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Horizontal structure of the tree layer and natural regeneration on permanent research plots (PRP) 1-5.
Source publication
Biological invasions threaten global biodiversity and forest ecosystems; therefore, it is necessary to use appropriate strategies for combating the spread of invasive species. Natural regeneration of eastern beech (Fagus orientalis Lipsky) is considerably limited by an aggressive invasive shrub, pontic rhododendron (Rhododendron ponticum L.), in th...
Contexts in source publication
Context 1
... each PRP, the position, height, and crown width were measured for recruits with height ≥100 cm and DBH <4 cm. Natural regeneration (recruit) from one year of age (DBH <4 cm) was measured on four nested subplots of 10 × 10 m in size within each PRP (Figure 2). The position, height, and crown width were recorded for each recruit. ...
Context 2
... spatial patterns of tree layer, dead wood, and natural regeneration for each PRP are presented in Figure 2. Based on the computed structural indices, horizontal structure of the tree layer was indistinctly aggregated or moderately regular, while random distribution prevailed (Table 4). ...
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Citations
... Total diversity is composed of the following components of diversity: tree species diversity, diversity of vertical structure, diversity of tree spatial distribution, and diversity of crown differentiation. The input variables are the number of tree species, maximum and minimum tree species proportion, maximum and minimum tree height, maximum and minimum tree spacing, minimum height to crown base, and minimum and maximum crown diameter [77]. [75] monotonous structure B < 4; uniform structure B = 4-5.9; ...
Turkey oak (Quercus cerris L.) is a thermophilic oak species that is gaining importance in the context of ongoing climate change because of its better resistance to climatic extremes and drier conditions. Therefore, this article focuses on Turkey oak’s role and growth properties in the coppice forests of Southern Europe (Italy, Bulgaria) compared to similar site conditions in Central Europe (Slovakia, Czechia). The aims are to evaluate the basic dendrometry indicators, stand biodiversity, growth dynamics, and the effect of climatic factors on tree-ring increment on specific site chronologies. We found that the tree density in coppices of 50–60 years varied between 475 and 775 trees ha−1, and the stand volume ranged from 141 to 407 m3 ha−1. The complex stand diversity of all plots ranged from a monotonous to uniform structure. The size of tree-ring growth was closely related to indicators of stand density. The lowest influence of climatic factors on tree-ring growth was found in sites in Italy and the highest in Slovakia. The primary limiting factor for growth was the lack of precipitation during the growing season, especially in June and July. In contrast, temperature had a marginal effect on radial growth compared to precipitation. The radial growth in research plots in Southern Europe goes through longer 6 to 8-year growth cycles, and in Central European sites, it goes through shorter cycles of 2.4 to 4.8 years, which confirms better growth conditions in this region. The studied coppice stands exhibit a stable reaction to climate change. Yet, regarding cyclical growth, the Central European stands benefit from an advantageous climate and grow better than in Southern Europe. As part of the changing environmental conditions, Turkey oak is becoming an important tree species that can achieve high production potential even in drier habitats due to its regeneration characteristic as coppice and may play a critical role in its northerly introduction in Europe.
... For a comprehensive assessment of diversity, the total diversity index (Jaehne and Dohrenbusch, 1997) was calculated, which includes a diversity of species composition, diversity of vertical structure, diversity of crown differentiation, and diversity of spatial distribution of trees. Detailed information and equations of these calculated indices are given in detail by Vacek et al. (2020b). ...
