PICO
Global change and anthropogenic intervention are putting enormous pressure on forests, affecting the ecosystem services they provide through water quantity and quality, and biogeochemical cycles. The conventional wisdom that forest hydrology emphasizes the role of forests and forest management practices on runoff generation and water quality has expanded in light of rapid global change.
Improving our understanding of how forest-water interactions are shaped by physiographic, biogeochemical and hydrometeorological factors and how forested catchments respond to dynamic environmental conditions and disturbances, is critical for protecting and managing our forest ecosystems. Building this knowledge requires interdisciplinary approaches in combination with new monitoring methods and modeling efforts.
This session brings together studies that aim to improve our understanding of water-forest dynamics and stimulate discussion on the impact of global change on hydrological processes in forest ecosystems at different scales.
We invite field experimentalists and modelers working in forests from boreal to tropical regions to submit contributions that:
1) Improve our understanding of forest (eco)hydrological processes using an experimental or modeling approach or a combination of both;
2) Assess the hydrology-related impacts of land use/cover change and environmental disturbances on forested ecosystems;
3) Feature innovative methods and observational techniques, such as optical sensors, tracer-based experiments, monitoring networks, citizen science, and drones, that reveal new insights or data sources in forest hydrology;
4) Include interdisciplinary research that supports consideration of overlooked soil-plant-atmosphere components in hydrological studies.
Globally, many mountain catchments transition from snow-dominated to rain-dominated behavior, which raises the question on how drought and wildfire regimes may be altered by these shifts. In 2023, the Lookout Fire burnt about two thirds of the H. J. Andrews Experimental Forest (HJA) in the Oregon Cascades and motivated a range of hydrological studies. Here, we evaluate how future changes to temperature and precipitation patterns, especially shifts from snow to rain, alter hydrological storages and fluxes across (nested) sub-catchments of the HJA.
To evaluate this, we rely on the conceptual hydrological model HBV-light and regional climate projections. We analyzed five catchments within HJA with differences in elevation. Hydrological changes were simulated under RCP 4.5 and RCP 8.5 emission scenarios for the near future (2021–2050) and far future (2071–2100) and compared against observations. Projections for 2071–2100 under RCP 8.5 indicate a strong temperature increase, resulting in a near-total loss (98–100%) of maximum snow water equivalent (SWE) in the study catchments. While winter precipitation is projected to increase by 30%, summer precipitation will decrease by up to 34%. This seasonal redistribution leads to significantly higher winter runoff but exacerbates summer deficits in soil moisture, groundwater, and streamflow.
These changes pose two interconnected challenges for mountain catchments. First, the pronounced shift toward earlier snowmelt and increased winter runoff substantially reduces streamflow and hydrological storages in summer, advancing the onset and prolonging the duration of seasonal dryness. Second, the earlier depletion of soil moisture and groundwater amplifies the spatial and temporal extent of high forest fire risk, enabling fires to occur earlier in the year, to affect larger areas, and to spread into or to start more likely at higher elevations. These patterns are consistent with recent observations of earlier wildfire occurrence and larger burnt areas in the Pacific Northwest. Our findings highlight that snow-to-rain transitions fundamentally alter water availability and disturbance by wildfire in mountain catchments, with implications that likely extend to many temperate mountain regions worldwide.
How to cite: Klaus, J., Kupfer, H. L., Klein, L., and Segura, C.: From Snow to Rain: Declining Snowpack, Earlier Dryness, and Changes to Fire Risk in the Oregon Cascades, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6795, https://doi.org/10.5194/egusphere-egu26-6795, 2026.
Understanding the relationship between forest cover and hydrological processes is challenging due to the high temporal variability of water cycles and their interactions with both land-use and land-change activities. In tropical headwater catchments, rapid responses to intense rainfall events often occur at sub-daily scales, where concentration times are frequently shorter than 24 hours. These event-scale dynamics are particularly sensitive to land cover and forest management, which can strongly modulate runoff generation, storage, and flow timing in headwater catchments. However, hydrological catchments response is commonly analyzed using daily or longer-term aggregated data, potentially obscuring key processes controlling event runoff generation and its timing.
