PICO
Our previous work reveals that daily maximum temperature (Tmax) over land has warmed at an accelerated rate in recent decades, contrasting with the faster warming of daily minimum temperature (Tmin) observed in earlier periods. This faster warming of Tmax relative to Tmin globally has led to a broadening of the diurnal temperature range (DTR), defined as the difference between Tmax and Tmin. However, the impacts of this accelerated daytime warming and increased DTR on the water and carbon cycles have remained largely unexplored.
Here, we show that the asymmetric warming rates between Tmax and Tmin have amplified the atmospheric vapor pressure deficit (VPD)—the difference between saturated vapor pressure (SVP) and actual vapor pressure (AVP). This amplification arises because a faster rise in Tmax compared to Tmin drives a larger SVP increase, due to the near-exponential relationship between temperature and SVP. Simultaneously, AVP is more strongly influenced by Tmin, as air is typically closer to saturation during the cooler nighttime hours. We quantified that the increase in DTR accounted for approximately 20% of the additional increase in global VPD over land.
We further investigated the response of terrestrial net primary production (NPP) to changes in DTR in the extratropical Northern Hemisphere over the past two decades. Our findings reveal divergent impacts of increased DTR on vegetation productivity in humid and arid zones, mirroring the contrasting effects of VPD on vegetation productivity in these regions. In humid zones, increases in DTR have promoted NPP, while in arid zones, the opposite effect is observed. This contrast is largely explained by the greater impact of accelerated daytime warming on increased VPD in arid zones, which inhibits NPP.
Additionally, we employed flux tower measurements to analyze the effects of DTR on net ecosystem carbon exchange (NEE, with negative values indicating net carbon uptake by the land) across various ecosystems. Our results demonstrate differential responses of ecosystems to changes in DTR. For example, in deciduous broadleaf forests, increases in DTR have had a dual negative impact on NEE, enhancing plant daytime photosynthesis driven by higher daytime temperatures while a more gradual rise in Tmin slows nighttime respiration increases. In evergreen needleleaf forests, the faster increase in Tmax relative to Tmin generally resulted in increased NEE, leading to a weak positive correlation between DTR and NEE.
Our findings provide compelling evidence that accelerated daytime warming over recent decades has significantly contributed to increased atmospheric dryness and has had divergent impacts on vegetation productivity in humid and arid zones. These results underscore the importance of understanding the responses of land surface hydrological processes, ecosystem productivity, and extreme events such as drought and wildfires to recent asymmetric warming dynamics.
How to cite: Zhong, Z. and Chen, H.: The impact of recent diurnally asymmetric warming on atmospheric dryness and terrestrial vegetation productivity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8926, https://doi.org/10.5194/egusphere-egu25-8926, 2025.
Flash drought (FD), characterized by its increasing frequency and rapid onset, has emerged as a critical threat to ecosystem stability and functions. However, a global consensus on how forests respond to FD events remains elusive. Furthermore, the roles of FD characteristics (e.g., onset rate, peak stress, and stress duration) and forest management practices in mediating these responses have yet to be fully explored. Here, we explored the responses of intact and managed forests to FD events using a newly produced high-resolution Standardized Precipitation-Evapotranspiration Index (SPEI) dataset from 1982 to 2022 and investigated the synergistic regulations of forest management practices, FD characteristics, background climate, and meteorological anomalies during FD events based on an interpretable machine learning framework. Global forests have experienced faster onset, greater intensity, and prolonged duration FD events over the past four decades. Those FD events drive the browning of managed forests worldwide, which are unable to adapt to sustained extreme high temperatures. However, elevated temperatures during FD events leads to forest greening in the Amazon and Siberia regions due to enhanced photosynthesis. Notably, current management practices have further exacerbated the vulnerability of managed forests to FD events globally. Our findings underscore the escalating risks posed by more frequent and prolonged FD events to managed forests, highlighting the urgent need to incorporate forest resistance and resilience to extreme climatic events into the development of forest management strategies.
How to cite: Pang, J., Zhang, Z., Xu, H., Wu, X., and Xing, K.: Flash droughts threaten global managed forests, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6804, https://doi.org/10.5194/egusphere-egu25-6804, 2025.
In forest management, there is an outstanding importance of water cycle of the forest because of ecological and economical viewpoints, including the water management of woody plants. Examining the reactions of trees to environmental stress – warming, extreme drought or intense rains – and the phenomena derived from this, help to provide the correct answers to challenges affecting forestry. An investigation was started in a beech stand in Magas-Bakony, which was significantly affected by early leaf loss caused by the drought of 2022. Taking into account the meteorological data of the site, the study focuses on the change in trunk diameter, on the state of health and regeneration through photosynthetic activity and on the annual growth change with annual ring analysis.
The research was supported by Verga forestry, Private Limited Liability Company, Veszprém, Hungary, the OTKA grant 143972SNN, the Slovenian Research and Innovation Agency grant N2-0313 and the associated project TKP2021-NKTA-43. The project TKP2021-NKTA-43 was implemented with the support of the Ministry of Innovation and Technology through the National Fund for Research Development and Innovation, funded by the TKP2021-NKTA call for proposals and the Project No. 2023-2.1.2-KDP-2023-00013 was implemented with the support of the Ministry of Culture and Innovation through the Fund of National Research Development and Innovation, funded by the KDP-2023 Tender Program.
How to cite: Kökény, G. L., Gribovszki, Z., and Kalicz, P.: Research on the responses of a beech stand to extreme drought in Eastern Bakony, Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15843, https://doi.org/10.5194/egusphere-egu25-15843, 2025.
