Precipitation Interception Research Articles

Simulating the Thermal Regime and Surface Energy Balance of a Permafrost‐Underlain Forest in Mongolia

AbstractForests overlap with large parts of the northern hemisphere permafrost area, and representing canopy processes is therefore crucial for simulating thermal and hydrological conditions in these regions. Forests impact permafrost through the modulation of radiative fluxes and exchange of turbulent fluxes, precipitation interception and regulation of transpiration. Forests also feature distinct soil layers of litter and organic matter, which play central roles for the infiltration and evaporation of water, while also providing thermal insulation for deeper ground layers. In this study, we present a new module within the CryoGrid community model to simulate forest ecosystems and their impact on the surface water and energy balance. The module includes a big‐leaf vegetation scheme with adaptations for canopy heat storage and transpiration. Furthermore, we account for the effect of surface litter layers on water and energy transfer. We show that the model is capable of simulating radiation, snow cover and ground temperatures below a deciduous needleleaf forest on a north‐facing slope in the Khentii Mountains in Central Mongolia. A sensitivity analysis of topographic aspect and ecosystem configuration confirms the important role of the litter layers for the energy and water balance of the ground. Furthermore, it suggests that the presence of permafrost is primarily linked to topographic aspect rather than the presence of forest at this site. The presented model scheme can be used to study the development of the ground thermal regime in forests, including the state of permafrost, under different climate, ecosystem, and land use scenarios.

Model simulation of vegetation canopy precipitation interception in grassland ecosystems on the northeast margin of the Qinghai-Tibet Plateau

Canopy interception plays a crucial role in eco-hydrological processes, and the development of spatiotemporal simulation models of canopy interception is essential for the study of this phenomenon. This study aims to fill the gap in the application of modeling to the study of canopy interception in grassland ecosystems. By using the A.P.J. DE ROO model and the RS-Gash model in conjunction with remote sensing data, we quantitatively simulate and analyze the interception capacity of the grassland vegetation canopy in the study area during the decade. Remote sensing data and measured data are used to assess the simulation accuracy of the models. The model with higher accuracy is used to analyze the spatiotemporal interception of the vegetation canopy in the study area. The results show that the vegetation canopy interception model can be applied not only to forest ecosystems but also to grassland ecosystems; the RS-Gash model has higher simulation accuracy than the A.P.J.DE ROO model; the two models show different simulation accuracy for different grassland types; the vegetation canopy interception rates of different grassland types are different, respectively: alpine meadows is 3.11 %, mountain meadows is 3.82 %, temperate grassland is 2.45 % and temperate desert grassland is 1.13 %; the ratio of vegetation canopy interception area at different levels is roughly low interception area: medium interception area: high interception area = 5:4:1. It can be seen that the application of mechanistic models combined with remote sensing data to simulate canopy interception in grassland ecosystems has great potential. Alpine meadows and mountain meadows are the main contributors to the interception of the grassland vegetation canopy in the study area.

The effects of leaf traits on litter rainfall interception with consequences for runoff and soil conservation

Abstract 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.

The deterioration and restoration of dried soil layers: New evidence from a precipitation manipulation experiment in an artificial forest

Ongoing climate change alters the amount and frequency of precipitation, deteriorating the water status of soils and the ecosystem services that they provide. The decline of soil water formed the dried soil layers (DSLs), which is particularly relevant for dryland ecosystems like the forests planted on the Chinese Loess Plateau (CLP), because there is an increased water demand for vegetation transpiration. To assess the impacts of precipitation changes on DSLs, we conducted a large throughfall manipulation experiment comprising seven precipitation gradients, ranging from 30%, 50%, and 65% precipitation interception treatments (PIT) to the ambient condition and then to 30%, 50% and 65% precipitation accession treatments (PAT), under a Robinia pseudoacacia planting forest on the CLP. We measured changes in soil water content (SWC) and examined the development of DSLs for over a year. We found that: (1) mean SWC in the 0–2100 cm soil profile and in DSLs decreased by 0.44%–0.77% and 0.13%–0.36% under the PIT, respectively, while increasing by 0.13%–0.36% and 0.16%–0.92% under the PAT, respectively; (2) DSLs were observed c. 100 cm and c. 100–180 cm below the soil surface under the PIT and PAT, respectively; (3) DSLs varied seasonally, with the largest reduction occurring during the transition period between the dry and rainy seasons, while the reduction developed more rapidly under the PAT than the PIT; (4) the incremental rate of SWC in DSLs increased linearly (p < 0.05) with increasing precipitation, while the increase was faster when precipitation was above (PAT) than below the ambient conditions (PIT), indicating greater precipitation sensitivity of DSLs under enriched than limited water supply. These changes in DSLs provide experimental evidence for the effects of climate change on soil water, and may have strong effect on the sustainable development management of drylands.

