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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]

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]

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]

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 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 (stormbased, 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. [ABSTRACT FROM AUTHOR]

• 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]

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]

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]

• 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 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]

Arid pomegranate ( Punica granatum ) orchards are frequently rainfed. In these systems, orchard managers might be able to manipulate a stand’s canopy structure ( e.g. , thinning, pruning) to improve rainfall water input to the soil. The aim of this research was to determine how changes in management activities in rainfed pomegranate orchards in arid regions of Central Iran affects rainfall partitioning into throughfall, stemflow, and rainfall interception loss. We monitored gross rainfall, throughfall, stemflow and rainfall interception loss in three stands with varying levels of thinning and pruning. Management practices sufficiently altered the stand and canopy structure of pomegranate orchards to impact the quantity and pathway (throughfall v. stemflow) of rainfall reaching the ground. Decreases in tree height, canopy cover, crown length and LAI were correlated to a significant increase in rainfall reaching the forest floor. Results indicate that orchard managers may be able to prune 40% of the live crown and thin 70% of the stand if the objective it to significantly increase water inputs into the soil. Future research should focus on the impact of canopy management on soil moisture content and soil evaporation and transpiration. [ABSTRACT FROM AUTHOR]

Rainfall partitioning is an important part of the ecohydrological cycle, influenced by numerous variables. Rainfall partitioning for pine ( Pinus nigra Arnold) and birch ( Betula pendula Roth.) trees was measured from January 2014 to June 2017 in an urban area of Ljubljana, Slovenia. 180 events from more than three years of observations were analyzed, focusing on 13 meteorological variables, including the number of raindrops, their diameter, and velocity. Regression tree and boosted regression tree analyses were performed to evaluate the influence of the variables on rainfall interception loss, throughfall, and stemflow in different phenoseasons. The amount of rainfall was recognized as the most influential variable, followed by rainfall intensity and the number of raindrops. Higher rainfall amount, intensity, and the number of drops decreased percentage of rainfall interception loss. Rainfall amount and intensity were the most influential on interception loss by birch and pine trees during the leafed and leafless periods, respectively. Lower wind speed was found to increase throughfall, whereas wind direction had no significant influence. Consideration of drop size spectrum properties proved to be important, since the number of drops, drop diameter, and median volume diameter were often recognized as important influential variables. [ABSTRACT FROM AUTHOR]

The temporal dynamics of forest canopy rainfall partitioning are important to forest ecology and management as it influences all subsequent hydrological processes along the rainfall-to-discharge flow path. Despite a growing body of literature on the importance of coupled hydrological-ecological interactions during periodic forest life cycle events, little work has examined how canopy rainfall partitioning varies across transitional leaf states (between the leafed vs. leafless states). This study analyzed a 3 year field monitoring campaign for two tree species in semiarid Iran (Robinia pseudoacacia and Platanus orientalis) to describe rainfall partitioning dynamics across the full-leaf, senescence, leafless, and leafing states. Crown saturation point, canopy storage capacity, free throughfall coefficient and the ratio of wet canopy evaporation rate to mean rainfall intensity were related to decreases/increases in plant area index and canopy closure. The high variability of rainfall partitioning observed in this study highlights the importance of transitional leaf states in the temporal characterization of water inputs to forest surfaces and boundary layer. [ABSTRACT FROM AUTHOR]

Rainfall interception is a process scarcely studied in arid and semiarid environments. The aim of this study was comparatively analyze two field techniques to evaluate the water storage capacity in Chuquiraga erinacea Don., characteristic shrub species of the CaldenalMonte Occidental ecotone region, Argentina The study was conducted in the annexed field of INTA in Chacharramendi, La Pampa. Water storage capacity was measured on whole plants from two techniques on field: rainfall simulation and immersion. Water storage capacity, expressed in percentage of biomass was determined by difference wet weight fresh weight. Equality of results from field techniques for whole plants of Chuquiraga erinacea justified the application of immersion method in the study to be more expeditious implementation and more economical in terms of time and costs. [ABSTRACT FROM AUTHOR]

An understanding of the relationship between canopy structure and the water balance is needed for predicting how forest structure changes affect rainfall partitioning and, consequently, water resources. The objective of this study was to predict rainfall interception ( I ) and canopy storage capacity ( S ) using canopy structure variables and to investigate how seasonal changes influence their relationship. The study was conducted in twelve 50 m × 50 m plots in the Zagros forest in the western Iranian state of Ilam, protected forests of Dalab region. Average cumulative I was 84.2 mm, accounting for 10.2% of cumulative gross precipitation ( G P ) over a 1-year period. Using a regression based method, S averaged ~ 1 mm and 0.1 mm in the leafed and leafless periods, respectively. There were no relationships between tree density and I:G P or S , but I:G P and S increased with leaf area index, canopy cover fraction, basal area, tree height, and diameter at breast height in the leafed period. In addition, wood area index and canopy cover fraction were related to I:G P or S in the leafless period. [ABSTRACT FROM AUTHOR]

