly larger Stemflow intensities (517.5 and 367.3 mm h −1 ) than those of rain (4.7 h and 4.5 mm h −1 ). As branch size increased, both species shared the decreasing funneling ratios (97.7–163.7 and 44.2–212.0) and Stemflow intensities (333.8–716.2 and 197.2–738.7 mm h −1 ). Tested by the multiple correspondence analysis and stepwise regression, rainfall amount and duration controlled Stemflow volume and duration, respectively, at the event scale by linear relations ( p < 0.01). Rainfall intensity and raindrop momentum controlled Stemflow intensity and time lags to rain for both species within the event by linear or power relationships ( p < 0.01). Rainfall intensity was the key factor affecting Stemflow process of C. korshinskii, whereas raindrop momentum had the greatest influence on Stemflow process of S. psammophila. Therefore, rainfall characteristics had temporally dependent influences on corresponding Stemflow variables, and the influence also depended on specific species.
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Temporal-dependent effects of rainfall characteristics on inter-/intra-event Stemflow variability in two xerophytic shrubs
2019Co-Authors: Chuan Yuan, Guangyao Gao, Xingwu Duan, Xiaohua WeiAbstract:Abstract. Stemflow is important for recharging root-zone soil moisture in arid regions. Previous studies have generally focused on Stemflow volume, efficiency and influential factors but have failed to depict temporal Stemflow processes and quantify their relationships with rainfall characteristics within events, particularly for xerophytic shrubs. Here, we measured the Stemflow volume, intensity, duration and time lags to rain events of two xerophytic shrub species (Caragana korshinskii and Salix psammophila) and rainfall characteristics for 54 events in the Liudaogou catchment of the Loess Plateau, China, during the 2014-2015 rainy seasons. The results indicated that Stemflow dynamics were well synchronized to rainfall processes. The Stemflows of C. korshinskii and S. psammophila had larger average intensities (4.7 ± 1.5 and 4.8 ± 1.6 mm h−1, respectively) than that of rain at the event scale (4.5 ± 1.0 mm h−1), and the Stemflows were even more intense (20.3 ± 10.4 and 16.9 ± 8.8 mm h−1, respectively) than that of rain at 10-min intervals (10.9 ± 2.1 mm h−1). The average Stemflow durations of C. korshinskii and S. psammophila (3.8 ± 0.8 and 3.4 ± 0.9 h, respectively) were shorter than the rainfall duration (4.7 ± 0.8 h). Tested by a multiple correspondence analysis and stepwise regression, rainfall amount and duration controlled Stemflow volume and duration, respectively, at the event scale by linear relationships (p
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Comparisons of Stemflow and its bio-/abiotic influential factors between two xerophytic shrub species
Hydrology and Earth System Sciences, 2017Co-Authors: Chuan Yuan, Guangyao GaoAbstract:Abstract. Stemflow transports nutrient-enriched precipitation to the rhizosphere and functions as an efficient terrestrial flux in water-stressed ecosystems. However, its ecological significance has generally been underestimated because it is relatively limited in amount, and the biotic mechanisms that affect it have not been thoroughly studied at the leaf scale. This study was conducted during the 2014 and 2015 rainy seasons at the northern Loess Plateau of China. We measured the branch Stemflow volume (SFb), shrub Stemflow equivalent water depth (SFd), Stemflow percentage of incident precipitation (SF %), Stemflow productivity (SFP), funnelling ratio (FR), the meteorological characteristics and the plant traits of branches and leaves of C. korshinskii and S. psammophila. This study evaluated Stemflow efficiency for the first time with the combined results of SFP and FR, and sought to determine the inter- and intra-specific differences of Stemflow yield and efficiency between the two species, as well as the specific bio-/abiotic mechanisms that affected Stemflow. The results indicated that C. korshinskii had a greater Stemflow yield and efficiency at all precipitation levels than that of S. psammophila. The largest inter-specific difference generally occurred at the 5–10 mm branches during rains of ≤ 2 mm. Precipitation amount was the most influential meteorological characteristic that affected Stemflow yield and efficiency in these two endemic shrub species. Branch angle was the most influential plant trait on FR. For SFb, stem biomass and leaf biomass were the most influential plant traits for C. korshinskii and S. psammophila, respectively. For SFP of these two shrub species, leaf traits (the individual leaf area) and branch traits (branch size and biomass allocation pattern) had a great influence during lighter rains ≤ 10 mm and heavier rains > 15 mm, respectively. The lower precipitation threshold to start Stemflow allowed C. korshinskii (0.9 mm vs. 2.1 mm for S. psammophila) to employ more rains to harvest water via Stemflow. The beneficial leaf traits (e.g., leaf shape, arrangement, area, amount) might partly explain the greater Stemflow production of C. korshinskii. Comparison of SFb between the foliated and manually defoliated shrubs during the 2015 rainy season indicated that the newly exposed branch surface at the defoliated period and the resulting rainfall intercepting effects might be an important mechanism affecting Stemflow in the dormant season.