Modelling water/heat transfer and crop growth under film mulching condition in a seed–maize field

Film mulching has been widely applied in arid and semi–arid areas around the world. Current models simulating the process of water, heat, and crop growth generally neglect or simplify the role of film mulching in energy balance and water/heat exchange. In this study, CropSMPAC model was established based on previously developed model (CropSPAC, the soil water/heat transfer and crop growth model), by incorporating the influence of film mulching on energy budget and partition, sensible and latent heat fluxes of the soil surface, precipitation interception, and crop growth. The CropSMPAC model was calibrated and validated using experimental data from a seed–maize field located in arid Northwest China for the years 2017, 2018, and 2019. The experimental setup included two mulching treatments, i.e., full film mulching (M1) and no mulching (M0) along with three irrigation treatments, i.e., full irrigation (WF), medium irrigation (WM, 70%WF), low irrigation (WL, 40%WF). The results demonstrated that the model performed well in simulating the dynamics of field water, heat, and crop growth under various film mulching and irrigation conditions. The Nash-Sutcliffe efficiency coefficients for net radiation, soil heat flux, soil water storage (SWS), soil temperature (ST), leaf area index (LAI), aboveground dry biomass (ADB) were 0.57, 0.37, 0.79, 0.76, 0.95, 0.95, respectively. The relative errors for seed-maize yield, crop evapotranspiration (ET) were 9.38%, 9.10%, respectively. Furthermore, the model accurately reflected the differences in SWS and ST due to different mulching conditions (M1 and M0). The observed differences in SWS between M1 and M0 ranged from –30.6 to 32.9 mm, while the simulated differences ranged from –30.5 to 30.2 mm under various irrigation treatments. Similarly, the observed differences in ST between M1 and M0 were 1.8, 1.7, 1.0 and 1.4 °C at 10, 20, 40 and 80 cm soil depths, respectively, while the simulated differences were 2.3, 2.1, 1.7 and 0.8 °C under WF treatment. Additionally, the model effectively simulated the effects of film mulching on advancing the crop growth period and promoting LAI, ADB and yield. Overall, the model accurately captured the changes in energy fluxes, soil water, heat and crop growth caused by plastic film mulching, demonstrating that it is a useful tool for irrigation water management and crop production in crop land with film mulching.

The influence of vegetation on the microstructure and erosivity of precipitation

The process of precipitation interception, in which vegetation retains precipitation, has a major influence on natural processes such as soil erosion. Assessing this influence requires measurements of the microstructure of precipitation using modern instruments that allow measurements of the velocity, size, and number of raindrops. The precipitation microstructure data were obtained using 1-minute measurements from three optical disdrometers placed under the birch canopy, under the black pine canopy and above the canopies. In the period under consideration between 12 July 2022 and 16 February 2023, 48 rainfall events were recorded, for which the duration, the amount of precipitation, the average intensity of precipitation, and the characteristics of the raindrops (size, velocity, and number of drops) were calculated. Additionally, the kinetic energy (KE), the maximum 30-minute intensity (max I30), and the rainfall erosivity factor (R) were calculated. All these variables were calculated for measurements above and below the tree canopies. The results show that the proportion of intercepted precipitation decreases with the duration of the events for both birch and pine. Droplets increased on average during the leafed period, as they passed through the tree canopy, and decreased during the leafless period. During the entire period, the diameter of the droplets increased on average by 46% under birch and by 26% under black pine. The droplet velocity decreased on average by 38% under the pine, while it increased minimally under the birch by 1%, which is the result of an increase in the average velocity under the birch during the leafless period by 7%. The analysis of the results shows that the rainfall interception has a large impact on soil erosion, as, for example, the rainfall erosivity factor (R) under birch decreased by 43% and under pine by 90%.

