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The rapid expansion of impermeable surfaces in cities has a major impact on urban hydrology by reducing rainwater infiltration and increasing runoff rates and peaks. The use of urban trees as stormwater management tools is gaining recognition for their potential to mitigate flood risk and provide additional ecosystem services. We conducted an in-situ field experiment to measure throughfall on Norway maple (Acer platanoides) and small-leaved lime (Tilia cordata) to assess the interception capacity of solitary urban trees under different degrees of surface sealing in the city of Freiburg, Germany. We examined the relationships between rainfall characteristics, tree morphological traits, and the interception behaviour, analysing eight trees per species over 76 recorded rainfall events from April to September 2021. Average interception values were higher for small-leaved lime trees (70.3% ± 6.6%) than for Norway maple (54.8% ± 10.3%) surpassing those in typical forested environments. The average interception loss of all recorded events was 2.6 ± 0.6 mm for Norway maple and 3.7 ± 0.3 mm for small-leaved lime. For both tree species, significant linear correlations were found between the relative interception and factors such as rainfall depths, the leaf area index (LAI), and the plant area index (PAI) (adj. R2 >0.45). Unlike Norway maple, small-leaved lime demonstrated significant relationships between several tree morphological parameters and interception (adj. R2 >0.43). The LAI of both species significantly decreased with the increasing degree of surface sealing, which in turn affected interception rates. Our results enhance the understanding of the interception process by solitary trees in urban contexts and enables the parameterization of interception rates using measurable properties. To develop a comprehensive database for modelling parameters and aid urban planners in stormwater management, further field experiments involving various tree species are essential. [ABSTRACT FROM AUTHOR]

The forest canopy affects the water entering the forest ecosystem by intercepting rainfall. This is especially pertinent in forests that depend on rainfall for their ecological water needs, quantifying and simulating interception losses provide critical insights into their ecological hydrological processes. In the semi‐arid areas of the Loess Plateau, afforestation has become an effective ecological restoration measure. However, the rainfall interception process of these plantations is still unclear. To quantify and model the canopy interception of these plantations, we conducted a two‐year rainfall redistribution measurement experiment in three typical plantations, including a deciduous broadleaf plantation (Robinia pseudoacacia) and two evergreen coniferous plantations (Platycladus orientalis and Pinus tabuliformis). Based on this, the revised Gash model was used to simulate their interception losses, and the model applicability across varying rainfall types was further compared and verified. The experiment clarified the rainfall redistribution in the three plantations, and the proportions of throughfall to gross rainfall in Robinia pseudoacacia, Platycladus orientalis, and Pinus tabuliformis were 84.8%, 70.4%, and 75.6%; corresponding, the stemflow proportions were 2.0%, 2.2%, and 1.8%; the interception losses were 13.2%, 27.4%, and 22.6%, respectively. The dominant rainfall pattern during the experiment was characterized by low‐amounts, moderate‐intensity, and short‐duration, during which the highest interception proportions across the three plantations were observed. We used the Penman‐Monteith equation and the regression method, respectively, to estimate the canopy average evaporation rate of the revised Gash model, finding that the latter provides a closer match to the measured cumulative interception (NSE >0.7). When simulating interception under the three rainfall patterns, the model with the regression method better simulated the cumulative interception and event‐scale interception for Platycladus orientalis and Pinus tabuliformis plantations under the dominant rainfall pattern. The results contribute valuable information to assess the impact of forest rainfall interception on regional hydrologic processes. [ABSTRACT FROM AUTHOR]

The interception of rainfall by plant canopies alters the depth and spatial distribution of water arriving at the soil surface, and thus the location, volume, and depth of infiltration. Mechanisms like stemflow are known to concentrate rainfall and route it deep into the soil, yet other mechanisms of flow concentration are poorly understood. This study characterizes pour points, formed by the detachment of water flowing under a branch, using a combination of field observations in Western Australian banksia woodlands and rainfall simulation experiments on Banksia menziesii branches. We aim to establish the hydrological significance of pour points in a water‐limited woodland ecosystem, along with the features of the canopy structure and rainfall that influence pour point formation and fluxes. Pour points were common in the woodland and could be identified by visually inspecting trees. Throughfall depths at pour points were up to 15 times greater than rainfall and generally comparable to or greater than stemflow. Soil water content beneath pour points was greater than in adjacent controls, with 20%–30% of the seasonal rainfall volume infiltrated into the top 1 m of soil beneath pour points, compared to 5% in controls. Rainfall simulations showed that pour points amplified the spatial heterogeneity of throughfall, violating assumptions used to close the water balance. The simulation experiments demonstrated that pour point fluxes depend on the interaction of branch angle and foliation for a given branch architecture. Pour points can play a significant part in the water balance, depending on their density and rainfall concentration ability. Plain Language Summary: When rain hits a tree canopy, it either wets the canopy, falls off, or flows along the tree's surfaces (leaves, branches, and trunk). This interaction changes the amount and location of water arriving at the ground. The water flowing underneath branches is may eventually reach the ground by flowing along the tree trunk as stemflow. Using a combination of field observations in seasonally dry Banksia woodlands and rainfall simulation experiments on tree branches, we show that this water may, alternatively, peel off the branch and reach the ground at a "pour point." Rain gauges placed under pour points recorded 1.5–15 times the water recorded at rain gauges under the open sky. We showed that the quantity of water arriving at the pour points varies with the rain volume, and with branch properties including the upstream leaf area, angle, and shape of the branch. The changes in the distribution of water received beneath tree canopies and deeper infiltration into the soil due to pour points proved their hydrological significance. Understanding pour points represents one path toward an improved characterization of the complex processes occurring when rain hits a tree canopy. Key Points: Pour points occur when intercepted rain flowing under tree branches detach and their depths were 1.5–15 times the rainfallPour points increase spatial heterogeneity of throughfall and enhance infiltration into the soilRainfall simulation showed branch structure, foliation, and angle impose unclear controls on the volume of water received at the pour point [ABSTRACT FROM AUTHOR]