Here we investigate the impact of different forest management strategies on rainfall-runoff event dynamics in five tropical catchments (56–179 ha) located in São Paulo, Brazil. The study area, situated in a transition zone between the Cerrado and Atlantic Forest biomes, comprises catchments with contrasting land uses: actively restored forest (8 years), native vegetation regeneration (more than 13 years), commercial Eucalyptus plantations with short and long cutting cycles (7 and 14 years, respectively), and a mixed forest mosaic with management interventions in small areas (more than 20 years). We use an objective method for identification on discrete rainfall-runoff events based on detrending moving-average cross-correlation analysis (Giani et al., 2022) from continuous hydrometeorological time series of hourly and sub-hourly temporal resolution. A total of three years of monitoring data (2022–2025), covering contrasting wet and dry years, are analyzed, identifying and characterizing each discrete event by its event runoff coefficient, rise time, time scale, and normalized peak discharge. Given their variability dependence on antecedent wetness conditions, events are grouped by season (wet and dry) for each catchment. For each season, median values of event characteristics are calculated over the three-year period and compared across catchments to assess the effects of different forest management strategies on event-scale runoff response.
The results of this study will contribute to the understanding of how land-use changes in tropical regions, whether for commercial or conservation purposes, affect both hydrological processes and functions, and ecosystem services at the headwater scale.
Giani, G., Tarasova, L., Woods, R. A., & Rico-Ramirez, M. A. (2022). An Objective Time-Series-Analysis Method for Rainfall-Runoff Event Identification. Water Resources Research, 58(2), e2021WR031283. https://doi.org/10.1029/2021WR031283
How to cite: Foronda Ortega, N., Frosini de Barros Ferraz, S., and Tarasova, L.: Sub-daily rainfall-runoff dynamics in tropical headwater catchments under different forest management: insights from Brazil, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13668, https://doi.org/10.5194/egusphere-egu26-13668, 2026.
Forests regulate water through coupled ecohydrological processes interlinking land, water and climate. The hydrological response of a region, although driven by climate, is a function of intrinsic watershed properties determined by corresponding land use land cover (LULC) patterns, soil characteristics and topography. The increasing anthropogenic pressure on water resources, exacerbated by climate change and forest land use conversion threatens global and regional water security and availability. Understanding the water balance in forested watersheds using physical models that simulate hydrological responses under different land use types would enable evidence-based decision-making for tropical regions in the Global South. Therefore, this study explores the influence of LULC on streamflow and water balance components to examine differences in water regulation across two watersheds with varying forest density, cover and type. The process based, semi-distributed SWAT+ hydrological model was used for quantification and assessment of key water balance components including precipitation, actual evapotranspiration, surface runoff, lateral flow and percolation for Dindori and Barwani watersheds of Narmada River basin, India. Water balance of the Barwani (1999 to 2006) and Dindori watershed (1989 to 2009) was simulated using earth observation data and calibrated with station datasets. Both watersheds demonstrated satisfactory performance in water balance simulation after calibration. Dindori watershed (higher forest cover and located in the upper catchment area of Narmada River) display greater water regulation through sustained streamflow in dry periods, better percolation and water retention in sub-surface soils as well as recharge deep aquifers when compared to Barwani (lower forest cover and a greater percentage of degraded lands) wherein a greater proportion of water is lost to the atmosphere through ET. The comparative assessment shows how forest cover modulates hydrological partitioning and enhances water resilience in tropical catchments. Integrating process-based, physical models with earth observation data, the study attempts to understand the forest-water dynamics in non-glacial, data-limited river basins and highlights the importance of conserving forested upper catchments for sustaining downstream water availability under changing land-use and climatic variability.
How to cite: Srikar, R., Singh, M., Sinha, B., Bisaria, J., and Thomas, T.: Forested Watersheds and Water Regulation: A Comparative Assessment of Water Balance Using SWAT+, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20676, https://doi.org/10.5194/egusphere-egu26-20676, 2026.
In Japan, plantation forests have accumulated substantial timber resources; however, fragmented ownership and declining timber prices have resulted in management shortfalls.
Kumamoto Prefecture has enacted an ordinance requiring permit holders in designated priority areas to implement groundwater recharge equivalent to their extraction volume (in principle, 100%) to ensure sustainable groundwater use. If increases in water resources resulting from forest thinning can be scientifically quantified, this ordinance could provide an incentive for forest management under this framework. Currently, groundwater recharge is estimated using a simple coefficient-based formula, and quantitative evaluation remains limited.