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Stemflow of a xerophytic shrub (Salix psammophila) in northern China: Implication for beneficial branch architecture to produce Stemflow
Journal of Hydrology, 2016Co-Authors: Chuan Yuan, Guangyao GaoAbstract:Summary Stemflow is an important mechanism to replenish soil water for xerophytic shrubs in water-stressed ecosystems, whereas the biotic influences of leaf and branch on shrub Stemflow were not completely investigated. In this study, the Stemflow of 98 branches with various basal diameter under 42 rainfall events was measured for Salix psammophila in northern China during the rainy seasons of 2014 and 2015. The effects of rainfall characteristics, and plant traits of leaf and branch on Stemflow were detected. Stemflow productivity (branch Stemflow production of unit biomass) was proposed to determine the beneficial branch architecture for efficient Stemflow production. The developed allometric equations by expressing the plant traits as a power function of branch basal diameter could satisfactorily estimate the leaf traits and biomass. There were significant differences of branch Stemflow between different basal diameter and precipitation classes. The average shrub Stemflow depth and percentage was 0.77 mm (0.004–3.32 mm) and 5.54% (0.70–7.92%), respectively. The precipitation amount and leaf fresh biomass were identified as the most influential rainfall characteristic and plant trait of Stemflow, respectively. The Stemflow production increased linearly with precipitation amount, and Stemflow percentage increased with precipitation amount to approach the asymptotic value of 7.61%. The threshold precipitation amount of 2.1 mm was required to initiate shrub Stemflow. The Stemflow productivity decreased with basal diameter of branches and increased with precipitation amount. Allocating aboveground biomass to grow new branches and develop small ones was an energy-conserving strategy to ensure Stemflow production. The branch architecture with more small branches, higher leaf biomass, and larger branch angle was more efficient for Stemflow production.
Guangyao Gao - One of the best experts on this subject based on the ideXlab platform.
