NE Slovenia Research Articles

Urban hedges facilitate spontaneous woody plants

Most trees and other woody plants growing within urban areas are deliberately cultivated native or non-native plants. Opportunities for spontaneous establishment and spread of woody species are scarce in an urban environment, especially if the establishment begins from seeds. We hypothesized that urban hedges might offer safe sites for the spontaneous establishment of woody plants, which reach the hedges through propagule dispersal. We recorded the species composition of urban hedges in Maribor (NE Slovenia) in a gradient from the city centre outwards and evaluated the species’ invasive potential and ecological requirements, along with hedge characteristics. Results show that hedges facilitated the survival and growth of 69 woody plants from 28 families. Among these, 62% were non-native and 10% were locally invasive. Most of recorded non-native woody plants were ornamentals. Moreover, for native species, we show that the stressful, warmer urban environment mostly facilitates the establishment of species in the genera Hedera and Acer. Comparison of non-native and native plants showed the former are more drought and heat tolerant than the latter. We further show that with distance from the city centre, the number of bird-dispersed species increases, in contrast to the wind-dispersed species. Additionally, our results suggest evergreen hedges may be less permeable to wind-dispersed propagules than deciduous hedges. Next, we stress the importance of paved surfaces and urbanization, selecting for the thermophile, drought tolerant, wind-dispersed woody plants that find refuge in urban hedges. Our results suggest urban hedges can facilitate the establishment of a wide range of woody plant species.

Influence of the outflow from constructed wetlands on selected streams draining the agricultural landscape at the end of summer

We investigated the impact of the effluent from four constructed wetlands on the structure of the macroinvertebrate and macrophyte communities in the receiving watercourses including the river Pesnica and the Sejanci Stream and Pavlovci Stream in NE Slovenia. Macroinvertebrates and macrophytes were sampled on the sites upstream and downstream of the inflows. Selected environmental parameters were also analyzed on each site. Among the measured chemical and physical parameters, the concentration of NH4–N in the water was the only one that was changed significantly by the inflow from constructed wetlands (CWs). The metrics obtained on the base of the macroinvertebrate community, including the values of diversity indices, the proportion of sensitive taxa and the saprobic index, revealed no significant statistical differences between the upstream and downstream values. Inflows of effluent also have no detectable impact on macrophytes. The removal of degradable organic matter, nitrogen, phosphorus, and suspended solids from the wastewater in studied CWs was sufficient to support this situation, and this has been encouraging to construct new CWs.

Lowland forest fragment characteristics and anthropogenic disturbances determine alien plant species richness and composition

Loss of habitat and biological invasion are the main threats to biodiversity. In intensive agricultural or urban landscapes, forest fragments, even if they are small and isolated represent biodiversity refugia. Environmental variables such as landscape structure, abiotic conditions and anthropogenic disturbance affect the biodiversity of the fragments. In this study, we explored plant species richness in 48 forest fragments embedded in predominantly agricultural landscapes on the alluvial plains of the Mura and Drava rivers in NE Slovenia. We determined several forest fragment characteristics such as perimeter, area, shape complexity, length and proportion of edge shared with adjacent land-cover types and anthropogenic disturbance indicated by the presence of footpaths and waste disposed in fragments. The abiotic condition of these fragments was assessed by Ellenberg indicator values. We built generalized linear models and ordination analyses to assess the importance of environmental variables for the richness and composition of alien plant species and other ecologically meaningful plant groups. Shape complexity had a consistent positive effect on the richness of native and alien plants species. Major drivers of alien plant composition in forest fragments included adjacent land-cover and urbanization level. An increasing proportion of arable land along the forest fragment perimeter negatively affected the richness of alien plants, while the effect of urban areas was positive. Our results confirmed that forest fragments in the rural–urban matrix represent biodiversity refugia and support native plant species; however, they are not resistant to invasions; instead invasion depends on the land-cover type in the surroundings of a given forest fragment.