Determination of the Leaf Inclination Angle (LIA) through Field and Remote Sensing Methods: Current Status and Future Prospects

The leaf inclination angle (LIA), defined as the leaf or needle inclination angle to the horizontal plane, is vital in radiative transfer, precipitation interception, evapotranspiration, photosynthesis, and hydrological processes. This paper reviews the field and remote sensing methods to determine LIA. In the field, LIA is determined using direct and indirect methods. The direct methods include direct contact, photographic, and light detection and ranging (LiDAR) methods, while the indirect methods are composed of the gap fraction, four-component, and polarization measurement methods. The direct methods can obtain LIA accurately at individual leaves, crown, and plot scales, whereas the indirect methods work well for crops at the plot level. The remote sensing methods to estimate LIA are mainly based on the empirical, radiative transfer model, and gap fraction methods. More advanced inversion strategies and validation studies are necessary to improve the robustness of LIA remote sensing estimation. In future studies, automated observation systems can be developed and the LIA measurement can be incorporated into existing ground observation networks to enhance spatial coverage.

Distinct Rainfall Interception Profiles among Four Common Pacific Northwest Tree Species

Forest tree canopies have a critical influence on water cycles through the interception of precipitation. Nevertheless, radial patterns of canopy interception may vary interspecifically. We analyzed canopy interception using catchments along radial transects underneath four common forest tree species (Acer macrophyllum, Alnus rubra, Pseudotsuga menziesii, and Thuja plicata) in the Pacific Northwest over two years. Near the center of the canopy in the leaf-off season, interception was 51.6%–67.2% in conifer species and only 20.1%–40.1% in broadleaf species, and interception declined to 19.9–29.9 for all species near the edge of the canopy. One deciduous species (A. rubra) showed spatially uniform interception during the leaf-off period (19.9%–20.96%), while another varied from 23.1%–40.1%. Patterns were more pronounced in the leaf-on period (under high vapor pressure deficit conditions), where conifers intercepted 36.5%–95.9% of precipitation, depending on the species and position under the canopy. Deciduous species similarly intercepted 42.1%–67.7% of rainfall, depending on species and canopy position. Total throughfall was curvilinearly related to the amount of rainfall near canopy centers for conifer trees but less so for deciduous trees. Soil moisture was predictably related to interception across and within species. These data highlight interspecific differences in radial interception patterns, with consequences for soil moisture, hydrologic processes, and ecosystem function.

Measuring turfgrass canopy interception and throughfall using co-located pluviometers.

Turfgrass management relies on frequent watering events from natural precipitation or irrigation. However, most irrigation scheduling strategies in turfgrass ignore the magnitude of canopy interception. Interception is the process by which precipitation or irrigation water is intercepted by and evaporated from plant canopies or plant residue. The objective of this study was to quantify the magnitude of precipitation interception and throughfall in ‘Meyer’ zoysiagrass (Zoysia japonica L.) and ‘007’ creeping bentgrass (Agrostis stolonifera L.). We used a new method consisting of co-located pluviometers with and without circular turfgrass patches to measure interception and throughfall. The resulting dataset includes 15 storms and 25 individual rainfall events ranging in precipitation totals from 0.3 mm to 42.4 mm throughout the research study. Throughfall amount resulted in a strong (r = 0.98) positive linear relationship with precipitation totals. On average, zoysiagrass and creeping bentgrass canopies intercepted a minimum of 4.4 mm before throughfall occurred. This indicates that, on average, no precipitation reaches the soil surface for precipitation events <4.4 mm. After the point of throughfall, 16% of each additional millimeter of precipitation or irrigation is lost due to interception. Nearly, 45% of the area of the contiguous U.S. could result in >50% of the annual precipitation being intercepted by canopies of zoysiagrass and bentgrass. This study provides detailed insights to understanding the interception dynamics in turfgrass and highlights the inefficient nature of small precipitation and irrigation events in turfgrass systems.