During rainfall, plant litter interception regulates overland flow with an impact on water runoff generation and sediment displacement. Besides the rainfall characteristics, the effects of litter mass, thickness, storage and drainage properties on rainfall interception are reasonably well understood. In contrast, less is known about the influence of leaf traits, which we hypothesized to affect interception, soil hydrology and conservation via litter structure assembly.We measured the runoff and soil loss generation as determined by litter layer structural and hydraulic properties of 16 coexisting tropical woody species with wide‐range morphological leaf traits in a rainfall simulator experiment.Our results show that litter produced by coexisting species can differ in precipitation interception, thereby influencing runoff and soil loss. This is because there is important interspecific variation in litter water storage and drainage, which are negatively affected by leaf area (LA). Leaf water repellency positively affected litter water storage. Moreover, LA also negatively affected litter layer density. Litter density, in turn, increased runoff, but decreased soil loss, possibly due to protection against splash erosion.These results can be used to predict the effects of plant traits on the soil water balance and soil integrity protection through ecohydrological interception by the litter layer. The next research steps will be to extend our model to multiple‐species litter layers, and to validate and calibrate our model in different field situations in different ecosystems.Synthesis: We revealed the direct and indirect effects of species leaf size and hydraulic traits on litter rainfall interception, runoff and soil loss. We propose a new litter‐soil ecohydrological model, by using structural equation models, which can be used as a tool to predict ecosystem functioning, and guide management and restoration actions with water and soil conservation targets. [ABSTRACT FROM AUTHOR]

The Grain for Green Program (GFGP) has promoted vegetation restoration and environmental improvement in the Loess Plateau (LP) and has sparked considerable interest in its effects on local hydrological cycle processes. However, few studies have examined the spatiotemporal evolution characteristics of rainfall interception (RI) and its influencing factors in the LP after GFGP implementation, even though RI directly controls the potential available water resources entering the ecosystem (Peffective) and largely influences the changes in hydrological fluxes in water‐limited regions. This study employed the remote sensing (RS)‐Gash model to investigate RI and Peffective in the LP. Results showed that RI and Peffective increased at a rate of 0.7 (p < 0.01) and 2.5 mm/year (p = 0.12), respectively, during the complete implementation of the GFGP (2001–2018). Spatially, the two were dominated by significantly increasing (area share, 50.3%) and nonsignificantly increasing (74.2%) trends, respectively. The dominant drivers of the changes in RI and Peffective are vegetation factors and precipitation, respectively. The results imply that after the implementation of the GFGP, water scarcity in most areas of the LP seems to show signs of improvement, rather than worsening at source. However, people should remain alert about issues that can occur in semihumid areas, including vegetation's degradation due to excessive afforestation or single‐species plantations, particularly at the Ziwuling Mountains. The successful greening experience of the GFGP in the LP is worth promoting, but lessons should also be learned regarding its unsustainability in areas with relatively abundant water. [ABSTRACT FROM AUTHOR]

During rainfall events, leaves in the canopy absorb kinetic energy from falling raindrops causing the leaves to vibrate after each individual drop impact. Additionally, intercepted water gradually increases on foliar surfaces adding greater mass exerted on each leaf. This accumulated mass of water increases the leaf inclination angle and may enable the drainage of water from the leaf surface as the water drop retention angle is surpassed. This study explored the dynamic process of leaf vibration and changes in steady‐state leaf inclination angles after raindrop impact for three species (Acer saccharinum, Quercus gambelii, and Ulmus pumila) and with four different drop sizes. An incremental increase in steady‐state leaf inclination angle was measured from processing single frames of videos as each additional raindrop impacted leaf surfaces. In general, larger drops increased leaf inclination angles to a larger degree than the smaller drops. As maximum leaf surface storage or the water drop retention angle was approached, water drained from leaf surface causing an abrupt rebound of the leaf inclination angle. The maximum changes in steady‐state leaf inclination angle before rebound (LIAmax) and the number of drops needed for leaf inclination angle rebound were significantly correlated with the initial leaf inclination angle (LIAi) for experiments with A. saccharinum and U. pumila, but not for the experiments with Q. gambelii. No significant correlations were found between LIAmax and any leaf trait (i.e., leaf area, leaf mass, petiole length, petiole diameter, leaf hydrophobicity, and water drop retention) for A. saccharinum and U. pumila; however, a significant negative correlation was found for Q. gambelii between maximum changes in leaf inclination angle and petiole diameter. Of the leaf characteristics examined, leaf surface storage is most influenced by LIAi before drop impact. [ABSTRACT FROM AUTHOR]