Human-environment interactions in two Karst catchments – Gradole (NW Croatia) and Ljubija springs (NE Slovenia)

Human-environment interactions in two Karst catchments – Gradole (NW Croatia) and Ljubija springs (NE Slovenia)

Observation of heterospecific mating attempt of Blue Chaser <i>Libellula fulva</i> Müller, 1764 and Broad-bodied Chaser <i>L. depressa</i> Linnaeus, 1758 (Anisoptera: Libellulidae)

A successful copula formation between a male of Libellula fulva and a female of L. depressa was documented photographically on 23. 6. 2022 at a small stream in the Natura 2000 site Ličenca pri Poljčanah in NE Slovenia. This represents the first record of an anomalous mating attempt with copula formation between the species involved. Their distribution in Slovenia as well as syntopic and syntemporal observations in the country are presented and briefly discussed, as are the site-specific factors and aged female coloration that may have contributed to the described rare attempt of heterospecific mating.

Impact of Open-Loop Systems on Groundwater Temperature in NE Slovenia

To achieve sustainable and efficient use of shallow geothermal resources, it is important to understand the heat transfer in the subsurface of the planned geothermal system. In the City Municipality of Murska Sobota, NE Slovenia, the use of geothermal open-loop systems has increased in recent years. Their high spatial density raises the question of possible mutual interference between the systems. By compiling geological, hydrogeological, and thermal data, obtained from the monitoring network, fieldwork, and knowledge of regional hydrogeological conditions, we have developed a transient groundwater flow and heat transfer model to evaluate the impact of the open-loop systems on the subsurface and surrounding systems. The transient simulation showed that the thermal state in the observed area is restored over the summer, when the systems are not in operation. Also, the systems do not have significant mutual interference that would affect their efficiency. However, as interest in installing new systems in the area increases, simulations of the thermal plumes of new geothermal systems are needed to ensure sustainable and efficient use of shallow geothermal energy in the future.

Ground-ivy (Glechoma hederacea L., Lamiaceae) habitats in NE Slovenia

Ground-ivy (Glechoma hederacea L.) is a widespread stoloniferous plant that grows in several ecologically diverse habitats: in the open, at the forest edge, and in understorey. The vegetation of ground-ivy habitats was studied in NE Slovenia in terms of floristic richness and diversity, biological spectrum, phytogeography and syntaxonomy. We identified five clusters of ecologically distinct habitats with the occurrence of ground-ivy, differentiated according to environmental conditions and flora composition: eutrophic forest edges, trampled habitats, forests, which are divided into two groups with different soil moisture, and meadows. The habitats were assessed using Ellenberg indicator values, thus confirming the ecological differentiation of ground-ivy habitats. Ground-ivy coexists with 169 plant species from 49 families. The highest plant species richness and Shannon diversity is found in meadows (100 plant species), while the lowest diversity is found in trampled habitats (12 plant species). Plant species coexisting with ground-ivy belong to 10 geoelements of which circumboreal, sub-cosmopolitan, Euro-Caucasian and Eurasian geoelements are represented in all habitats. The most represented life form is the hemicryptohytes with up to 88 % of all species per relevé. The syntaxon Molino-Arrhenatheretea dominates in the meadows, the shrub species of the forest edges belong to the syntaxon Rhamno-Prunetea, while Querco-Fagatea predominates in the forests. Ruderal species of the syntaxon Stellarietea mediae occurred in all habitats except in the understorey where light is a limiting factor. A non-negligible proportion of species belongs to Galio-Urticetea, a community characteristic of eutrophic forest edges, an optimal habitat for ground-ivy.

Correction: Bernardi et al. OH-Defects in Detrital Quartz Grains from the Julian Basin (NE Italy and Slovenia): A Fourier Transform Infrared Study. Geosciences 2022, 12, 90

The authors would like to correct the published article [...]