The hydrological cycle in Hungary, and consequently in its west Transdanubian region, has undergone significant changes in recent decades due to climate change. The distribution of precipitation throughout the year has changed, and the probability of intense precipitation events has increased, but the annual amount of precipitation has not changed much. Furthermore, droughts have become more severe and prolonged due to rising average annual temperatures and longer rain-free periods. Consequently, evaporation intensity has also increased, which, when combined with the previously mentioned factors, has decreased the quantity of groundwater and surface water resources.
In our previous work, we examined the changes in the specific discharge of several watercourses in the West-Transdanubian region over the past 40 years. We found that the annual specific discharge of all watercourses shows a decreasing trend, despite the fact that the annual precipitation amount does not change significantly. In the case of watercourses originating in the Alps, this decreasing trend is not as steep as in the case of watercourses whose catchment area is entirely located in the Carpathian Basin. In this work, we examined the trends in the change of the watershed land cover and the annual water resource decrease of the watercourses, in order to explore possible connections between the change in watershed land cover and the decrease in specific discharge.
The research was supported by the OTKA grant 143972SNN, the Slovenian Research and Innovation Agency grant N2-0313 and the associated project TKP2021-NKTA-43. The project TKP2021-NKTA-43 was implemented with the support of the Ministry of Innovation and Technology through the National Fund for Research Development and Innovation, funded by the TKP2021-NKTA call for proposals.
How to cite: Juhász, I., Gribovszki, Z., and Kalicz, P.: Changes in water resources due to climate change and watershed land cover in the West-Transdanubian region of Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12165, https://doi.org/10.5194/egusphere-egu25-12165, 2025.
Precipitation patterns have become increasingly extreme in recent decades, leading to more frequent droughts. For certain vegetation types, such as the riparian alder forest (Alnus glutinosa), surplus water is essential for survival. To address this, we investigated the effects of temporary water retention in the Hidegvíz Valley, located in the Sopron Hills.
A detailed groundwater monitoring network has been operational in this area for over a decade, focusing on the impacts of temporary water retention. As part of this study, the network was expanded to include 21 groundwater wells, some of which were equipped with automatic water level recorders. Data from six and a half years of manual measurements were analyzed, and automatic data loggers recorded the water table for one month following the installation of a log weir.
The water retention intervention resulted in a 40 cm rise in streamwater levels and a several-decimeter (dm) increase in groundwater levels within 3–4 meters of the streambed within a few hours. This rise provided a more favorable groundwater table for the alder forest along the stream during the typically dry months of July and August.
Acknowledgement: The research was supported by the OTKA grant 143972SNN and the associated project TKP2021-NKTA-43.
How to cite: Gribovszki, Z., Kovács, J., Herceg, A., Zagyvai-Kiss, K. A., and Kalicz, P.: Mitigating the Effects of Climate Change through Water Retention: A Case Study from the Hidegvíz Valley, Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18772, https://doi.org/10.5194/egusphere-egu25-18772, 2025.
The effects of climate change can be studied using a wide variety of methods and measurements. It is important to monitor the different impacts of climate change not only regionally, but also locally, as this can provide valuable information and help local interventions to succeed. Using the available data (long-term daily air temperature and precipitation data series), we have carried out studies focusing on changes in the hydrological system. Changes in the elements of the hydrological regime, changes in snow and changes in seasonality were investigated. The results show that the largest changes in the elements of the water balance was a decrease in runoff and recharge potential by 58.7%, followed by a decrease in snow storage by 46.8%, a decrease in soil moisture storage by 12%, an increase in evapotranspiration by 9.5%, and finally a decrease in water input by 2.2%. The snow analysis also shows a decrease in average annual snowfall and the number of snow days. The seasonality test shows seasonality, with July as the average month of occurrence in both periods, but with a slight increase for the present (from 0.188 to 0.227).
Acknowledgements: This study was financially supported by the Slovak Research and Development Agency under Contract No. VEGA 1/0577/23. The research was supported by the OTKA grant 143972SNN, the Slovenian Research and Innovation Agency grant N2-0313 and the associated project TKP2021-NKTA-43. The project TKP2021-NKTA-43 was implemented with the support of the Ministry of Innovation and Technology through the National Fund for Research Development and Innovation, funded by the TKP2021-NKTA call for proposals.
How to cite: Muraközy, L., Gribovszki, Z., Hlavčová, K., and Szolgay, J.: Investigating the effects of climate change over two periods at the Botanical Garden station, in Sopron, Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9668, https://doi.org/10.5194/egusphere-egu25-9668, 2025.
As climate change accelerates, European regions are increasingly vulnerable to extreme weather events, rising temperatures, and other climate-related hazards, posing significant threats to communities, economies, and ecosystems. The urgent need for adaptation is further exacerbated by limited resources and expertise in many municipalities, leaving them unprepared to address these escalating challenges effectively. The CLIMAAX (CLIMAte risk and vulnerability Assessment framework and toolboX) project addresses this critical gap by equipping local authorities with advanced tools to develop robust and targeted climate adaptation strategies.
Featuring a user-friendly interface and real-time data integration, the CLIMAAX toolboxes empower municipalities to identify and address localized risks, optimize resource allocation, and foster collaboration with scientific institutions and stakeholders. These innovative tools offer actionable insights for climate risk assessment and scenario planning, ensuring accessibility and relevance. As a vital resource, the CLIMAAX toolboxes enable cities to implement scientifically sound and locally tailored adaptation strategies, building resilience against the growing impacts of climate change.
How to cite: Kubáňová, M., Kubáň, M., Kalaš, M., Aleksic, M., Aleksandrova, N. A., and Polster, C.: Climaax project: Heat wave toolbox, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4115, https://doi.org/10.5194/egusphere-egu25-4115, 2025.
