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Query: "author" (Janez Kermavnar) .

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Gozdna tla in vegetacija eno leto po požaru na Goriškem Krasu
Valerija Babij, Lado Kutnar, Aleksander Marinšek, Janez Kermavnar, 2024, original scientific article

Abstract: V letu 2023 − eno leto po obsežnem požaru na Goriškem Krasu, ki je divjal julija leta 2022 − smo na izbranih gozdnih vzorčnih ploskvah popisali zeliščno, grmovno in drevesno vegetacijo in analizirali tla do globine 10 cm. Ploskve smo izbrali na lokacijah stalnih vzorčnih ploskev ZGS z različno stopnjo poškodovan osti zaradi požara. Na izbranih ploskvah smo skupno popisali 260 vrst praprotnic in semenk. V drevesni plasti smo popisali trinajst vrst (enajst domorodnih in dve tujerodni), v grmovni plasti trideset, v zeliščni pa 255. V drevesni plasti so bili najpogostejši mali jesen, črni gaber in črni bor, v grmovni mali jesen, navadni ruj in robide. V zeliščni plasti smo med drugimi popisali tudi devetnajst drevesnih vrst, ki so pomembna zasnova pri naravni obnovi požganega gozda na Krasu; najpogostejša sta bila črni gaber in rešeljika. Gradient poškodovanosti po požaru se jasno kaže v večini vegetacijskih in talnih spremenljivk. Statistično značilne razlike med skupinami ploskev z različno stopnjo poškodovanosti smo ugotovili za šest parametrov: pH-vrednosti in vsebnosti žvepla v organskem delu tal, zastiranje drevesne plasti, zastiranje mahov, število vrst v spodnji drevesni plasti, število vrst zeliščne plasti. Na ploskvah smo prepoznali devet (ter še tri vrste na požarišču zunaj ploskev) invazivnih ali potencialno invazivnih tujerodnih rastlinskih vrst; med drevesnimi sta bila najpogostejša robinija in visoki pajesen. Študija pomembno prispeva k razumevanju razvoja vegetacije, pomlajevanja ključnih drevesnih vrst in poškodb gozdnih tal v inicialni fazi po obsežnem požaru.
Keywords: gozdna vegetacija, poškodbe tal, gozdni požar, drevesne vrste, pestrost vrst, invazivne rastlinske vrste, Kras, Slovenija
Published in DiRROS: 21.05.2024; Views: 250; Downloads: 124
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3.
ReSurveyEurope : a database of resurveyed vegetation plots in Europe
Ilona Knollová, Milan Chytrý, Helge Bruelheide, Stefan Dullinger, Ute Jandt, Markus Bernhardt-Römermann, Idoia Biurrun, Francesco de Bello, Michael Glaser, Stephan M. Hennekens, Mateja Germ, Aleksandra Golob, Janez Kermavnar, Lado Kutnar, Urban Šilc, 2024, review article

Abstract: Aims We introduce ReSurveyEurope — a new data source of resurveyed vegetation plots in Europe, compiled by a collaborative network of vegetation scientists. We describe the scope of this initiative, provide an overview of currently available data, governance, data contribution rules, and accessibility. In addition, we outline further steps, including potential research questions. Results ReSurveyEurope includes resurveyed vegetation plots from all habitats. Version 1.0 of ReSurveyEurope contains 283,135 observations (i.e., individual surveys of each plot) from 79,190 plots sampled in 449 independent resurvey projects. Of these, 62,139 (78%) are permanent plots, that is, marked in situ, or located with GPS, which allow for high spatial accuracy in resurvey. The remaining 17,051 (22%) plots are from studies in which plots from the initial survey could not be exactly relocated. Four data sets, which together account for 28,470 (36%) plots, provide only presence/absence information on plant species, while the remaining 50,720 (64%) plots contain abundance information (e.g., percentage cover or cover–abundance classes such as variants of the Braun-Blanquet scale). The oldest plots were sampled in 1911 in the Swiss Alps, while most plots were sampled between 1950 and 2020. Conclusions ReSurveyEurope is a new resource to address a wide range of research questions on fine-scale changes in European vegetation. The initiative is devoted to an inclusive and transparent governance and data usage approach, based on slightly adapted rules of the well-established European Vegetation Archive (EVA). ReSurveyEurope data are ready for use, and proposals for analyses of the data set can be submitted at any time to the coordinators. Still, further data contributions are highly welcome.
Keywords: biodiversity, monitoring, species richness, vascular plants, vegetation dynamics
Published in DiRROS: 23.04.2024; Views: 274; Downloads: 114
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4.
Habitat degradation facilitates the invasion of Neophytes : a resurvey study based on permanent vegetation plots in oak forests in Slovenia (Europe)
Janez Kermavnar, Lado Kutnar, 2024, original scientific article