Tick-borne diseases are a significant health problem worldwide and have become even more pervasive in Europe due to the increasing abundance of tick species, especially the common tick (Ixodes ricinus L.). Moreover, in recent years, there have been changes in tick geographical distribution, the occurrence of new tick species, and an expansion in abundance driven by changes in forest management and climate change. Therefore, this paper's objective is to determine the effect of tree species composition and forest structure on the abundance of I. ricinus in various forest stands in Czechia. Altogether, we analyzed 4195 collected ticks on 56 monitored research plots, of which 4182 individuals were I. ricinus, 4 individuals were Dermacentor reticulatus Fabricius, and 7 individuals were Haemaphysalis concinna C. L. Koch. The average density reached 1.21 ticks per 10 m 2. The highest I. ricinus abundance was observed in coniferous stands (especially in Scotch pine-Pinus sylvestris L.) and forest edges with a high incidence of wild ungulate habitat signs. Contrarily, the lowest tick numbers were in clear-cut biotopes and mixed stands. Increasing vertical structure had a significant (p < 0.05) negative effect on I. ricinus abundance , similar to tree species diversity (richness, evenness, heterogeneity) and complex stand diversity on nymph stage abundance. Close-to-nature silviculture of mixed forests, which are resistant to climate extremes, could reduce the tick abundance, as well as the presence of tick-borne diseases compared to standard coniferous monocultures, which are receding now due to climate change. Based on this knowledge, it should be possible to predict the I. ricinus abundance under changing environmental conditions in the Central European region.
... Many studies primarily use species richness or the abundance of woody species (Morin et al., 2011;Gillman et al., 2015) to explain the relationship between diversity and stand production, but species evenness should also be considered. Species evenness characterizes the abundance distribution across tree species in a forest stand (Yeboah et al., 2016;Vacek et al., 2020c). Research worldwide has confirmed that species evenness is the best indicator for explaining production potential (Zhang et al., 2012). ...
The ongoing global climate change is challenging all sectors, forestry notwithstanding. On the one hand, forest ecosystems are exposed to and threatened by climate change, but on the other hand, forests can influence the course of climate change by regulating the water regime, air quality, carbon sequestration, and even reduce climate extremes. Therefore, it is crucial to see climate change not only as a risk causing forest disturbances and economic consequences but also as an opportunity for innovative approaches to forest management, conservation , and silviculture based on the results of long-term research. We reviewed 365 studies evaluating the impact of climate change on European forest ecosystems, all published during the last 30 years (1993-2022). The most significant consequences of climate change include more frequent and destructive large-scale forest disturbances (wildfire, windstorm, drought, flood, bark beetle, root rot), and tree species migration. Species distribution shifts and changes in tree growth rate have substantial effects on ecosystem carbon storage. Diameter/volume increment changed from − 1 to +99% in Central and Northern Europe, while it decreased from − 12 to − 49% in Southern Europe across tree species over the last ca. 50 years. However, it is important to sharply focus on the causes of climate change and subsequently, on adaptive strategies, which can successfully include the creation of species-diverse, spatially and age-wise structured stands (decrease drought stress and increase production), prolongation of the regenerative period, or the use of suitable introduced tree species (e.g., Douglas fir, black pine, and Mediterranean oaks). But the desired changes are based on increasing diversity and the mitigation of climate change, and will require significantly higher initial costs for silviculture practices. In conclusion, the scope and complexity of the topic require further comprehensive and long-term studies focusing on international cooperation. We see a critical gap in the transfer of research results into actual forest practice, which will be the key factor influencing afforestation of forest stands and forest growth in the following decades. What our forests will look like for future generations and what the resulting impact of climate change will be on forestry is in the hands of forest managers, depending on supportive forestry research and climate change policy, including adaptive and mitigation strategies.
... ponticum occurs over a large part of the Black Sea Region, including South-East Bulgaria, North Turkey and the Taurus Mountains in South Turkey, Georgia and southwestern most part of Russia (Cross 1975;Çolak et al. 1998). While the species is vulnerable in North-West Turkey and Bulgaria, it is abundant in the northeastern part of its range so that it is sometimes considered as a weed (Rotherham 2001) or an "invasive" shrub that needs to be controlled Vacek et al. 2020). ...
... Rhododendron ponticum is a long-lived shrub, able to form dense monospecific bushes in suitable conditions, which shade out native plant species of the understories (Milne 1998). Even in the native range, in Turkey, native tree species (including beech) hardly regenerate and grow below rhododendron canopies (Eşen 2000;Vacek et al. 2020). In the invasive range, only 2% of the daylight can reach the ground so that most herb species die and natural regeneration fails (Barron 2007). ...