Recent improvements in satellite-based soil moisture mapping (higher spatial and temporal resolution) add value to using remotely sensed soil moisture estimates in many hydrological applications (e.g. flood forecasting, drought monitoring, understanding climate change impacts, etc.). However, further analyses are required to validate these data sets reasonably in an alpine environment. This study aims (1) to compare satellite-derived ASCAT-DIREX soil moisture data with in situ surface soil moisture measurements in the well-documented experimental catchment (the Jalovecký Creek catchment), located in the Western Tatra Mountains in Slovakia, (2) to assess the factors controlling the mapping accuracy. As a reference, we used in situ surface soil moisture measurements between 2012 and 2019 at depths of 5 cm (open area, 1500 m a.s.l.) and 10 cm (forest, 1420 m a.s.l.), respectively. Satellite soil moisture estimates are obtained by combining ASCAT and Sentinel-1 data (the ASCAT-DIREX dataset), offering relative daily soil moisture measurements at a 500 m spatial resolution. These estimates represent four characteristic timescales (T = 1, 2, 5, and 10 days) and are compared with in situ surface soil moisture observations. The Pearson correlation coefficient (r) is used to describe the consistency between the two soil moisture estimates. The results reveal that satellite-derived soil moisture correlates more strongly with in situ measurements at the open site and with a T-value of 10 days. The correlations exhibit a pronounced seasonal pattern, with low (negative) values in winter/spring and higher correlations in summer/autumn. The primary cause of low correlations during winter/spring is the insufficient masking of the snowpack. After masking days with snowpack, the correlation in April increases to 0.68 (open site) and 0.92 (forest site), respectively. The reliability of soil moisture estimates during summer is influenced by factors such as small-scale variations in precipitation and vegetation dynamics.
Acknowledgments
This work was supported by the Slovak Research and Development Agency under Contract No. APVV-23-0332 and the VEGA Grant Agency No. 2/0019/23. The support by the Danube Region Programme: DRP0200156 Danube Water Balance is also gratefully acknowledged.
How to cite: Danko, M., Sleziak, P., Jančo, M., Holko, L., Greimeister-Pfeil, I., Vreugdenhil, M., and Parajka, J.: Evaluation of ASCAT-DIREX soil moisture product using in situ measurements in a small mountain catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8736, https://doi.org/10.5194/egusphere-egu25-8736, 2025.
The runoff coefficient still represents a crucial part of predicting extreme runoff for the safe design of water structures. Despite its importance, it remains a subject of many hydrological discussions. The issue lies in how many unknown processes control the runoff in catchments. Therefore, in recent years, we have witnessed that the estimation of the runoff coefficient using tables and formulas has been abandoned, and the current hydrological community focuses on direct estimations from real observed data. The presented study uses rainfall-runoff data to directly estimate the peak runoff coefficient for the return period for 2-, 5-, 10-, 50- and 100- years.
The subjects of the study are three catchments with sizes from 45 to 250 km2 located in the territory of Slovakia. The catchments Horné Orešany (stream Parná), Liptovský Mikuláš (stream Jalovecký potok) and Liptovský Hrádok (stream Belá) have different landscape characters, from rural lowlands to mountains landscape.
The runoff and rainfall data series used to estimate the peak runoff coefficient are measured in hourly time steps from 1989 to 2023.
The data were subsequently subjected to the manual and automatic separation of flood wave characteristics, such as flood volume, flood peak, duration of the flood wave, and the time to peak duration. The maximum flood waves from the summer and winter seasons were selected for each year. The reason for dividing the annual data into summer and winter seasons is to reduce the impact of phenomena that we cannot yet exclude from the measured data (snow, soil saturation).
The study shows differences in the chosen method of estimating the peak runoff coefficient. The winter seasons revealed higher values of estimated peak runoff coefficients than the summer seasons. The question also arises about the impact of the length of the available data series on the estimated runoff coefficients.
The study results are intended to help understand the extent to which different estimation methods are applicable in practical engineering.
Acknowledgements
This study was supported by the VEGA Grant Agency No 1/0577/23. The authors thank the agency for supporting their research.
How to cite: Paulíková, L. and Kohnová, S.: Estimation of the runoff coefficient: Advantages and disadvantages of using observed rainfall-runoff data in a small catchment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4109, https://doi.org/10.5194/egusphere-egu25-4109, 2025.
Sustainable management of water resources relies on accurate river flow prediction. This study explored how multi-model data fusion techniques enhance the reliability of rainfall-runoff modeling by integrating the strengths of process-based and data-driven approaches. Accordingly, we employed different streamflow prediction models, comprising the TUW (Technische Universität Wien) model and the Long-Short-Term Memory (LSTM)-based models, LSTM and Stack-LSTM, to predict streamflow in the Hron River basin in Slovakia during the 2007–2020 time period. An enhanced streamflow prediction system was then developed by merging predictions from multiple models using the Simple Average Method (SAM) and the Bayesian Model Averaging (BMA) approach. The findings revealed that the Stack-LSTM model performed similarly to the LSTM algorithm, and both outperformed the TUW method. Evaluation and analysis showed that the Stack-LSTM model achieved a Nash-Sutcliffe efficiency coefficient (NSE) of 0.98 and a Mean Absolute Percentage Error (MAPE) of 6.96% during the test stage. Furthermore, the comparison of outcomes from the multi-model averaging methods revealed that the BMA approach outperformed the SAM. As a result, the MAPE for the BMA method was reduced by 50.2% compared to the SAM. This research provides a robust tool for streamflow prediction, enhancing decision-making in water resources management.
How to cite: Tanhapour, M., Parajka, J., Kohnová, S., and Hlavčová, K.: Multi-model data fusion for improved streamflow prediction based on hydrological and data-driven models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4103, https://doi.org/10.5194/egusphere-egu25-4103, 2025.
Understanding how daily air temperature characteristics are expected to evolve in the future is critical for all countries, as air temperature influences numerous societal sectors. Reliable estimates of future extreme air temperatures are essential for public health, agriculture, hydrology, engineering, and economic planning.