Forest water-balance studies have extensively examined canopy interception and tree transpiration; however, knowledge of forest floor evaporation remains limited, despite its importance for accurately assessing changes following thinning. Lysimeters provide high-accuracy measurements of forest floor evaporation but are difficult to operate unattended over long periods. Soil-moisture sensors allow stable continuous measurements but have limited spatial representativeness. In contrast, the eddy covariance method enables non-destructive, wide-area flux observation. While eddy covariance studies have recently been conducted in forests with low tree density, applications in dense forests remain scarce. This study aims to develop a simplified measurement approach and an estimation model for forest floor evaporation to improve water-balance evaluation in managed forests.
Field experiments were conducted during summer (June 28–September 30) in Japanese cypress plantations with stand densities of 454, 927, and 1268 trees ha⁻¹. Forest floor evaporation was measured using lysimeters and an LI-710 evapotranspiration sensor based on a simplified eddy covariance approach. As a simplified method, soil-moisture sensors were installed at depths of 5, 10, and 15 cm. Hourly evaporation rates were derived from each dataset, evaporation between rainfall events was compared, and an estimation model was examined using the measurements together with forest microclimate data.
Across observation periods, forest floor evaporation showed broadly similar temporal patterns among lysimeter, soil-moisture-derived, and simplified eddy-covariance estimates. This consistency suggests that forest floor evaporation can be reasonably represented using simplified measurements under different forest management conditions. Although seasonal variability was not assessed, the results indicate the applicability of sensor-based estimation methods and their usefulness for improving water-balance evaluation related to groundwater recharge in managed forests.
How to cite: Yamaguchi, T., Okubo, T., Nakagawa, K., Yamada, Y., Hashimoto, A., and Onda, Y.: Linking forest management to groundwater recharge: modeling forest floor evaporation in plantation forests, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12799, https://doi.org/10.5194/egusphere-egu26-12799, 2026.
Evapotranspiration (ET) is a key component of forest ecohydrological functioning and land–atmosphere coupling in tropical regions. In fragmented landscapes, forest edges may strongly influence the spatial variability of ET and microclimate, yet this aspect remains insufficiently studied. Here, we examine wet-season ET patterns across 83 forest fragments in western Ecuador using ECOSTRESS satellite observations. A changepoint analysis showed that the frequency of ET shifts increased toward fragment edges, with 61% of cases displaying higher ET near edges. A random forest model with target-oriented cross-validation achieved a spatial prediction accuracy of 64%, identifying elevation, aridity, and distance to edge as the most important predictors. SHAP analysis further emphasized the role of edge effects, revealing greater ET rates near edges, particularly at mid-elevations and in areas with high canopy cover. These patterns likely arise from a combination of climatic conditions, forest structure, edge orientation, and surrounding land-use types in this human-modified landscape. The high spatial variability observed at edges underscores the need to better integrate edge processes into forest hydrology and land–atmosphere models. Our findings suggest that forest edges can locally enhance ET under wet conditions, thereby contributing to microclimatic and hydroclimatic regulation. While this does not substitute for the broader climate function of intact, continuous forest, small remnant fragments may still play a meaningful role in sustaining local hydrological processes in fragmented tropical landscapes.
How to cite: Valdés-Uribe, A. and Hölscher, D.: Edge effects on evapotranspiration from tropical forest fragments , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2725, https://doi.org/10.5194/egusphere-egu26-2725, 2026.
Forest ecosystems are increasingly exposed to climate-driven shifts in water availability, yet the underlying changes in evapotranspiration (ET) processes remain poorly quantified at landscape scale. Building on a recently established operational soil-moisture monitoring framework for Central German forests (https://life.hydro.tu-dresden.de/BoFeAm/dist_bfa/index.html), we combine long-term observations and climate projections with process-based modeling to examine how climate change affects both the magnitude and the component structure of actual ET. Using the LWF-BROOK90 model, we quantify transpiration, rain and snow interception evaporation, and soil and snowpack evaporation across more than 3,000 forest sites in Central Germany. The model was driven by homogenized historical climate data (1961–2020) and an ensemble of 21 CMIP5 regional climate projections (2021–2100), covering major Central European tree species: Norway spruce (Picea abies), Scots pine (Pinus sylvestris), European beech (Fagus sylvatica), and pedunculate oak (Quercus robur).
