Contemporary environmental concerns highlight the vulnerability of karst environments to changing hydrometeorological patterns and vegetation disturbance, necessitating a unified, interdisciplinary strategy for comprehensive understanding. This paper critically examines the current state of research. To overcome the identified gaps, it presents an integrated multi-scale ecohydrogeological monitoring approach tailored to karst critical zones (KCZ) and its spatio-temporal variability. Forested karst aquifer in Slovenia is used as a case study to demonstrate and assess the strengths and limitations of the proposed monitoring framework. To decipher flow dynamics and propose customized data collection strategies the approach combines surface and underground sites and employs advanced methods adapted to the challenges of karst environments. The results highlight the benefits and advancements of monitoring and sampling approaches to ensure representativeness in heterogeneous environments. The focus is on the use of enhanced precipitation monitoring systems to expand sampling areas nearly fivefold and improve precipitation and throughfall measurements. Additionally, customized lysimeter techniques for karst soils and microscale adaptations for cave exploration have been developed, addressing the challenges of instrument placement in environments with significant variability. Further opportunities lie in improving instrument protection, integrating sensor networks, combining remote sensing and scaling from plot to aquifer level. However, challenges remain in achieving spatio-temporal representativeness and ensuring the operational reliability of snow monitoring, soil solution sampling and drip flow measurements. Threats include environmental pressures and hydrometeorological conditions, equipment tampering and funding stability. Nevertheless, this comprehensive approach improves monitoring of ecohydrogeological processes in the KCZ, promotes interdisciplinary collaboration and environmental resource management.

This study investigated the sources of carbon and nitrogen in a small, silicate-dominated catchment (Oplotnica River, Pohorje, Slovenia) with two creeks, Lukanjski and Javorski, from 2012 to 2014. Additionally, carbon and nitrogen cycling in soil profiles was studied at Javorski Creek. Isotopic analyses of river water, particulates, and sediments provided a more holistic view of the sources of carbon and nitrogen, weathering contributions, and the evasion or sequestration of CO2 in the atmosphere within the catchments. The weathering of rocks, such as granodiorite and quartz diorite, influences water geochemistry. The Oplotnica River and its tributaries were characterized by the ion composition: Na+ > Ca2+ > Mg2+ > K+ and HCO3− > SO42− > Cl− > NO3−. Partial pressure of CO2 concentrations in river and creeks ranged from 1.1 to 13.4 times that of atmospheric pressure, representing a source of CO2 to the atmosphere. The carbon isotope value of dissolved inorganic carbon (δ13CDIC) ranged from − 9.8 to − 1.4‰ in river, while in the creeks, it ranged from − 26.1 to − 4.7‰, reflecting the degradation of organic matter and exchange with the atmosphere. The intensity of bicarbonate weathering for the Oplotnica River at its gauging station was 10.4 mmol/(l⋅km2⋅s), characteristic of silicate watersheds. The isotopic composition of carbon (δ13C) and nitrogen (δ15N) in river sediments reflects values typical of soil and temperate (C3) plants. This study is significant on both local and global levels, as it addresses the contribution of weathering rates and the release of CO2 to the atmosphere from small silicate watersheds.

Tropospheric ozone (O3) increased globally in the 20th century, contributes to climate change and can have adverse effects on terrestrial ecosystems. The response of forest vegetation to ozone is modulated by species- and site-specific factors and visible foliar symptoms (VFS) are the only direct evidence of ozone effects on vegetation. VFS have been observed and reproduced under (semi-) controlled conditions and their field assessment has been largely harmonized in Europe. We analyzed ozone concentration and VFS data as measured at (respectively) 118 and 91 intensive monitoring sites of the International Co-Operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) spanning over five European biogeographic regions from 2005 to 2018. Average values for VFS were calculated accounting for the number of species present and their observed frequency. Spatial and temporal variation of ozone concentrations, VFS, and their relationships across Europe were then investigated by applying Generalized Linear Mixed Models (GLMMs) and combined GLMMs. Ozone concentrations exceeded 40 ppb on 37.3 % of the sites and were significantly higher (p < 0.05) in the Alpine and the Mediterranean regions. Over the 2005–2018 period there was a substantial stagnation of ozone concentrations with a tendency towards decreasing values in the Alpine-Boreal sites and increasing values in the Atlantic sites. Ozone left a “fingerprint” in terms of VFS on 38 % of the observed broadleaved woody species across Europe, with no significant difference among biogeographic regions. Overall, and again with the exception of an increase at the Atlantic sites, the frequency of VFS remained unchanged or has been slightly declining over the investigated period. We found positive relationship between ozone concentrations and VFS across Europe (p < 0.05), while their temporal trends (both insignificant) were not related. The species with the highest frequency of VFS were those classified as sensitive species under controlled/semi-controlled experimental conditions. Frequency of VFS tends to be modulated by vegetation traits such as specific leaf area and leaf thickness (p < 0.10). Our results showed that, although ozone levels suggested a North-to-South gradient of increasing potential risk to vegetation with hot spots in the Alps and in the Mediterranean, VFS observed on the actual species assemblage at the sites modifies this picture. According to frequency of VFS, ozone risk for vegetation may be higher in parts of the Alpine and Continental Europe than in the Mediterranean region.