In this study, the long-term trends of selected daily air temperature indices—average, minimum, and maximum—were analyzed for the Hurbanovo and Liptovský Hrádok climatological stations in Slovakia over the period 1871–2020. Furthermore, empirical histograms of daily minimum (TN), mean (Td), and maximum (TX) air temperatures were constructed using data from five climatological stations at different altitudes in the High Tatra Mountains, covering the period 1961–2010. The causes of asymmetry and bimodality observed in these temperature characteristics were investigated.
The findings indicate that the asymmetric bimodal shape of air temperature histograms in Central Europe is primarily caused by the latent heat of freezing, as thermal coupling occurs between snow/ice surfaces and the air. The asymmetry in these histograms is attributed to the lower specific heat capacity of cold air below 0°C compared to the heat capacity of air above 0°C. The energy-intensive phase transitions of ice and water near the freezing point result in a higher frequency of ground-layer air temperatures around 0°C, producing the observed local maximum. This has significant implications for the calculation of annual mean air temperatures at climatological stations, where negative temperatures should be assigned less weight than positive ones, while temperatures in the range of 0–6°C should receive higher weight.
Finally, theoretical probability distributions were developed for individual temperature indices to estimate T-year temperatures at the Hurbanovo station. The distribution functions were analyzed for three periods: 1901–1960, 1961–2020, and 1991–2020. For TN,min, the 100-year temperature increased from –35.75°C in 1901–1960 to –28.69°C in 1961–2020 and further to –26.52°C in 1991–2020. For TX,max, the 100-year temperature increased from 39.4°C in 1901–1960 to 39.63°C in 1961–2020. The most notable changes were observed for TN,min, where an increase of up to 9.23°C was recorded.
Acknowledgment: This research was supported by the project APVV-20-0374, “Regional detection, attribution and projection of impacts of climate variability and climate change on runoff regimes in Slovakia”
How to cite: Pekarova, P., Pekar, J., Miklánek, P., and Lescesen, I.: Asymmetry, Bimodality and Design Values of Daily Air Temperature, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5372, https://doi.org/10.5194/egusphere-egu25-5372, 2025.
Vegetated roofs are valuable solutions for water management improvements in urban areas as they can store and delay rainfall water. Vegetated roofs cannot be considered static systems, whose performances remain constant over time. This study is based on the use of a laboratory-scale experiment. In addition to evaluating the hydrological performance of the vegetated roof substrate after rainfall events, the impact of humus fraction transport as sediment in roof runoff are assessed.
The laboratory experiment simulated a 15-minute rainfall event with different intensities (low, medium and extreme). After each simulated rainfall event, runoff was filtered through a filter paper to capture the fine substrate particles. A total of 27 measurements were taken. The results showed that with increasing rainfall intensity, there was a higher volume of runoff, which led to an increase in the amount of sediment captured in the runoff. The sediment sampling is crucial for an accurate quantitative assessment of erosion processes on vegetated roofs, transport of humus parts of substrate and their environmental impacts.
The composition of the roof substrate plays a key role in the initial performance and sustainability.
Keywords: roof substrate, rainfall, vegetated roof, rainfall simulator
Acknowledgement: VEGA 1/0577/23
How to cite: Grečnárová, J., Danáčová, M., and Tomaščík, M.: The influence of rainfall intensity on runoff and humus content of roof substrate, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8897, https://doi.org/10.5194/egusphere-egu25-8897, 2025.
A comprehensive understanding of rainfall distribution processes within tree canopies is crucial for studying the forest hydrological cycle and its ecosystem. Canopy interception is a dynamic component of the water balance, as the canopy's storage capacity varies seasonally. Building on these insights, the primary aim of this study was to develop a canopy interception model for the European beech (Fagus sylvatica L.). The model incorporates physical parameters as well as considers the seasonally variable storage capacity of the canopy, by the help of remotely sensed Leaf Area Index (LAI) data. The model was tested using annual precipitation data from 2017 to 2022.
The model results highlighted the significant impact of interception on rainfall distribution, with interception accounting for 20% of total precipitation, particularly affecting small rainfall events (0-5 mm) with 61 %. The results of seasonal variability for the investigated six years are 23% in the growing season, while 13% in the dormancy.
Acknowledgement
This article was made within frame of Project No 143972SNN (OTKA) and TKP2021-NKTA-43. The TKP2021-NKTA-43 project which has been implemented with support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund and financed under the TKP2021-NKTA funding scheme.
How to cite: Herceg, A. and Zoltán, G.: Rainfall interception estimation of a Beech Forest with dynamic storage capacity model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16066, https://doi.org/10.5194/egusphere-egu25-16066, 2025.
The aim of this study was to compare the rainfall characteristics and rainfall erosivity between two locations in the Danube River Basin, the Hydrological Open Air Laboratory (HOAL) agricultural catchment in Austria and an experimental plot located in an urban park in Ljubljana, Slovenia. The variability of rainfall characteristics and rainfall erosivity were investigated using 5-year-long measurements (2014 – 2018) of rainfall (amount, duration and intensity of rainfall) and drop size distributions (diameter, velocity and median volume diameter of the drops). Despite having the same Köppen-Geiger climate classification, differences were found between the two study sites. The long-term annual average total precipitation was almost twice as much in Ljubljana compared to the HOAL. According to the results of the hierarchical clustering analysis, larger and more intense rainfall events occurred in Ljubljana than in the HOAL, but the average drop characteristics were lower for the events in Ljubljana. Furthermore, if the events were not extreme, their characteristics were similar regardless of location. The rainfall intensities tended to peak in the summer months at both sites, when rainfall durations were shorter, and larger and faster drops were observed. The rainfall erosivity was found to be between 2-5 times greater in each year in Ljubljana than in the HOAL because of the more intense rainfall and single faster and larger drops during events.