Carbon isotopic composition of methane and its origin in natural gas from the Petišovci-Dolina oil and gas field (Pannonian Basin System, NE Slovenia) – a preliminary study

The carbon isotopic composition of methane (δ13CCH4) in natural gas from the Petišovci-Dolina oil and gas field (NE Slovenia) was measured for the first time in August and September 2021. The gas samples from different depths were taken from three wells: Dolina-deep (Pg-6) from the depth interval 3102–3104 m, Petišovci-deep (Pg-5) from the depth interval 2772–2795 m, and Petišovci-shallow (D-5) from the depth interval 1212–1250 m. According to the available composition dataset of gas, available from the Petrol Geo d.o.o. documentation, the “deep” gases sampled from the Pg-6 and Pg-5 wells consist of 85 % methane (C1), 11 % hydrocarbons heavier than methane (C2–C6) and 4 % CO2. The “shallow” gas from well D-5 contains more than 89 % methane, up to 11 % C2–C6 gases, while the CO2 content is negligible. The “deep« gas from the Pg-6 and Pg-5 wells has δ13CCH4 -36.7 ‰ and -36.6 ‰, respectively, while the “shallow” gas from the D-5 well has the δ13CCH4 of -38.6 ‰. The methane from the “shallow” gas is slightly enriched in the lighter 12C isotope. δ13CCH4 in the range from -38.6 to -36.6 ‰ clearly indicates the thermogenic origin of methane formed during the catagenesis phase of gas formation.

Presence of alien Prunus serotina and Impatiens parviflora in lowland forest fragments in NE Slovenia

Temperate alluvial, riparian and lowland forests are the European forests with the greatest presence of invasive alien plants. Consequently, identifying the environmental conditions for and other drivers behind the establishment of invasive species in natural forest communities is crucial for understanding the invasibility of these habitats. We focused on fragments (patches) of Illyrian oak-hornbeam forest in NE Slovenia, which are the least studied in this regard. Because alien phanerophytes and therophytes are significantly over-represented compared to native plants in lowland forests, we selected two representative invasives: the phanerophyte Prunus serotina and the therophyte Impatiens parviflora. By using logistic regression models on vegetation surveys, environmental data based on Ellenberg´s indicator values, and patch metrics, we identified patch characteristics explaining the presence of each species. Moreover, we included human impact in the models. We reveal significant characteristics differentiating P. serotina from I. parviflora. We also show that the perimeter-area ratio and soil nutrients of the forest patches correlate significantly with the presence of P. serotina, while human disturbance correlates significantly with the presence of I. parviflora. Our results and a similar approach for other invasive plant species can be applied to assess habitat invasibility on potential and species’ current geographic distribution, as well as to develop management plans.

Intra and between population genetic relationships among wild cherries [Prunus avium (L.) L.] based on molecular markers

Wild cherries [Prunus avium (L.) L.] are considered typical trees of the Slovenian landscape and often form vigorous natural populations. The determination of genetic relationships among cultivated and wild cherry tree genotypes is important for scientific and economic reasons. Both old trees and young plants were included in our genetic analysis. Sampling took place at two different locations near Maribor, NE Slovenia. The aim of the study was to determine the genetic relationships and variability among plants belonging to the studied populations. We focused on young trees and seedlings growing around old trees, which could be their hypothetical parents. We also analysed genetic uniformity within populations and identified genetically distant plants that had likely migrated as seeds from other populations. Three microsatellite loci were taken into account, 38 genotypes were examined, and 19 polymorphic alleles were detected, corresponding to an average of 6.3 per locus. Genetic distances between the studied genotypes were calculated using the Jaccard’s coefficient and a dendrogram was constructed. Genetic structure was analysed using both Principal Coordinate Analysis (PCoA) and Bayesian model-based analysis. Our study showed that there were differences between the two populations, however, there was some “communication” between them. We observed genetic relatedness as well as a relatively high level of uniformity within each of the wild cherry populations.