Mistletoes have a global distribution and are the largest group of parasitic plants living within the canopies of woody plants. In European forests, Viscum album L. ssp. album (common mistletoe) is a common sight and, despite being considered a pest, can play beneficial roles in the ecosystem. However, mistletoe infections are becoming more severe and widespread throughout Europe, including recent reports of large‐scale host tree mortality events. These mortality events are hypothesized to be a result of increased water stresses from severe mistletoe infections in tandem with drought. In this study, we estimate an additional water loss from mistletoe‐infected forests that has not yet been described: interception, or the storage and evaporation of rainfall. Results from rainfall simulations on mistletoes sampled from Gostynin Forest District (central Poland) indicate mistletoes can store 0.16–1.32 mm of rainwater. Inputting this additional water storage capacity from mistletoes into a rainfall interception model suggests that, depending on the severity of the infection, mistletoes could reduce annual rainwater supply beneath the canopy by 2–11%. In forests experiencing water stress from mistletoe infection and climate change, the rainfall interception by mistletoes represents an additional water loss of a magnitude worthy of future investigation. [ABSTRACT FROM AUTHOR]

Woody plant encroachment (WPE) has been found to alter ecosystem functioning and services in savannas. In rain‐limited savannas, increasing woody cover can reduce streamflow and groundwater by altering evapotranspiration rates and rainfall partitioning, but the ecological relevance of this impact is not well known. This study quantified the altered partitioning of rainfall by two woody plant structural types (fine‐ and broad‐leaved trees) across a gradient of encroachment in a semi‐arid savanna in South Africa. Averaged across both plant functional types, loss of rainfall through canopy interception and subsequent evaporation roughly doubled (from 20.5% to 43.6% of total rainfall) with a roughly 13‐fold increase in woody cover (from 2.4 to 31.4 m2/ha tree basal cover). Spatial partitioning changes comprised fourfold increases in stemflow (from 0.8% to 3.9% of total rainfall) and a decline in throughfall proportion of about two‐fifths (from 80.2% to 47.3% of total rainfall). Changes in partitioning were dependent on plant functional type; rainfall interception by the fine‐leaved multi‐stemmed shrub Dichrostachys cinerea was almost double that of the broad‐leaved tree Terminalia sericea at the highest levels of woody encroachment (i.e., 49.7% vs. 29.1% of total rainfall intercepted at tree basal area of 31.4 m2/ha). Partitioning was also dependent on rainfall characteristics, with the proportion of rainfall intercepted inversely related to rainfall event size and intensity. Therefore, increasing tree cover in African grassy ecosystems reduces the amount of canopy throughfall, especially beneath canopies of fine‐leaved species in smaller rainfall events. Rainfall interception traits may thus confer a selective advantage, especially for fine‐leaved woody plant species in semi‐arid savannas. [ABSTRACT FROM AUTHOR]

The distribution and structure of leaves and branches influence the rainfall interception ratio (RIR) and water cycling processes in forests. However, measuring the three‐dimensional structure features of canopy organs to evaluate their effects on the RIR is labour‐intensive and time‐consuming. Modelling the spatial distribution of the RIR within a forest canopy after rainfall thus remains challenging. To address this difficulty, we used point clouds scanned by a terrestrial laser scanner (TLS) from Masson's Pines to extract fine‐scale canopy structure features. Next, we applied an exploratory factor analysis (EFA) to evaluate quantitatively how the various canopy structure features affect the RIR of canopy components. Finally, we simulated the RIR distribution by combining the interception coefficient of canopy organs estimated from the EFA results and throughfall volume measured by rain gauges set in the study site. The results show that the inclination angle of canopy organs and their upper gap fraction more strongly affect their RIR. The average absolute error of simulated rainfall interception volume (VIN) is less than 0.57 mm, and the related root mean squared error (RMSE) is less than 0.41 mm after rainfall. For measured rainfall events, the mean absolute error and RMSE of simulated VIN intercepted by nearby canopy organs above each rain gauge are less than 0.52 and 0.39 mm, respectively. The accuracy of the RIR simulation is degraded by the uneven distribution of canopy receivable rainfall volume, noise and missing point clouds in the TLS datasets. Modelling RIR distribution within the canopy based on TLS point clouds provides a chance for simulating water cycling processes in forests during rainfall. [ABSTRACT FROM AUTHOR]