Our results show a clear seasonal redistribution and shift of the forest water balance. Springs are projected to become wetter and more evaporative, supporting increased early-season transpiration. In contrast, summers exhibit strong declines in precipitation and reduced ET, accompanied by a substantial rise in soil-moisture stress days (REW < 0.4), particularly in upland conifer forests. Annual ET increases slightly due to higher winter rain interception, driven by a shift from snowfall to rainfall, most notably in Norway spruce. However, these annual increases hide growing summer water limitations, as higher evaporative demand exceeds declining soil-water supply.
By resolving individual ET components, this study highlights how changing climatic conditions propagate through canopy processes, soil moisture dynamics, and species-specific water use. The findings support assessments of forest resilience, help identify drought-tolerant species, and inform expectations of ecohydrological feedbacks in temperate agroforestry landscapes. Looking ahead, our combined monitoring–modeling framework is transferable to other regions where long-term climate data and stand-level information on vegetation and soils are available, supporting improved characterization of water and carbon cycle responses under future climate conditions.
How to cite: Luong, T. T., Vorobevskii, I., Kronenberg, R., and Mauder, M.: Seasonal redistribution of Forest Evapotranspiration Under Climate Change in Central Germany, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-392, https://doi.org/10.5194/egusphere-egu26-392, 2026.
Conventional models of plant-water relations prioritize climatic and edaphic factors, largely overlooking the foundational role of bedrock. In water-limited karst ecosystems, where soil is thin and hydrology is fracture-controlled, the lithological template may critically govern vegetation function. This study tests the hypothesis that bedrock composition—specifically, the contrast between dolomite and limestone—creates distinct hydrological niches that filter for divergent plant functional strategies, thereby determining ecosystem vulnerability. We conducted a monthly trait-based analysis of 13 dominant woody species across paired dolomite and limestone terrains in Southwest China. We integrated measurements of water-source use (xylem δD and δ¹⁸O) with key leaf economic traits (water content, area, specific area, chlorophyll). We found that dolomite-supported plants exhibit a consistent water-conservative syndrome: significantly lower leaf water content, smaller leaf area, lower specific leaf area, and reduced chlorophyll (P < 0.01). Isotopic data revealed that dolomite plants underwent pronounced seasonal shifts in water acquisition, indicative of reliance on fleeting, shallow moisture pockets. In stark contrast, limestone-supported plants maintained more stable trait values and exploited a more reliable water source, likely from deeper, rock-hosted reservoirs. This fundamental divergence demonstrates that bedrock lithology is a primary selective force, engineering plant hydraulic strategies at the community level. Consequently, dolomite landscapes foster inherently less resilient communities more vulnerable to climatic extremes, while limestone systems support greater hydrological buffering capacity. Our findings establish a bedrock-centric framework for plant hydrology, with urgent implications for predicting climate change impacts and guiding conservation in karst regions and other bedrock-dominated ecosystems worldwide.
How to cite: Ding, Y., Nie, Y., Chen, H., and Zhou, J.: Bedrock lithology dictates plant water-use niches in Karst ecosystems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18934, https://doi.org/10.5194/egusphere-egu26-18934, 2026.
Soil moisture (SM) in the topsoil horizon is a key variable in terrestrial ecosystems, regulating water and energy exchange at the interface between the soil and the atmosphere. In forest ecosystems, SM exhibits pronounced spatio-temporal variability within the active root zone as a result of complex interactions among multiple factors including soil properties, topography, climate and vegetation. Formulating broadly reliable statements about spatio-temporal soil moisture characteristics and its effects remains challenging. Existing research is limited and sometimes contradictory regarding when and to what extent controls such as tree species influence topsoil SM variability across space and time.
This study investigates spatio-temporal dynamics of topsoil SM and their controls in different forest ecosystems. The objectives are to quantify the spatial variability at the plot scale and its temporal evolution from event to seasonal scale, thereby improving our understanding of SM dynamics between wet and dry states and across different mono- and mixed-species forest stands. We investigate the variables governing spatial soil moisture variability and how they modulate SM patterns over time, with a focus on how ecohydrological processes amplify or mitigate SM variability.