Acknowledgment: This contribution is part of the ongoing research project entitled “Evaluation of the impact of rainfall interception on soil erosion” supported by the Slovenian Research and Innovation Agency (J2-4489) and the Austrian Science Fund (FWF) I 6254-N.
How to cite: Széles, B., Parajka, J., Šraj, M., Blöschl, G., Marjanovic, D., Bezak, N., Lebar, K., Vidmar, A., Strauss, P., Krammer, C., Schmaltz, E., Hogan, P., and Zabret, K.: Comparison of rainfall characteristics and rainfall erosivity between two experimental sites in Austria and Slovenia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15439, https://doi.org/10.5194/egusphere-egu25-15439, 2025.
Green roofs are often proposed as climate change adaptation and environmental protection measures in urban environments. The goals are to cool down the environment, to handle the extreme precipitation events, to increase the CO2-sequestration and to enhance the biodiversity. However, the most widely used extensive roof greening is not very efficient for climate cooling, CO2 sequestration and biodiversity. Intensive green roofs are much more efficient, but often are resource- and energy-consuming. The aim of our study was, therefore, to investigate the microclimatic effects of semi-intensive rainwater-irrigated green roof, which could be implemented with little technical and financial effort. For this purpose, an extensive green roof was equipped with solar-powered rainwater irrigation system and planted with selected plant species. The substrate used (10 cm layer) has maximum water storage capacity of vol. 40%. The roof is irrigated during the summer months with 2 l m-2 day-1. The effects on microclimate, water balance, particulate matter binding and biodiversity are measured continuously starting in 2020. The microclimatic effects are measured with automatic weather stations on the semi-intensive model roof and a control area (parking lot) at the heights of 2m and 0.5 m above surface. In addition, manual albedo measurements as well as the measurements with manual and drone-borne thermal cameras were carried out. The green roof albedo values vary between 0.147-0.174 and are higher than parking lot (0.139-0.145). The measurements show that the effects of semi-intensive roof on the microclimate are quite variable. The reduction of temperature extremes (up to 2°C) and especially warm nights is observed. The roof surface is particularly cooler under calm conditions, with minimal external influences. There are, however, also the well-expressed warming effects of the roof depending on the weather conditions. The effects of different plant species and substrate to total cooling or warming of green roof were also quantified.
How to cite: Panferov, O., Hietel, E., Rößner, U., and Seelos, K.: Semi-intensive green roofs - a solution for negative impacts of climate change in urban landscapes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16000, https://doi.org/10.5194/egusphere-egu25-16000, 2025.
In the current period of global warming, declining biodiversity and continued pressures of urbanisation, it is the moment to reconsider the role and quality of urban streams. Unfortunately, they have become increasingly invisible: over-built, channelised and degraded by anthropogenic use. Creating green and blue corridors not only significantly contributes to building climate-resilient cities by improving microclimatic conditions in overheated cities or providing fresh air corridors, but it also connects stream reaches, provides floral and faunal habitats, as well as recreational spaces that improve human wellbeing. However, stream restorations in urban areas using nature-based approaches (NBA) face many barriers and challenges: lack of space in intensively built-up areas, property rights of surrounding land, funding, different stakeholder interests, acceptance, and flood protection. To face these challenges, it is necessary to perform an integrated analysis of river hydraulics, ecology, stakeholder interests, institutional frameworks, social perspectives and urban space requirements.
Pilot restoration measures are being implemented in four study urban stream areas located in Dresden (DE), Jablonec nad Nisou (CZ), Poznan (PL) and Senica (SK). Current urban challenges and opportunities of these four case studies are being identified and analysed together with stakeholder groups with different perspectives. The trade-offs between the social and ecological requirements in the context of urban planning and institutional settings are being extracted.
The Slovak pilot reach - Teplica River in Senica is struggling with specific problems of insufficient flood capacity, poor morphological and ecological quality, low summer flows, upstream dam operation and poorly utilized public space. All of these are being addressed in case study, the outcomes of which will serve as inputs for further analysis. Experiences from multiperspective, transdisciplinary, participatory and integrated analyses in four pilot reaches will help to better design future urban restoration projects and will enable practitioners and decision makers in urban planning to utilise social-ecological integrated NBA for urban multifunctional areas that promote biodiversity and provide ecosystem services.
Acknowledgements:
This research has been supported by the Interreg CE programme under Contract No. CE0200754 ReBioClim and Scientific Grant Agency under Contract No. VEGA 1/0067/23. The author thanks the agencies for their research support.
How to cite: Škrinár, A.: Restoring urban streams to promote biodiversity, climate adaptation and to improve quality of life in cities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9196, https://doi.org/10.5194/egusphere-egu25-9196, 2025.
Flash droughts pose a serious threat to agriculture due to their abrupt onset and rapid intensification. The increasing frequency of such events presents considerable challenges and uncertainties for agricultural carbon sequestration, particularly during the growing season. To effectively assess carbon dynamics in agroecosystems under ongoing climate change, it is crucial to understand the complex interactions among energy, water, and carbon fluxes, as well as their connection to vegetation.
An open-path eddy-covariance (EC) measurement system (Licor Smartflux Measurement Suite) was installed over an apple tree stock in eastern Germany (Brandenburg) to monitor microclimatic conditions and the water and carbon budgets at the ecosystem level. Brandenburg, one of the driest regions in Germany, has approximately 48.79% of its land used for agriculture. These agricultural landscapes are highly vulnerable to climate-related stresses, such as water scarcity and flash droughts. The stress conditions can increase irrigation demands, disrupt phenological cycles, and influence atmospheric water and carbon cycles, making them critical areas of investigation in the context of land use and climate change. This study investigates the interactions between microclimatic conditions and soil water levels, and their effect on gross primary production (GPP) in an agricultural region of eastern Germany during a flash drought event that occurred during the growing season. Key variables analyzed include surface energy fluxes (sensible heat H, latent heat LE), the net-ecosystem exchange (NEE) with its partitioned components of GPP and ecosystem respiration (Reco), as well as the water-related variables such as precipitation, irrigation, and soil water content (SWC).
