1. Ragweed leaf beetle Ophraella communa LeSage, 1986 (Coleoptera, Chrysomelidae) successfully crossing the Slovenian-Austrian borderMirjana Šipek, Eva Horvat, Nina Šajna, 2025, izvirni znanstveni članek Opis: In the past two decades, several alien insect species have been introduced to Europe. One of these is the chrysomelid beetle Ophraella communa, a promising biocontrol agent against its host plant, Ambrosia artemisiifolia. Ambrosia artemisiifolia produces highly allergenic pollen that causes significant health issues, leading to substantial healthcare costs. Since its first recorded occurrence in Italy and Switzerland in 2013, O. communa has been rapidly spreading across Europe. In 2023 and 2024, we monitored 27 populations of A. artemisiifolia in various habitats in northeastern Slovenia and one population across the border in Austria. We recorded the presence of O. communa, its developmental stages, herbivory damage, and associated fauna. Ambrosia artemisiifolia population sizes ranged from a single plant to entire fields with over 100 individuals. We confirmed the presence of O. communa in 89% of the monitored Slovenian populations as well as in the Austrian site. Ophraella communa was observed in Radkersburg, Austria, on July 31, 2024, with a single adult specimen found in a large A. artemisiifolia population growing in a pumpkin field. One week later, eggs were detected, and by the end of August, all developmental stages of O. communa were present. Despite this, the herbivory rate remained relatively low in all monitored populations. The accompanying fauna of A. artemisiifolia in agricultural fields included several specimens of Corythucha arcuata. In an urban environment, at a ruderal parking lot in Maribor, we observed one adult Cicadella viridis on an A. artemisiifolia stem and a final instar of Zicrona caerulea preying on a larva of O. communa. This research provides valuable insights into the dynamics of invasive species and their rapid range expansion. Ključne besede: biological invasions, alien insects, herbivory, biocontrol, range expansion, ambrosia Objavljeno v DKUM: 01.10.2025; Ogledov: 0; Prenosov: 1
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2. Response of the invasive alien plant Duchesnea indica (Andrews) Teschem. to different environmental and competitive settingsMaja Kreća, Nina Šajna, Mirjana Šipek, 2025, izvirni znanstveni članek Opis: Indian mock strawberry (Duchesnea indica, syn. Potentilla indica), a clonal invasive plant native to Asia, has rapidly spread in Europe, where its ecological adaptation allows it to thrive under varying environmental conditions. It is mostly found in urban habitats such as lawns, parks, and urban and peri-urban forests, where it thrives in various plant communities. It can become dominant in certain communities, indicating its competitive advantage over native plants. Due to similar habitat preferences, it often coexists with the native species Glechoma hederacea, with which it shares other characteristics such as clonal growth. This study investigates the effects of light, nutrients, and competition on the growth, morphology, and physiology of D. indica. A controlled pot experiment exposed plants to combinations of sunlight and shade, optimal and increased nutrient levels, and competitive scenarios with the native plant G. hederacea. The plant traits of biomass, leaf and ramet number, stolon and flower production, leaf greenness, the photosynthetic efficiency of Photosystem II, and stomatal conductance were assessed. Results revealed that light and nutrient availability significantly enhanced growth metrics. In shaded conditions, D. indica adapted with elongated petioles and increased specific leaf area. Competition significantly reduced growth, with G. hederacea outperforming D. indica. These findings highlight the complex interplay between abiotic and biotic factors in influencing invasive species impact, providing essential insights for ecosystem management. Ključne besede: non-native species, light availability, nutrient availability, intraspecific competition, interspecific competition, pot experiment, morphological traits, ecophysiological traits Objavljeno v DKUM: 23.06.2025; Ogledov: 0; Prenosov: 6
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3. Additional records of Megabruchidius dorsalis (Fåhræus, 1839) (Coleoptera, Chrysomelidae, Bruchinae) in Zagreb, CroatiaEva Horvat, Mirjana Šipek, Nina Šajna, 2022, izvirni znanstveni članek Opis: In this paper, we report two new locations of the alien invasive seed beetle Megabruchidius dorsalis in Zagreb, Croatia. Additionally, we confirm for the second time the presence of M. dorsalis at one location in the same city. All beetles were reared from mature Gleditsia triacanthos pods collected from the ground (three locations) and from trees (one location). These records contribute to the knowledge of the distribution of M. dorsalis in Europe. Ključne besede: new locations, seed beetle, alien species, range expansion, coexistence, Europe Objavljeno v DKUM: 04.02.2025; Ogledov: 0; Prenosov: 12