Part of precipitation is intercepted by forest canopies, while the rest reaches the ground as throughfall or stemflow. This process is influenced by various meteorological variables, of which we have mainly focused on drop diameter and velocity. Rainfall in the open and throughfall under birch and pine trees have both been measured since 2014 in Ljubljana, Slovenia. The results demonstrate that the total throughfall during 3.5 years was 73% and 53% of rainfall under birch and pine trees, respectively. During the 236 analysed events, the median volume diameter was 1.8 mm (1.7 mm), and kinetic energy between 0.01 mJ/cm² and 23.3 mJ/cm² was recorded. We closely analysed the effect of rainfall microstructure on throughfall under pine and birch trees during three specific rainfall events. The increase in drop diameter and fall velocity during a rainfall event instantaneously increased throughfall under pine trees between 25% and 47%, whereas no such changes were observed under birch trees. This may be the consequence of different tree properties of the two species. Additionally, in the case of a saturated canopy, throughfall under pine trees exceeded rainfall in the open after an onset of larger and faster drops. [ABSTRACT FROM AUTHOR]

Evaporation from wet-canopy ( $$E_\mathrm{C}$$ ) and stem ( $$E_\mathrm{S}$$ ) surfaces during rainfall represents a significant portion of municipal-to-global scale hydrologic cycles. For urban ecosystems, $$E_\mathrm{C}$$ and $$E_\mathrm{S}$$ dynamics play valuable roles in stormwater management. Despite this, canopy-interception loss studies typically ignore crown-scale variability in $$E_\mathrm{C}$$ and assume (with few indirect data) that $$E_\mathrm{S}$$ is generally $${<}2\%$$ of total wet-canopy evaporation. We test these common assumptions for the first time with a spatially-distributed network of in-canopy meteorological monitoring and 45 surface temperature sensors in an urban Pinus elliottii tree row to estimate $$E_\mathrm{C}$$ and $$E_\mathrm{S}$$ under the assumption that crown surfaces behave as 'wet bulbs'. From December 2015 through July 2016, 33 saturated crown periods (195 h of 5-min observations) were isolated from storms for determination of 5-min evaporation rates ranging from negligible to 0.67 $$\hbox {mm h}^{-1}$$ . Mean $$E_\mathrm{S}$$ (0.10 $$\hbox {mm h}^{-1}$$ ) was significantly lower ( $$p < 0.01$$ ) than mean $$E_\mathrm{C}$$ (0.16 $$\hbox {mm h}^{-1}$$ ). But, $$E_\mathrm{S}$$ values often equalled $$E_\mathrm{C}$$ and, when scaled to trunk area using terrestrial lidar, accounted for 8-13% (inter-quartile range) of total wet-crown evaporation ( $$E_\mathrm{S}+E_\mathrm{C}$$ scaled to surface area). $$E_\mathrm{S}$$ contributions to total wet-crown evaporation maximized at 33%, showing a general underestimate (by 2-17 times) of this quantity in the literature. Moreover, results suggest wet-crown evaporation from urban tree rows can be adequately estimated by simply assuming saturated tree surfaces behave as wet bulbs, avoiding problematic assumptions associated with other physically-based methods. [ABSTRACT FROM AUTHOR]

In this paper an assessment of shallow landslides susceptibility in a tropical and mountainous terrain is made. A method that allows to model slope stability over large areas is used. Tree contribution is quantified by means of three parameters: rainfall interception, root reinforcement and tree surcharge. A rainfall interception model is used to determine the rain available for infiltration and its temporal distribution during the simulation. The hydrological models included in TRIGRS are described, which allows to determine the pore water pressure depending on the initial conditions. This pore water pressure is used in the revised infinite slope stability model, along with root reinforcement and tree surcharge, in order to determine the slope stability in terms of a factor of safety (FS) for an entire basin. Different scenarios of tree density are modeled in a basin of the Valle de Aburra and the results are compared with a model performed without considering the effects of trees on the stability. The results obtained showed values of FS < 1 (predicting failure with the occurrence of the simulated rainfall event) in the delimited area due to the null presence of trees. On the 26th October 2016, months after the investigation was concluded and the paper submitted to Revista EIA, a shallow landslide occurred in the studied area (municipality of Copacabana, landslide on the Medellín-Bogotá Highway K12+200, in the El Cabuyal zone), indicating that the proposed methodology can be a useful tool for the prediction of shallow landslides. [ABSTRACT FROM AUTHOR]

Accurately quantifying the vegetation rainfall interception at a high resolution is critical for rainfall-runoff modeling and flood forecasting, and is also essential for understanding its further impact on local, regional, and even global water cycle dynamics. In this study, the Remote Sensing-based Gash model (RS-Gash model) is developed based on a modified Gash model for interception loss estimation using remote sensing observations at the regional scale, and has been applied and validated in the upper reach of the Heihe River Basin of China for different types of vegetation. To eliminate the scale error and the effect of mixed pixels, the RS-Gash model is applied at a fine scale of 30mwith the high resolution vegetation area index retrieved by using the unified model of bidirectional reflectance distribution function (BRDF-U) for the vegetation canopy. Field validation shows that the RMSE and R2 of the interception ratio are 3.7% and 0.9, respectively, indicating the model's strong stability and reliability at fine scale. The temporal variation of vegetation rainfall interception and its relationship with precipitation are further investigated. In summary, the RS-Gash model has demonstrated its effectiveness and reliability in estimating vegetation rainfall interception. When compared to the coarse resolution results, the application of this model at 30-m fine resolution is necessary to resolve the scaling issues as shown in this study. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergetic degree index is used to analyze the co-benefits of multiple ES. • Although multiple ES supply rates are synergetic, the co-benefit is not high. • Sustaining co-benefits of multiple ES requires optimizing synergy of supply–demand. 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. [ABSTRACT FROM AUTHOR]