SM was recorded in four stands in the ECOSENSE forest in southwestern Germany, using 400 time domain transmissometry sensors (SMT100, Truebner GmbH, Germany) installed at 12 cm depth in a tree-centered design across stands of mixed and pure Douglas fir, Beech and Silver fir. A continuous 2.5-year dataset (2023 – 2025) was analysed using statistical and geostatistical approaches to identify dominating spatial SM patterns during wet and dry periods. Temporal stability was evaluated to determine the pattern persistence. Spatial SM differed significantly among plots during most of the observation period. Mean SM followed a similar annual cycle throughout all plots, with typical maxima in late winter and minima in early fall. Despite comparable soil properties and topography, the pure Beech and Douglas fir plots revealed significant seasonal differences in mean SM. Beech has more prominent autumn wetting, while Douglas fir has stronger spring drying, likely reflecting changes in evapotranspiration dynamics. The individual probability density functions of spatial soil moisture distribution transitioned between wet- or dry-preferential unimodal states and intermediate bimodal states. Across plots, spatial mean SM and the coefficient of variation exhibited an upward-convex relationship: variability was low under dry and wet (<10% or > 30% mean SM) and high under intermediate moisture conditions. The geostatistical variogram analyses showed short autocorrelation lengths, and pronounced spatial variability at few meters’ distance. Temporal stability of SM varied across plots with a range of persistently wet and dry spots. Individual locations deviated by up to 50% from temporally averaged SM at the Beech, Douglas fir and mixed plot, and up to 75% for the Silver fir plot.
Combined with LiDAR derived canopy structure metrics, micro topographic maps, soil properties, and continuous ecohydrological- and meteorological observation, the presented soil moisture dataset provides a unique framework to investigate jointly modulating factors of soil moisture. It enables detailed analysis of wetting-drying cycles, including seasonal and species-specific differences.
How to cite: Dedden, L., Brzozon, J., Dumberger, S., Gassilloud, M., Göritz, A., Sulzer, M., Werner, C., and Weiler, M.: Spatio-temporal dynamics of topsoil moisture and the influence of tree species on pattern persistence, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16476, https://doi.org/10.5194/egusphere-egu26-16476, 2026.
Forests regulate hydrological processes and support water resources through rainfall partitioning and evapotranspiration, forming the basis of forest water balance. Previous studies have shown that thinning alters stand structure and affects throughfall, forest floor evaporation, and tree transpiration. However, quantifying individual components of the forest water balance within a stand typically requires multiple measurement systems operating simultaneously, making observations technically demanding and labor-intensive. As a result, systematic assessments of water balance responses to forest management remain limited.
In this study, we evaluated the applicability of a soil moisture balance approach for event-scale estimation of forest water balance components using a single soil moisture time series. Field observations were conducted in a Japanese cedar (Cryptomeria japonica) plantation subjected to row thinning. Multi-depth soil moisture sensors were installed at 20 locations in both thinned and control plots at depths of 5, 15, 25, 35, and 45 cm. In addition, two weighing lysimeters equipped with soil moisture sensors were installed in the thinned plot to directly measure soil water dynamics and forest floor evaporation.
During rainfall events, throughfall was estimated from increases in soil moisture within the 0–50 cm soil layer. The estimated throughfall showed excellent agreement with rain gauge measurements. Moreover, its spatial variability successfully reproduced increasing interception associated with canopy volume derived from LiDAR point cloud data. Forest floor evaporation was quantified during rain-free periods using changes in lysimeter weight and soil moisture depletion within the 0–20 cm layer. Tree water uptake was then estimated as the residual of soil moisture decreases in the 0–50 cm layer after accounting for forest floor evaporation, using an empirical relationship between radiation and forest floor evaporation.
The results revealed clear spatial contrasts in evapotranspiration components within the thinned stand: forest floor evaporation dominated in the center of thinning rows, while tree water uptake was more pronounced near tree stems. These findings demonstrate that the soil moisture balance approach enables separation and quantitative evaluation of forest water balance components at the event scale without reliance on large or complex measurement systems. This method provides a scalable and efficient framework for assessing hydrological impacts of forest management and offers valuable insights for sustainable forest and water resource management.
How to cite: Onda, Y., Iwamoto, J., Takahashi, J., Uehara, Y., Nakamura, H., Hashimoto, A., Takamura, S., and Yoshimura, K.: Event-Scale Responses of Forest Water Balance Components to Thinning Revealed by Soil Moisture Dynamics, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17010, https://doi.org/10.5194/egusphere-egu26-17010, 2026.