Repeated measures refer to multiple observations obtained in the same sampling plot or experimental unit. Such observations can be taken in a particular period and the same local space in many cases. In either case, repeated measures lead to correlated data. Statistical analysis using correlated data without an appropriate covariance structure would lead to Type I or Type II errors. This study used rainfall interception data from a coniferous forest in Mexico, May to September 2010, to develop a multi‐level linear model by assessing different covariance structures. Our main objectives were to evaluate the implications of these covariance structures in tests of fixed effects over categories of basal area and estimate differences between means and standard errors of each test. Based on the numerical inspection of the estimated correlations, their graphic representation, values of the statistics of fit (AICC and BIC) and considering that it is desirable to model a covariance structure in a parsimonious way, we concluded that the best selection for the structure of covariance was "heterogeneous Toeplitz." Therefore, F$$ F $$‐values of fixed effects and the estimates of differences between means and standard errors of each test based on the "heterogeneous Toeplitz" covariance structure were considered the most appropriate among the analyzed covariance models. [ABSTRACT FROM AUTHOR]

Rainfall interception represents the amount of water trapped in natural cover that is not drained directly to the ground. Intercepted rainfall may evaporate after a rain event, making it one of the main drivers of water balance and hydrologic regionalization. This process can be affected by factors such as climate, altitude, vegetation type, and topography. Here is a simple method of calculating rainfall interception in temperate forests using in Santa Maria Yavesia, Oaxaca, and Mexico as an illustrative study area. We used two rain gauges to measure net precipitation (Np) under the canopy at each study site and one gauge outside the canopy to obtain gross precipitation (Gp). Throughfall (Th) was indirectly measured using hemispherical photographs. Rainfall interception was obtained through a combination Th and Gp and Np. The mean rainfall interception was 50.6% in the Abies forests, 23%–40% in the coniferous‐mixed forests, and 27.4% in the broad‐leaved forests. We classified rainfall events by intensity to determine the effect of canopy structure and precipitation and found that 75% of the events were weak events, 24% were moderate events, and 1% were strong events. In addition, we found that rainfall interception was lower when the intensity of precipitation was higher. Our method can be replicated in different ecosystems worldwide as a tool for assessing the influence of rainfall interception in terms of ecological services. Research Impact Statement: Quantification of rainfall interception (RI) is important in hydrologic studies. The proposed indirect method to measure RI is easy to reproduce in different ecosystems. [ABSTRACT FROM AUTHOR]

Rainfall interception (RI) by forest canopies is an important process in hydrological cycling in forest ecosystems. However, accurately predicting RI is a challenging topic. In this study, a dimensionless descriptor, canopy interception index (CII), for predicting RI was defined. The terrestrial laser scanning was used to estimate CII in four temperate forest types, including Korean pine (Pinus koraiensis) plantation forest (KPF) stands, larch (Larix spp.) plantation forest (LPF) stands, mixed broadleaved forest (MBF) stands and Mongolian oak (Quercus mongolica) forest (MOF) stands. Using the measured RI values over the rainy seasons in 2017 and 2018, CII's performance for predicting RI was tested and also compared with several other indices (LAI: leaf area index, PAI: plant area index and ACH: average canopy height). The results indicated that CII was significantly and strongly related with RI for the four forest types together (R2 = 0.79), as well as for an individual forest type (R2 = 0.55–0.63). More importantly, its performance was better than those from LAI (R2 = 0.33–0.43), PAI (R2 = 0.40–0.53) and ACH (R2 = 0.35). All those results demonstrated that CII was an efficient index for accurately predicting RI. The potential applications of CII were also discussed. [ABSTRACT FROM AUTHOR]

The translation of rainfall to runoff is significantly affected by canopy interception. Therefore, a realistic representation of the role played by vegetation cover when modelling the rainfall–runoff system is essential for predicting water, sediment, and nutrient transport on hillslopes. Here, we developed a new mathematical model to describe the dynamics of interception, infiltration, and overland flow on canopy‐covered sloping land. Based on the relationship between rainfall intensity and the maximum interception rate, the interception process was modelled under two simplified scenarios (i.e., re ≤ Intm and re > Intm). Parameterization of the model was based on consideration of both vegetation condition and soil properties. By analysing the given examples, we found that Intm reflects the capacity of the canopy to store the precipitation, k reveals the ability of the canopy to retain the intercepted water, and the processes of infiltration and runoff generation are impacted dramatically by Intm and k. To evaluate the model, simulated rainfall experiments were conducted in 2 years (2016 and 2017) across six cultivation plots at Changwu State Key Agro‐Ecological Experimental Station of the Chinese Loess Plateau. The parameters were obtained by fitting the unit discharge (simulated rainfall experiments in 2016) using the least squares method, and estimation formulas for parameters pertaining to vegetation/soil factors (measured in 2016) were constructed via multiple nonlinear regressions. By matching the simulated results and unit discharge (simulated rainfall experiments in 2017), the validity of the model was verified, and a reasonable precision (average R2 =.86 and average root mean square error = 6.45) was obtained. The model developed in this research creatively incorporates the canopy interception process to complement the modelling of rainfall infiltration and runoff generation during vegetation growth and offers an improved hydrological basis to analyse matter transport during rainfall events. [ABSTRACT FROM AUTHOR]