Vegetation growing concrete (VGC) is a kind of concrete composed of a sand-free porous concrete skeleton and plant-growing substrate, which has a certain strength and is suitable for plant growth. In this study, Lolium perenne , Festuca arundinacea , and Festuca rubra were used to construct VGC. The variation and temporal changes in the effects of these three herbaceous plants on the performance of VGC in terms of soil stabilization and slope protection were assessed herein. Plant growth at different growth stages, rainfall interception by the aboveground parts of the plants, and the erosion resistance and shear strength of the substrates were evaluated concurrently. The growth rate of the stems, leaves, and root systems of the three species of plants decreased over time. Overall, L. perenne had the best growth state, followed by F. rubra and F. arundinacea. The maximum interception amount and the maximum interception rate of the aboveground part of the vegetation increased initially then decreased over time. L. perenne had the highest maximum interception amount and rate, which were 83.5% and 12.7% higher than those of F. arundinacea , respectively, and 32.7% and 7.7% higher than those of F. rubra , respectively. Plant roots enhanced the erosion resistance and shearing strength of VGC. The erosion resistance and shearing strength of VGC increased over time and reached the maximum value at the later stages of plant growth. L. perenne had the highest enhancement effect on erosion resistance and the highest shearing strength, which were 5.9% and 8.3% higher than those of F. rubra , respectively, and 10.7% and 16.4% higher than those of F. arundinacea , respectively. Among the three herbs, L. perenne is the appropriate species for the construction of VGC for slope protection in the mountainous areas of southwest China. • Lolium perenne , Festuca arundinacea , and Festuca rubra vegetation concrete differed significantly in the rainfall interception. • Plant roots enhanced the erosion resistance and shearing strength of the vegetation concretes. • Among the three herbs, L. perenne is the appropriate species for the construction of vegetation concrete for slope protection. [ABSTRACT FROM AUTHOR]

As plantations become increasingly important sources of wood and fiber in arid/semiarid places, they have also become increasingly criticized for their hydrological impacts. An examination and comparison of gross rainfall ( GR ) partitioning across commonly-planted tree species ( Pinus eldarica , Cupressus arizonica , Robinia pseudoacacia , and Fraxinus rotundifolia ) in semiarid regions has great value for watershed and forest managers interested in managing canopy hydrological processes for societal benefit. Therefore, we performed a field study examining GR partitioning into throughfall ( TF ), stemflow ( SF ), and rainfall interception ( I ) for these species in the semiarid Chitgar Forest Park, Tehran, Iran. An advantage to our study is that we explore the effects of forest structural differences in plantation forests experiencing similar climatic factors and storm conditions. As such, variability in GR partitioning due to different meteorological conditions is minimized, allowing comparison of structural attributes across plantations. Our results show that commonly-selected afforestation species experiencing the same climate produced differing stand structures that differentially partition GR into TF , SF , and I . P. eldarica might be the best of the four species to plant if the primary goal of afforestation is to limit erosion and stormwater runoff as it intercepted more rainfall than other species. However, the high SF generation from F. rotundifolia , and low GR necessary to initiate SF , could maximize retention of water in the soils since SF has been shown to infiltrate along root pathways and access groundwater. A consideration of GR partitioning should be considered when selecting a species for afforestation/reforestation in water-limited ecosystems. [ABSTRACT FROM AUTHOR]

Summary Mulching of agricultural fields and gardens with pebbles has long been practiced to conserve soil moisture in some semi-arid regions with low precipitation. Rainfall interception by the pebble mulch itself is an important part of the computation of the water balance for the pebble mulched fields and gardens. The mean equivalent diameter (MED) was used to characterize the pebble size. The maximum static rainfall retention in pebble mulch is based on the water penetrating into the pores of pebbles, the water adhering to the outside surfaces of pebbles and the water held between pebbles of the mulch. Equations describing the water penetrating into the pores of pebbles and the water adhering to the outside surface of pebbles are constructed based on the physical properties of water and the pebble characteristics. The model for the water between pebbles of the mulch is based on the basic equation to calculate the water bridge volume and the basic coordination number model. A method to calculate the maximum static rainfall retention in the pebble mulch is presented. Laboratory rain simulation experiments were performed to test the model with measured data. Paired sample t-tests showed no significant differences between the values calculated with the method and the measured data. The model is ready for testing on field mulches. [ABSTRACT FROM AUTHOR]