Gross primary production (GPP) constitutes a fundamental component of terrestrial carbon sequestration, underpinning climate equilibrium and the provision of ecosystem services. Among various environmental factors influencing GPP, soil moisture (SM) is critical for the regulation of stomatal conductance and photosynthetic processes. In light of climate change and intensive land use, understanding the impact of soil moisture on plant productivity across diverse Brazilian biomes and ecosystems is of strategic significance. This study conducts a distributed analysis examining the relationship between soil moisture and GPP within six major Brazilian biomes: Amazon, Cerrado, Caatinga, Atlantic Forest, Pampa, and Pantanal. The methodology integrates spatio-temporal remote sensing and reanalysis data for GPP and soil moisture to generate response curves of GPP to soil moisture variations. Random sampling points were established throughout all Brazilian biomes, with GPP and SM time series extracted from the FLUXCOM-X and ERA5 datasets, respectively. Daily means for both variables were calculated for the observational period, and results were evaluated via biome-specific scatter plots. The analysis enabled the identification of areas susceptible to water stress as well as those with acclimatization potential, thereby informing improvements in climate modeling and land use strategies. Distinct patterns emerged among the Brazilian biomes; most exhibited a positive correlation between GPP and SM, except for the Pampa biome in southern Brazil, which is predominantly characterized by open fields and grasslands. Notably, the Amazon and Cerrado displayed contrasting hysteresis patterns in the GPP-SM relationship over the years. In the Amazon, GPP increases during spring and summer at a greater rate than its decline during fall and winter, whereas in the Cerrado, the increase in GPP is more gradual during spring and summer and declines more sharply in fall and winter. Consequently, seasonal responses to water availability vary significantly among the principal Brazilian biomes.
How to cite: Ayach Anache, J. A., Okai, B. E., Hernández Sánchez, M., de Mello Martins Rocco, P., Almeida Dutra Júnior, S., Jardim Machado, L., de Sousa Pantarotto, H., Mendiondo, E. M., Wendland, E., and Simões Ballarin, A.: Water and Carbon feedbacks: How Soil Moisture dynamics shape Gross Primary Productivity across Brazil's contrasting Biomes?, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15818, https://doi.org/10.5194/egusphere-egu26-15818, 2026.
Deadwood is a substantial part of a healthy forest ecosystem. Natural disturbances such as windthrow can generate large amounts of deadwood and alter forest structure, with cascading effects on ecosystem processes. To study the effect of its biological legacies on soil water retention and the microclimate is of particular interest to support future guidelines and decisions for management (forest regeneration, potential fuel load and fire susceptibility) in post-disturbance scenarios. This also includes an improved understanding of the water storage capacities and responses to precipitation of deadwood across different decay stages. Additionally, deadwood mitigates natural hazards by modulating soil water storage, thereby influencing runoff and flood peaks. Post-disturbance roughness from logs, litter, and root mats can curb erosion, shallow landslides, rockfall, and avalanches; quantifying these effects is key for integrated hazard protection.
In this case study, we take advantage of three adjacent sites (all within a radius of 1 km), ensuring comparable stand history and climatic conditions. The sites include a cleared windthrow area; a windthrow area with unaltered deadwood cover; and an intact mature forest stand. We continuously monitor soil water content across all sites, and additionally measure the water content of a representative log within the uncleared windthrow area. Using TDR sensors (Teros 10, METER Group, Pullman, WA, USA), we track long-term volumetric water content in both soil and deadwood. Soil moisture is measured at one profile per site at 10, 20, and 50 cm depth. To capture spatial variability, two additional TDR sensors were installed near each soil profile at 10 cm depth, complemented by four independently operating TDT sensors (TMS cable, TOMST s.r.o., Prague, Czech Republic) placed at greater distances. To improve the accuracy of deadwood measurements, we established a specific calibration for different decay classes. Precipitation and air temperature are recorded by a stationary weather station located in the cleared windthrow area. High-resolution UAV LiDAR flights provide the basis for analyzing the influence of micro-topography and surface roughness on water storage and deadwood volume along the slope.
How to cite: Richter, P., Behringer, M., Scheidl, C., Kitzler, B., Baggio, T., and Lingua, E.: Long-Term Monitoring of Soil and Deadwood Water Content Across Windthrow Post-Disturbance Scenarios, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3105, https://doi.org/10.5194/egusphere-egu26-3105, 2026.
Climate change, including an increasing frequency and intensity of disturbances, is progressively threatening the resilience and productivity of forests. In the same time, the demand for ecosystem services provided by forests, such as carbon sequestration, water purification or habitat provision, is steadily increasing. To develop strategies to better cope with this pressure on forests, the LabForest project, funded by the German Federal Ministry of Research, Technology and Space (BMFTR), investigates the effectiveness and efficiency of silvicultural measures in relation with calamities within a living lab in a forest of the Ludwig-Maximilians-University in southern Germany.