Spatiotemporal Variations in Vegetation Canopy Interception in China Based on a Revised Gash Model

Vegetation canopy interception (Ic) of precipitation is a considerable component of the global hydrological cycles. Although the measurement and modeling of canopy interception have been explored worldwide at the individual, stand or ecosystem scale, it is still unclear how to recognize this process at the regional or global scales within the context of global climate change. In this study, a revised Gash model was employed to estimate canopy interception based on remote sensing and meteorological data. The spatial and temporal variations in Ic were investigated and the main environmental factors were explored in China for the 2000–2018 period. The results showed that the revised Gash model performed well in modeling canopy interception at the regional scale compared with the PML_V2 dataset product and the in-situ measurements. The average annual Ic in China from 2000 to 2018 was 166.55 mm, with a significant decreasing spatial pattern from the Southeastern to the Northwestern regions. The ratio of canopy interception to precipitation (Ir) displayed a similar spatial pattern, with an average value of 22.30%. At the temporal scale, the mean annual Ic significantly increased at a rate of 1.79 mm yr−1 (p &lt; 0.01) during the study period, and the increasing trend was more pronounced during the 2000–2009 period, at a rate of 3.34 mm yr−1 (p &lt; 0.01). In most vegetation types, except for the deciduous broad-leaved forest and temperate desert, canopy interception showed a significant increasing trend (p &lt; 0.01). Precipitation, temperature, and the normalized differential vegetation index (NDVI) were considered to be the main factors affecting the variations of Ic in China during the last two decades, with specific dominant factors varying in different areas. Specifically, precipitation was considered to control the variations of Ic in the Northwestern regions, temperature mainly influenced the Southern regions, and the NDVI was identified as the main factor in regions where significant ecological conservation projects are established, such as the Loess Plateau. Our findings are expected to not only contribute to the understanding of regional ecohydrological cycle but also provide valuable insights into the methodology of interception modeling at the regional and global scales.

Canopy precipitation interception in a lowland tropical forest in relation to stand structure

It is generally accepted that vegetation provides important ecosystem services especially in term of rainfall partitioning. This study aims to evaluate the influence of canopy structure namely crown area (CA), diameter at breast height (DBH), tree height (TH) and crown spread (CS) and stand density on the partitioning of rainfall. Twelve throughfall plots of 20 x 20 m with 64 gauges randomly placed within each plot were established. For stemflow measurements, all trees within a 100 m2 plot within the study area were collared. Interception loss was computed as the difference between precipitation and throughfall plus stemflow. Throughfall ranged from 73.47 – 82.32 % of the gross rainfall. Stemflow was found to be roughly around 2.01% of the gross rainfall. Highest interception was 24.52 % attributed to the plot having the highest above ground biomass (AGB) density. The relation between canopy interception and forest structure were analyzed by regression method. Multiple regression analysis on the potential influence of stand structure to the throughfall percentage shows that all the forest structures variables measured in this study are negatively correlated to the amount of throughfall generated. This study suggests that forests with higher value of DBH, CA, CS and TH had higher interception rate.

Forest Fires, Land Use Changes and Their Impact on Hydrological Balance in Temperate Forests of Central Mexico

Temperate forests play a fundamental role in the provision, regulation, and support of hydrological environmental services, but they are subject to constant changes in land use (clearing, overgrazing, deforestation, and forest fires) that upset the hydrological balance. Through scenarios simulated with the Water Evaluation and Planning (WEAP) hydrological model, the present study analyzes the effects of forest fires and land use changes on the hydrological balance in the microwatersheds of central Mexico. The land use changes that took place between 1995 and 2021 were estimated, and projections based on the current scenario were made. Two trend scenarios were proposed for 2047: one with a positive trend (forest permanence) and the other with a negative trend (loss of cover from forest fires). The results show that with permanence or an increase in forest area, the surface runoff would decrease by 48.2%, increasing the base flow by 37% and the soil moisture by 2.3%. If forest is lost, surface runoff would increase up to 454%, and soil moisture would decrease by 27%. If the current forest decline trends continue, then there will be negative alterations in hydrological processes: a reduction in the interception of precipitation by the canopy and an increase in the velocity and flow of surface runoff, among others. The final result will be a lower amount of water being infiltrated into the soil and stored in the subsoil. The provision of hydrological environmental services depends on the maintenance of forest cover.

