1. 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: 120; Downloads: 57
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2. Transnational strategy on the sustainable management and responsible use of non-native trees in the Alpine SpaceKatharina Lapin, Anja M. Bindewald, Giuseppe Brundu, Aleksander Marinšek, Debojyoti Chakraborty, Janine Oettel, Janine Oettel, Konrad Heino, Nicola La Porta, Ajša Alagić, 2023, review article Abstract: Non-native tree species – defined as those species intentionally or unintentionally introduced by humans – have long been a part of the Alpine Space, providing numerous benefits, but also posing a potential threat to native biodiversity and related ecosystem services. Compared to the urban space where non-native trees comprise most tree species, the number of non-native trees in forests and plantations is relatively low. To evaluate potential risks and benefits of non-native trees in the Alpine Space, a transnational strategy for the responsible use and management of non-native trees is needed. The goals of the strategy are to tailor management practices for a sustainable and responsible use or admixture of non-native trees, to reduce the risks connected with the invasive potential of some non-native tree species, to help forests and urban areas to adapt to climate change, and to improve coordination and cooperation regarding best practices between different regions of the Alpine Space. A proposal was developed in a four-step process including expert-based assessment, stakeholder mapping, an extensive data review, and a public consultation. For implementing the strategy fully, strong collaboration among diverse stakeholders is anticipated and robust governance and an adequate long-term and fair funding scheme is needed.
Keywords: adaptive forest management, non-native tree species, Alpine Space, biosecurity, green infrastructure
Published in DiRROS: 19.01.2024; Views: 214; Downloads: 119
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3. Fertilisation with potato starch wastewater effect on the growth of Scots pine (Pinus sylvestris L.) forest in PolandNella Waszak, Filipe Campelo, Iain Robertson, Radosław Puchałka, Fatima-Zahraa El Balghiti, Jožica Gričar, Ali Boularbah, M. Koprowski, 2024, original scientific article Abstract: Fertilisation is often used to increase plant productivity in agriculture but has also been used in forestry. In our study, Scots pine forest growing in a nitrogen-poor environment was fertilised with NPK post-production wastewater from a potato starch factory. Our research aimed to investigate the dependence of tree growth on different NPK concentrations. Cell characteristics such as cell wall thickness (CWT), lumen diameter (LD) and tree-ring features such as ring width (RW), total number of cells in annual growth (nTotal), earlywood (EW) and latewood (LW) were investigated. Twenty-six years of regular fertilisation of the forest with different doses of wastewater rich in NPK elements have affected the anatomical structure of Scots pine trees. It is presumed that the reduction in CWT and LD on the fertilised site was due to deficiencies in plant water conductivity, which may have occurred due to physiological drought. The influence of nitrogen on unfertilised site from the wastewater area could contribute to the CWT thickening. The results confirm that the use of NPK in excessive doses is detrimental to trees' conductive system.
Keywords: wastewater effluents, forest fertilisation, cell measurements, tree-ring width, wood anatomy
Published in DiRROS: 03.01.2024; Views: 237; Downloads: 131
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4. Infestation intensity by the invasive oak lace bug, Corythucha arcuata (Say) in mixed and pure oak standsGernot Hoch, Alex Stemmelen, Eötvös Csaba Béla, Werner Hinterstoisser, Miran Lanšćak, Srđan Stojnić, Máté Tóth, Marjana Westergren, Simon Zidar, Milica Zlatković, Nikola Zoric, Maarten De Groot, 2024, original scientific article Abstract: There has been accumulating evidence for effects of tree species composition on herbivory with many examples of lower damage by specialist feeders in tree species rich forests. In a joint study in five Central and Southeastern European countries, we studied the effect of tree species richness on infestation intensity of the oak lace bug, Corythucha arcuata (Say) (Heteroptera, Tingidae), an invasive pest on oak trees that has spread rapidly across the Balkan Peninsula and Central Europe. Intensity of infestation by C. arcuata on oaks was assessed on three or four study plots with high (pure stands) and three or four plots with low percentage of oak (mixed stands) in each country. Ordinal regression analysis showed that intensity of infestation of trees by C. arcuata differed between countries; no significant effect of stand type (mixed or pure) on infestation levels was detected. When analysing the percentage of trees in the highest infestation class, stand type had a significant effect with more intensive infestation in pure stands. We conclude that mixed stands will not prevent severe infestation but may help mitigating the impact of established C. arcuata populations.
