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Allometric models describe properties of trees that are difficult to measure. Here, we provide a set of allometric models for estimating branch properties for European beech (Fagus sylvatica L.). Branches affect rainfall and snow interception, provide habitat for other organisms and contribute to the economic and aesthetic value of trees. Using randomized branch sampling (RBS) of 27 beech trees in Austria we developed models for branch surface area, branch number, branch base diameter and branch length, depending on stem diameter, tree height and crown ratio. For individual branches, branch diameter was the best predictor of branch surface area while including branch length or position along the stem did not improve the models. For the entire tree, stem diameter was the most important predictor. Branch surface area (and in consequence also branch volume) assessed by RBS was greater than the branch surface area estimated as a cylinder from measurements of branch length and branch base diameter. Since the branch allometry of beech differs considerably from a previous study on branches of Picea abies, we conclude that assumptions and models derived from other tree species can lead to considerable biased results in assessing the functions of tree branches. [ABSTRACT FROM AUTHOR]

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]

Leaf area index (LAI) is an important vegetation leaf structure parameter in forest and agricultural ecosystems. In the paper, we deal with the estimation of leaf area index (LAI) and woody area index (WAI) values in a decline climax spruce forest. The research is conducted on the Červenec research plot at an altitude of 1,420 m a.s.l. in the Western Tatra Mountains in the Jalovecký Creek catchment. We carried out the initial measurements during June, August and October 2023. We estimated the values of the LAI and WAI in the mature living and dead spruce stands using hemispherical photography and HemiView software. LAI and WAI values weren't corrected with clumping index. The average values in the living and dead forest stands were 4.7 and 3.0, respectively. In addition to the estimation of the spruce canopy layer LAI, we measured the LAI values of the understorey vegetation in the living, dead stand and in an open area using the SunScan instrument and the SunData software. The highest LAI values of the understorey in the living stand (1.9), in the dead stand (5.3) and in an open area (2.9) were obtained in August, when the vegetation was fully leafy. On the other hand, the lowest LAI values in the understorey were reached in the living stand (1.2) and in an open area (1.8) in October, when the vegetation was already without leaves. [ABSTRACT FROM AUTHOR]

RESUMENLa interceptación de la precipitación por la cubierta vegetal es uno de los principales componentes del balance hídrico en los sistemas forestales. Este trabajo describe el diseño de instalaciones de medición y registro de redistribución de precipitación y presenta información de siete parcelas experimentales ubicadas en plantaciones de Eucalyptus de Uruguay. Los resultados muestran que la fracción de precipitación que es interceptada por el dosel forestal de primera rotación o de replantación varía entre 14 y 30% de la precipitación total, mientras que en la plantación sin manejo de rebrote se alcanza el valor máximo de 50%. La precipitación neta que alcanza al suelo se compone principalmente de precipitación directa y en menor medida de escurrimiento fustal (42–80% y 2–8% respectivamente). Mediante regresión lineal múltiple y prueba de análisis de varianza (ANOVA) se identificó dependencia significativa (p-valor < 0.01) de la interceptación con la especie, edad y densidad de plantación. La información local obtenida es fundamental para la cuantificación del proceso de redistribución de la lluvia en plantaciones forestales de rápido crecimiento, bajo clima templado húmedo y su análisis resulta relevante para la modelación numérica de este proceso.

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]

Urban vegetation can influence urban hydrology and reduce the risk of flooding. Urban forestry studies have suggested that tree type and species choice affect the amount of rainwater intercepted and retained. Little information exists, however, for other landscape typologies, and the sorts of ground-cover plants that are best used to retain/detain rainwater during storm events. This is important as many urban spaces are too small to facilitate trees, but can accommodate roadside vegetation, buffer strips, rain gardens, green roofs and stormwater planters. Thus, this research aimed to determine how choice of ground-cover taxa affected rainwater interception and retention. Six model species with contrasting leaf morphologies were used to determine how well rainwater was intercepted, but also dissipated through evapotranspiration (ET). A pot-based system was used to determine how plant water balance changed during late summer in the UK, with the aim to understand how leaf traits affected hydrological processes. Plant choice was important, with fine-leaved taxa, Festuca glauca and Dianthus 'Haytor White' showing best rainwater interception and Festuca demonstrating highest rates of dissipation from the substrate. Overall, compared to non-planted pots, those with plants present were more effective at capturing water (by 2.3–3.0x), and evapo-transpiring water (by 2.5-4.0x). Results indicate that ground cover vegetation has potential to aid urban water management in those localities where space is limited for trees. Plant choice and community-structure should be considered, especially when there is a desire to dry out soil/substrate quickly and restore maximum soil moisture holding capacity. [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]

Rainfall interception process is an important part of the biohydrological cycle, in which vegetation plays an important role by regulating the amount and dynamics of rainfall reaching the ground. In this paper, an event-based analysis is performed to discuss the influence of vegetation on dynamic of temporal response of soil volumetric water content (VWC) in the upper soil layer during rainfall events. More specifically, six events that occurred between 19 November 2021 and 30 June 2022, characterized by different hydro-meteorological and vegetation conditions, are analyzed based on continuous measurements of VWC in the open and below groups of two deciduous (Betula pendula Roth.) and two coniferous trees (Pinus nigra Arnold), as well as rainfall in the open and throughfall on an urban experimental plot in Ljubljana, Slovenia. VWC values at the upper depth (16 cm) were the highest under the birch tree, followed by the location in the open and under the pine tree. However, in the lowest depth (74 cm) VWC values were the lowest under the birch tree. VWC responses to rainfall and throughfall showed seasonal patterns related to the pre-event wetness conditions, with a faster occurrence of maximum VWC values in the leafless period. Additionally, rainfall amount and its dynamics during the event significantly affect the response, as VWC in general reaches its peak after the occurrence of more intense rainfall. Such an event-based analysis, offering an insight into the dynamics of the event development, is crucial and very beneficial for understanding of the biohydrological processes.