The results indicated that during the flash drought event, the concurrence of low SWC and high vapor pressure deficit (VPD) led to elevated net radiation (Rn), which caused high H and depleted soil water availability. This exacerbated plant water stress and suppressed GPP. Furthermore, irrigation efforts during the event were insufficient to mitigate these adverse impacts, underscoring the vulnerability of agroecosystems to extreme climatic events. The findings highlight the critical role of the coupling between SWC and VPD in regulating carbon sequestration during flash droughts.
How to cite: Sayeed, M., Murkute, C., Ahmed, R., Scholz, S., and Trachte, K.: Flash drought effects on carbon dynamics in an agroecosystem – insights from the eastern German lowlands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7124, https://doi.org/10.5194/egusphere-egu25-7124, 2025.
In a terrestrial ecosystem, water and carbon cycles are coupled with the linking eco-hydrological trait, water use efficiency (WUE). Understanding the dynamics of these fluxes in managed croplands is crucial in implementing sustainable irrigation strategies. However, knowledge of these fluxes, especially in semi-arid regions is poorly addressed due to lack of long-term flux measurements. This study is aimed at analysing the dynamics of carbon, water and WUE fluxes observed in a maize crop irrigated with both alternative furrow (AFI) and conventional furrow (CFI) schemes. During the experiments, water-carbon fluxes and other related micro-metrological and environmental variables are continuously monitored using two eddy covariance (EC) flux towers installed in the maize fields. The results showed that: mean WUE is in the range 1.61 ± 0.23, and 1.21 ± 0.25 µmol m-2 s-1 CO2 mm day-1 H2O for AFI and CFI respectively. A higher WUE in AFI by 1.33 times over CFI treatment is attributed to the differences in net ecosystem exchange (NEE). The correlation analysis showed that WUE is mainly affected by net ecosystem exchange (R2 = 0.75 in AFI and 0.60 in CI) rather than ET fluxes. The environmental drivers of vapor pressure deficit of air and net solar radiation are mainly controlling WUE dynamics. Results concluded that the AFI irrigation treatments have more significant water-saving potential without compromising on carbon intake. These findings can set as a reference for the scientific development of typical water-saving practices of agriculture in India.
How to cite: Chintala, S. and kbvn, P.: Understanding the dynamics of carbon, water and water use efficiency fluxes at ecosystem scale in Maize crop, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-607, https://doi.org/10.5194/egusphere-egu25-607, 2025.
The global need for sustainable natural resource management and climate mitigation has highlighted the significance of nature-positive watershed management strategies for climate change mitigation. Carbon sequestration is one of the prudent steps in climate change mitigation. So, the study was conducted in the Chichondi village of Ahmednagar district, Maharashtra, focusing on two distinct watersheds: Watershed 1 (136 ha) and Watershed 2 (63 ha). The region experiences a tropical monsoon climate with an average annual rainfall of 1,740 mm. Both watersheds were treated with diverse soil and water conservation measures, including deep Continuous Contour Trenches (CCT), contour bunding, recharge pits and farm ponds. These treatments were implemented on about 30% of the area for both watersheds. The primary objectives were to assess soil and carbon loss and evaluate the impact of watershed development measures on carbon sequestration. Soil loss was estimated using the Universal Soil Loss Equation (USLE), while carbon loss was measured through sediment yield using total organic carbon (TOC) analyser. Runoff and sediment were measured using installed weirs and stage-level recorders at watershed outlets. Key findings demonstrated the efficacy of implemented conservation measures. In Watershed 1, soil loss reduced from 32.63 t/ha/yr to 26.73 t/ha/yr (18% reduction) and carbon loss decreased from 554 kg/ha/yr to 412 kg/ha/yr (25% reduction). Watershed 2 exhibited a similar trend, with soil loss decreasing from 30.82 t/ha/yr to 24.65 t/ha/yr (20% reduction) and carbon loss reducing from 612 kg/ha/yr to 479 kg/ha/yr (22% reduction). Over a five-month period, Watershed 1 recorded a runoff volume of 10,29,792 m³, corresponding to a cumulative carbon loss of 19.35 tonnes (142.4 kg/ha), whereas Watershed 2 experienced a runoff of 4,31,068 m³, with a cumulative carbon loss of 8.04 tonnes (126.6 kg/ha). The outcomes affirm that nature-positive interventions in watershed management significantly reduce soil erosion and enhance carbon sequestration. These conservation measures not only conserve soil and water resources but also mitigate carbon loss, contributing to climate resilience. The findings provide data-driven insights for policymakers, enabling the promotion of sustainable, climate-adaptive solutions in similar agro-ecological regions. This research underscores the transformative potential of watershed management programs, advocating for broader implementation of nature-positive solutions to achieve dual goals of natural resource sustainability and climate change mitigation.
How to cite: nandgude, S., Tripathi, M., Sikka, A., Rana, J., Gavit, B., Shinde, S., Shelar, R., and More, D.: Nature-Positive Watershed Management Strategies for Enhanced Carbon Sequestration: A Case Study of Watersheds in Maharashtra, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4927, https://doi.org/10.5194/egusphere-egu25-4927, 2025.
One of the greatest challenges of the 21st century is combating global climate change and adapting to its effects. In addition to reducing CO2 emissions, natural processes capable of absorbing CO2 are of paramount importance. Forest ecosystems play a critical role in this regard as they are the largest terrestrial absorbers of CO2 and organic carbon reservoirs.