• Rainfall interception (RI) was affected by rainfall amount levels (RMLs) • RI amount was closely related to rainfall amount regardless of RMLs. • RI proportion was most determined by humidity at heavy rain events. • RI proportion was governed by canopy interception index at light and middle RMLs. Rainfall interception (RI) by forest canopy is an important part of the ecohydrology cycle, influenced by rainfall characteristics, weather conditions, forest structures and their interactions. Rainfall events with different amounts are likely to change the ways that rainfall interacts with forest canopies, and consequently vary the effects of influential variables on RI markedly. Thus, analyzing the influential variables on RI separately according to rainfall amounts need further attention. In this study, rainfall partitioning was measured in 60 plots of four forest types during June to September from 2017 to 2019. Weather conditions were obtained from four weather stations spatially representing all the study plots. Detailed canopy structural variables were retrieved from the terrestrial laser scanning. Then, boosted regression trees (BRT) analyses were performed to evaluate the contributing variables of RI at different rainfall amounts. As a result, a total of 77 rainfall events were measured, and 43, 19 and 15 events were classified as light rainfall events (LR, gross rainfall < 10 mm), middle rainfall events (MR, 10 mm ≤ gross rainfall < 25 mm) and heavy rainfall events (HR, gross rainfall ≥ 25 mm). The average values of RI amounts (the difference between gross rainfall and the sum of throughfall and stemflow) for LR, MR and LR were 2.0 mm, 3.5 mm and 6.6 mm, respectively. The average RI proportions (the proportion of RI amount to gross rainfall) for LR, MR and HR were 74.8 %, 20.2 % and 17.1 %, respectively. Both RI amount and RI proportion were significantly different among the rainfall amount levels (LR, MR and HR). BRT results showed that, for all rainfall amount levels together, RI amount was governed by rainfall amount, followed by canopy interception index (CII) and humidity. Whereas RI proportion was most influenced by CII, followed by rainfall amount, humidity and average canopy height (ACH). As expected, for a given rainfall amount level, rainfall amount was the most influential variable on RI amount. Naturally, the most influential variable on RI proportion varied with rainfall amount levels. For LR and MR, the most influential variables were CII; while it was humidity for HR. Furthermore, a variety of significant variables (with the relative influence value higher than the averaged value), such as rainfall intensity, wind speed and ACH, intricately and complexly affected RI amount and proportion at each rainfall amount level. In addition, the Rainfall amount exerted a stepwise positive correlation with RI amount. CII showed a stepwise positive and humidity a negative influence on RI proportion, respectively. A comprehensive understanding of the influence variable on RI at distinct rainfall amount levels provides valuable insights into how forest canopies intercept rainfall and greatly supports understanding of canopy hydrological processes in temperate forests. [ABSTRACT FROM AUTHOR]

• Drop-size distribution measurements below and above tree canopy were conducted. • Effect of birch tree on the soil erosion related processes was analysed. • A decrease in the raindrops erosivity below the canopy was demonstrated. • Impact of leafed and leafless period on the rainfall erosivity was significant. Healthy soils are one of the key priorities of the EU Soil Strategy, and soil erosion can present a threat to soils around the world. Rainfall erosivity is the main driver of soil erosion by water. Rainfall interception by vegetation can reduce the erosive power of raindrops, and consequently measures involving vegetation can mitigate soil erosion losses. In this study, the effect of rainfall interception on the erosive power of raindrops under the birch tree in an urban park in the city of Ljubljana is investigated. More than one year of measurements of drop-size distribution using two optical disdrometers placed above and below the birch tree canopy were used to investigate the impact of rainfall interception on the erosive power of raindrops. The number of drops, fall velocity, and drop diameter were, on average smaller below the canopy in comparison to the measurements above the canopy for 20%, 7% and 27%, respectively. This also resulted in a reduction in the rainfall kinetic energy (3% and 30% in the leafless and leafed periods, respectively) and rainfall erosivity (21% and 50% for the leafless and leafed periods, respectively). The results demonstrate that rainfall interception has a significant seasonal influence on the erosive power of raindrops. Therefore, vegetation characteristics should be considered as time-varying rather than constant parameters in soil erosion modelling studies. [ABSTRACT FROM AUTHOR]

In precision agriculture, methods for analysing 3D point clouds of plants have been introduced, particularly pointing to the high accuracy of light detection and ranging (LiDAR) laser scanning under field conditions. In the present work, LiDAR-based 3D point clouds of cherry trees (n = 255) were analysed for estimating the leaf area as the main factor for water interception. Canopies were scanned for segmenting leaf area pointing to a high variability of canopy surface. The derived tree-specific data of leaf area index (LAI) were implemented into the Community Land Model (CLM), which takes into account canopy interception processes during rainfall events. During canopy development of perennial trees the LAI increased resulting in increased water interception. Events with low rain fall the interception reached 38–100 % capturing LAI of 0.76 – 2.11 m2/m2, respectively. In high rainfall events, interception varied 10–14 % capturing the same LAI range. An equation for describing the varying effects of rainfall intensity and LAI is proposed. The evapotranspiration and water interception data point to a substantial decrease of effective water supply that varies tree-individually during the season. In commercial fruit production, the proposed method can support precise irrigation management. • Method for analysing LAI of perennial fruit trees was employed. • CLM model was modified for calculating tree-wise water interception. • Seasonal course of tree-wise LAI can support precise irrigation management. • Water interception was a substantial factor for calculating gross water supply. [ABSTRACT FROM AUTHOR]

Evaporation from wet canopies ( E ) can return up to half of incident rainfall back into the atmosphere and is a major cause of the difference in water use between forests and short vegetation. Canopy water budget measurements often suggest values of E during rainfall that are several times greater than those predicted from Penman–Monteith theory. Our literature review identified potential issues with both estimation approaches, producing several hypotheses that were tested using micrometeorological observations from 128 FLUXNET sites world-wide. The analysis shows that FLUXNET eddy-covariance measurements tend to provide unreliable measurements of E during rainfall. However, the other micrometeorological FLUXNET observations do provide clues as to why conventional Penman–Monteith applications underestimate E . Aerodynamic exchange rather than radiation often drives E during rainfall, and hence errors in air humidity measurement and aerodynamic conductance calculation have considerable impact. Furthermore, evaporative cooling promotes a downwards heat flux from the air aloft as well as from the biomass and soil; energy sources that are not always considered. Accounting for these factors leads to E estimates and modelled interception losses that are considerably higher. On the other hand, canopy water budget measurements can lead to overestimates of E due to spatial sampling errors in throughfall and stemflow, underestimation of canopy rainfall storage capacity, and incorrect calculation of rainfall duration. There are remaining questions relating to horizontal advection from nearby dry areas, infrequent large-scale turbulence under stable atmospheric conditions, and the possible mechanical removal of splash droplets by such eddies. These questions have implications for catchment hydrology, rainfall recycling, land surface modelling, and the interpretation of eddy-covariance measurements. [ABSTRACT FROM AUTHOR]