Abstract: Groundwater levels in the northern jarrah forest have declined at rates up to 0.5 m year−1 owing to increased aridity in south‐western Australia in the last 40 years. The forest has also been mined and rehabilitated resulting in significant areas of postmining forest. We tested the impact of declining groundwater levels and mining on evapotranspiration by jarrah forest overstorey. We hypothesized that trees in jarrah forest are facultative phreatophytes (will use groundwater where available but are not reliant on it) and water use per unit overstorey leaf area index (Los) of postmining forest is the same as that of postharvest forest. We measured sapflow at 7 sites in the northern jarrah forest and measured rainfall interception by the canopy at 9 sites. Stemflow was measured at 3 sites. Shallow depth to groundwater was associated with a larger ratio of transpiration per unit leaf area (Eos/Los), but there was little difference in Eos/Los between postmining and postharvest jarrah forest. Eos/Los ranged from 250 ‐ 340 mm year−1 (m2 m−2)−1 at sites where depth to groundwater was >15 m but was up to 400–500 mm year−1 (m2 m−2)−1 at some sites with shallow groundwater. Based on relationships between transpiration, rainfall interception, and Los, it is possible to estimate overstorey evapotranspiration in jarrah forest from Los, especially if spatial layers are available for depth to groundwater. We conclude that jarrah forest is conservative in its water use and likely to be resilient to a drying climate. Management implications for the northern jarrah forest are briefly discussed. [ABSTRACT FROM AUTHOR]

Litter layers develop across a diverse array of vegetated ecosystems and undergo significant temporal compositional changes due to canopy phenological phases and disturbances. Past research on temporal dynamics of litter interception has focused primarily on litter thickness and leaf fall, yet forest phenophases can change many more litter attributes (e.g., woody debris, bark shedding, and release of reproductive materials). In this study, weekly changes in litter composition over 1 year were used to estimate litter water storage dynamics and model event-based litter interception. Litter interception substantially reduced throughfall (6-43%), and litter water storage capacity ranged from 1 to 3 mm, peaking when megastrobili release and liana leaf senescence occurred simultaneously during fall 2015. Tropical storm disturbances occurred during the sampling period, allowing evaluation of how meteorological disturbances altered litter interception. High wind speeds and intense rainfall from 2 tropical storms increased litter interception by introducing new woody debris, which, in this study, stored more water than the pre-existing woody debris. After 2 extreme weather events, a third (Hurricane Hermine) did not increase woody debris (or litter interception), suggesting that the canopy pool of branches susceptible to breakage had been largely depleted. Needle and bark shedding had minor effects on litter interception. Results suggest that the release of reproductive materials and meteorological disturbances appear to be the major compositional drivers of litter interception beyond their obvious contribution to litter thickness. [ABSTRACT FROM AUTHOR]

Stable isotopes of water can give clues to the physical processes of forest canopy interception. We examined whether fine-scale canopy structure is related to throughfall amount and isotopic variation by intensively quantifying both throughfall and canopy structure in a broadleaf, deciduous forest in Louisiana, USA. Local throughfall amount was correlated with canopy structure quantified as distance to the nearest tree, local crown coverage, and local crown length; isotopic composition was also correlated with the same variables but weakly. Spatial patterns of throughfall amount showed some consistency across storms, but spatial patterns of stable isotopes were much weaker and inconsistent. Spatial autocorrelation was consistent in throughfall amount across events, which suggests fixed controls over patterning of throughfall to the forest floor by the canopy. In contrast, lower spatial and temporal autocorrelation in isotopic composition suggested temporally varying controls over patterning, and that routing through the canopy, intra-storm isotopic variation of rainfall, isotopic exchange, and evaporation interacted to affect the stable isotopic composition. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Forests that recover from disturbance predominately via vegetative resprouting may be expected to have different catchment water balance dynamics following wildfire than forests recovering from seed. However, the impacts of wildfire on forest water use are largely unknown in resprouting forest types. This is despite their dominance across the majority of southern Australia's forested catchments and the large areas burnt in recent years. We hypothesized that postfire changes in evapotranspiration ( Et) would be a function of fire severity and topography and that partitioning of Et would change after fire because of altered stand structure. We tested these hypotheses by monitoring Et and component fluxes across different topographic positions and fire severities in a mixed eucalypt species forest located in water supply catchments for the city of Melbourne. For this forest type, wildfire triggers vegetative resprouting from lignotubers and epicormic shoots on the bole and branches of the overstorey trees, in addition to prolific seedling germination. Monitoring was undertaken over 1-3 years following the 2009 Black Saturday wildfires. We found that Et was on average 41% lower in forest burnt at high severity compared with unburnt forest, whereas Et from forest burnt at moderate severity was only 3% lower than unburnt forest over 1-2 years postfire but on average 9% higher over 2-3 years postfire. Et losses were driven by tree and shrub mortality in conjunction with lower transpiration in surviving trees. Lower Et was partially offset by regenerating seedlings that drove increases in forest floor Et and interception loss. Finally, we found that topography, through its effects on evaporative demand and forest structure, was a strong determinant of total Et but did not affect the nature of postfire recovery. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT 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. [ABSTRACT FROM AUTHOR]