Interception and Redistribution of Precipitation by Parkinsonia aculeata L.: Implications for Palo Verde National Park Wetlands, Costa Rica

Seasonal wetlands in the tropics are important habitats for local and migratory bird species. In the northwestern Pacific of Costa Rica, Palo Verde National Park has one of the most important seasonal wetlands of Central America. The management history of this wetland has shown the impact of invasive plant species such as Parkinsonia aculeata L. whose cover extension and canopy structure impact not only the ecological niches of bird species, but also the wetland hydrology. A 300 m2 plot was established in a P. aculeata stand to evaluate the role of P. aculeata on the partitioning and redistribution of precipitation. Gross precipitation (PGr), throughfall (PTF) and stemflow (PSF) were measured on a daily basis to determine the interception of precipitation (PI) and net precipitation (PNet). A total of 43 precipitation events were sampled during the wet season of 2003. We measured 530.5 mm of PGr and 458 mm of PTF, with an average sampling error of 0.7 mm or 6.1%. Canopy storage capacity was estimated at 1.47 mm, throughfall 88.73%, stem flow 2.63% and a total interception of 8.64%, with a PNet coefficient of 0.9475. The relationships between gross precipitation (PGr) with throughfall (PTF), stemflow (PSF) and net precipitation (PNet) were evaluated using linear regression models. P. aculeata showed to have one of the highest net precipitation and lowest precipitation interception among small trees.

Impacts of forest biomass operations on forest hydrologic and soil erosion processes

The use of biomass from forests by humans has been practiced since the dawn of time. Such practices have resulted in severe watershed degradation historically and in today's world. As modern society seeks alternative energy sources, they are once again turning to forests, but now use mechanized harvesting systems to remove the biomass and transport it to processing or utilization sites. This study investigated the impacts of different mechanized biomass operations on sediment displacement, soil hydraulic conductivity, and canopy interception to determine if severe watershed impacts associated with biomass utilization in the northwest U.S.A. may occur as seen elsewhere. Three field sites were selected that used different biomass operation methods: the Payette National Forest (NF) in Idaho using a forwarder system, the Colville NF in Washington State using a tractor-skidder system, and the Flathead NF in Montana using a skyline system. A total of 47 silt fences (5 m × 10 m) were installed to monitor soil movement from biomass operations: 28 silt fences on disturbed plots and 19 on control plots. No soil loss was observed except on the forwarder trails in the Payette NF where animal disturbances were responsible for some soil movement into the silt fences. Infiltration rates measured using a constant head permeameter showed that the saturated hydraulic conductivity on the disturbed plots for the ground-based operations was lower than the control plots, but unlikely to cause significant changes in runoff on any of the plots except the Payette forwarder trails, where the saturated hydraulic conductivity values averaged only 5.3 mm h−1, compared to greater than 20 mm h−1 on all other observations. Ground cover increased on the disturbed plots to levels observed on undisturbed plots within two years. The only significant increase in bulk density was observed on the forwarder trails at the Payette NF site where the density averaged 1.41 on the trails, compared to the densities of 1.0 elsewhere. The loss of canopy observed on the three biomass studies led to a complementary study on the effects of canopy loss on snow accumulation and melt on the Priest River Experimental Forest in Northern Idaho. The study found that the canopy only intercepted an average of 7 mm of snow water equivalent during three winter months, but average annual interception of precipitation was 114 mm, indicating that interception of rainfall is greater than snow. Overall, these results suggest that there were no direct detrimental hydrologic impacts due to biomass operations except on the compacted, and sometimes pulverized forwarder trail conditions observed in the Payette NF. The impact of the canopy on rainfall interception is less than the water yield differences due to clear cutting on nearby forested watersheds that were attributed to differences in evapotranspiration.