Interactions between precipitation and forest canopy elements (bark, leaves, and epiphytes) control the quantity, spatiotemporal patterning, and the chemical concentration, character and constituency of precipitation to soils. Canopy epiphytes exert a range of hydrological and biogeochemical effects due to their diversity of morphological traits and nutrient acquisition mechanisms. We reviewed and evaluated the state of knowledge regarding epiphyte interactions with precipitation partitioning (into interception loss, throughfall, and stemflow) and the chemical alteration of net precipitation fluxes (throughfall and stemflow). As epiphyte species are quite diverse, this review categorized findings by common paraphyletic groups: lichens, bryophytes, and vascular epiphytes. Of these groups, vascular epiphytes have received the least attention and lichens the most. In general, epiphytes decrease throughfall and stemflow and increase interception loss. Epiphytes alter the spatiotemporal pattern of throughfall and increase overall latent heat fluxes from the canopy. Epiphytes alter biogeochemical processes by impacting the transfer of solutes through the canopy; however, the change in solute concentration varies with epiphyte type and chemical species. We discuss several important knowledge gaps across all epiphyte groups. We also explore innovative methods that currently exist to confront these knowledge gaps and past techniques applied to gain our current understanding. Future research addressing the listed deficiencies will improve our knowledge of epiphyte roles in water and biogeochemical processes coupled within forest canopies—processes crucial to supporting microbe, plant, vertebrate and invertebrate communities within individual epiphytes, epiphyte assemblages, host trees, and even the forest ecosystem as a whole. [ABSTRACT FROM AUTHOR]

The dynamic properties of rainfall interception were investigated at three growth stages in Chinese fir plantations. The results showed that the annual interception ratio was significantly higher in mature stands than in young stands. For a storm event, interception rainfall amount increased with increasing rainfall, but interception ratio decreased. In contrast to dry season conditions, the interception amount was high in the wet seasons, while the interception ratio was low. The rates of change in interception ratio were extremely rapid in small rainfall events. There was little stemflow in Chinese fir forests due to the pyramid-shaped crowns and thick rough bark of the trees. The power model was suitable to describe the interception process for an individual rainfall event for stands of any age. Our results indicate that the interception process varied for stands of different ages in Chinese fir plantations due to contrasting canopy structures. [ABSTRACT FROM AUTHOR]

Increasing urban forest canopy coverage due to greening initiatives requires watershed managers to balance societal water practices with forest hydrological processes. One such process, canopy rainfall interception, can remove substantial portions of precipitation from catchments by simply intercepting, storing, and evaporating meteoric water. We performed a field study examining interception losses across temporal scales comparing two landscaping species of contrasting crown structures (Fagus grandifoliaEhrh., American beech, andLiriodendron tulipiferaL., yellow poplar), native to the highly urbanized northeastern United States, to highlight the effect of landscape design on urban water and storm water management. Results show that landscape designs using the rougher bark texture, lower branch inclination, and thinner canopy ofL. tulipiferacan increase water losses during rainfall and, therefore, can be used to improve storm water management. On the other hand, the smoother bark, higher branch inclination, and deeper canopy ofF. grandifoliadecreased water losses, allowing greater water transfer to the surface or subsurface. Thus, interception-related water resource losses during urban forestry projects can be manipulated to benefit urban sustainability efforts if designers consider the multifaceted ramifications of planting different tree species with differing canopy structures. [ABSTRACT FROM PUBLISHER]

• Patterns of wetting and drying were characterized in a forest canopy. • Significant variability was seen in wetting patterns and sources seasonally. • Dew formed on upper canopy layers on ∼ 28% of dry season nights. • Dewfall was accurately predicted using a one-variable logistic model. • Dewfall was accurately predicted using the Penman equation. Canopy wetting and drying has a variety of effects on the function of plant foliage, ranging from increased risk of pathogenic infection to reduced diffusion of gases to enhanced leaf water status in plants capable of foliar water uptake (FWU). Projected shifts in rainfall regimes and increases in summertime vapor pressure deficit will likely change the timing and duration of canopy wetting, yet current patterns of wetting are poorly understood. In this study, we investigated patterns of wetting by source (rain, dew, or frost), at different canopy heights, and at annual, seasonal and diurnal time scales using leaf wetness sensor data collected over a 4-year period in an old growth Douglas-fir tree in a temperate wet forest. We found that canopy layers were wet for roughly half the year with strong seasonal variation, staying wet 83% of the cold winter season but only 1.9% of the dry season. Upper canopy layers experienced higher wetting frequency and shorter wetting duration in all seasons compared to lower canopy layers. Outside of the dry season, wetness was predominantly caused by rain, while in the dry season the predominant source was dewfall. Throughout the year and particularly in the dry season, dewfall was restricted to the upper canopy, occurring on 28.5% of dry season nights. Multiple models which use meteorological variables to predict dewfall timing and length were developed and evaluated. Using in-tree observations, dry season dewfall was best predicted with a logistic model using dewpoint depression as a predictor. Using observations from a nearby weather station in a clearing, dry season dewfall was best predicted with the Penman equation, a biophysical model. The most important determinant of dry season dewfall in our study was sufficient nighttime cooling of the air, suggesting that increasing nighttime temperatures will lead to a decrease in dew formation frequency in the future. [ABSTRACT FROM AUTHOR]