In recent years, Moso bamboo ( Phyllostachys pubescens) forests have rapidly expanded in Japan by replacing surrounding coniferous and/or broadleaved forests. To evaluate the change in water yield from forested areas because of this replacement, it is necessary to examine evapotranspiration for Moso bamboo forests. However, canopy interception loss, one of the major components of evapotranspiration in forested areas, has been observed in only two Moso bamboo forests in Japan with relatively high stem density (~7000 stems/ha). There are, in fact, many Moso bamboo forests with much lower stem density. Thus, we made precipitation ( Pr), throughfall ( Tf) and stemflow ( Sf) observations for 1 year in a Moso bamboo forest with stem density of 3611 stems/ha and quantified canopy interception loss ( Ic). Pr and Ic for the experimental period were 1636 and 166 mm, respectively, and Ic/ Pr was 10%. The value was approximately the same as values for the other two Moso bamboo forests and lower than values for coniferous and broadleaved forests. On the other hand, Tf/ Pr and Sf/ Pr for our forest (86% and 4%, respectively) were approximately 10% of Pr larger and smaller than values for the other two Moso bamboo forests. These results suggest that the difference in stem density greatly affects precipitation partitioning (i.e. Tf/ Pr and Sf/ Pr) but does not greatly change Ic/ Pr. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

ABSTRACT Canopy storage capacity is influenced by several variables, including canopy surface area, canopy architecture, and wind. Different species with the same canopy area, but with differences in leaf hydrophobicity and water droplet retention, may produce different values of canopy storage capacity. The objective of this study was to investigate if leaf hydrophobicity and water droplet retention are additional influences on canopy storage capacity. Specifically, this study tested the hypothesis that species with the highest leaf hydrophobicity and the lowest water droplet retention had the lowest canopy storage capacity on a per leaf area basis. Seven tree species from Colorado, United States were selected for experimentation. Five branches from each species were lopped, positioned under a rainfall simulator, and connected to a balance to record the mass gain of the branches by rainfall interception during 17 min of rainfall simulation. Each branch was destructively sampled following rainfall simulation to calculate the leaf and woody surface areas. The rank order of leaf surface storages at canopy storage capacity for each species corresponded to the rank order of leaf hydrophobicity and water droplet retention for each species. Species with the highest leaf surface storage had the lowest leaf hydrophobicity and the lowest water droplet retention. The significance of leaf hydrophobicity and water droplet retention as variables that influence canopy storage capacity is a largely unexplored topic in ecohydrology. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The evapotranspiration ( E) from a sugarcane plantation in the southeast Brazil was measured by the eddy-covariance method during two consecutive cycles. These represented the second (393 days) and third year (374 days) re-growth (ratoon). The total E in the first cycle was 829 mm, accounting for 69% of rainfall, whereas in the second cycle, it was 690 mm, despite the total rainfall (1353 mm) being 13% greater. The ratio of E to available energy, the evaporative fraction, exhibited a smaller variation between the first and second cycles: 0.58 and 0.51, respectively. The estimated interception losses were 88 and 90 mm, respectively, accounting for approximately 7% of the total rainfall. The sugarcane yield in the second cycle (61.5 ± 4.0 t ha−1) was 26% lower than the first cycle, as well as lower than the regional average for the third ratoon (76 t ha−1). The below average yield was associated with less available soil water at the beginning of the cycle, with the amount of rainfall recorded during the first 120 days of re-growth in the second cycle being 16% of that recorded in the first (203 mm). [ABSTRACT FROM AUTHOR]

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The article discusses the study which assesses the feasibility of simultaneous optimization of interception and stemflow parameters in southeast South Australia. The study reveals that daily simulated matching from throughfall to fornightly measurements of cumulative throughfall is an important method to determine rainfall interception. On the other hand, Linking test investigates the causes of falsely linked parameters and validates the objective equifinality.

Rainfall interception (RI) over an outdoor urban-scale model was investigated from the perspectives of water and energy balance. On average, RI was 6% of the gross rainfall and smaller than typical values in forests. No correlation was found between RI and gross rainfall or rainfall duration unlike the correlations found in forests. Most RI occurred in the first several hours of rainfall, and then RI rapidly decreased with time during a rainfall event. RI was dependent on the saturation deficit at the beginning of the rainfall event. The latent heat for RI was approximately balanced by heat conduction from the concrete surfaces. Differences in the canopy structure are considered as possible reasons for the different behaviors of RI between the present site and forests. Accordingly, three aspects of the canopy structure, i.e., effective wet surface area, efficiency for scalar transfer, and canopy heat capacity, are discussed. [ABSTRACT FROM AUTHOR]

The article presents a study on the impact of a hedgerow on rainfall distribution, soil-water potential gradient, lateral water transfer, and water balance. It states that in the study, a hillslope with a hedgerow perpendicular to the slope was monitored. It discusses that rainfall was measured both next to and up to 16 meters upslope and 12 meters downslope perpendicularly away from the hedgerow to evaluate hedgerow rainfall interception. Results of the study indicated that hedgerows influences spatial rainfall distribution, soil rewetting and groundwater recharge.