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temporally dependent effects of rainfall characteristics on inter and intra event branch scale Stemflow variability in two xerophytic shrubs
Hydrology and Earth System Sciences, 2019Co-Authors: Chuan Yuan, Guangyao Gao, Xingwu Duan, Xiaohua WeiAbstract:Abstract. Stemflow is important for recharging root-zone soil moisture in arid regions. Previous studies have generally focused on Stemflow volume, efficiency and influential factors but have failed to depict Stemflow processes and quantify their relations with rainfall characteristics within events, particularly for xerophytic shrubs. Here, we measured the Stemflow volume, intensity, funneling ratio and time lags to rain at two dominant shrub species (Caragana korshinskii and Salix psammophila) and rainfall characteristics during 54 events at the semiarid Liudaogou catchment of the Loess Plateau, China, during the 2014–2015 rainy seasons. The funneling ratio was calculated as the ratio between Stemflow and rainfall intensities at the inter- and intra-event scales. Our results indicated that the Stemflow of C. korshinskii and S. psammophila, on average, started at 66.2 and 54.8 min, maximized 109.4 and 120.5 min after rain began, and ended 20.0 and 13.5 min after rain ceased. The two shrubs had shorter Stemflow duration (3.8 and 3.4 h) and significantly larger Stemflow intensities (517.5 and 367.3 mm h −1 ) than those of rain (4.7 h and 4.5 mm h −1 ). As branch size increased, both species shared the decreasing funneling ratios (97.7–163.7 and 44.2–212.0) and Stemflow intensities (333.8–716.2 and 197.2–738.7 mm h −1 ). Tested by the multiple correspondence analysis and stepwise regression, rainfall amount and duration controlled Stemflow volume and duration, respectively, at the event scale by linear relations ( p < 0.01). Rainfall intensity and raindrop momentum controlled Stemflow intensity and time lags to rain for both species within the event by linear or power relationships ( p < 0.01). Rainfall intensity was the key factor affecting Stemflow process of C. korshinskii, whereas raindrop momentum had the greatest influence on Stemflow process of S. psammophila. Therefore, rainfall characteristics had temporally dependent influences on corresponding Stemflow variables, and the influence also depended on specific species.
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Temporal-dependent effects of rainfall characteristics on inter-/intra-event Stemflow variability in two xerophytic shrubs
2019Co-Authors: Chuan Yuan, Guangyao Gao, Xingwu Duan, Xiaohua WeiAbstract:Abstract. Stemflow is important for recharging root-zone soil moisture in arid regions. Previous studies have generally focused on Stemflow volume, efficiency and influential factors but have failed to depict temporal Stemflow processes and quantify their relationships with rainfall characteristics within events, particularly for xerophytic shrubs. Here, we measured the Stemflow volume, intensity, duration and time lags to rain events of two xerophytic shrub species (Caragana korshinskii and Salix psammophila) and rainfall characteristics for 54 events in the Liudaogou catchment of the Loess Plateau, China, during the 2014-2015 rainy seasons. The results indicated that Stemflow dynamics were well synchronized to rainfall processes. The Stemflows of C. korshinskii and S. psammophila had larger average intensities (4.7 ± 1.5 and 4.8 ± 1.6 mm h−1, respectively) than that of rain at the event scale (4.5 ± 1.0 mm h−1), and the Stemflows were even more intense (20.3 ± 10.4 and 16.9 ± 8.8 mm h−1, respectively) than that of rain at 10-min intervals (10.9 ± 2.1 mm h−1). The average Stemflow durations of C. korshinskii and S. psammophila (3.8 ± 0.8 and 3.4 ± 0.9 h, respectively) were shorter than the rainfall duration (4.7 ± 0.8 h). Tested by a multiple correspondence analysis and stepwise regression, rainfall amount and duration controlled Stemflow volume and duration, respectively, at the event scale by linear relationships (p
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Comparisons of Stemflow and its bio-/abiotic influential factors between two xerophytic shrub species
Hydrology and Earth System Sciences, 2017Co-Authors: Chuan Yuan, Guangyao GaoAbstract:Abstract. Stemflow transports nutrient-enriched precipitation to the rhizosphere and functions as an efficient terrestrial flux in water-stressed ecosystems. However, its ecological significance has generally been underestimated because it is relatively limited in amount, and the biotic mechanisms that affect it have not been thoroughly studied at the leaf scale. This study was conducted during the 2014 and 2015 rainy seasons at the northern Loess Plateau of China. We measured the branch Stemflow volume (SFb), shrub Stemflow equivalent water depth (SFd), Stemflow percentage of incident precipitation (SF %), Stemflow productivity (SFP), funnelling ratio (FR), the meteorological characteristics and the plant traits of branches and leaves of C. korshinskii and S. psammophila. This study evaluated Stemflow efficiency for the first time with the combined results of SFP and FR, and sought to determine the inter- and intra-specific differences of Stemflow yield and efficiency between the two species, as well as the specific bio-/abiotic mechanisms that affected Stemflow. The results indicated that C. korshinskii had a greater Stemflow yield and efficiency