Abstract: The spread of neophytes (non-native plant species) challenges the conservation status and ecological integrity of forests, especially in lowland areas. Long-term resurvey studies are needed to evaluate the temporal dynamics of neophytes in forests; however, such data are scarce. In 2023, we resampled a set of 45 permanent vegetation plots (established in 1992/93) in two forest vegetation types: oak–hornbeam forests dominated by Quercus robur and colline oak–beech forests dominated by Q. petraea. Over the last 30 years, oak forests have experienced extensive oak tree mortality, with the degree of habitat degradation being greater in Q. robur forests. In the early 1990s, only three neophytes with low abundance were recorded across all plots. In the 2023 resurvey, the total number of neophytes increased to 22 species (15 herbaceous and 7 woody species), comprising 6.9% of the total species pool in the understory layer. The increase in the plot-level number and cover of neophytes was significant in plots dominated by Q. robur but not in those with Q. petraea. The most frequent neophytes were Impatiens parviflora (present in 31% of plots), Solidago gigantea (27%), Erigeron annuus (16%) and Erechtites hieraciifolia (16%). The richness and cover of neophytes were significantly affected by the tree layer cover (negative correlation) and the degree of soil disturbance (positive correlation). All neophytes established in disturbed patches, whereas the occurrence of I. parviflora was exceptional as it was able to colonize less degraded, shaded understory environments. Habitat degradation (the mortality-induced loss of stand-forming oak trees resulting in extensive tree layer cover decrease) emerged as a key driver promoting neophyte proliferation, coupled with the impact of management-induced disturbances affecting overstory and soil conditions. The spread is expected to continue or even intensify in the future because novel light regimes and disturbances make forest habitats less resistant to neophyte proliferation.
Keywords: long-term vegetation change, invasive non-native plants, oak mortality, Quercus robur, Quercus petraea, canopy openness, Impatiens parviflora, Slovenia
Published in DiRROS: 19.04.2024; Views: 244; Downloads: 103
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5.
Mixed signals of environmental change and a trend towards ecological homogenization in ground vegetation across different forest types
Janez Kermavnar, Lado Kutnar, 2024, original scientific article

Abstract: Forest ground vegetation may serve as an early warning system for monitoring anthropogenic global-change impacts on temperate forests. Climate warming may induce a decline of cool-adapted species to the benefit of more thermophilous plants. Nitrogen deposition has been documented to potentially result in soil eutrophication or acidification, which can increase the proportion of species with higher nutrient requirements and species impoverishment caused by competitive exclusion. Abiotic forest disturbances are changing the light conditions in the forest understorey environment. In this resurvey study, we tested the magnitude and direction of change in alpha (species richness) and beta (within-site dissimilarity) diversity and composition of forest ground vegetation in forests of different types in Slovenia over fifteen years. Using plant-derived characteristics (Ellenberg-type indicator values) and by testing a priori predictions concerning expected effects of environmental drivers, we show that the magnitude and direction of forest ground vegetation diversity and floristic changes varies greatly between forest sites. Divergent responses at different sites resulted in low net change of alpha and beta diversity and a weak overall environmental signal. The largest decrease in species number was observed in lowland oak-hornbeam forests, which were also among the sites with the greatest compositional shifts. Changes in beta diversity did not show any consistent trend, and anticipated floristic convergence was not confirmed when all sites were considered. Thermophilization was mainly detected in montane beech sites and alpine spruce forests whereas eutrophication signal was most significant on nutrient-poor sites. Vegetation responses were strongly dependent on initial site conditions. Shrinkage of ecological gradients (process of ecological homogenization) suggests that sites positioned at the ends of the gradients are losing their original ecological character and are becoming more similar to mid-gradient sites that generally exhibit smaller changes. Our results point to the importance of local stand dynamics and overstorey disturbances in explaining the temporal trends in forest ground vegetation. Ground vegetation in Slovenian forests is changing in directions also dictated by multiple regional and global change drivers.
Keywords: vegetation resurvey, thermophilization, eutrophication, forest disturbances, alpha and beta diversity, initial site conditions, ICP-Forests network
Published in DiRROS: 09.04.2024; Views: 371; Downloads: 175
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6.
Importance of habitat context in modelling risk maps for two established invasive alien plant species : the case of Ailanthus altissima and Phytolacca americana in Slovenia (Europe)
Maarten De Groot, Erika Kozamernik, Janez Kermavnar, Marija Kolšek, Aleksander Marinšek, Andreja Nève Repe, Lado Kutnar, 2024, original scientific article