Keywords: associational resistance, Corythucha arcuata, diversity, host tree concentration, invasive forest pest
Published in DiRROS: 14.11.2023; Views: 307; Downloads: 185
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5. Radial increment of beech (Fagus sylvatica L.) Is under a strong impact of climate in the continental biogeographical region of CroatiaTom Levanič, Damir Ugarković, Ivan Seletković, Mladen Ognjenović, Mia Marušić, Robert Bogdanić, Nenad Potočić, 2023, original scientific article Abstract: European beech (Fagus sylvatica L.) is an important component of forests in the alpine and continental biogeographical regions of Croatia. This study aimed to (1) analyze the long-term response of beech to climate, (2) identify potentially critical climatic conditions that could negatively affect the radial increment (RI) and vitality of beech, and (3) evaluate differences in the response of beech between the two biogeographical regions in Croatia. We used the 16 × 16 km Croatian ICP Forests Level 1 network. On a total of 25 plots, we cored between 5 and 24 trees for dendrochronological analysis. Tree-ring widths (TRW) were measured and standardized using cubic spline. TRW chronologies for the two regions were calculated and correlated to the temperature and precipitation data and Standardized Precipitation and Evapotranspiration Index (SPEI) using bootstrapped correlations. Continental region precipitation from April to August and alpine region precipitation from June to August were significantly important for RI. Temperature was less important for RI than precipitation in both regions, but the importance of the negative impact of above-average temperatures in the continental region and the positive impact of above-average precipitation in the alpine region has increased over the last two decades. A comparison with the 3-month SPEI confirmed the significant influence of high temperatures and the lack of precipitation in August on the RI of beech trees in both regions.
Keywords: climate change, tree growth, forest productivity, drought, European beech
Published in DiRROS: 28.06.2023; Views: 451; Downloads: 225
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6. Forest managers’ perspectives on environmental changes in the biosphere reserve Mura-Drava-DanubeMarcus Sallmannshofer, Rok Damjanić, Harald Vacik, Marjana Westergren, Tjaša Baloh, Gregor Božič, Mladen Ivanković, Gyula Kovács, Miran Lanšćak, Katharina Lapin, Laszlo Nagy, Silvija Krajter Ostoić, Saša Orlović, Srđan Stojnić, Peter Železnik, Milica Zlatković, Silvio Schueler, 2023, original scientific article Abstract: Riparian forests are particularly vulnerable to environmental change and anthropogenic influences because they are highly dynamic ecosystems, thus proper adaptation measures are crucial. The implementation of these measures, however, strongly depends on the actors’ perceptions of the specific problems occurring in such forests. For understanding the constraints of specific interest groups toward different adaptation activities, information in this field is essential. By conducting a questionnaire survey we explore how different types of forest managers, i.e., forestry professionals, forest owners, and conservation managers, perceive the effects of environmental change on forest management in the recently established Transboundary Biosphere Reserve Mura-Drava-Danube. We show that these forest managers are highly aware of ongoing environmental changes and appraise deteriorating forest conditions, especially after observing changes themselves. Abiotic damage is expected to increase the most, followed by biotic damage, the spread of non-native species, and tree dieback. Nearly 80% of the survey respondents expect further changes and almost all of them intend to adapt their management of forests to mitigate or prepare for these changes. Nevertheless, we show differences in sensitivity to change and willingness to initiate adaptation actions by assessing adaptation thresholds: conservation managers appear generally more tolerant to changes, which results in higher thresholds to initiate management adaptation than forestry professionals
Keywords: biosphere reserve Mura-Drava-Danube, forest management, sensitivity to environmental change, stakeholder perception, adaptation thresholds, riparian forest tree species
Published in DiRROS: 31.05.2023; Views: 367; Downloads: 284
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7. Tree and stand growth differ among soil classes in semi-natural forests in central EuropeAndrej Bončina, Matija Klopčič, Vasilije Trifković, Andrej Ficko, Primož Simončič, 2023, original scientific article Abstract: We determined the size of differences in stand and tree growth in semi-natural forests with respect to 16 reference soil groups. The forest area of Slovenia (11.8 thousand km2) was used as the study area, and reference soil units were derived from the national soil map at a 1:25,000 scale consisting of 10,781 polygons with an average size of 117.95 ha. Stand growth was defined as periodic stand basal area increment, while the growth of Norway spruce, silver fir, Scots pine, European beech and sessile oak trees was estimated by the periodic diameter increment of 238,349 dominant trees on 67,061 permanent sampling plots. A linear fixed-effects model and linear mixed-effect models were used for studying stand and tree growth in different site, stand and tree conditions. The soil unit was the dummy variable with Dystric Cambisols set as the reference category. Soil contributed 4.3 % to the explained variability of basal area increment and 4–27 % to the explained variability of the diameter increment of the five tree species. Soil was a stronger driver of stand and tree growth than climate or topography. Stand and tree species production rate on soil units was in the interval of −28 % to +5 % and −47 % to +14 % of that on the reference soil unit, respectively. Stand growth was the highest on Eutric Gleysols and the lowest on Histosols, and tree species generally exhibited the highest and the lowest growth rates on different soil units. We suggest that soil should be considered in growth models and studied interrelatedly with climatic, site and stand variables.