From 30 January 2011 to 30 January 2012, we measured the rainfall interception (I) and canopy storage capacity (S) of individual trees of Pinus eldarica and Cupressus arizonica planted in the Chitgar Forest Park near Tehran, Iran. Gross rainfall (GR) in this semiarid region was measured using the mean of 6 plastic rain gauges placed in an open area adjacent to the trees. To measure throughfall (TF), 20 plastic rain gauges were installed beneath the crowns of 5 individual trees of each species. I was calculated as GR minus TF. S was estimated using indirect methods: the minimum, Gash and Morton, mean, and Pereira methods. The cumulative mean values of relative percentage of I (I:GR) for P. eldarica and C. arizonica trees averaged 44.2% and 34.4%, respectively. Significant negative relationships were observed between the percent of I:GR and GR for P. eldarica (R² = 0.63) and C. arizonica (R² = 0.67) trees. For P. eldarica, S was estimated to be 1.10 mm, 1.00 mm, 1.09 mm, and 1.05 mm using the minimum, Gash and Morton, mean, and Pereira methods, respectively. For C. arizonica, the corresponding values are 0.58 mm, 0.52 mm, 0.56 mm, and 0.55 mm. This study proposes that in this climate dominated by small storms, planting C. arizonica is preferable to planting P. eldarica. However, the differences in the transpiration of these species should be quantified. Our results also indicated that the I value in this semiarid climate was higher than that of a humid climate. [ABSTRACT FROM AUTHOR]

Highlights: [•] We quantified and modeled interception losses by adjacent native and exotic forests. [•] We compared two interception models under subtropical coastal condition. [•] Interception was greater in the pine plantation due to higher canopy storage capacity and aerodynamic conductance. [•] The optimized RGAM model performed slightly better than the WiMo model. [•] Both models predicted the seasonal and annual interception reasonably well. [Copyright &y& Elsevier]

Highlights: [•] Canopy wetness duration in a Mediterranean deciduous forest stand is presented. [•] Noticeable seasonal and diel differences in wetness duration were identified. [•] Current methods for separating rainfall events fail to define real canopy drying duration. [•] Findings raise a challenge to interception models that assume a completely dry canopy between events. [Copyright &y& Elsevier]

Highlights: [•] Revised landslide model can improve model performance. [•] Rainfall interception affects the time when shallow landslide initiates. [•] Root reinforcement and tree surcharge affects shallow landslide development. [ABSTRACT FROM AUTHOR]

Abstract: The water and energy fluxes of a shaded coffee plantation in the lower montane cloud forest (LMCF) zone of central Veracruz, Mexico, were measured over a two-year period (September 2006–August 2008) using the eddy covariance method. Complementary measurements of throughfall and stemflow were made to study rainfall interception. The sum of the observed sensible (H) and latent (λE) heat fluxes was almost 95% of the net radiation (R n) minus the canopy heat storage fluxes, indicating very good energy balance closure. The mean annual evapotranspiration was 1066mm, and 95% of the corresponding FAO Penman-Monteith reference evapotranspiration (ET0) of 1117mm yr−1. Interception loss was 8% of annual rainfall (1386mm). Both the eddy covariance, and the throughfall and stemflow measurements showed average wet-canopy evaporation rate to be very low (0.05mmh−1) compared to the corresponding rainfall rate (3.06mmh−1). As a result, and despite the low canopy storage capacity of the coffee plantation (C m, 0.50mm), interception was dominated by post-event evaporation of intercepted water rather than by within-event evaporation. Comparing the results for the coffee plantation with interception data from mature and secondary LMCFs in the study area suggests that the conversion of LMCF to shade-coffee may lead to a decrease in interception loss of 8−18% of incident rainfall. This decrease is caused by a three- to seven-fold decrease in C m, probably due to the lower leaf area and smaller epiphyte biomass of the coffee plantation. The mean annual dry-canopy evaporation was 992mm, and 89% of ET0. Comparing the eddy covariance-based estimate of dry-canopy evaporation for the coffee plantation with sapflow-based estimates of transpiration for the LMCFs did not show any clear differences. [Copyright &y& Elsevier]

Highlights: [•] Simple canopy generator reproduces observed canopy gap fraction. [•] Model predicts dripping locations, which can trigger localized soil erosion. [•] Model confirms splashing as considerable source of small throughfall droplets. [•] Predicted throughfall spatial distribution poses a challenge to correct sampling. [Copyright &y& Elsevier]