The wide variability in functional traits that enable the cosmopolitan distribution of lichens often includes the water storage capacity, S, of their thallus. Lichen S in forest canopies can be large enough to intercept and evaporate significant amounts of rainwater, contributing to the runoff-reduction ecosystem services provided by urban forests; however, S is likely influenced by the presence of air pollutants (polycyclic aromatic hydrocarbons, PAHs) in urban areas. PAHs, being both chemically hydrophobic and damaging to lichen thalli, are expected to reduce lichens’ S and, thereby, limit their contribution to hydrologic ecoservices of urban forests. Hence, the relationship between PAH accumulation and rainwater uptake was examined for two lichen species, common in urban forests around the world – Platismatia glauca and Pseudevernia furfuracea. Samples were collected from an area of low air pollution and another area in a highly urbanized city centre with high air pollution exposure (Kraków, Poland). Lichen S was determined using laboratory-simulated rainfall. PAH bioaccumulation differed between species and among the samples from clean and polluted environments. After exposure to polluted air, the concentration of PAHs was higher in P. glauca than P. furfuracea. Samples from the non-urban setting, however, showed no differences between the two species. In the case of P. glauca, S decreased from 35.8% in samples from clean environment to 8.3% after six months of exposure in the urban setting. The respective S values for P. furfuracea were 25.4% and 12.4%. Results strongly suggest that PAH exposure reduces S in both lichen species.

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]

Objective: To quantify and characterize the canopy rainfall interception of two dominant forest species of a coniferous forest in Mexico, in order to determine its magnitude and importance in the hydrological cycle and have a source of estimation of interception to improve the accuracy of water balance calculation. Methodology: Twenty-one rainfall events in the period May-June 2018 were analyzed in two 0.25-ha experimental plots, one with pine (Pinus hartwegii) and the other with oyamel (Abies religiosa), at the Zoquiapan Experimental Forest Station (EFEZ), located in the Sierra Nevada in the State of Mexico. Rainfall was measured with an automated weather station and interception was recorded by placing collectors under the canopy and collars on the trunks. Results: The pine tree P. hartwegii intercepted 16.37% of the precipitation, 79.86% of the throughfall, and 3.74% of the stemflow. For A. religiosa, recorded interception was 24.68%, throughfall 72.42%, and stemflow 2.90%. Precipitation had a linear relationship with both throughfall and stemflow, and an exponential one with canopy rainfall interception. Implications: The analysis should be extended to other rainy periods to strengthen the study. Conclusions: The intercepted volume depends on the forest measurement characteristics and leaf area index (LAI) of the species, and the rainfall amount. The fraction of rainfall intercepted is considerable and should be included in hydrological balances. [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]

Tea is a popular crop in Asia and Africa, yet only limited information on tea watershed hydrology is available. This study attempts to experimentally establish the rainfall partitioning parameters (RPPs), namely throughfall (TF), stemflow (SF), and rainfall interception (IC), for a plantation of 27-year-old tea plants grown in West Bengal, India. The relative proportions of TF, SF and IC were 59–89%, 0.12%, and 10–40% with coefficients of variation of 10%, 29%, and 27%, respectively. The SF proportion, being insignificant (≤2%), can be omitted. RPP responses were also analysed against rainfall depth, intensity, and duration. All RPPs except SF showed an exponential decay with rainfall depth. The fitted/validated models were evaluated for goodness of fit using coefficient of determination, mean absolute error, root mean square error, and Nash-Sutcliffe efficiency as error metrics. These results have pragmatic significance in tea watershed hydrology. [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]

[Display omitted] • Rainfall (R) and throughfall (TF) were measured over 18 months in a dry forest. • Canopy reduces kinetic energy (KE) and rainfall erosivity (EI30) by 30% and 39%. • Higher attenuation of KE and EI30 was observed in the season with high leaf density. • Wischmeier and Smith (WS) model underestimates kinetic energy in the study region. • WS model was recalibrated and validated for R and TF in the tropical semiarid site. Empirical relationships have been widely used to estimate kinetic energy of rainfall (KE) and its erosivity potential (EI30) due to scarcity of direct and continuous measurements. Two disdrometers were installed − one in an open field and another under the canopy − in a fragment of Tropical Dry Forest (TDF) in a semiarid region, Northeast of Brazil, to quantify the role of the canopy on attenuating rain kinetic energy and erosivity potential, for all events and at the seasonal scale. The data was also used to test available KE and EI30 models, as well as to recalibrate the models for the study area. Data were collected from December/2019 to July/2021, totaling 95 events. Rainfall (R) was higher than throughfall (TF) due to canopy interception, but rainfall duration and the total number of drops were higher under the canopy. The TDF canopy reduces rainfall kinetic energy by 30% and its erosivity potential by 39%, with higher KE and EI30 attenuation being observed during the high leaf density stage, which highlights the major seasonal role of this vegetation in protecting the soil surface from the impact of raindrops and, consequently, against erosion. The relationship between KE and mean intensity of R and TF is best expressed as a function of time (J m−2 h−1), by a linear model (r2 > 0.98 – p-value = 0.000). The Wischmeier and Smith-WS model for KE and EI30 was recalibrated for the semiarid region, underestimating KE of open field rainfall by 2% and overestimated TF KE by 1%, against underestimations of 24% and 20% of the original model for R and TF, respectively. The results presented here contribute to understanding the role of dry forests in attenuating the erosivity potential of the rainfall in semiarid environments, as well as to improving the capacity on predicting rainfall and throughfall erosivity under such conditions. [ABSTRACT FROM AUTHOR]

Abstract 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.