Our research revealed that in recent decades, systematic surveys of soil (and litter layer) organic carbon content have not been conducted in Hungary. Existing soil data are often incomplete (e.g., lack measurements of bulk density), were obtained using different analytical methods (e.g., determining soil humus content), and do not always include forest stand data. Data on litter layers are even more scarce. Consequently, our primary goal was to expand this dataset. To achieve this, we began assessing the effects of tree species, site conditions, and silvicultural interventions on the organic carbon stocks of soils and litter layers in Hungarian forest stands.
Soil samples were collected using a motorized auger to a depth of 1–1.1 meters. The undisturbed samples were divided into 10 cm sections rather than genetic horizons, and for each section, a 100 cm³ cylinder was used to extract undisturbed samples for bulk density determination. The remaining soil in each section was retained for further analysis. From a 5-meter radius around each sampling point, litter samples were randomly collected from three locations per stand. The litter included all decomposing leaves and small to medium-sized twigs above the raw soil surface. Each sample was placed in a separate bag, resulting in 25 samples per location.
This study focuses on results from beech (Fagus sylvatica) stands, as laboratory analyses are still ongoing. The collected soil samples were analyzed for bulk density, pH, lime content, acidity, particle size distribution, and organic carbon content. For the litter samples, in addition to dry mass, pH, the proportions of various fractions, and C/N content were determined.
In the approximately 40 examined beech stands, the average soil pH was 5.17 pHH2O, with minimum and maximum values of 3.87 pHH2O and 8.4 pHH2O, respectively. Humus content in individual layers ranged from 0.16% to 15.65%. The average organic carbon stock of the 10 cm soil layers was 6.39 C t/ha, with a minimum of 1.46 C t/ha and a maximum of 34.03 C t/ha.
Based on the results, the carbon stocks under beech stands in Hungary, which are retreating due to climate change, are likely to disappear if the pace of climate change accelerates in the Carpathian Basin.
This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. Some of the tools used during the research were acquired within the framework of the "Investigation of the conditions for the cultivation of wood biomass - GINOP-2.3.3-15-2016-00039" project.
How to cite: Horváth, A., Balázs, P., Katona, M., Végh, P., and Bidló, A.: Analysis of changes in forest soil carbon stocks due to different site conditions and the impact of climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15715, https://doi.org/10.5194/egusphere-egu25-15715, 2025.
Ecosystem health is an important approach to measuring urban and regional sustainability. In previous studies, the spatiotemporal changes of ecosystem health have been addressed using comprehensive assessment index system. However, the quantitative contribution of human activities and climate change to ecosystem health was less examined. In this study, Shuozhou City, a coal resource-based city, was chosen to explore the response of ecosystem health to human activities using the Geographically Weighted Artificial Neural Network (GWANN) model. The results showed a distinct improvement of ecosystem health in Shuozhou City from 1990 to 2020. The contribution of human activities increased during the study period, while the contribution of climate change decreased as a consequence of coal mining expanding. By 2020, human activities contributed 76% to ecosystem health compared with 24% of climate change. The direct impact of coal mining on ecosystem health occurred mainly in the surrounding areas within a radius of 6 km and 17 km under low and high mining intensity respectively. Ecosystem health will further decline by 2030 based on the scenario in which current coal mining is continued. However, only stopping mining activities in small coal mining areas for ecological restoration but keeping large coal mining areas in production, will realize 92.6% of restoration effects on ecosystem health as compared to ceasing all mining activities. This study examines the effects of coal mining on ecosystem health in resource-based cities, and underscores the importance of large coal mining sites in ecological restoration.
How to cite: Chen, Y., Yu, X., Xu, D., and Peng, J.: A spatial machine learning approach to exploring the impacts of coal mining and ecological restoration on regional ecosystem health, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7744, https://doi.org/10.5194/egusphere-egu25-7744, 2025.
Pedunculate oak (Quercus robur L.) and Common ash (Fraxinus angustifolia Vahl.) mixed forest represent common mixture in central and southeastern Europe. They are vulnerable in the context of global change, especially to the rise of temperature and groundwater table decline, which is present in Serbian floodplain forests. We took wood samples of pedunculate oak and common ash from Sava River Basin. Samples were dried, polished, and scanned in high resolution. Tree-ring widths were measured. General trend of growth decline in past decades was observed. Special emphasize was on analyzing past 10 years period, which were the hottest period since the beginning of measurements on Earth. Significant correlations between temperature and precipitation were observed. Further analysis in context of interactions between two species will be carried out.
Acknowledgment:
The study was supported by the Ministry of Science, Technological Development and Innovation of the Republic of Serbia (Contract No. 451-03-66/2024-03/200197 and co-funded by Science Fund of the Republic of Serbia, call DIASPORA, project SmartTogether and Long-term cooperation between Institute of Lowland Forestry and Environment and PE “Vojvodinašume”.
How to cite: Stojanovic, D., Perendija, N., Đilas, M., Tubić, B., Marinković, M., Bauer-Živković, A., Matović, B., Višacki, V., and Orlović, S.: Response of Pedunculate oak – Common ash mixed floodplain forests to global and climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17071, https://doi.org/10.5194/egusphere-egu25-17071, 2025.
Over the past hundred years, Hungary's forest area has increased from 12% to 24%, thanks to afforestation efforts. Accordingly, it is crucial to examine the impact of forests on soils.
In our study, we compared 1. a cropland, 2. a 19-year-old pedunculate oak stand, and 3. a 79-year-old pedunculate oak stand at the Szentkirály area of the Great Hungarian Plain to investigate changes in the soil. On adjacent areas with calcareous chernozem soil, undisturbed soil samples were taken every 10 cm down to a depth of 110 cm and analyzed in the laboratory.