Revisit the Performance of MODIS and VIIRS Leaf Area Index Products from the Perspective of Time-Series Stability

As an essential vegetation structural parameter, Leaf Area Index (LAI) is involved in many critical biochemical processes such as photosynthesis, respiration, and precipitation interception. The MODerate resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imager Radiometer Suite (VIIRS) LAI sequence products have long supported various global climate, biogeochemistry, and energy flux research. These applications all rely on the accuracy of the product's long time series. However, uncontrolled interferences (e.g., adverse observation conditions and sensor uncertainties) potentially introduce substantial uncertainties to time series in product applications. As one of the most sensitive areas in response to global climate change, the Tibet Plateau (TP) has been treated as a crucial testing ground for thousands of studies on vegetation. To ensure the credibility of the studies arising from MODIS/VIIRS LAI products, the temporal quality uncertainties of data need to be clarified. This paper proposed a method to revisit the temporal stability of the MODIS (MOD and MYD) and VIIRS (VNP) LAI in the TP, expecting to provide useful information for better accounting for the uncertainties in this area. Results show that the MODIS and VIIRS LAI were relatively stable in time series and available to be used continuously, among which the temporal quality of the MODIS LAI was the most stable. Moreover, the MODIS and VIIRS LAI products performed similarly in both time-series stability and time-series anomaly distribution, magnitudes and fluctuations. The time-series stability evaluation strategy applied to the MODIS and VIIRS LAI can also be employed to other remote sensing products.

Vegetation structure controls on snow and soil moisture in restored ponderosa pine forests

AbstractThinning of semi‐arid forests to reduce wildfire risk is believed to improve forest health by increasing soil moisture. Increased snowpack, reduced transpiration and reduced rainfall interception are frequently cited mechanisms by which reduced canopy density may increase soil moisture. However, the relative importance of these factors has not been rigorously evaluated in field studies. We measured snow depth, snow water equivalent (SWE) and the spatial and temporal variation in soil moisture at four experimental paired treatment‐control thinning sites in high elevation ponderosa pine forest northern Arizona, USA. We compared snow and soil moisture measurements with forest structure metrics derived from aerial imagery and 3‐dimensional lidar data to determine the relationship between vegetation structure, snow and soil moisture throughout the annual hydrologic cycle. Soil moisture was consistently and significantly higher in thinned forest plots, even though the treatments were performed 8–11 years before this study. However, we did not find evidence that SWE was higher in thinned forests across a range of snow conditions. Regression tree analysis of soil moisture and vegetation structure data provided some evidence that localized differences in transpiration and interception of precipitation influence the spatial pattern of soil moisture at points in the annual hydrologic cycle when the system is becoming increasingly water limited. However, vegetation structure explained a relatively low amount of the spatial variance (R2 &lt; 0.23) in soil moisture. Continuous measurements of soil moisture in depth profiles showed stronger attenuation of soil moisture peaks in thinned sites, suggesting differences in infiltration dynamics may explain the difference in soil moisture between treatments as opposed to overlying vegetation alone. Our results show limited support for commonly cited relationships between vegetation structure, snow and soil moisture and indicate that future research is needed to understand how reduction in tree density alters soil hydraulic properties.

Simulations of Water and Thermal Dynamics for Soil Surfaces With Residue Mulch and Surface Runoff

AbstractWater and thermal dynamics at soil surfaces are influenced by multiple ambient factors, for example, weather, soil, residue mulch, and surface runoff. A surface water and temperature model should address those ambient factors, and their interactions and derivatives. In this study, we developed a process‐based simulation model for surface water and heat transfer with two main ambient factors, residue mulch and surface runoff. Surface water content and temperature are simulated with a modified Philip and de Vries (1957) model, including precipitation interception and radiation attenuation in residue mulch. Surface runoff is modeled with the Saint‐Venant equation. Residue decomposition, as a derivative, is computed via a modified CERES‐N model. Interactions between surface runoff and residue mulch, and dynamic decreases in residue mulch thickness due to decomposition are also included. The model was modularized and deployed with a “layered module architecture” in MAIZSIM, such that the main ambient factors, interactions, and derivatives can be activated or deactivated based on scenarios or user settings. Illustrative examples include non‐decomposable residue mulch, surface runoff and mulch decomposition scenarios. Results demonstrate that residue mulch can conserve soil water and reduce temporal variations of surface temperature. Surface runoff and its effects on water infiltration and surface temperature, and nitrogen mineralization during decomposition are also illustrated. The simulated surface temperature, water content, and mulch decomposition results are similar to literature results from field experiments. This study demonstrates the model workability in simulating surface water and temperature dynamics, and the feasibility of synthesizing multiple factors via a modularized model architecture.