An Integrated Approach to Characterising Sulphur Karst Springs: A Case Study of the Žvepovnik Spring in NE Slovenia

We present an integrated approach to characterizing the Žvepovnik sulphur spring, comprising detailed basic geological (mapping), geochemical (physico-chemical, elementary), isotopic (δ2H, δ18O, δ13CDIC, δ34S and 3H), and microbiological analyses. We used a multi-parameter approach to determine the origin of the water (meteoric or deeper infiltration), the origin of the carbon and sulphur, and water retention times. Our special research interest is the origin of the sulphur, as sulphur springs are rare and insufficiently investigated. Our results show that the Žvepovnik spring occurs along the fault near the contact between the dolomite aquifer and overlying shales and volcanoclastic beds. The spring water is the result of the mixing of (1) deeper waters in contact with gypsum and anhydrite and (2) shallow waters originating from precipitation and flowing through the surface carbonate aquifer. The results of δ2H and δ18O confirm local modern precipitation as the main source of the spring. δ13CDIC originates from the degradation of organic matter and the dissolution of carbonates. We therefore propose four possible sources of sulphur: (1) the most probable is the dissolution of gypsum/anhydrite; (2) barite may be a minor source of sulphur; (3) the microbial dissimilatory sulfate reduction; and (4) the oxidation of pyrite as the least probable option.

Potentially Toxic Elements and Pb Isotopes in Mine-Draining Meža River Catchment (NE Slovenia)

In the present study it was observed that Pb, Zn, Cd and As are still present at elevated concentrations in the environment of the upper Meža Valley. In particular, the concentrations of Pb indicate possible new sources have emerged. The main objective of this study was to determine the Pb isotope composition in both the water and the sediments (fractions < 0.150 and <0.063 mm) from the Meža River and its tributaries for the first time and then use them as identifiers of Pb pollution sources. In addition, by calculating the PEC-Q values, the potential hazard of the present concentrations of Pb, Zn, Cd and As to the river environment was evaluated. The results showed elevated Pb and Zn concentrations in the water and sediments at the majority of sampling sites. In general, higher concentrations of Pb, Cd and As were determined in the <0.063 mm fraction, while Zn was higher in the <0.150 mm fraction. The isotope composition of Pb in both fractions differed slightly, indicating an additional Pb source.

OH-Defects in Detrital Quartz Grains from the Julian Basin (NE Italy and Slovenia): A Fourier Transform Infrared Study

In this study, we analyzed up to 80 detrital quartz grains from four lithic greywackes along the stratigraphic column of the Julian Basin, a synorogenic basin in the southeastern Alps between Italy and Slovenia. Fourier transform infrared spectroscopy of detrital quartz was used to investigate the sample set with interest to its OH-defect speciation and content of each associated substitution. According to several recent studies, OH-defects in quartz are correlated to petrogenetic conditions of the source material and can be used as a provenance tool. The aim of this study is to compare results based on this method with previous studies that used other methods, to better constrain the palaeogeographical reconstruction of sedimentary fluxes. Detrital quartz within the samples of the basin shows different patterns of OH-defects and water content, indicating substantial petrogenetic differences between the sediment source rocks. For the oldest analyzed sample (ca. 66 Ma), the distribution of OH-defects suggests a mixed source between igneous and non-igneous rocks, with a predominance of metamorphic material supply. Another sample (56 Ma) reveals a great variability of OH-defects and water content, indicating that the magmatic component dominates over the metamorphic component. The distribution of OH-defects in the samples at the top of the sequence (52–53 Ma) suggests an almost solely metamorphic source. These results are in line with previous studies based on heavy minerals and geochemistry.

Habitat use by waterbirds at Rački ribniki, NE Slovenia

Abstract The difference in habitat use by the observed waterbird species at Rački ribniki (Rače Ponds, NE Slovenia) was studied between June and August 2011. It was assessed that different waterbird species, even closely related species like Aythya ducks, use wetlands differently, with Tufted Ducks A. fuligula observed more on Open water and Ferruginous Ducks A. nyroca more often amongst Floating vegetation. The latter was used more often probably due to the abundance of food in the habitat. Highest species richness was recorded on Floating vegetation as well. This was reflected in species richness of individual ponds, where ponds with more floating vegetation had higher species richness. Although Coots Fulica atra were expected to utilize Floating vegetation more often due to their feeding preferences, they were observed more often on Open water probably feeding on fish fodder available there. The difference in habitat use by the families and nonbreeding individuals of the same species was noted, too, mostly by observing families in habitats that provide more cover from predators (Reeds), or more invertebrate food (Floating vegetation) for the young that often feed on different food than adults. Furthermore, it was suggested that overall management of wetlands should consider providing more suitable wetlands with larger aquatic vegetation cover.