Procesi klimatskih promjena stimulisali su brojna istraživanja usmjerena na potencijal tla da djeluje kao skladište ugljika. Dok su zalihe organskog ugljika u tlu (Corg) u vezi s tipom tla, topografijom i vrstama drveća opsežno dokumentovani drugdje, primjećuje se značajan nedostatak podataka o tlima u šumama dinarskih kraških planina. Dinarska regija se karakteriše prisustvom mješovitih raznodobnih šuma bukve i jele (sa smrčom) kojima se upravlja prebornim sistemom, smatranim održivim i pogodnim za očuvanje zaliha Corg tla. U ovom istraživanju, provedenom na četiri uporedive lokacije kraških planinskih šuma (Bjelašnica, Bosna i Hercegovina; Kočevski Rog, Snežnik i Trnovski gozd, Slovenija) istraživano je kako zaliha Corg i odnos C/N variraju u odnosu na uslove staništa, vegetacije i reljefne pozicije. Glavni rezultati obuhvataju podatke o zalihama Corg, procijenjene na temelju izmjerenih koncentracija Corg, izračunatih gustina, grubih fragmenata i efektivnih dubina organskog (Ol, Of, Oh) i mineralnog tla do 60 cm dubine. Istraživanje je otkrilo značajno variranje vrijednosti Corg i C/N u odnosu na stanište i vegetaciju, naročito u organskim horizontima i površinskom mineralnom sloju. Osim toga, istraživanje je pružilo uvid u stabilnost organske materije na temelju odnosa C/N u tlu. Rezultati daju vrijedne informacije o dinamici Corg u tlima dinarskih kraških planina, značaju očuvanja sitnog organskog otpada u šumi i bitne su za održive prakse upravljanja šumama u smislu ublažavanja uticaja klimatskih promjena.

The soil organic carbon (SOC) was determined in soils of enclosed karst depressions (dolines) (NW Dinaric Mts.) to define their potential for organic carbon sequestration. SOC was measured in the forest, succession (scrub-land), and grassland plots at the bottom of dolines at four depths (0-40 cm) and for 40 cm soil layer SOC stock was calculated. We demonstrated that the prevailing fine soil fractions, the C/N ratio and soil thickness play a positive role in the storage capacity of SOC in dolines regardless land use type. Grasslands have the lowest SOC storage capacity (106 t/ha/40 cm), while the highest SOC storage capacity is in succession plots (130 t/ha/40 cm). The last are covered by shrub communities dominated by Prunus spinosa, forming dense communities, and are typical of abandoned croplands or meadows that have been impacted by high levels of nutrients during cultivation phase. At this stage, there is no additional nutrient input in studied plots, which lowers the nutrient content and increases the C/N ratio. C/N ratio is the highest in the forest, where SOC stock capacity is 116 t/ha/ 40 cm. Given the trend towards the abandonment of agricultural land at Kras Plateau (SW Slovenia), we can expect more overgrowth of dolines, and thus an increase in carbon stocks and stabilization of organic carbon in forest soils. In contrary, we noticed the alarming decrease in grasslands and increase in urban land. The SOC storage in 2020 was for 12,538 t/ha/40 cm lower than in 2002. Although grasslands showed the lowest SOC storage, their contribution to total SOC storage in dolines is very important. Since there is a lack of studies on carbon stocks in doline soils, our research is of great importance and a novelty and gives an important back-ground for further research on SOC stock in karst landscapes worldwide.