Abstract: Forests are important ecosystems that face threats from climate change and global environmental shifts, with invasive alien plant species being a significant concern. Some of these invasive species have already become established, while others are in the process of naturalisation. Although forests are a relatively stable ecosystem, extreme weather events increase their vulnerability to change, and clearings left after natural disturbances are particularly susceptible to invasion by alien plant species (IAPS). We created risk maps of two species that have spread rapidly in the last decade: American pokeweed (Phytolacca americana) and the tree of heaven (Ailanthus altissima). We prepared a generalised linear model based on the occurrence data collected within the LIFE ARTEMIS project. Eleven environmental variables were used to determine habitat characteristics. We constructed two models for each species: one covering the entirety of Slovenia and the other specifically for the forested areas in Slovenia, with the latter incorporating forest-specific variables (such as forest sanitation felling and monocultures). We observed the presence of both species at lower altitudes and in close proximity to water sources. American pokeweed tends to occur nearer to railways, while the presence of the tree of heaven is associated with areas lacking carbonate parent material and influenced by land use patterns. In forested areas, the occurrence of American pokeweed is influenced by forest habitat characteristics, such as disturbances caused by extreme weather events or the prevalence of Norway spruce monocultures. In contrast, the occurrence of the tree of heaven is influenced by more general environmental variables, such as altitude and proximity to railways. Consequently, we have generated risk maps for the entirety of Slovenia and separately for forested areas, both of which indicate similar levels of risk, particularly for the tree of heaven. The risk map for American pokeweed highlights numerous vulnerable areas, especially forest edges, which are highly susceptible to invasion. Furthermore, there is a higher likelihood of this species occurring in areas that have undergone sanitation felling. This study suggests that the production of risk maps of IAPS could be improved by focussing on habitat types and taking into account habitat-specific variables. This approach could enhance the early detection and management of these invasive species.
Keywords: American pokeweed, tree of heaven, species distribution modelling, forests, forest disturbance, habitat suitability
Published in DiRROS: 26.03.2024; Views: 311; Downloads: 1738
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More losses than gains? : Distribution models predict species-specific shifts in climatic suitability for European beech forest herbs under climate change
Janez Kermavnar, Lado Kutnar, Aleksander Marinšek, 2023, original scientific article

Abstract: Introduction: Herbaceous plant species constitute an essential element of the flora of European beech (Fagus sylvatica) forests. There is increasing evidence that rapidly changing climate is likely to modify the spatial distribution of plant species. However, we lack understanding of the impact that climate change might have on beech forest herbs across the European continent. We investigated the possible effects of predicted increasing rates of global warming and altered precipitation regimes on 71 forest herbs closely associated with beech forests, but with varying biogeographic and climatic niche attributes. Methods: By using a total of 394,502 occurrence records and an ensemble of species distribution models (SDMs), we quantified the potential current distribution and future (2061-2080) range shifts in climatic suitability (expressed as occurrence probability, OP) according to two climate change scenarios (moderate SSP2-4.5 and severe SSP5-8.5). Results: Overall, precipitation of the warmest quarter and temperature seasonality were the most influential predictors in shaping current distribution patterns. For SSP5-8.5 scenario, all studied species experienced significant reductions (52.9% on average) in the total size of highly suitable areas (OP >0.75). However, the magnitude and directions of changes in the climatic suitability were highly species-specific; few species might even increase OP in the future, particularly in case of SSP2-4.5 scenario. The SDMs revealed the most substantial decline of climatic suitability at the trailing edges in southern Europe. We found that climatic suitability is predicted to show unidirectional northward shift and to move toward higher elevations. The gain/loss ratio was generally higher for narrow-ranged species compared to widespread taxa. Discussion: Our findings are contextualized with regards to potential confounding factors (dispersal limitation, microclimatic buffering) that may mitigate or accelerate climate change impacts. Given the low long-distance migration ability, many beech forest herbs are unlikely to track the velocity with which macroclimatic isotherms are moving toward higher latitudes, making this species group particularly vulnerable to climate change.
Keywords: species distribution modelling, global warming, range shift, climatic niche, biogeography, Europe
Published in DiRROS: 29.11.2023; Views: 415; Downloads: 212
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Congruence between vascular plants and bryophytes in response to ecological conditions in sustainably managed temperate forests (taxonomic- and trait-based levels)
Lado Kutnar, Janez Kermavnar, Marko S. Sabovljević, 2023, original scientific article

Abstract: Vascular plant species (VP) and bryophytes (B) constitute a significant portion of forest biodiversity and respond to both management intensity and natural disturbances within forests. In this study, we investigated the cross-taxa congruence between understorey VP and B at both diversity and composition levels across a wide range of sustainably managed forests in Slovenia. The taxonomic and functional characteristics of the selected plant groups were studied, with a particular emphasis on ground-dwelling species. We employed a trait-based approach to examine the functional characteristics. On average, the species richness of B in sustainably managed temperate forests increased with the corresponding number of VP. Furthermore, a moderate positive correlation in species composition between the studied groups of ground-dwelling organisms was also observed. The ground-dwelling VP and B were congruent in terms of trait-based composition, which was influenced by soil reaction and nutrients and light availability, while trait-based diversity was only slightly similar in response to moisture. A negative correlation between the composition of stress-tolerant VP and B hemeroby was found, indicating forest environments with a low level of disturbance. This is likely due to the sustainable management of Slovenian forests, where climate change and natural disturbances have intensified in recent years. A cross-taxon comparison of the two groups at four different levels, namely taxonomic-based diversity and composition and trait-based diversity and composition, revealed varying degrees of congruence. It is therefore important to monitor the status and temporal trends of both groups from different aspects to draw reliable conclusions.
Keywords: understory, mosses, terricolous species, diversity, composition, taxonomy, life-history traits, environmental gradients, managed forest, ICP Forests program, Slovenia
Published in DiRROS: 10.10.2023; Views: 608; Downloads: 250
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