Groundwater level oscillation analysis in shallow alluvial aquifers in Pomurje, NE Slovenia

Systematic hydrologic monitoring of groundwater quantity at the national level in Slovenia has been ongoing since 1952. An insight into long-term groundwater level data enables us to delineate parts of aquifers with similar groundwater level oscillation properties as well as to identify changes of those properties in time. We used variety of statistical methods to identify long-term behaviour of groundwater level oscillation of groundwater body (GWB) Murska kotlina. Results showed that fluctuation of groundwater level in time reflect complex set of events that originate in natural or anthropogenic interferences. Using percentile analysis in combination with cluster analysis, we were able to isolate areas with a related groundwater fluctuation. Results of long-term data trends analyses of monthly groundwater level showed the impact of the research area climate on long-term and seasonal groundwater level fluctuation. In addition to natural causes, by performing trend analysis on groundwater level data, we were able identify some human induced interventions into the environment made in the past.

Local host ant usage of scarce large blue Phengaris teleius and dusky large blue P. nausithous (Lepidoptera: Lycaenidae) at Goričko Nature Park (NE Slovenia)

In our contribution we report on the local host ants of two threatened and protected butterfly species, the scarce large blue (Phengaris teleius) and the dusky large blue (P. nausithous) at Goričko (NE Slovenia), which hosts one of the largest and the most important metapopulation for both species of large blues in Slovenia. Larvae of both species are developing in Myrmica ant nests and different ant species may be used as larval hosts in different parts of the species range. During our study, seven species of potential host ants of the genus Myrmica were found at 12 selected sampling sites. A total of 142 ant nests were examined for the presence of Phengaris larvae. Larvae of P. teleius were found in 25 nests of three ant species: M. scabrinodis, M. rubra and M. gallienii, while larvae of P. nausithous were found in 9 nests, all of M. rubra. The results of the present study provide the first insight into the local host ants of the two Phengaris species in Slovenia and could serve as an important source for active conservation of both species in Slovenia.

Lower Cretaceous heteromorph ammonites (Ancyloceratina) from Leše near Prevalje (North Karavanke Mts. NE Slovenia)

The paper deals with newly discovered Valanginian-Hauterivian fauna of heteromorphic ammonites (Ancyloceratina) from locality south of the village of Leše above the Meža River valley (North Karavanke Mountains). Fossils were recovered from the pelagic limestone. Among the studied heteromorphic ammonites are Lower Cretacaoeus species Himantoceras trinodosum (Upper Valanginian) and Crioceratites cf. nolani (Hauterivian). Based on the accompanied ammonites (Ammonitina) from the outcrop, we biostratigraficaly confirm the presence of Lower Cretaceous ammonites fauna in the Northern Karavanke Mountains. This is also the first report on heteromorphic ammonites in Slovenia.

The MallardAnas platyrhynchosin Slovenia: a review with an estimation of its current population