It is widely acknowledged that synergetic supplies of multiple ecosystem services (ESs) can improve the efficiency of multifunctional landscape management. However, even though the satisfaction of demands for ESs clearly and comprehensively reflects their efficiency, little is known about the efficiency of co-benefits for multiple ESs when both the supply and demand sides are considered. For the first time, we analyzed the co-benefits of the supply of and demand for multiple ESs in urban areas according to the degrees of synergy found among five typical urban ESs. We found that although supplies of multiple ESs were synergetic, and the degrees of synergy of single ES supply–demand were positively correlated with each other, the co-benefits of supply–demand for multiple ESs were not substantial. We also found that the demand for ESs critically affects ES efficiency, which should therefore be assessed from the perspectives of both supply and demand. Any initiative that focuses on just one aspect cannot bring about genuine synergy; nor can it prompt the re-entry of the natural ecosystem in urban areas into a positive cycle. We elucidated the different patterns of synergy that foster a balance in the supply and demand of multiple ESs, which can provide a basis for their differentiation and for grouped management approaches to enhance the co-benefits of the supply of and demand for multiple ESs. Evidently, the supply side of ESs requires attention, especially the key aspect of ecological processes that affect the synergy of ES supplies. Consequently, an in-depth exploration of the key ecological process affecting ES supplies and their synergy is warranted in the future.

Urban afforestation is an important strategy for promoting sustainable urban development. In cities where large new green spaces are not available, the planting of curbside trees is deemed to be an important afforestation strategy. However, variations in the ecosystem services provided by street tree assemblages across socioeconomic gradients have been unexplored. We examined such variations in ecosystem services provided by street tree assemblages along an urban–suburban continuum. Our findings were as follows. (i) Not all ecosystem services showed increasing trends along the urban–suburban continuum. Some ecosystem services at the street tree assemblage level, such as air purification and rainfall interception were prominent in areas of high urbanization intensity. (ii) Diverse ecosystem service trends were found in relation to differential characteristics of street trees assemblages. Structural properties of street tree assemblages, such as tree density and age structure, are likely key factors influencing variations. (iii) Although street tree density could partially compensate for the loss of large old trees, the protection of such trees is important because of their close associations with key ecosystem services, such as total carbon storage. To maximize the value of street trees in promoting urban sustainable development, trade-offs among multiple ecosystem services should be integrated within the overall planning process and adjustments of planting regimes. [ABSTRACT FROM AUTHOR]

Canopy interception is an important part of forest ecosystem hydrological processes. It is the first stage of water distribution when rainfall reaches the canopy and has an important impact on nutrient inputs and water exchange. Pinus tabulaeformis is a main tree species in the rocky mountain areas of Northern China, and it is also a primary species for artificial afforestation. In previous studies of canopy interception, applications of the revised Gash model did not take rainfall characteristics into account. Therefore, in this study, rainfall patterns were divided according to the local rainfall characteristics in the rocky mountainous areas of Northern China. Rainfall was divided into three patterns. Rain pattern A was the main rainfall type. Rainfall patterns B and C were two types of rainstorms. Next, the revised Gash model was used to simulate Pinus tabulaeformis plantations under different rainfall patterns. The results showed that the canopy interception rate of Pinus tabulaeformis plantations in this area ranged from 14.7% to 17.9%. The revised Gash model can be used to simulate Pinus tabulaeformis plantations in the rocky mountainous areas of Northern China, with good simulation results for more than 80% of the conventional rainfall patterns. Furthermore, the canopy interception effect of simulated cumulative rainfall events was better than the individual rainfall event. The simulation effect for special rainfall patterns was not good, so it is necessary to improve the model parameters or collect more rainfall samples. These results can be used to explore the applicability of the revised Gash model in Pinus tabulaeformis plantations in the rocky mountain areas of Northern China. They also demonstrate different applicability of the model under different rainfall characteristics. [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]

Rainfall interception (I) can considerably influence the transport process of water. The revised sparse Gash model (RSGM) is a tool for determining the I, which assumes that the two climate parameters in the model are equal for all storms. However, few studies have provided additional cases to reexamine the correctness of this assumption and investigated the response of I of single storms to the time-step variability in climatic parameters. Hence, rainfall partitioning was measured during the growing season in 2017 for Pinus tabuliformis, Platycladus orientalis, and Acer truncatum in Northern China, and we ran RSGM on an event basis using different time-step climatic parameters (storm-based, monthly, and fixed) to estimate I. In summary, the modeling accuracy of both cumulative I and individual I was enhanced by increasing the time step of the climatic parameters in this study. These positively support the assumption in the RSGM. These results suggest that it is more appropriate to run the RSGM using fixed climate parameters to estimate I for these tree species during the growing season in northern China. Additionally, the assumption in the RSGM should be appealed to be further confirmed across the widest possible range of species, regions, and time scales. HIGHLIGHTS The reasonableness of an assumption in the revised sparse Gash model (RSGM) was reexamined.; Effects of time-step climatic parameters on the RSGM were compared.; Fixed climatic parameters were more appropriate for the simulation in the studied species.; Simulations of single intercepted events are problematic no matter the time step.; Good model accuracy is from complementation between small and large rainfall events.;

Mosses are often overlooked; however, they are important for soil-atmosphere interfaces with regard to water exchange. This study investigated the influence of moss structural traits on maximum water storage capacities (WSCmax) and evaporation rates, and species-specific effects on water absorption and evaporation patterns in moss layers, moss-soil-interfaces and soil substrates using biocrust wetness probes. Five moss species typical for Central European temperate forests were selected: field-collected Brachythecium rutabulum, Eurhynchium striatum, Oxyrrhynchium hians and Plagiomnium undulatum; and laboratory-cultivated Amblystegium serpens and Oxyrrhynchium hians.