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4. Urban hedges facilitate spontaneous woody plantsEva Horvat, Mirjana Šipek, Nina Šajna, 2024, izvirni znanstveni članek Opis: 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. Ključne besede: biodiversity, green infrastructure, ornamental plants, species richness, urban ecosystem, vegetation Objavljeno v DKUM: 03.12.2024; Ogledov: 0; Prenosov: 23
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5. Lowland forest fragment characteristics and anthropogenic disturbances determine alien plant species richness and compositionMirjana Šipek, Nina Šajna, 2024, izvirni znanstveni članek Opis: 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. Ključne besede: agricultural land, urban area, settlements, fragment size, fragment shape complexity, ornamental plants Objavljeno v DKUM: 29.11.2024; Ogledov: 0; Prenosov: 17
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6. First records of seed beetles Megabruchidius dorsalis (Fåhræus, 1839) and M. tonkineus (Pic, 1904) from three Balkan countriesMirjana Šipek, Eva Horvat, Nina Šajna, 2022, izvirni znanstveni članek Opis: Asian seed beetles of the genus Megabruchidius have been recorded recently in many European countries. Our contribution serves to formally report the first records of M. dorsalis in Bosnia and Herzegovina, Montenegro and Albania and the first record of M. tonkineus in Montenegro, all found in 2021. Both species develop inside the hard seeds of the ornamental tree Gleditsia triacanthos. Mature G. triacanthos pods were collected from the ground in urban parks of Nikšić and Podgorica (Montenegro) and Tirana (Albania) in July 2021, and Banja Luka (Bosnia and Herzegovina) in August 2021. Fully developed beetles were recorded after two weeks. Megabruchidius dorsalis emerged from the pods collected in all locations, while M. tonkineus was reared only from the pods collected in Podgorica. Because in Podgorica both species were found in the same pods, this also represents confirmation that in some locations these species do co-exist. Overall, M. dorsalis was more widespread and abundant. Ključne besede: alien species, invasive species, range expansion, Gleditsia triacanthos, Europe Objavljeno v DKUM: 25.09.2024; Ogledov: 0; Prenosov: 7
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7. Transpiracija in alelopatski potencial sončnih in senčnih rastlin indijskega jagodnjaka (Potentilla indica (Andrews) Th.Wolf) : magistrsko deloAnamari Draškovič, 2024, magistrsko delo Opis: V sklopu magistrske naloge smo preučevali razlike v prevodnosti listnih rež in alelopatski potencial indijskega jagodnjaka (Potentilla indica (Andrews) Th.Wolf) med sončnimi in senčnimi rastlinami. Na izbranem rastišču indijskega jagodnjaka smo skozi daljše časovno obdobje s porometrom spremljali prevodnost listnih rež. Za testiranje alelopatskega potenciala indijskega jagodnjaka smo izbrali test kalitve s semeni vrtne kreše (Lepidium sativum L.). Slednje smo za 4 dni izpostavili različnim koncentracijam vodnih izvlečkov sončnih in senčnih listov (0,1 %, 1 %, 5 %, 10 %). Na podlagi deleža vzkaljenih semen in rasti radikule in hipokotila smo ugotovili, da vodni izvlečki listov indijskega jagodnjaka močno vplivajo na kalitev semen, medtem ko na rast vrtne kreše nimajo takšnega vpliva. Z naraščanjem koncentracije vodnih izvlečkov listov indijskega jagodnjaka se je delež vzkaljenih semen zmanjševal. Razlike v alelopatskem potencialu sončnih in senčnih rastlin niso bile tako očitne kot smo pričakovali. Smo pa opazili sezonsko nihanje alelopatskega potenciala. Ugotovili smo, da je ta bil najnižji v času, ko so bili prisotni plodovi. Razlike med sončnimi in senčnimi rastlinami pa so bile bolj opazne pri merjenju prevodnosti listnih rež. Ta je bila skozi celotno raziskavo višja pri sončnih rastlinah. Ugotovili smo tudi, da prevodnost listnih rež pada z naraščajočo temperaturo in svetlobnim sevanjem ter narašča s povečevanjem vlage tal. Ključne besede: indijski jagodnjak, prevodnost listnih rež, alelopatija, tujerodne invazivne vrste, porometrija Objavljeno v DKUM: 05.09.2024; Ogledov: 41; Prenosov: 27