... Rhododendron ponticum invasion can stop the natural forest succession by drastically reducing the seed germination and seedling recruitment of native trees and shrubs (Stephenson et al. 2006;Stout et al. 2006). For example, in their study Vacek et al. (2020) indicate that the natural regeneration of Turkish beech forests is limited by a dense understory of R. ponticum. Even decades after R. ponticum removal, the understory plant communities did not recover their original composition, possibly due to seed limitation and the rapid formation of a bryophyte layer (Maclean et al. 2017a(Maclean et al. , 2018b, but also because of the re-invasion by R. ponticum. ...
This report presents information on all aspects of the biology, ecology and invasion behaviour of Rhododendron ponticum L., particularly R. ponticum subsp. baeticum (Boiss. & Reut.) Hand.-Mazz. The main topics presented are: taxonomy, distribution, history of introduction and spread, ecology, biology, impacts, and management. The subspecies baeticum is native to the Iberian Peninsula, where it is close to extinction. This shade-tolerant evergreen shrub has been broadly introduced throughout Europe since the 18th century, mainly for ornamental purposes. The invasive taxon likely results from artificial introgressive hybridization with the Appalachian species R. catawbiense Minchx. It is now naturalized in many countries across western Europe and has become a serious invader in the British Isles. In continental Europe, it mostly invades forest ecosystems of the Atlantic domain, especially on acidic, nutrient-poor but moist soils. R. ponticum subsp. baeticum has perfectly adapted to the humid temperate climate of these regions. As a shade-tolerant species, it can spread out its dense canopy below tree canopies, thereby shading out most herb species and tree seedlings and saplings. Its thick litter likely impacts soil chemical and biological features and hence alters ecosystem processes. Though it produces thousands of seeds, the species mostly propagates vegetatively via layering and forms extended clonal thickets. Long-distance dispersal occurs via seeds, but those can only germinate on moss mats, decaying wood and bare soil and seedlings are very vulnerable to drought. The shrub is also known to be a reservoir for phytopathogenic oomycetes of the genus Phytophthora, including P. ramorum and P. kernoviae. R. ponticum subsp. baeticum invasion is an emerging threat to natural habitats and their associated fauna and flora in western continental Europe. Control is still challenging since management operations are not only expensive and time-consuming but also poorly effective due to vigorous resprouting from stumps after cutting and herbicide resistance.
... Despite numerous publications devoted to progress in counteracting to alien organisms, problems related to biological invasions still occur in many regions worldwide (Zernov & Mirzayeva 2016;Liebhold et al. 2017;Pyšek et al. 2010;Blossey et al. 2021). By having lists of invasive or potentially invasive species, it is possible to combat further alien organism introductions as well as to monitor them (Sintayehu et al. 2020;Vacek et al. 2020). Such lists of all historical records of alien species play an important role in their managing as well as in helping to implement management plans. ...
Biological invasions represent a highly important research field in modern plant biology. They could serve as dangerous processes that threaten natural ecosystems. The distribution patterns of alien plants serve as a basis for the development of biological invasion management plans and counteraction to them. Tyumen Region is situated in the south of West Siberia. This area is one of the least studied in Russia in terms of alien plant composition and distribution. This study aimed to demonstrate the current distribution of some alien plants in the Tyumen Region, namely Echinocystis lobata, Impatiens glandulifera, Heracleum sosnowskyi and Calystegia sepium subsp. americana (C. inflata). We compared their distribution within the entire Tyumen Region and the Tyumen Urban Area. The study was based on two data types, including expert (observations of professional, graduated, botanists, herbarium specimens, publications) and citizen science (observations made by amateur naturalists presented in the platform iNaturalist) data. To visualise the alien plant distribution, we used two grid mapping schemes, including 10×10 km cells for Tyumen Region and 1×1 km cells for Tyumen Urban Area. We found that in the Tyumen Region, Heracleum sosnowskyi occurs in nine grid cells (37 expert data records and 12 citizen science data), Echinocystis lobata in 17 grid cells (70 expert data records and five citizen science data records), Impatiens glandulifera in 15 grid cells (123 expert data records and nine citizen science data records) and Calystegia sepium subsp. americana in 20 grid cells (43 expert data records and five citizen science data records). We demonstrate the significant differences (p<0.05) in number of alien plant records between the territories of inside and outside of the Tyumen Urban Area. We suppose a further increase in the number of records of these alien plant species in the Tyumen Region provided by intense botanical investigations. We propose the need of similar studies in relation to other alien plants in the Tyumen Region.