The article provides information on the research conducted to evaluate the duration of clearcutting and the effects of draining in boreal forested wetlands of eastern Canada. It also discusses hydrologic recovery, the process by which a water table increasingly drops back to its normal level after the cut. It presents the methods used in the study as well as its results, which provide a comparison of water table levels in undrained plots and pre-cut levels 10 years after clearcutting. Facts on water table level recovery, rainfall interception by vegetation, and water table drawdown are also given. Moreover, it encourages the use of sylvicultural systems adapted to boreal forested wetlands to prevent stand conversion and productivity loss.

In this article tile effect of redistribution of rainfall by banana on local water fluxes and the possible impact of these fluxes on surface runoff has been studied. First the water redistribution by a banana canopy at three development stages (vegetative, flowering, and bunch stage) was measured. The results showed a considerable stemflow, proportional to the leaf area index (LAI), which represented 18 to 26% of the incident rainfall volume according to the age of the crop. Consequently, the rainfall rate was 28-fold higher at the plant collar for a fully developed banana canopy. For the throughfall, on average, the higher the LAI, the lower the mean throughfall. In addition, the spatial distribution of the throughfall varied according to the distance from the pseudostem. Notably, for the earlier stages, the area between the pseudostem and 0.5 m from it received weak throughfall. Secondly, simulations were carried out with a simple two-compartment model simulating the total surface runoff volume. The simulations showed stemflow combined with the agronomical practice of furrowing has an effect on runoff compared to bare soil. A relative increase in surface runoff volume of three-fold was encountered on a plot with a fully developed banana and a infiltration rate of 60 mm h-1. However, the absolute increase was only a few percentage of the incident rainfall volume, although it represented large water volumes given the tropical rains. These features must be taken into account for hydrological management of such systems. [ABSTRACT FROM AUTHOR]

Crop canopies and residues have been shown to intercept a significant amount of rainfall. However, rainfall or irrigation interception by crops and residues has often been overlooked in hydrologic modelling. Crop canopy interception is controlled by canopy density and rainfall intensity and duration. Crop residue interception is a function of crop residue type, residue density and cover, and rainfall intensity and duration. We account for these controlling factors and present a model for both interception components based on Merriam's approach. The modified Merriam model and the current modelling approaches were examined and compared with two field studies and one laboratory study. The Merriam model is shown to agree well with measurements and was implemented within the Agricultural Research Service's Root Zone Water Quality Model (RZWQM). Using this enhanced version of RZWQM, three simulation studies were performed to examine the quantitative effects of rainfall interception by corn and wheat canopies and residues on soil hydrological components. Study I consisted of 10 separate hypothetical growing seasons (1991-2000) for canopy effects and 10 separate non-growing seasons (1991-2000) for residue effects for eastern Colorado conditions. For actual management practices in a no-till wheat-corn-fallow cropping sequence at Akron, Colorado (study [1), a continuous 10-year RZWQM simulation was performed to examine the cumulative changes on water balance components and crop growth caused by canopy and residue rainfall interception. Finally, to examine a higher precipitation environment, a hypothetical, no-till wheat-corn-fallow rotation scenario at Corvallis. Oregon, was simulated (study III), For all studies, interception was shown to decrease infiltration, runoff, evapotranspiration from soil, deep seepage of water and chemical transport, macropore flow. leaf area index, and crop/grain yield. Because interception decreased both infiltration and soil evapotranspiration, no significant change in soil water storage was simulated. Nonetheless, these findings and the new interception models are significant new contributions for hydrologists. [ABSTRACT FROM AUTHOR]

Redistribution of ground-level rainfall and interception loss by an isolated Quercus ilex tree were measured over 2 years in a Mediterranean oak savannah. Stemflow, meteorological variables and sap flow were also monitored. Rainfall at ground level was measured by a set of rain-gauges located in a radial layout centred on the tree trunk and extending beyond the crown limits. Interception loss was computed as the difference between the volume of rainwater that would reach the ground in the absence of the tree and the volume of water that actually fell on the ground sampling area (stemflow included). This procedure provided correct interception loss estimates, irrespective of rainfall inclination. Results have shown a clear non-random spatial distribution of ground-level rainfall, with rainwater concentrations upwind beneath the crown and rain-shadows downwind. Interception loss amounted to 22% of gross rainfall, per unit of crown-projected area. Stand interception loss, per unit of ground area, was only 8% of gross rainfall and 28% of tree evapotranspiration. These values reflect the low crown cover fraction of the stand (0.39) and the specific features of the Mediterranean rainfall regime (predominantly with few large storms). Nevertheless, it still is an important component of the water balance of these Mediterranean ecosystems. [ABSTRACT FROM AUTHOR]