AbstractAlthough the Mallard is one of the most numerous and best-studied waterbirds in the world, it received almost no attention in Slovenia. It is one of the most frequently observed waterbirds in our country, with frequency often reaching 100%. Sites with lower frequency either freeze in winter or have a low number of individuals to start with. The Mallard is also the most dominant species (17.5% and 89.0%) with higher dominance at sites less suitable for waterbirds due to the lack of available shoals. Mallards reach their maximum numbers during fall migration and winter. Spring migration has no discernible peak and has been significant only for Lake Cerknica. On shallow waters, the maximum is reached in August and September, a month before fall migration begins, indicating local movement to food-rich sites. Females make up only 36.7% of the observed Mallards and reach the maximum proportion (41.5%) in winter and the lowest in April and May (14.7%), when they nest. The breeding season in Slovenia lasts from mid-January to early December, with the majority of females rearing broods from April to July. Average brood size is 6.2 ± 2.66 and declines with season, age of young and altitude. It varies between habitat types and is highest on Treatment and Coastal Wetlands (7.3) and lowest on deep waters such as Reservoirs (5.7) and Lakes (5.6). No really high breeding densities were found in Slovenia and were similar to those in other countries. Breeding densities are higher on smaller Ponds (< 8 ha), on sites with isolated islands and breeding colonies of gulls and terns (e.g. Lake Ptuj). Breeding density also decreases with elevation. Slovenian breeding population is estimated at 1,473–3,763 bp and wintering population averages 22,237 (10,376–32,010) individuals. Data suggest a decline in the wintering population most likely due to warmer winters. The majority of Mallards winter in NE Slovenia, where eight of eleven sites have a maximum of more than 1,000 Mallards. Most Mallards winter on the Drava river with Ptuj and Ormož lakes, where the highest numbers of Mallards were also recorded (Lake Ptuj: 8,330 ind., Lake Ormož: 5,400 ind.). The highest number of individuals during spring migration was recorded on Lake Cerknica (4,581) and during autumn migration on Medvedce reservoir (3,379). Apart from standing waters, the highest density of wintering Mallards is found in urban sections of slow-flowing rivers, probably due to higher safety and food availability.72,731 Mallards were hunted between 2001 and 2018, mainly in NE Slovenia (28% in the Pomursko hunting management district). The number of Mallards hunted is declining in all hunting areas and has declined by 64% since 2001 and even more since the 1990s. According to hunt data, hunting is by far the most important cause of the Mallard mortality in Slovenia (97.4%), followed by predation (1.1%). The Mallard mortality in Slovenia is largely unstudied and natural mortality is most likely underestimated, not only because it does not include mortality in the pre-fledging period, a period with the lowest survival, but also because the detectability of natural mortality is considerably lower. In contrast to the hunted numbers, there have been only nine recoveries of ringed individuals from abroad in the last 100 years, suggesting that hunters may not be reporting recoveries to the ringing centre. Apart from the 1972–1975 period, when 87% of Mallards were ringed, the intensity of ringing of Mallards in Slovenia is low, resulting in only seven Mallards recovered abroad. The longest distance of a Mallard ringed in Slovenia comes from Ukraine (1,290 km), while the longest distance between ringing and recovery sites is 2,075 km from an individual ringed in Finland. The only colour morphs documented in Slovenia are Mallards with paler feathers, attributed to one of the colour aberrations resulting from lower melanin productivity. Only few hybrids and mixed pairings with other wild duck species were observed.

Land consolidation negatively affects farmland bird diversity and conservation value

Land consolidation can negatively affect biodiversity, as it is usually followed by the expansion of arable land, a decrease in crop and land cover diversity, and an increase in the application of agrochemicals. The aim of our study was to compare the species’ composition and abundance of farmland birds, as well as habitat structure, on consolidated and non-consolidated sites in Goričko, NE Slovenia. Habitat diversity was much lower on consolidated sites compared to non-consolidated ones, with arable fields and associated habitats (e.g. grass field margins, field tracks) prevailing on the former. Non-consolidated sites held higher proportions of different types of meadows, hedgerows, solitary trees, succession and traditional orchards. Farmland bird diversity and the abundance of a majority of farmland bird species were higher on non-consolidated sites. The only two exceptions to this were the Eurasian Skylark and the Common Stonechat, which were more abundant on consolidated sites. Both of the species suffered population declines at Goričko in the period 1997–2016, bringing into question the suitability of intensively managed arable fields as their breeding and foraging habitat. Individual species’ regression analysis revealed that the most influential positive explanatory variable for the presence of Red-backed Shrike, Tree Sparrow and Common Whitethroat was non-consolidated, extensively managed mosaic landscape, whereas for the Yellowhammer this explanatory variable was superseded only by forest islands without traditional orchards. Land consolidation, as performed in Slovenia, negatively affects farmland bird diversity and its European conservation value, which is why it should not be performed on Natura 2000 sites, designated for nature conservation.