at all precipitation levels than that of S. psammophila. The largest inter-specific difference generally occurred at the 5–10 mm branches during rains of ≤ 2 mm. Precipitation amount was the most influential meteorological characteristic that affected Stemflow yield and efficiency in these two endemic shrub species. Branch angle was the most influential plant trait on FR. For SFb, stem biomass and leaf biomass were the most influential plant traits for C. korshinskii and S. psammophila, respectively. For SFP of these two shrub species, leaf traits (the individual leaf area) and branch traits (branch size and biomass allocation pattern) had a great influence during lighter rains ≤ 10 mm and heavier rains > 15 mm, respectively. The lower precipitation threshold to start Stemflow allowed C. korshinskii (0.9 mm vs. 2.1 mm for S. psammophila) to employ more rains to harvest water via Stemflow. The beneficial leaf traits (e.g., leaf shape, arrangement, area, amount) might partly explain the greater Stemflow production of C. korshinskii. Comparison of SFb between the foliated and manually defoliated shrubs during the 2015 rainy season indicated that the newly exposed branch surface at the defoliated period and the resulting rainfall intercepting effects might be an important mechanism affecting Stemflow in the dormant season.
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Stemflow of a xerophytic shrub (Salix psammophila) in northern China: Implication for beneficial branch architecture to produce Stemflow
Journal of Hydrology, 2016Co-Authors: Chuan Yuan, Guangyao GaoAbstract:Summary Stemflow is an important mechanism to replenish soil water for xerophytic shrubs in water-stressed ecosystems, whereas the biotic influences of leaf and branch on shrub Stemflow were not completely investigated. In this study, the Stemflow of 98 branches with various basal diameter under 42 rainfall events was measured for Salix psammophila in northern China during the rainy seasons of 2014 and 2015. The effects of rainfall characteristics, and plant traits of leaf and branch on Stemflow were detected. Stemflow productivity (branch Stemflow production of unit biomass) was proposed to determine the beneficial branch architecture for efficient Stemflow production. The developed allometric equations by expressing the plant traits as a power function of branch basal diameter could satisfactorily estimate the leaf traits and biomass. There were significant differences of branch Stemflow between different basal diameter and precipitation classes. The average shrub Stemflow depth and percentage was 0.77 mm (0.004–3.32 mm) and 5.54% (0.70–7.92%), respectively. The precipitation amount and leaf fresh biomass were identified as the most influential rainfall characteristic and plant trait of Stemflow, respectively. The Stemflow production increased linearly with precipitation amount, and Stemflow percentage increased with precipitation amount to approach the asymptotic value of 7.61%. The threshold precipitation amount of 2.1 mm was required to initiate shrub Stemflow. The Stemflow productivity decreased with basal diameter of branches and increased with precipitation amount. Allocating aboveground biomass to grow new branches and develop small ones was an energy-conserving strategy to ensure Stemflow production. The branch architecture with more small branches, higher leaf biomass, and larger branch angle was more efficient for Stemflow production.
Takahisa Mizuyama - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of Stemflow for tall stewartia (Stewartia monadelpha) growing on a hillslope.
Journal of Hydrology, 2009Co-Authors: Wei-li Liang, Ken'ichirou Kosugi, Takahisa MizuyamaAbstract:Summary The characteristics of Stemflow were observed in a tall stewartia ( Stewartia monadelpha ) deciduous forest on a hillslope in central Japan, revealing new findings for a previously unreported type of deciduous forest. Using 2-year observations of 250 rainfall events, we analyzed seasonal and spatial variations in Stemflow for several trees, and applied additional data sets of throughfall and plant area index (PAI) to produce a rough estimate of seasonal variations in rainfall redistribution processes and canopy architecture for a single tree. Compared to previous findings for other deciduous tree species, the ratios of throughfall, Stemflow, and interception to open-area rainfall obviously varied with PAI changes for tall stewartia. Meteorological conditions of rainfall amount, rainfall intensity, wind speed, and wind direction had little effect on Stemflow generation, which was mainly affected by variation in canopy architecture. Three novel characteristics of Stemflow were identified for several tall stewartia trees. First, the yearly Stemflow ratio at the forest-stand level for tall stewartia (12%) was high compared to previous findings on beech and oak stands, indicating tall stewartia has considerably high potential to generate a great amount of Stemflow. Second, Stemflow tended to be 1.3–2.0 times greater in the leafed period than in the leafless period. Third, the amount of Stemflow was 12–132 times greater on the downslope side of the stem than on the upslope side. It likely caused by the uneven area between the upslope and downslope sides of the canopy and by asymmetrical Stemflow pathways between the upslope and downslope sides of the trunk due to downslope tilting of the tree trunk.