General weather conditions may have a strong influence on the individual elements of the hydrological cycle, an important part of which is rainfall interception. The influence of general weather conditions on this process was analysed, evaluating separately the influence of various variables on throughfall, stemflow, and rainfall interception for a wet (2014), a dry (2015), and an average (2016) year. The analysed data were measured for the case of birch and pine trees at a study site in the city of Ljubljana, Slovenia. The relationship between the components of rainfall partitioning and the influential variables for the selected years was estimated using two statistical models, namely boosted regression trees and random forest. The results of both implemented models complemented each other well, as both indicated the rainfall amount and the number of raindrops as the most influential variables. During the wet year 2014 rainfall duration seems to play an important role, correlating with the previously observed influence of the variables during the wetter leafless period. Similarly, during the dry year 2015, rainfall intensity had a significant influence on rainfall partitioning by the birch tree, again corresponding to the influences observed during the drier leafed period.

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]

Different canopy characteristics of industrial eucalyptus may lead to differences in water evaporation and availability to plants. This study aims to understand rainfall partitioning in a young clonal plantation (age of 2–4.5 years) of three eucalyptus species by relating tree parameters: diameter at breast height, total height, and leaf area index. We measured rainfall, throughfall, stemflow and litter interception, along with the tree parameters. The eucalyptus trees had rainfall interception varying between 22 mm (for 178 mm of rainfall) and 42 mm (for 87 mm of te rainfall), throughfall between 106 mm (for 186 mm of rainfall) and 44 mm (for 74 mm of rainfall), and stemflow between 0.5 mm (for 92 mm of rainfall) and 1.4 mm (for 24 mm of rainfall). For the three species, rainfall interception varied between 12 and 48%, throughfall between 57 and 90%, and stemflow between 0.3 and 5.4%. The coefficient of determination between interception and rainfall was 0.76, indicating interception depends on other variables, possibly including antecedent rainfall, rainfall intensity, and seasonality. Interception decreased with a reduction in leaf area index caused by eucalyptus defoliation. The E. benthamii had 0.75 mm of throughfall per 1 mm of rainfall, whereas in E. dunnii and E. saligna, these ratios were 0.71 and 0.68, respectively. Stemflow in E. benthamii and E. dunii had a higher positive relationship with the diameter at breast height of the trees, whereas in E. saligna the highest relationship was with the rainfall. These results contribute to establishing management strategies, such as choosing suitable eucalyptus species to local climate, and to improve the synchronization of crop-demand versus soil-water-supply while maintaining streamflow to fulfill ecological and production needs.

It is widely believed that community forest management concurrently improves the social, ecological and economic conditions of local populations. Accordingly, large areas of Nepal's Mid-hills’ forests are used and managed by local Community Forest User Groups (CFUGs). The CFUGs plant seedlings as well as thin and prune forest trees at varying intensities as determined by local forest conditions and the need for forest products (mainly timber, firewood, livestock fodder and compostable litter). However, the hydrological effects of these activities are uncertain. We present results of throughfall (Tf), stemflow (Sf) and overland flow (OF) measurements made between June 2015 and December 2016 (including two consecutive rainy seasons) in three types of community-managed forests subject to different levels of community usage in the Kavre district (East Central Nepal): (i) regenerating natural broad-leaved (BF), (ii) predominantly-planted pine (PF), and (iii) mixed pine-broad-leaved (MF). The BF and MF were used more intensively than the PF. Overall Tf fractions were 72.0%, 73.7% and 77.5% of incident precipitation (P) for the BF, MF and PF, respectively, with corresponding Sf fractions of 1.6%, 1.3% and 0.6%. Overall rainfall interception fractions were 26.4%, 25.1% and 21.9% for the BF, MF and PF, respectively, and reflected the trend in leaf area index. Total amounts of OF constituted 11.4%. 9.8% and 4.7% of net precipitation (Tf+Sf) inputs to the forest floor in the BF, MF and PF, respectively and broadly followed the relative intensity of forest usage. Observed amounts of OF in the study forests represent ca. 50–115 mm of foregone infiltration opportunity per year under average rainfall, implying reductions in the recharge of soil and groundwater reserves of ∼6% in the PF to 12–14% in the MF and BF. Our results thus show that regular harvesting of litter, fodder and firewood combined with surface compaction by human traffic constitute important determinants of hillslope hydrological functioning, particularly regarding amounts of foregone infiltration and runoff as OF in the more intensively used community-managed forests of Nepal's Mid-hills.

Plants are dynamic systems during rainfall events. As raindrops splash on leaf surfaces, the momentum of the raindrop is transferred to the leaf, causing the leaf to oscillate. The emphasis of this review is on the general principles of leaf oscillation models after raindrop impact and the ecological importance. Various leaf oscillation models and the underlying physical properties from biomechanics theory are highlighted. Additionally, we review experimental methods to derive the model parameters for and explore advances in our understanding of the raindrop–leaf impact process. [ABSTRACT FROM AUTHOR]