Karst systems represent 10–15% of land surface in the world and supply around 25% of the global demand for drinking water. In Slovenia karst areas are merely covered by forest and important for their rich and unique ecosystems. However, prevailing beech and mixed fir-beech forests in the region have been exposed to severe large-scale disturbances in the past few years, e.g., ice storms and heavy snow, windthrow, severe and prolonged periods of droughts and secondary insect damage, which have caused episodes of forest decline. Modification of the vegetation cover indirectly impacts the water balance. Despite the important role of karst water resources for supplying the population with drinking water, few studies exist that adequately evaluate the impact of predicted global changes on their quantity and quality. The effects of large-scale forest disturbances have been only marginally addressed, despite evaporation of water from the soil and epikarst being recognized as a significant process affecting hydrological cycle in karst regions. In many hydrological studies, the role and importance of vegetation in infiltration mechanisms, in particular the effect of trees and their root networks, has been widely neglected. In this study we present a holistic approach to infiltration processes research. An in-situ environmental monitoring network of the atmosphere-vegetation-soil-unsaturated zone of the aquifer has been designed to better understand infiltration in different compartments of the karst aquifer. Special focus is given to different forest development phases after large-scale disturbances and karst terrain morphology. The amount of precipitation in the open, canopy interception in mature forest and in canopy gaps with varying forest development phases, soil moisture and soil temperature are measured on the surface and subsurface. These measurements are performed in the area of an eLTER site Postojna-Planina cave system, i.e., on the top and bottom of karst depressions, while in the underground water discharge and electrical conductivity are measured in cave drips. By observing the time lag of the measured parameters to the recharge events, the effective infiltration of precipitation into the aquifer is evaluated and quantified. The results enabled to distinguish the recharge conditions under different forest development phases after large-scale disturbances and under different geomorphological conditions. The findings will in the later stage of the research serve as an input information for coupled vegetation-hydrological modelling of recharge conditions. Upscaling the modelling results from local to entire catchment scale would be useful for the evaluation of impacts of large-scale forest disturbance on the water balance of the entire karst aquifer system.

The present study addresses the short-term effects of different harvest intensities under close-to-nature selective management on the upper soil layers in Slovenian and Bosnian Dinaric karst fir-beech forests. The different harvest intensities coincided with the single-tree and irregular shelterwood management, common in the region. The effect of harvesting intensity on the upper soil layers (Ol, Of, Ol and 0–10 cm mineral soil) was investigated by a repeated measurements experiment in Slovenia on 27 research plots in close-to nature managed forests. The properties of the upper layers (concentration of SOC and TN, C/N ratio, weights, BD and SOC stocks) were analyzed twice, before (2011) and after (2014) treatment of 50% and 100% harvest intensity in relation to the total standing growing stock of trees. As a control, we used no-treatment <20% harvesting intensity plots. To extend this experiment, we added three comparable plots from the Bosnian site: one in an old-growth forest with 0% harvest intensity and two in the managed forest with <20% harvest intensity. The results of the assessment of mean differences indicated a significant influence of harvesting intensity on the decrease in SOC, TN concentrations, weights and SOC stocks in the organic layers and the increase in BD and SOC stocks in the 0–10 cm mineral soil. The highest relative decreases in Ol, Of and Oh SOC stocks occurred in 50% (−10 and −38%) and 100% (−16 and −49%) harvest intensities. Negligible relative differences in both organic and 0–10 cm mineral layers were found for the <20% harvest intensity in the region. The change in forest light conditions resulting from differences in canopy openness as a function of applied harvest intensity explained the significant difference in the properties of the upper soil layers. The impact of the short-term losses in SOC stocks, in terms of overall soil productivity, may depend on the regeneration dynamics and melioration methods.