Within the LabForest project, two replications of a two factorial experimental design are established on a 1 km2 area. The first factor compares plots with and without advance regeneration (before the calamity), and the second factor compares the post calamity treatment with fully cleared sites versus sites, were all dead wood was gouged and kept on site. This setup includes eight 0.25 ha experimental plots equipped with an extensive measurement network to assess hydrometeorological differences between forest management strategies.
During the first growing season following the disturbance, microclimatic measurements reveal lower mean and maximum soil temperatures at -6 cm depth and reduced diurnal temperature amplitudes at uncleared and gouged compared to cleared sites. These differences diminish above the ground (+2 cm) and are negligible at +15 cm height. Advanced regeneration had a weaker influence on soil and near-ground temperatures than complete clearing. Furthermore, differences in soil moisture patterns and evapotranspiration rates were observed.
The improved understanding of hydrological and micrometeorological conditions associated with the investigated forest management strategies, enables recommendations for establishing economically and ecologically resilient forests to cope with the increasing pressure on forests by anticipated climatic changes and societal demands.
How to cite: Svanidze, D., Obermeier, W. A., Lehnert, L. W., and Ludwig, R.: Effects of Advance Regeneration and Deadwood Retention on Forest Hydrometeorology after Disturbance, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5709, https://doi.org/10.5194/egusphere-egu26-5709, 2026.
Wildfires are among the most transformative disturbances in forested catchments, with profound effects on post-fire water quantity and quality. The severity and extent of wildfires has grown over the past decades raising concerns over their impact on streamflow and water resources. Wildfires affect streamflow through multiple mechanisms, yet their individual effects are highly specific to pre-fire catchment characteristics. In 2023, the Lookout Creek catchment in the H.J. Andrews Experimental Forest (Oregon, USA) was affected by the Lookout Fire, which burned 70 % of the catchment at varying severity. Building on three pre-fire synoptic campaigns (2022–2023), we conducted two post-fire campaigns in 2025, collecting stable water isotope samples along twelve streams spanning unburned to severely burned watersheds. We combine end-member mixing analysis with Spatial Stream Network models to (i) quantify changes in baseflow source contributions after the fire and (ii) identify the landscape controls that govern spatial patterns in streamwater isotopes.
We model campaign-to-campaign isotopic differences to isolate fire-related shifts while accounting for network structure and flow-connected spatial dependence. Additionally, we fit models separately within each campaign to test whether the strength and direction of landscape–isotope relationships have changed through time. Explanatory factors include soil burn severity and vegetation mortality, alongside geomorphic and geologic descriptors that function as proxies for storage and connectivity.
We hypothesize that (i) burn severity and fire-induced vegetation mortality modify flow-generating processes in ways that are detectable as systematic shifts in streamwater isotope composition; and (ii) sub-catchments with greater effective storage and longer flow pathways are more resilient, exhibiting muted isotopic change due to buffering and longer lag times. The anticipated outcome is a process-based assessment of where and why baseflow sources shift after wildfire, and a set of transferable indicators to identify catchments most vulnerable to post-fire alterations in water supply.
How to cite: Klein, L., Segura, C., and Klaus, J.: Effects of wildfire on stream baseflow sources in varyingly burned forested watersheds, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9239, https://doi.org/10.5194/egusphere-egu26-9239, 2026.
Decentralized retention measures in forested catchments are increasingly discussed as a complementary approach to traditional flood protection. Although forests are generally considered to naturally mitigate flooding, the quantitative contribution of small technical retention structures associated with forest infrastructure, such as ditch modifications, culverts, cross-drains, and small retention elements, remains poorly understood and insufficiently integrated into flood risk management strategies. In particular, a lack of transferable planning methodologies and evidence-based evaluation frameworks limits their systematic application.
The AquaSilva project aims to address this issue by developing a structured, model-based approach for assessing and planning decentralized technical retention measures in forested catchments. The project combines a comprehensive inventory of existing measures with hydrological modeling and targeted monitoring. Retention structures in forested environments, including road-related drainage elements and small-scale retention features, are systematically classified based on their hydrological function, spatial context, and technical design.