While the hydrological balance of forest ecosystems has often been studied, quantitative studies on the seasonal variability of rainfall Interception (I) and Canopy Storage Capacity (S) by individual trees are less frequently reported. Hence, the effects of the seasonal variation in I and S by individual Persian oak trees (Quercus brantii var. Persica) in the Zagros forests of Iran were studied over a 1-year period. Annually, I accounted for 84.9 mm (20%) of Gross Rainfall (GR) that significantly differed between the in leaf (47.4 mm or 30% of GR) vs. leafless (37.7 mm or 14% of GR) periods. Negative logarithmic correlations existed between I:GR and GR both for in leaf (r2= 0.808) and leafless (r2= 0.709) periods. An indirect method, outlined by Pereira et al. (2009), estimated S to be 1.56 mm in the in Leaf Period (LP) and decreased considerably to 0.56 mm in the Leafless Period (LLP). The results indicate that while I decreased during the LLP, it still exerts considerable influence on the hydrology of forests. Hence, measurement of I in both the LP and LLP is essential when assessing the water balance on the catchment scale. [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]

Abstract: This study was undertaken to quantify interannual variations of total evaporation (ET) in a tropical rainforest in Sarawak, Malaysia. To this end, we conducted 10-year meteorological measurements and formulated a simplified big-leaf model that reproduces transpiration (Et), rainfall interception (Ei), and ET as the sum of these. The model was validated independently using eddy covariance fluxes, rainfall interception based on throughfall and stemflow measurements, and sap flow measurements conducted for more than 2 years. Using the model, Et, Ei, and ET were estimated for the period 2000–2009. Annual Et, Ei, and ET averaged over 10 years were estimated as 1114, 209, and 1323mm, respectively, with small seasonal fluctuations. The derived estimates showed conservative year-to-year variations in annual Et, Ei, and ET (CV=5–7%) in contrast to considerable year-to-year variations in annual rainfall (CV=11%). Specific rainfall characteristics (e.g. intense short duration storms) at this site can explain the conservative year-to-year Ei variations. Small interannual variations in meteorological conditions and absence of severe drought during the study period can explain the small year-to-year Et variations. To characterize ET at our site, we also compared Ei and ET at our site with those of other tropical forests. Based on the derived ET characteristics, we discuss possible ET changes in response to changes in rainfall regime at this site. [Copyright &y& Elsevier]

Abstract: In this study, we used a pair of optical disdrometers, one under and one outside the maize canopy, to measure the drop-size and the velocity distribution of hydrometeors during 12 storms and identified four distinct regions by examining how the fraction of drops recorded on the throughfall changed with respect to the drop diameter. The first region, containing drops with diameters smaller than 0.5mm, showed an elevated number on the throughfall. Their numbers were comparable to the numbers of drops that lacked enough energy to adhere to the leaf. The second region, featuring drops with diameters larger than 0.5mm and smaller than 3mm, had a number ratio very close to the canopy gap fraction, indicating that their most likely origin was direct throughfall. The third region entailed drops with diameters ranging from 3mm to 5.5mm that featured a high throughfall to rainfall count ratio, with one of the diameter classes having higher counts under the canopy than outside of it. Through simplified calculations, we showed that drop weights in this region should exceed surface tension forces and lead to their detachment. In the fourth and final region, the throughfall to rainfall ratio decreased converging to the canopy gap fraction. By comparing the number of drops on each of the 440 diameter/velocity classes under and outside of the canopy, we were able to identify preferential drop sizes on the throughfall, i.e. classes of drop diameters with higher drop-size distributions under the canopy. The drop classes presenting higher counts under the canopy had diameters ranging from 3.25mm to 5.75mm with velocities between 1.4ms−1 and 5ms−1. We were able to trace the origin of those drops to heights of between 0.10m and 1.05m within the canopy, confirming that these drops constitute the indirect throughfall. The capability to estimate the detachment height of drops allows us to reconstruct the drop-size distribution at different levels of the canopy and offers unique insight into the mechanics of interception, indirect throughfall formation and re-interception of raindrops by the maize canopy. [Copyright &y& Elsevier]

Abstract: Subtropical thicket dominated by the leaf- and stem-succulent tree Potulacaria afra (spekboom) accumulates extraordinarily high amounts of soil organic carbon for a semi-arid ecosystem. This has been attributed to high leaf litter production of canopy trees — especially spekboom — and the relatively cool beneath-canopy temperatures, which reduces mineralization of organic matter. High rainfall interception by the dense thicket canopy may also contribute to reduced mineralization of soil organic carbon stocks via a reduced Birch effect (wet–dry cycles) and overall reduced moisture of organic matter. Here we provide preliminary data on one easily measurable component of canopy interception, namely throughfall, which is the amount of rain falling on the canopy that is not intercepted by the canopy or diverted as stemflow. For 23 rainfall events >1mm in the period Jan–Jun 2006, we measured 275±21mm gross rainfall at three spekboom thicket sites. Mean throughfall was 56.4% across all events and ≤20% for small (≤5mm) events. These values are the lowest recorded in the literature. Throughfall in tropical and temperate forests ranges from 70 to 90%, Mediterranean woodland trees 70–80%, and Savanna trees 75–84%. The low rates of throughfall recorded in this study support the hypothesis that the extreme accumulation of soil organic carbon in thicket soils is partly due to interception of rainfall and concomitant constraints on soil microbial activity. The extraordinary high interception of rainfall by the spekboom thicket canopy warrants further research at the ecosystem level. [ABSTRACT FROM AUTHOR]