By examining the soil pH, it was determined that the soil under the cropland and the young stand was weakly alkaline to alkaline (7.9 (pHH2O) to 8.6 (pHH2O)). In contrast, the upper soil layers under the old forest exhibited an acidic pH (5.4 (pHH2O)). Intensive leaching was observed, affecting the upper 50 cm layer. The soil carbonate content values also corresponded to the pH levels. Based on particle size distribution analysis, the soil was classified as sandy loam, with no differences observed under the various land uses.
The humus content in the soil samples ranged from 0.1% to 3.5%. The lowest humus content (0.1%-1.7%) was found in the cropland, while the highest humus content was observed in the old oak forest, where the top layer contained 3.0% humus. Overall, it can be concluded that the nearly 80 years of afforestation significantly impacted soil development. Leaching intensified, and following the cessation of plowing, organic matter accumulation began in the soils. Field observations also indicated a marked improvement in soil structure. The forest improved the soil properties, creating conditions more favorable for itself.
This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme. Some of the tools used during the research were acquired within the framework of the "Investigation of the conditions for the cultivation of wood biomass - GINOP-2.3.3-15-2016-00039" project.
How to cite: Bidló, A., Balázs, P., Katona, M., Végh, P., and Horváth, A.: The impact of afforestation on soil properties, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15498, https://doi.org/10.5194/egusphere-egu25-15498, 2025.
Gap-cuttings in the framework of a continuous cover forestry system have an ecological effect on the chemical soil properties. The Pilis Gap Experiment (https://piliskiserlet.ecolres.hu/en) starting in 2019 in the Pilis Mountains in Hungary, investigates the effect of gap size and shape on soil properties in a mature oak-hornbeam forest. This study analyses the soil samples from 2023 regarding the effect of treatments on the pH value, the humus, and soil water content.
A full-factorial design was applied for gap size (small: 150 m2 or large: 300 m2) and shape (circular or elongated) including an uncut control. For each treatment, six replicates were used in block design (five treatments, six replicates, altogether 30 plots). From each plot, two 20 cm deep soil samples were taken in the spring of 2023.
The statistical analysis concludes that the effect of the different treatments is not significant on the pH-value, on the humus content of the soil and the soil water content.
The pH value, measured in H2O, ranges between 4.2 and 5.3 with a mean of 4.60. The values in the circular gaps are higher than the values in the elongated gaps, but the models are not significant. Due to less litter, the soil could be less acidic in circular gaps, where the tree crown is less able to reach the middle of the gap.
The result is similar in the humus content with a mean of 2.8 %. Here, the values in the elongated gaps are higher than the values in the circular gaps, but not significantly. This also can be explained by the amount of litter that reaches the soil. Therefore, with more litter more organic material can be degraded into humus.
Also, the soil water content did not significantly differ from each other. The values are higher in circular gaps than in the elongated gaps and the control. This can be explained by the lower evapotranspiration and interception effect in the circular gaps, where neither the roots nor the crowns of the neighbouring trees can reach the gap centre compared to the elongated ones.
We can conclude that gap-cutting in these dimensions does not modify the soil conditions. In circular gaps, a moderate soil water increment is detectable which can accelerate the regeneration processes.
This article was made in the frame of the project TKP2021-NKTA-43 which has been implemented with the support provided by the Ministry of Innovation and Technology of Hungary (successor: Ministry of Culture and Innovation of Hungary) from the National Research, Development and Innovation Fund, financed under the TKP2021-NKTA funding scheme.
How to cite: Nolte, M., Horváth, A., Balázs, P., Ódor, P., and Bidló, A.: Effect of gap size and gap shape on chemical soil characteristics in a Hungarian oak-hornbeam forest, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11197, https://doi.org/10.5194/egusphere-egu25-11197, 2025.
Forest calamity events such as wind breakage, forest fires, and pest infestations have increased in the past due to anthropogenic climate change. These disturbances, while natural succession processes, now occur with unprecedented frequency and severity. To prevent subsequent degradation spirals involving soil erosion, humus loss, and carbon release, rapid ecosystem restoration through reforestation has become crucial, with emphasis on establishing both pioneer vegetation and target tree species. The direct sowing of pelletised seeds by drone is an inexpensive and effective method for reforestation, in contrast to the frequently practised planting. Even areas that are difficult to access can be reached through a targeted species-specific composition and biodiversity can be increased. However, the low germination and establishment rates of the seedlings are challenging. Water availability and other site characteristics have been identified as decisive factors for success. But harsh conditions after calamities are difficult to control.
In the PICO we present a study aiming to reduce the negative impacts through improved germination and establishment rates under dry environmental conditions. To achieve this, different pellet compositions were analysed in a factorial germination experiment for three tree species (Pinus sylvestris, Ulmus laevis, Alnus glutinosa) on undisturbed topsoil samples. The six weeks experiment has three replications for every pellet composition. The pellets exposed to different a) moisture, b) soils, c) sowing depth, and d) to herbaceous vegetation as additional seeds. The biomass, the number and the survival rate of the seedlings were used as variables from 300 individual samples. The influencing variables were identified using generic multivariate models (Random Forest and Boosted Regression Tree). The experiment complemented with data from field trials for a wide range of species and locations for evaluation.
Using generic multivariate models, their supporting effect is confirmed. Moisture and site characteristics were identified as essential influencing variables. The positive effect of hydrogel and magnesium lime in the pellet composition is evident at different moisture levels at the locations. Dry climatic phases can be specifically overcome. The results corroborate the improvement of germination and establishment of seedlings in direct sowing by drones in reforestation. They also point to site-specific optimisation options for direct sowing of pellet seeds by drone.
How to cite: Pollok, L.-M., Goldenberg, S., Bebre, I., and Jackisch, C.: Reforestation after Calamity Events with Direct Sowing of Pellet Seeds by Drone, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19145, https://doi.org/10.5194/egusphere-egu25-19145, 2025.