Skladno z Zakonom o gozdovih del Javne gozdarske službe (JGS) opravlja tudi Gozdarski institut Slovenije (GIS). Aktivnosti JGS na GIS so usmerjene predvsem v strokovno podporo Ministrstvu za kmetijstvo, gozdarstvo in prehrano ter Zavodu za gozdove Slovenije. Podrocja dela JGS / GIS so naslednja: spremljanje stanja razvrednotenja in poskodovanosti gozdov, usmerjanje in strokovno vodstvo porocevalske, prognosticno-diagnosticne službe za gozdove, strokovno usmerjanje gozdne semenarske in drevesnicarske dejavnosti, razvoj informacijskega sistema za gozdove, priprava strokovnih podlag za opravljanje del v gozdovih. GIS v okviru JGS opravlja tudi javna pooblastila. V 25 letih obstoja JGS/GIS so se nabrali stevilni dosežki ter za slovensko gozdarstvo pomembni rezultati. V prispevku predstavljamo poudarke JGS/GIS, za katere menimo, da so aktualni in zanimivi za strokovno javnost.

Change history: In the HTML version of this Article, author 'Filipa Cox' had no affiliation in the author list, although she was correctly associated with affiliation 3 in the PDF. In addition, the blue circles for 'oak' were missing from Extended Data Fig. 1. These errors have been corrected online.

UDK 630*114:630*242(497.6) Large areas of European fir-beech forests are characteristic for the Dinaric Mountains and represent one of the most important forest ecosystems in the region. Such forests extend in high karst plateaus from the eastern Alps in SE Slovenia to the N Albanian massifs at the altitudes from 700 to 1200 (1500) m a.s.l. This is the area with a diverse landscape configuration. The bedrock is consisted of limestone, occasionally of dolomite limestone and dolomite. There are various soil conditions, where in a small area, a mosaic of Leptosols, Rendzic Leptosols, Chromic Cambisol, Calcaric and Chromic Luvisols occur. As climate conditions are very favourable for the growth of forests (high precipitation and air humidity), production function of wood is much more emphasized. Very little is known about the long-term effects of forest management and intensity of logging on soil organic matter quality and carbon stocks in these forest soils. Therefore, with an objective to understand better variations in soil properties, both in space and time, aiming to minimize the uncertainties of the SOC (soil organic carbon) and TN (total nitrogen) stocks, we have set up a research objects in silver fir-beech forests, in Slovenia (research plots in Kočevje, Snežnik and Trnovo) and Bosnia and Herzegovina (research plots on MT Bjelašnica). We analysed soil properties of the unmanaged and managed sites studying differences between treatments and also changes for the two years period of observations. Preliminary results from Slovenian sites show that the high intensity of logging (50 and 100% cut of growing stock) causes a decrease in SOC and TN contents, wider C/N ratio and higher pH values, with the largest level of alternations in the organic part of the soils. The study in Bosnia gave information on inherent SOC and TN concentrations in the organic and surface mineral soil, and also indicated no differences in soil properties between unmanaged and managed sites characterized by low (14-18%) intensities of logging.

Forest condition is influenced by a multitude of stress factors, including air pollution and climatic factors. In Europe, forest condition is assessed by the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and EU regulation. In order to detect the influence of various stress factors the continuous monitoring on the plots throughout Europe is carried out. Croatia is participating with 7 Level II plots and Slovenia with 11 Level II plots. Climate change could influence the levels of acidity and nitrogen in forests. Exceedance of their critical loads describes the vulnerability of forests to environmental stress caused by anthropogenic impact. A critical load for nitrogen is exceeded on many plots in Europe. Following the ICP Forests methodology, annual bulk and throughfall deposition of nitrogen was calculated as the means of the yearly sums (kg ha-1 y-1) from 2008 to 2010 for two Level II plots. One plot is located in Croatia (Jastrebarski lugovi, 110) and the other in Slovenia (Murska suma, 11), both at similar latitude and longitude, with similar age both dominated by Quercus robur L. (Pendeculate oak). The aims of this study are the following: (1) to identify differences in nitrogen deposition and precipitation between the sites and across time ; (2) to evaluate the nitrogen loads in Croatia and Slovenia (3) to compare actual and critical loads of the plot Preliminary results of this study showed that nitrogen loads for bulk and throughfall deposition is not exceeded the critical level on both plots. Therefore, it`s still not influencing the stress on in the Quercus robur L. forest ecosystem. The average nitrogen deposition is higher on plot 11 than on plot 110. The nitrogen deposition was the highest in 2008 on plot 110 and in 2009 on plot 11.