Rainfall is the main water source of crops. Crops maintain their normal growth and development by absorbing water from the soil. However, the role of rainfall is often overestimated in water resource evaluation and farmland water balance research because the rainfall interception effect of crop canopy is not considered. It is difficult to calculate crop interception quantitatively, which seriously restricts the impact assessment of rainfall on crops. Therefore, in order to determine the interception effect in different growth stages of maize under different rainfall, the rainfall interception experiment of maize is carried out at Jinzhou Agricultural Meteorological Experimental Station of Liaoning Province in 2018. A total of 10 rainfall levels (rainfall over 20 mm is designed for the measurement of saturated interception) and 8 leaf area indexes (representing 8 different growth periods) are examined in the experiment. The rainfall interception effect of maize canopy is systematically analyzed by simulation. Results show that under certain rainfall, the relationship between the interception of maize canopy and leaf area index conforms to the relationship of quadratic polynomial, exponential function and power function, among which the quadratic polynomial has the highest explanation rate. Under the assumption of fixed leaf area index, the rainfall interception of maize canopy is in accordance with the quadratic polynomial, exponential function, power function and logarithmic function. When leaf area index is above 3, the explanation rate of power function is the highest, and the relationship between saturated interception of maize and leaf area index is in accordance with the quadratic polynomial, exponential function and power function, among which the explanation rate of quadratic polynomial is the highest. The comprehensive leaf area index and rainfall analysis indicate a positive correlation between canopy interception and the square of leaf area index and the logarithm of rainfall. According to the traditional planting mode of maize in China, the maximum leaf area index of high-yield maize is generally about 5-6. Therefore, the maximum interception of a rainfall process is usually 1.5-2.3 mm. When leaf area index is less than 1, the rainfall interception of maize can be ignored. Results are of practical significance for the evaluation of the effectiveness of rainfall resources and the study of farmland water balance.

• Clarified rainfall interception and redistribution by single and mixed leaf litters. • Small leaves fill gaps in large leaves' structure to enhance effective interception. • Strong interception capability of litters reduces infiltration flow on sloped land. As a crucial component within the vertical structure of the forests, leaf litter plays a significant role in the hydrological effects of the forest ecosystem. Studying the impact of different types of leaf litter combinations on the hydrological performance, as well as understanding how the ratio of leaf types in the litter layer influences it, are crucial for achieving a deeper comprehension of the role of the litter layer in forest hydrological processes. The objectives of this study were to determine the rainfall interception characteristics of single leaf litters with different types (Pinus massoniana , Cinnamomum camphora and Magnolia grandiflora) and mixing degrees (P. massoniana × C. camphora , P. massoniana × M. grandiflora , and C. camphora × M. grandiflora , with mixing ratios of 1:3, 1:1, and 3:1) under various slope gradients (0°, 5° and 25°). The results showed that with varying combinations of leaf litters and different mixing degrees, there existed certain disparities in runoff mitigation efficiency. In particular, the response time of the P. massoniana × M. grandiflora to rainfall gradually advanced as the proportion of P. massoniana increased. The maximum and minimum interception capacity of the leaf litters were both highest for C. camphora , and minimum interception capacity of the mixed litters of P. massoniana × C. camphora decreased with an increasing proportion of P. massoniana. When C. camphora accounted for a larger proportion in the mixed litters of C. camphora × M. grandiflora , the minimum interception capacity was larger. In the combination of P. massonian × C. camphora , the proportion of infiltration flow was the highest when the mixing ratio was 1:1, while that of slope and lateral flow was the lowest. On the sloped land, the infiltration flow of P. massoniana × M. grandiflora increased with the increasing proportion of P. massoniana , while the slope flow was opposite. Mixtures of litters affect the accumulation spatial structure of the litter layer, consequently altering the interception and redistribution characteristics of rainfall. The research provides a reliable foundation for objectively assessing the water transfer mechanism and conservation function of the litter layer. [ABSTRACT FROM AUTHOR]

• Alpine herbs exhibited tens of fold variations in plant surface water storage (PWS). • The correlations between PWS and plant traits were complex for predicting PWS. • Plant strategy theory clarified the multifaceted traits effects on PWS per projected area. • Expansion of competitive species in alpine meadows may intensify interception loss and exacerbate water scarcity. Rainfall interception by vegetation is essential in precipitation redistribution within ecosystems and greatly affects water services. However, the patterns of interspecies variation in plant surface water storage (PWS) remain unclear, which greatly limits our understanding of the relationship between species composition and vegetation rainfall interception. Thus, we aimed to examine whether the plant ecological strategy, which is an internal driving force and comprehensive characteristic of plant traits, can serve as a PWS predictor. The PWS of thirty-nine common plant species in natural, degraded, and restored alpine meadows within the Ruoergai wetland was compared, and the variability in PWS between these species was examined from both plant trait and ecological strategy perspectives. The results showed that PWS per plant (IWSC) ranged from 0.12 to 9.32 mL plant−1, and PWS based on projected area (PSCI) and fresh weight (PMS) ranged from 0.01 to 0.94 mm and 0.11 to 1.29 g g−1, respectively. The PSCI was comparatively lower in Cyperaceae, whereas the PMS was relatively lower in Polygonaceae, and Poaceae. The correlations between PWS and multidimensional plant traits are complex for predicting PWS but can be clarified by considering plant ecological strategies. Further regression analysis revealed that as an evolutionary representation of the crucially related plant traits, plant competition significantly positively affected both IWSC and PSCI, and stress tolerance obviously negatively affected these two parameters (P < 0.05). The correlation between plant strategy and PSCI implied that the increased dominance of competitive species in alpine meadows may intensify interception loss, thereby hindering rainfall allocation to soil and exacerbating water scarcity. [ABSTRACT FROM AUTHOR]

We determined 116 globally important woody tree species, classified them based on the differences between plant life-forms, leaf textures and trichomes on leaves and measured the indices of some plant morphological traits in the Guizhou karstic regions of China. The water adsorbed on the upper surfaces of branches and leaves and the water adsorbed on the upper and lower surfaces of branches and leaves (WWu and WWul) of these species was measured. The ratios of the weight of adsorbed water on the upper surfaces of branches and leaves to the weight of branches and leaves (RWWu) and the ratios of the weight of adsorbed water on the upper and lower surfaces of branches and leaves to the weight of branches and leaves (RWWul) were calculated. The adsorption of water and morphological trait indices follow the approximately normal distributions. The weight of branches and leaves (weight), total leaf area (TLA) and mean leaf area (MLA) significantly impacted the adsorption of water by branches and leaves. The different rates of the adsorption of water for 116 tree species can explain the interspecific variation in rainfall interception. Interpretation of these data is provided in Effects of the morphological characteristics of plants on rainfall interception and kinetic energy[J]. Journal of Hydrology, 2020: 125807. https://doi.org/10.1016/j.jhydrol.2020.125807.