Keywords: reference soil groups, FAO soil unit, natural forest, stand growth, tree growth
Published in DiRROS: 29.12.2022; Views: 581; Downloads: 289
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8. Handbook for non native tree species in the urban spaceAjša Alagić, Aleksander Marinšek, Ana Dolenc, Andrey Krasovskiy, Anica Simčič, Anja M. Bindewald, Anja Müller-Meißner, Bénédicte Baxerres, Claudia Cocozza, Debojyoti Chakraborty, Janez Kermavnar, Lado Kutnar, Simon Zidar, Tina Trampuš, Živa Bobič Červek, 2022, dictionary, encyclopaedia, lexicon, manual, atlas, map Keywords: non-native tree species, Alps, invasive alien species, forest management, urbanspace, climate changes
Published in DiRROS: 12.08.2022; Views: 562; Downloads: 204
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9. Management of non-native tree species in forests of the Alpine spaceSonia Abluton, Ajša Alagić, Bénédicte Baxerres, Frédéric Berger, Anja M. Bindewald, Sylvain Bouquet, Martin Braun, Giuseppe Brundu, Patricia Detry, Freya-Isabel Georges, Janez Kermavnar, Lado Kutnar, Aleksander Marinšek, Anica Simčič, Simon Zidar, 2022, dictionary, encyclopaedia, lexicon, manual, atlas, map Keywords: non-native tree species, Alps, invasive alien species, forest management, climate changes
Published in DiRROS: 12.08.2022; Views: 593; Downloads: 191
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10. Early-warning signals of individual tree mortality based on annual radial growthMaxime Cailleret, Vasilis Dakos, Steven Jansen, Elisabeth M.R. Robert, Tuomas Aakala, Mariano M. Amoroso, Joe A. Antos, Christof Bigler, Harald Bugmann, Marco Caccianaga, Katarina Čufar, Tom Levanič, 2019, original scientific article Abstract: Tree mortality is a key driver of forest dynamics and its occurrence is projected to increase in the future due to climate change. Despite recent advances in our understanding of the physiological mechanisms leading to death, we still lack robust indicators of mortality risk that could be applied at the individual tree scale. Here, we build on a previous contribution exploring the differences in growth level between trees that died and survived a given mortality event to assess whether changes in temporal autocorrelation, variance, and synchrony in time-series of annual radial growth data can be used as early warning signals of mortality risk. Taking advantage of a unique global ring-width database of 3065 dead trees and 4389 living trees growing together at 198 sites (belonging to 36 gymnosperm and angiosperm species), we analyzed temporal changes in autocorrelation, variance, and synchrony before tree death (diachronic analysis), and also compared these metrics between trees that died and trees that survived a given mortality event (synchronic analysis). Changes in autocorrelation were a poor indicator of mortality risk. However, we found a gradual increase in interannual growth variability and a decrease in growth synchrony in the last %20 years before mortality of gymnosperms, irrespective of the cause of mortality. These changes could be associated with drought-induced alterations in carbon economy and allocation patterns. In angiosperms, we did not find any consistent changes in any metric. Such lack of any signal might be explained by the relatively high capacity of angiosperms to recover after a stress-induced growth decline. Our analysis provides a robust method for estimating early-warning signals of tree mortality based on annual growth data. In addition to the frequently reported decrease in growth rates, an increase in inter-annual growth variability and a decrease in growth synchrony may be powerful predictors of gymnosperm mortality risk, but not necessarily so for angiosperms.
Keywords: tree mortality, ring-width, forest, growth, resilience indicators, drought, biotic agents, variance
Published in DiRROS: 20.07.2022; Views: 636; Downloads: 409
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