Abstract: Mechanistic modeling of crop interactions with the atmosphere requires knowledge of the canopy architecture. For example, studies of light and rainfall interception and microwave radiative transfer modeling have motivated the development of a number of virtual canopies by agronomists, computer scientists, and hydrologists. While a number of canopy measuring techniques are already available, recent improvements in digital photography and the availability of affordable commercial photogrammetry packages have created an opportunity to develop highly detailed three-dimensional digital models of maize canopies. Here, we present a non-destructive one-man methodology to digitize plants that uses an unmodified consumer grade digital single-lens reflex (SLR) camera and commercially available photogrammetry software. This methodology allows tracking of individual plant development, which was not possible in earlier techniques. The construction of the digital plant model is divided into three parts: plant preparation, where several artificial targets are placed on the plant and their relative distances are measured; leaf digitizing in which the targets are marked and referenced by the software, thereby allowing the photographs to be oriented; and the creation of three-dimensional models of individual leaves and the final model buildup when, through cross-referencing, the complete digital plant model is arranged. We demonstrate the applicability of the presented methodology by digitizing the same plant at two different stages of development (6 and 10 leaves) and subsequently assessing the models’ precision. In both cases, the objective is to define the edges and mid-rib of the leaves as well as their vertical and horizontal orientation; this allows the calculation of geometric descriptive parameters including plant area, leaf overlap, leaf area index, and gap fraction. The two presented models were built from 48 and 119 pictures, respectively, which correspond to 348 and 1553 three-dimensional points. [Copyright &y& Elsevier]

Abstract: Emergent trees may have an influence on the volume and the spatial distribution of water input into agroforestry stands and may thus affect water availability for the main crops. Our goal was to analyze the influence of such trees on rainfall distribution in a cacao agroforest area in the rainforest margin zone of Central Sulawesi, Indonesia. The emergent trees studied belong to the species Bischofia javanica (Phyllanthaceae) and were 15m high remnants from the natural forest. A set of 96 throughfall gauges was systematically distributed underneath canopies of cacao only, and underneath canopies of cacao plus emergent trees (cacao plus trees). From an earlier study we knew that stemflow can safely be estimated with less than 1% of gross precipitation (Pg). Median throughfall tended to be lower in gauges underneath cacao plus trees than under cacao only (p⩽0.1), and the estimated rainfall interception loss was 4% and 16% of Pg in cacao only and cacao plus trees plots, respectively. This difference was most likely caused by a tree-induced enhancement of the canopy water storage capacity and an increase in canopy roughness. Underneath the canopy of emergent trees (cacao plus trees), throughfall exceeded gross precipitation east of the tree stems (113%) and was significantly lower (p⩽0.05) west and north of the tree stems (67–77% of Pg). Significant effects of trees on throughfall did not extend beyond their canopy area. We assume that wind-driven rain was stripped out east of the stems causing an increase in throughfall, while rain-shadow effects led to a decrease in throughfall west and north of the tree stems. Thus, at our study site emergent trees tended to reduce rain water input, and produced clear spatial patterns in throughfall distribution. A reduced water availability may lead to reduced cacao bean yields in times of water scarcity but a more complete assessment of the hydrological function of shade trees in agroforestry systems may also reveal positive influences of shade trees on cacao trees. Such an advanced analysis of hydrological functions still remains to be done. [Copyright &y& Elsevier]

Summary: Plant leaf can absorb water when the leaf is in contact with water. This happens when the rainfall is intercepted by plant leaves, where the intercepted part of rain remains on the leaf surface. When the intercepted water is either absorbed or subsequently evaporated into the atmosphere, the plant leaves can dissipate water through the desorption process until the plant is dry or rewatered. In this paper, two symptomatic models in the form of exponential functions for leaf water absorption and leaf water desorption were derived and validated by experimental data using leaves of three turfgrasses (Tall fescue, Perennial ryegrass and Kentucky bluegrass). Both the models and measured data showed that the rate of leaf water absorption was high at the low initial leaf water content and then gradually leveled off toward the saturated leaf water content. The rate of leaf water desorption was high at the high initial leaf water content then decreased drastically over time toward zero. The different plant leaves showed different exponents and other parameters of the functions which indicate the difference of plant species. Both the absorption and desorption rates were relatively higher for the Kentucky bluegrass and lower for the Tall fescue and Perennial ryegrass. The concept of specific leaf area (SLA) was used to understand the saturated leaf water content (Cs ) of the three turfgrasses. Linear relationships were found between Cs and SLA. The leaf water absorption and desorption functions are useful for deriving physiological parameters of the plant such as permanent wilting leaf water content, naturally irreducible leaf water content, exponential leaf water absorption coefficient, and exponential leaf desorption coefficient, as well as for evaluating the effects of rainfall interception on plant growth and water use efficiency. [Copyright &y& Elsevier]

Abstract: In a previous study, it was shown that an isolated, fully saturated tree-crown behaves like a wet bulb, allowing evaporation of intercepted rainfall to be estimated by a simple diffusion equation for water vapour. This observation was taken as the basis for a new approach in modelling interception loss from savanna-type woodland, whereby the ecosystem evaporation is derived by scaling up the evaporation from individual trees, rather than by considering a homogeneous forest cover. Interception loss from isolated trees was estimated by combining the aforementioned equation for water vapour flux with Gash''s analytical model. A new methodology, which avoids the subjectivity inherent in the Leyton method, was used for estimating the crown storage capacity. Modelling performance was evaluated against data from two Mediterranean savanna-type oak woodlands (montados) in southern Portugal. Interception loss estimates were in good agreement with observations in both sites. The proposed modelling approach is physically based, requires only a limited amount of data and should be suitable for the modelling of interception loss in isolated trees and savanna-type ecosystems. [Copyright &y& Elsevier]