A rainfall interception experiment was completed for Pinus sylvestris var. mongolica plots with stand densities ranging from 925 to 2700 plants ha−1 in Mu Us Sandy Land, China from June to September 2013. The revised Gash analytical model was then applied to the canopy interception of the Mongolian Scots pine plantations. During the experimental process, the incident rainfall (P), throughfall (Tf), and stemflow events (Sf) were collected and measured, and meteorological data were simultaneously obtained on site. The Penman-Monteith equation and Gash regression method were used to estimate the evaporation rate (E) from the saturated canopy. The classical revised Gash calculation procedure and Leyton-constraint method were applied to obtain the canopy storage capacity (S). Parameters such as E, S, stemflow partitioning coefficient (pt), and trunk storage capacity (St) were scaled to the canopy cover fraction per unit area: Ec, Sc, ptc, and Stc in the revised Gash analytical model, which was also used in the simulation of the rainall interception (Tf, Sf, and I). The proportions of the measured Tf, Sf, and I accounted for 62.82%, 1.13%, and 36.05% of P, respectively. The ratios of Ec to rainfall intensity (R), Sc, ptc, and Stc were 0.0260 (0.0458), 1.210 mm (2.006 mm), 0.0630, and 0.0486 mm, respectively, during the experimental period. The analytical model with Ec and Sc equal to 0.182 (Penman-Monteith equation) and 1.210 mm (classical revised Gash calculation procedure) accurately simulated the canopy interception of the Mongolian Scots pine plantations, and the canopy interception variation in the analytical model was sensitive to P, Sc, Stc, c, Ec, and R, but was relatively insensitive to ptc.

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]

The interception process impacts rainfall magnitude and intensity under the canopy. In this study, the effect of plant interception on throughfall characteristics was assessed in the deciduous Caatinga vegetation, at different canopy development stages and for temporal scales ranging from seasonal to the intra-event scale. Throughfall and stemflow percentages were slightly higher at the onset of the rainy season, when leaf area density is low, with resulting lower interception losses. However, there was no statistical difference among the variables at the seasonal scale. At the intra-event scale, average and maximum throughfall intensity at different time intervals showed statistical difference between the stages of canopy development. Regardless of leaf area density and rainfall depth, vegetation is able to retain all the water up to 2 min in the beginning of each rainfall event with accumulated rainfall smaller than 0.6 mm. Furthermore, the Caatinga vegetation attenuates the rainfall intensity by 30–40%. [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]

Wildfire can exert considerable influence on many watershed processes, including the partitioning of precipitation by forest canopies. Despite general acknowledgement that canopy interception is reduced following wildfire, effects on net rainfall and snow accumulation have not been quantified. The objectives of this study were to document net rainfall and snow water equivalent (SWE) in burned and unburned (reference) forest stands over a 10-year period to characterise the effects of severe wildfire on net precipitation in the Canadian Rocky Mountains. Differences in summer (June–September) rainfall between burned and reference stands suggest that wildfire reduced rainfall interception by 65%, resulting in a 48% increase in net rainfall from 2006 to 2008. This represented an average annual increase in net rainfall of 122 mm (36%) for 10 years after the fire. Similarly, a burned stand had 152 mm (78%) higher mean annual peak SWE than a paired reference stand. Collectively, burned stands had 274 mm (191–344 mm; 51%) more mean annual net precipitation for the first decade after fire. These results suggest that increases in net precipitation are likely following wildfire in subalpine forests and that, owing to the slow growth of these forests, post-fire changes may alter precipitation–runoff relationships for many years. Forest canopy interception can be significantly reduced after wildfire, allowing more precipitation to reach the forest floor. This study documents differences in net rainfall and snow accumulation between burned and unburned subalpine forest stands in the Canadian Rocky Mountains. The results suggest substantially higher net precipitation in burned stands during a 10-year period following a severe wildfire. [ABSTRACT FROM AUTHOR]