The majority of canopy interception models, simulating the driving processes that control the energy and water exchange between the canopy and the atmosphere, contain parameters that can not be measured directly, but can only be meaningfully inferred by calibration against a measured record of input-output data. The aim of the present paper is to explore the suitability of two different types of measurements for the identification of parameters in a single-layer forest canopy interception model. The first information source consists of measured throughfall dynamics, whereas the second consists of measured canopy water storage dynamics. The latter measurements were obtained using the attenuation of a microwave signal over a 12.5-m propagation line while scanning vertically through the forest canopy. Results demonstrate that measured throughfall dynamics contain only very limited information for the calibration of a canopy interception model and are particularly inadequate to identify the storage capacity and evaporation rate of the forest canopy. On the contrary, microwave-measured canopy water storage dynamics contain sufficient information to be able to identify the interception model parameters with a high degree of confidence. [ABSTRACT FROM AUTHOR]

Urbanization changes the natural environment, alters land use, and affects the hydrological cycle. Due to decreased infiltration, runoff appears faster with higher flow peaks. A nature‐based solution is to plant trees because they intercept precipitation and help to reduce water reaching the ground, forming surface runoff. Rainfall partitioning for birch (Betula pendula Roth.) and pine (Pinus nigra Arnold) trees is measured in the city of Ljubljana, Slovenia, during 2014 and 2015. The measured values for two consecutive years are used to estimate potential surface runoff reduction due to planting of the trees at a parking lot. The results demonstrate that birch and pine trees intercepted 23 and 45% of gross rainfall, respectively. Both tree species intercept more rainfall in the leafed period. Additionally, rainfall interception during wet (2014) and dry (2015) years has been compared. In 2014 rainfall interception is highly influenced by rainfall intensity, while it has a negligible impact on rainfall interception in 2015, when air temperature is more influential. The scenario of covering 10% of the parking lot area with the trees results in runoff reduction of up to 7.3% per year. In general, runoff reduction is higher in a wet rather than a dry year. The new findings about the performance of different tree species in different climate conditions can offer valuable information for the decision makers and landscape designers about the benefits of trees in urban areas. [ABSTRACT FROM AUTHOR]

Leaf wettability, adhesion or repulsion of water drops, varies greatly among species and plays an important role in plant–soil hydrological relations. This study aimed to examine the variability in leaf wettability among species in different habitats and growth periods, and their relationships with plant surface water retention in the semiarid Loess Plateau of China. The leaf adaxial and abaxial contact angles, the surface water retention of leaves and individual plants, and general plant traits of 68 species belonging to 28 families were examined from May to August in 2017. Results showed that leaf water contact angles ranged from 27.3° to 133.4° and leaves with higher contact angles normally had lower variation coefficients. Leaf wettability was affected by internal properties (including leaf side, family, and leaf age) and external conditions (growth period), whereas the life form and slope aspect did not show significant effects. There were 47 species having higher contact angles on adaxial than abaxial surfaces, and the differences were significant in 23 species. Gramineous and leguminous species were more unwettable than compositae and rosaceous species. New leaves were more unwettable than old leaves. Surface wettability increased from May–June to July–August period. Leaf wettability was positively correlated with leaf surface water retention and was the best predictor of individual plant surface water retention compared with other plant traits. Leaf wettability showed interspecific differences associated with family and growth stage and can be a considerable variable in predicting canopy interception and evaluating vegetation hydrological function in drought environments. [ABSTRACT FROM AUTHOR]

A rainfall interception measuring system was developed and tested for open-grown trees. The system includes direct measurements of gross precipitation, throughfall and stemflow, as well as continuous collection of micrometeorological data. The data were sampled every second and collected at 30-s time steps using pressure transducers monitoring water depth in collection containers coupled to Campbell CR10 dataloggers. The system was tested on a 9-year-old broadleaf deciduous tree (pear, Pyrus calleryana Bradford) and an 8-year-old broadleaf evergreen tree (cork oak, Quercus suber) representing trees having divergent canopy distributions of foliage and stems. Partitioning of gross precipitation into throughfall, stemflow and canopy interception is presented for these two mature open-grown trees during the 1996-1998 rainy seasons. Interception losses accounted for about 15% of gross precipitation for the pear tree and 27% for the oak tree. The fraction of gross precipitation reaching the ground included 8% by stemflow and77% by throughfall for the pear tree, as compared with 15% and 58%, respectively, for the oak tree. The analysis of temporal patterns in interception indicates that it was greatest at the beginning of each rainfall event. Rainfall frequency is more significant than rainfall rate and duration in determining interception losses. Both stemflow and throughfall varied with rainfall intensity and wind speed. Increasing precipitation rates and wind speed increased stemflow but reducedthroughfall. Analysis of rainfall interception processes at different time-scales indicates that canopy interception varied from 100% at the beginning of the rain event to about 3% at the maximum rain intensity for the oak tree. These values reflected the canopy surface water storage changes during the rain event. The winter domain precipitation at our study site in the Central Valley of California limited ouropportunities to collect interception data during non-winter seasons. T [ABSTRACT FROM AUTHOR]