Assessment of irrecoverable retention of liquid atmospheric precipitation by meadow grass stands of the Middle Urals

The process of retaining precipitation by grass vegetation is important in the processes of moisture circulation in forest landscapes. At the same time, there is an erroneous opinion that grasses are not able to retain a significant amount of rain moisture, which further forms the river flow. For this reason, the question remains poorly understood. In turn, grass stands are able to retain rainfall on their leaves in whole or in part. It depends on the duration and intensity of the rain. The leaves of grass stands have a specific morphology and are arranged more vertically than the leaves of woody plants; therefore, moisture on the leaves of grasses is held in film and drip forms (in woody plants-only in drip). When droplets roll down the stem, water is trapped in bowl-shaped recesses or funnels of grass leaves. The article discusses the relationship of precipitation and vegetation. The authors conducted field experiments on the retention of rainfall by grasses that grow in the landscapes of the Middle Urals. The experiments consisted of artificial sprinkling of grass samples and their subsequent weighing (weight experiments). In the course of the experiments, the connections were developed for the retention capacity of rain deposited on the leaves of species of grass vegetation with the leaf surface area of grass stands and their green mass. The magnitude of the loss of rainfall on grass stands is comparable with the magnitude of the rainfall of individual rains. According to the results of the experiment, it was found that under the forest canopy, the interception of precipitation is 0.1–0.2 mm, in the clearings – 1–2 mm, in the clearings – 2–4 mm. The results can be used to assess the actual rainfall to the surface of the soil and to calculate the change in the discharge of water from rain floods on rivers as a result of forest successions.

Localized Augmentation of Net Precipitation to Shrubs: A Case Study of Stemflow Funneling to Hummocks in a Salinity-Intruded Swamp

The interception of precipitation by plant canopies can alter the amount and spatial distribution of water inputs to ecosystems. We asked whether canopy interception could locally augment water inputs to shrubs by their crowns funneling (freshwater) precipitation as stemflow to their bases, in a wetland where relict overstory trees are dying and persisting shrubs only grow on small hummocks that sit above mesohaline floodwaters. Precipitation, throughfall, and stemflow were measured across 69 events over a 15-months period in a salinity-degraded freshwater swamp in coastal South Carolina, United States. Evaporation of intercepted water from the overstory and shrub canopies reduced net precipitation (stemflow plus throughfall) across the site to 91% of gross (open) precipitation amounts. However, interception by the shrub layer resulted in increased routing of precipitation down the shrub stems to hummocks – this stemflow yielded depths that were over 14 times larger than that of gross precipitation across an area equal to the shrub stem cross-sectional areas. Through dimensional analysis, we inferred that stemflow resulted in local augmentation of net precipitation, with effective precipitation inputs to hummocks equaling 100–135% of gross precipitation. Given that these shrubs (wax myrtle, Morella cerifera) are sensitive to mesohaline salinities, our novel findings prompt the hypothesis that stemflow funneling is an ecophysiologically important mechanism that increases freshwater availability and facilitates shrub persistence in this otherwise stressful environment.

Interception and runoff of the high Andean forest in the “El Malmo” Protective Forest Reserve

Tropical forests are globally important for their biodiversity and the ecosystem services, and they are key to the global water cycle. Anthropogenic changes and pressures affecting tropical forests affect the fundamental role of tropical forests in water supply. This study evaluates the relationship between the vegetation coverage in the high Andean forest of the “El Malmo” Protected Forest Reserve and the quality and quantity of intercepted runoff; the life zone analyzed comprises four types of cover: dense high Andean forest, low secondary vegetation, broadleaf plantation and mosaic of pasture with natural spaces. Eight setups (two per cover) were installed, each composed of a runoff plot and a precipitation meter under the canopy; data collection was carried out every eight days for 24 weeks. The results indicate that precipitation interception does not vary in each canopy, while surface runoff and its quality with respect to sediment are affected, which is mainly due to differences in soil physical conditions. The cover that allows the best dimensions of water quality and quantity is the dense high Andean forest. The influence of anthropic intervention in the area and the presence of invasive species negatively affect these variables. This work provides knowledge on the hydrological behavior of the reserve for forest management. It also generates information on the interception/runoff relationship in the forests of the Cundiboyacense region, which has not been available until now, becoming an starting point of comparison for further research in high Andean ecosystems.