Rainfall interception is of great significance to the fully utilization of rainfall in water limited areas. Until now, studies on rainfall partitioning process of typical ecosystems in Heihe River Basin, one of the most important inland river basins in China, is still insufficient. In this study, six typical ecosystems were selected, namely alpine meadow, coniferous forest, mountain steppe, desert, cultivated crop, and riparian forest, in Heihe River Basin for investigation of the rainfall interception characteristics and their influencing factors, including rainfall amount, duration, and intensity, based on the gross rainfall and high temporal resolution soil moisture data obtained from 12 automatic observation sites. The results show that the average interception amount and average interception rate of the six ecosystems are significantly different: alpine meadow 6.2 mm and 45.9%, coniferous forest 7.4 mm and 69.1%, mountain steppe 3.5 mm and 37.3%, desert 3.5 mm and 57.2%, cultivated crop 4.5 mm and 69.1%, and riparian forest 2.6 mm and 66.7%, respectively. The rainfall amount, duration, and intensity all had impact on the process of rainfall interception. Among these three factors, the impact of rainfall amount was most significant. The responses of these ecosystems to the rainfall characteristics were also different. Analyzing rainfall interception with high temporal resolution soil moisture data is proved to be a feasible method and need further development in the future. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • For the first time, the evaporation of intercepted water of a winter oilseed rape was determined. • Evaporation of intercepted water of winter oilseed rape cannot be neglected in making decisions on irrigation planning. • Less soil water is available with increasing amounts of fertilization because non-productive water losses increase. Abstract Oilseed rape (Brassica napus L.) is the major oil crop in Europe and Germany but its hydrological functioning is poorly understood. Studies on the interception processes in oilseed rape have been lacking until the present. The interception of rainfall by oilseed rape is expected to vary in response to substantial changes in canopy structure throughout the cropping cycle and fertilization treatment. To determine evaporation of intercepted water, field measurements of a winter oilseed rape crop were conducted for different stages of development and five treatments of fertilization (0, 60, 120, 180 and 240 kg N/ha). Precipitation (P) and throughfall (TF) were measured hourly, along with vegetation structure measurements of the leaf area index (LAI). A range of 0–21% for the percentage of stemflow (SF) of P was estimated from soil moisture measurements. For the vegetation period from March to June the cumulative P of 112 mm was converted into 49 mm TF (44%). The inferred evaporation of intercepted water (I) was 63 mm (56%). There was a gradual and clear increase in I from 45% to 67%, reflecting the increasing fertilization treatments. Hence, less soil water was available with increasing amounts of fertilization, since the water fraction evaporating from the canopy increases. Plant architecture, LAI and meteorological conditions during the cropping cycle appeared to be the main factors determining I. For irrigation planning and water use, studies of the evaporation of intercepted water must be considered. [ABSTRACT FROM AUTHOR]

• Systematic review of the urban forestry and forest hydrology literature. • Identification of physical tree traits that help optimize stormwater interception. • Identification of physical tree traits that help optimize stormwater infiltration. • Guidance for real-world applications in urban tree selection, care, and management. In this study, we conducted a systematic literature review to determine the physical tree traits, site conditions, and urban forest management strategies that provide optimal stormwater runoff mitigation through the interception of precipitation or enhanced infiltration of water routed toward the ground by urban tree cover. Our review found that foliar characteristics such as high leaf area index, low hydrophobicity, low inclination angles, and high surface roughness promote rainfall retention by the canopy, as do high bark water storage capacity and a denser crown. In addition, when soil conditions are suitable, infiltration can be enhanced by urban tree cover and promoted through efficient funneling of stemflow through the tree canopy, with this process facilitated by erectophile branching structure, bark of low microrelief and morphology conducive to water transport, and multi-leader canopies. Consideration of these traits should be made when selecting trees to enhance stormwater mitigation by urban tree cover. Applications related to the establishment, maintenance, and management of urban tree cover to maximize stormwater management benefits are also explored. Strategic selection and management of urban trees may significantly increase their collective capacity to reduce runoff volumes at a landscape scale. [ABSTRACT FROM AUTHOR]

• The Rutter model approach is a reasonable standard to determine wet canopy conditions. • Energy based methods were integrated and analyzed over periods of interception. • Analysis of 11 years eddy covariance data for dry and wet canopy conditions. • EC measurements are systematically underestimating wet canopy evaporation. • Performance of flux measurements declines for rain and wet conditions. Rain interception of a Norway spruce stand was analyzed based on canopy water balance measurements E mass and for two eddy covariance (EC) related methods covering a long period (2008–2018). E mass was calculated as residual between gross rainfall above and net rainfall below the canopy. EC related observations are based on the water equivalent either (i) directly measured by eddy covariance (ET EC) or (ii) as residual in the Energy Balance equation (ET EB). To relate the different methods to wet canopy conditions, the Rutter model was used to dynamically calculate water storage in the canopy. Finally, the different time series were integrated over the duration of modeled interception events. The canopy water balance shows a mean annual gross precipitation of 936 ± 173 mm/year of which 376 ± 56 mm/year evaporated due to interception. The majority of rainfall events (81%) is characterized by a depth <5 mm, which leads to a high fraction of annual precipitation being captured by the canopy surface (0.41). The application of the Rutter model yielded good agreement between observed and modeled throughfall and served as a reasonable standard to define interception events. Wet canopy evaporation as the residual of the energy balance ET EB and from gas analyzer measurements ET EC are both systematically underestimating E mass. The mean annual underestimation of E mass is 145 mm/year for ET EB and 288 mm/year for ET EC. Most of the discrepancy can be mainly explained by an underestimation of turbulent fluxes, at which data is most affected during raining conditions. An analysis of the linear relation between the annual sum of turbulent fluxes and available energy shows the lowest slope (0.57 ± 0.15) for measurements during rainfall, while the highest slope (0.76 ± 0.03) occurs under completely dry conditions. Both fluxes should be gap-filled and corrected separately for dry (transpiration) and wet (interception) conditions in order to determine proper amounts of evapotranspiration with the eddy covariance method. [ABSTRACT FROM AUTHOR]

The aim of this research was to estimate the ecohydological parameters of the canopy covers including estimated canopy saturation point (P´G Estimated), canopy storage capacity (S), the ratio of mean evaporation rate from the wet canopy to the mean rainfall intensity ( ), free throughfall coefficient (p), computed canopy saturation point (P´G), and stemflow funneling ratio (F) of a Picea abies plantation in Lajim, Mazanderan province, north of Iran. To measure throuhgfall (TF), 45 rain-gauges were installed beneath the crown of the stand. Stemflow (SF) was measured using the average of 12 individual trees equaled to the SF amount. Over the measurement period, the cumulative percentage of TF, SF, and rainfall interception (I) were 41.0%, 5.1%, and 53.9%, respectively. The abovementioned ecohydrological parameters were found to be 4.2 mm, 3.54 mm, 0.38, 0.18, 5.90 mm, and 4.6, respectively. The ecohydrological parameters should be considered while converting natural stands to plantations of exotic tree species as this altering would be alter soil humidity, soil pedogenesis, and forest floor composition.