Hydrological effectiveness is assessed using modeling approaches that allow the representation of runoff generation, flow routing, and temporary storage at the catchment scale. Scenario-based analyses explore the potential effects of individual and combined retention measures under varying hydrological conditions. When applicable, model-based results may be supplemented with empirical evidence from practice to better understand hydrological responses and refine conceptual assumptions.
The methodology is applied in a pilot area in the Vienna Woods, allowing the derivation of practical planning parameters and transferable recommendations. The main outcome is a practice-oriented framework that links hydrological modeling, monitoring, and decision support. By improving the understanding of how decentralized forest retention measures to runoff attenuation and peak flow reduction, the project supports hydrologically sensitive forest infrastructure planning and provides a scientific basis for integrating forest-based measures into flood risk management at catchment scale.
How to cite: Amerhauser, E., Holzleitner, F., Lechner, V., Behringer, M., and Scheidl, C.: Is there strength in numbers? – Assessing cumulative effects of decentralized retention measures in forested catchments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12205, https://doi.org/10.5194/egusphere-egu26-12205, 2026.
Increasing water colour concentrations in freshwater ecosystems worldwide pose significant challenges for treatment and the sustainable supply of drinking water. While this global trend has driven extensive research, studies remain heavily concentrated in boreal peatlands and lowland forests, leaving critical knowledge gaps regarding colour generation mechanisms in other ecosystems. Well-drained eucalyptus-dominated temperate forests of the Southern Hemisphere represent one such understudied system, yet produce water colour concentrations parallel to those from northern catchments. Understanding colour dynamics in these systems is essential for predicting climate change impacts on drinking water supplies across large regions of Australia and similar temperate forests globally. Therefore, we investigated the spatial and temporal drivers of water colour generation across temperate, eucalyptus forest-dominated drinking water catchments in south-eastern Australia to understand current variability and predict responses to future climate scenarios. We combined spatial surveys across diverse topographic gradients spanning 260 km2 of catchments, with a year-long event-based monitoring using automatic samplers at five contrasting study sites, collecting and measuring a total of approximately 650 samples, to capture colour at baseflow and stormflow conditions. Controlled laboratory incubation experiments were conducted for three months, using leaf litter collected across a climate gradient, enabling us to isolate mechanisms of colour generation under different environmental scenarios. Dissolved Organic Carbon concentrations were highly correlated with true colour (r2 = 0.75), indicating that colour originates from organic matter decomposition. Our findings reveal a productivity-moisture paradigm: high-productivity systems receiving high precipitation maintain consistently high colour concentrations year-round (108.5 ± 41.1 PCU: mg Pt-Co Equiv.), due to favourable conditions for microbial decomposition of abundant litter. In contrast, lower-productivity areas show pronounced seasonality, where low colour during dry periods (55 ± 14 PCU: mg Pt-Co Equiv.) due to limited microbial activity, but colour concentrations were more than double during wet seasons (123 ± 39 PCU: mg Pt-Co Equiv.) when accumulated dry litter rapidly decomposes. Supporting laboratory experiments also confirmed this mechanism, where litter stored under prolonged dry conditions generated equivalent colour concentrations (785 ± 193 PCU: mg Pt-Co Equiv.) upon rewetting as continuously moist litter (831 ± 161 PCU: mg Pt-Co Equiv.), regardless of initial field conditions. Event-based monitoring revealed that colour peaks, sometimes reaching 177 PCU: mg Pt-Co Equiv., coincide with hydrograph peaks, with predominantly anticlockwise hysteresis loops (67%) indicating distant catchment sources. The asymptotic discharge-colour relationships, which accounted for 50% of the variability in event-flow colour, suggest a finite pool of soluble organic compounds available for leaching during events. We integrated these data with hydrological models, including PERSiST and INCA-C, to investigate catchment-scale processes and climate projections. Our initial results indicate that predicted climate shifts toward prolonged droughts punctuated by intense rainfall will create a boom-bust dynamic, with extended low-colour periods followed by pronounced colour pulses with subsequent storms, amplifying challenges for drinking water management in a changing climate.
How to cite: Jayasekara, C., Smalley, F., Noske, P., Fischer, S., Keeble, T., Lukinykh, M., Lyell, C., Lane, P., Futter, M., and Sheridan, G.: Spatial and temporal drivers of water colour variability in temperate Eucalyptus forested catchments under a changing climate, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14394, https://doi.org/10.5194/egusphere-egu26-14394, 2026.