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A three-dimensional model of the effect of Stemflow on soil water dynamics around a tree on a hillslope.
Journal of Hydrology, 2008Co-Authors: Wei-li Liang, Ken'ichirou Kosugi, Takahisa MizuyamaAbstract:In forested stands, precipitation is intercepted by the canopy and partitioned into throughfall and Stemflow as diffuse input and point input, respectively. Therefore, the water reaching the forest floor is not spatially uniform. Although there are many numerical models that simulate precipitation redistribution processes, the rainwater concentrated by Stemflow is usually disregarded. In this study, we performed detailed observations of soil water dynamics during a storm event and developed a three-dimensional model of the effect of Stemflow on soil water dynamics around a tree on a forested hillslope. In the Stemflow infiltration process, water flowed rapidly through a deep layer, causing irregular changes in the vertical soil water content. This process is very different from the vertical rainfall infiltration process, in which the wetting front expands slowly from the upper layer to the deeper layer. Thus, simulations using the conventional net precipitation input assumption are likely to contain large errors as a result. The model proposed in this study, which considered the point input characteristic of Stemflow and parameterized Stemflow as a source flux spring in the soil layers, showed adequate spatial and temporal variations in soil water dynamics and closely agreed with observations. Applying the variable source term in the Richards equation to Stemflow is a new approach and makes it possible to represent the root-induced bypass flow infiltration process around a tree growing on a hillslope.
Lucy Chong - One of the best experts on this subject based on the ideXlab platform.
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The Stemflow of trees in a Bornean lowland tropical forest
Hydrological Processes, 2004Co-Authors: Odair J. Manfroi, Kuraji Koichiro, Tanaka Nobuaki, Suzuki Masakazu, Michiko Nakagawa, Tohru Nakashizuka, Lucy ChongAbstract:Stemflow volume generation in lowland tropical forests was measured over a 1-year period in the Malaysian state of Sarawak. The Stemflow volume generated by 66 free-standing trees with a diameter at breast height (DBH) over 1 cm and a tree height over 1 m were measured daily in a representative 10 m × 10 m plot of the forest. Throughfall in the plot was also measured using 20 gauges in a fixed position. Of the 2292 mm of total rainfall observed during the year-long period, Stemflow accounted for 3·5%, throughfall for 82% and there was an interception loss of 14·5%. Understory trees (DBH < 10 cm) played an important role in Stemflow generation, producing 77% of the overall Stemflow volume and 90% during storms with less than 20 mm of rainfall. Also, owing to their efficiency at funneling rainfall or throughfall water received by their crowns, some understory trees noticeably reduced the catches of the throughfall gauges situated under the reach of their crown areas. During storms producing greater than 20 mm of rainfall, 80% of the total Stemflow occurred; trees with a large DBH or height and for which the ratio between crown's diameter and depth is less than 1, tended to generate more Stemflow volume in these storms. Mean areal Stemflow as a fraction of rainfall in this lowland tropical forest was 3·4%, but may range from 1–10% depending upon the proportion of trees that are high or poor Stemflow yielders. Trees with DBH greater than 10 cm were likely to contribute less than 1% of the 3·4% mean areal Stemflow in the forest. Copyright © 2004 John Wiley & Sons, Ltd.