ABSTRACT In order to contribute to the discussion on how forest development interacts with hydrological processes related to rainfall partitioning, we aimed to characterize the rainfall interception (RI), throughfall (Tf), stemflow (Sf), and net precipitation (NP) in three Cerrado areas at different stages of natural regeneration conduction: treatment 1 = area with 4 years without human intervention; treatment 2 = 10 years; and treatment 3 = 43 years. In all areas, three 400-m2 plots were established, in each of which 12 rain gauges and stemflow collectors were installed on all trees having Diameter at Breast High (DBH) > 5 cm. Data was recorded from December 2015 through November 2016. At treatment 1, Tf corresponded to 100% of gross precipitation (GP) in the micro-basin, while Sf corresponded to 0.01%, RI to 0%, and NP to 100% of GP. At treatment 2, Tf corresponded to 96% of GP, whereas Sf corresponded to 0.19%, RI to 4%, and NP to 96% of GP. At treatment 3, Tf corresponded to 87% of GP, while Sf corresponded to 1.15%, RI to 12%, and NP to 88%. The results revealed significant differences among the study areas. Both RI and Sf increased with advancing natural regeneration, while Tf and NP decreased. Data varied according to vegetation features, like the number and density of individuals and species in each plot, and according to characteristics related to weather and precipitation in the area.

Study region: The area of woodland savanna (cerrado) is located in southeast Brazil (21°36′ to 44′ S, 47°34′ to 41′ W). Study focus: The cerrado sensu-stricto savanna evapotranspiration was observed using the eddy-covariance method over three years. New hydrological insights for the region: The first year total rainfall (R = 1664 mm) was 11% above the long-term rainfall (1498 mm) and the total evapotranspiration (ET = 1242 mm) and water equivalent of available energy (Av = 1835 mm) were approximately 4% and 2% greater, respectively, than in the second year when the rainfall total was 5% lower than the long-term average. In the third year despite the total rainfall (1259 mm) being 24% lower than the first year and 16% lower than the average, the totals of ET (1242 mm) and Av (1815 mm) were approximately the same. The small variation in the observed annual ET totals shows that in this cerrado vegetation the deep soil moisture content supports the ET in a dry year and the water available for recharging the soil profile and groundwater (∼R − ET) was dominated by the rainfall amount being significantly greater in the wet year (422 mm) than in the dry year (13 mm).

The study aims to estimate the canopy storage capacity (S) and the ratio of mean evaporation rate from the wet canopy to the mean rainfall intensity (), and the free throughfall coefficient (p) of Pinus eldarica (44 years-old-age) afforestation using three regression-based methods (Minimum, Gash and Morton and Mean methods) in the Chitgar Forest Park, near Tehran, with a semiarid climate zone. To measure gross rainfall (GR), 10 rain gauges were fixed in an open space nearby to the stand and throuhgfall (TF) was measured during a year using the 50 rain gauges randomly placed underneath the canopy cover. Rainfall interception (I) was computed as the difference between GR and TF. Fifty rain storms were recorded with a cumulative depth of 262.5 mm. The TF and (TF:GR)% were recorded 69.5% and 53.2% of the rainfall event on the cumulative-based, and event-based (each GR), respectively. Positive logarithmic correlations were observed between (TF: GR)% and GR during the study period (TF:GR = 16.598 ln GR + 35.494; R2 = 0.630). For dry (from May to November) and wet periods these values corresponded to 0.988 and 0966 by positive linear correlations. The mean value of S,, and p were estimated 1.23 mm, 0.10, and 0.19, respectively. Since measurements of the amount of GR and I are expensive and time-consuming in semiarid and arid regions, and attended measurements in the field are currently carried out, thereto, regression models for estimating I and its components, e.g., S, p, and coefficients can successfully been applied.

Changes in rainfall interception and consequently in water balance cause essential effects on reforestation by indigenous and exotic tree species in the degraded areas of the Caspian forests. The aim of the present study was to compare the interception of Quercus castaneifolia, Acer velutium, and Pinus brutia plantations during the growing season in Darabkola Forest in eastern part of Mazandaran province in northern Iran. The amount of rainfall (GR) and throughfall (TF) were measured from May to November 2012 by 6 and 20 polyethylene manual gauges with 8 cm diameter each. The rainfall interception was estimated as the difference between TF and GR. During the measurement period 20 rainfall events were recorded. The amount of cumulative GR depth was 346.5 mm. Moreover, the cumulative rainfall interception of Q. castaneifolia, A. velutium, and P. brutia were 86.2 mm, 107.9 mm and 178.3 mm, respectively. The results showed that the rainfall interception was higher during the dry season, from April to September. In addition, significant correlations were observed between rainfall interception and the relative interception for the three plantations (r2 =0.781, 0.716 and 0.618 for Q. castaneifolia, A. velutium and P. brutia, respectively). It is concluded that estimating the amount of rainfall interception is crucial for selecting adapted species for reforestation in the Caspian forests. It is also a prerequisite for calculation of the water balance within reforestations.

The evolution of vascular tissue is a key innovation enabling plants to inhabit terrestrial environments. Here, we demonstrate extra-vascular water transport in a giant, prop-rooted monocot from Lord Howe Island. Pandanus forsteri (Pandanaceae) produces gutter-like leaves that capture rainwater, which is then couriered along a network of channels to the tips of aerial roots, where it is stored by absorptive tissue. This passive mechanism of water acquisition, transport and storage is critical to the growth of aerial prop roots that cannot yet attain water via vascular conduction. This species therefore sheds light on the elaborate means by which plants have evolved to attain water. [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]