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8. Presence of alien Prunus serotina and Impatiens parviflora in lowland forest fragments in NE SloveniaMirjana Šipek, Eva Horvat, Ivana Vitasović Kosić, Nina Šajna, 2022, izvirni znanstveni članek Opis: 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 plantsin 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 perimeterarea 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. Ključne besede: biological invasions, forest fragmentation, landscape metrics, habitat characteristics, human presence, anthropogenic factors, neophytes, Slovenia Objavljeno v DKUM: 12.07.2024; Ogledov: 136; Prenosov: 13
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9. The importance of thermally abnormal waters for bioinvasions - a case study of Pistia stratiotesNina Šajna, Tina Urek, Primož Kušar, Mirjana Šipek, 2023, izvirni znanstveni članek Opis: Thermally abnormal waters represent safe sites for alien invasive plants requiring warmer conditions than provided by the ambient temperatures in the temperate zone. Therefore, such safe sites are frequently inhabited by tropical and sub-tropical plants. By performing a literature review we assessed that at least 55 alien aquatic plant taxa from 21 families were found in thermally abnormal waters in Europe. The majority of these taxa are submerged or rooted macrophytes. Six taxa are listed as quarantine pests according to EPPO. Among these, Pistia stratiotes is present in seven European countries, most of the records of this presence being recent. We studied P. stratiotes in a thermally abnormal stream where a persistent population was able to survive harsh winters. Models showed that the optimum temperature for P. stratiotes biomass was 28.8 ± 3.5 ◦C. Here, we show that air temperatures had a higher influence on the photosynthetic efficiency of P. stratiotes, estimated by chlorophyll fluorescence measurements, than did water temperatures. Generally, growth, and consequently surface cover for free-floating plants, cannot be explained solely by thermally abnormal water temperatures. We conclude that even though the majority of thermophile alien plant occurrences resulted from deliberate introductions, thermally abnormal waters pose an invasion risk for further deliberate, accidental, or spontaneous spread, which might be more likely for free-floating macrophytes. Ključne besede: macrophytes, alien invasive plants, chlorophyll fluorescence, plant mass, temperature gradient Objavljeno v DKUM: 05.06.2024; Ogledov: 158; Prenosov: 34
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10. Understorey species distinguish late successional and ancient forests after decades of minimum human intervention : a case study from SloveniaMirjana Šipek, Tim Ravnjak, Nina Šajna, 2023, izvirni znanstveni članek Opis: The main species composition drivers in temperate deciduous forests are environmental conditions, a stand's age and the site history, e.g., the succession stage and past land use, as well as disturbance regime and current management. We compared plant species diversity and composition in late successional and ancient forests, co-occurring on the same small river island applying species accumulation curves and nonmetric multidimensional scaling, respectively. Given the island's geomorphological characteristics, we expected these to be very similar before human intervention in the past. The forests experienced differing disturbance regimes in the past, while over the last 30 years, human intervention has been the same and reduced to a minimum. The ancient forest in this study had two major characteristics defining it as old, mature forest: continuity of presence for more than 200 years and specific composition. The late successional forest experienced major disturbance in the 20th century and was allowed natural regeneration by bordering on the ancient forest, representing a potential species pool, and by decades of minimum human intervention. Our results showed that, even though there was no difference in species richness, we could still detect differences between the forests, particularly in the abundance and species composition of the understorey, among which geophytes had the most indicative importance. To make our results useful on a broader scale, we composed from the literature a species list of plants indicative for ancient forest and tested its application. These results are important for distinguishing between old and mature secondary stands and particularly for identifying old forest stands, which should be conserved and, in the case of fragmented landscapes, included in a network connecting forest fragments. Ključne besede: forest community, successional forest, indicator plants, plant diversity, understorey, geophyte, Slovenia Objavljeno v DKUM: 03.06.2024; Ogledov: 151; Prenosov: 27
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