... The input variables are the number of tree species, maximum and minimum tree species proportion, maximum and minimum tree height, maximum and minimum tree spacing, minimum height to crown base, and minimum and maximum crown diameter. Detailed information about the calculation of the used indices can be found in the works by Vorčák et al. (2006) and Vacek et al. (2020a). ...
... A similar tendency to aggregation in beech and spruce monocultures at higher altitudes, as was in our case, also found in other areas of the Czech Republic (Vacek et al., 2014a;Král et al., 2015;Vacek et al., 2019c). The horizontal structure of the tree layer in natural and close-to-nature forests is random in most cases (von Oheimb et al., 2005;Hájek et al., 2020;Vacek et al., 2020a) but with increasing age and increasing habitat richness, the competition increases too, and the structure changes from aggregated to random and, finally, regular (Wijdeven, 2003;Rugani et al., 2013;Bulušek et al., 2016). In the initial growth stages (natural regeneration) or in extreme habitats (upper forest boundaries, rocks), aggregation of individuals occurs (Nagel et al., 2006;Vacek et al., 2015d). ...
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Forest ecosystems in Sri Lanka are under pressure from intensive human activity and climate change. Invasive species are one of the greatest threats to autochthonous species and ecosystems. In Bundala National Park of Sri Lanka, there are efforts to control and limit the spreading of unwanted invasive Prosopis juliflora (Sw.) DC. and Opuntia dillenii (Ker-Gawl.) Haw., which poses a significant risk to natural ecosystem conservation. Nine different treatment variants (four replications) were used to test which management approach provides the control of Prosopis juliflora. This research is based on nine repeated measurements from 2017 to 2021 on 36 permanent research plots (each 625 m2) with 27 observed plant species and a total of 90,651 recorded plant individuals. The results confirmed that the dynamics of species richness, heterogeneity, and evenness showed significant differences between treatments during the five years of dynamics. The lowest species diversity was found in the control variant, followed by treatments based on the hard pruning and thinning of Prosopis juliflora trees. In contrast, strategies emphasizing the complete uprooting of Prosopis juliflora trees, replanting, and support of the natural regeneration of native species showed high species diversity and a high overall number of plant species. Generally, treatments had a significant effect on species diversity and the number of individuals of Prosopis juliflora, while changes in the overall number of plant species were more affected by time and succession. Silvicultural treatments including pruning, uprooting, and thinning have proven to be essential tools for nature conservation across various sites, aimed at enhancing habitat diversity in the face of ongoing climate change.
Questions
Rhododendron ponticum subsp. baeticum is an invasive shrub of growing concern in continental Europe, but little is known about its impact on native plant communities. Here we ask: do environmental conditions differ between forest stands invaded by it and uninvaded stands? Do these differences correlate with R. ponticum 's cover? Are these differences associated with differences in taxonomic and functional diversity of vascular plant species of the herb layer? Can these vegetation changes be explained by the sorting of certain life‐history traits by R. ponticum ‐induced environmental changes?
Location
Several forests invaded by R. ponticum in the French Atlantic domain.
Methods
We recorded vegetation composition and a number of environmental variables in 400‐m ² plots that were established in 64 paired forest stands (32 invaded vs 32 uninvaded). We compiled traits from existing databases. We computed several metrics of taxonomic and functional diversity. We compared environmental variables and diversity metrics between invaded and uninvaded stands. We used correlation and regression analyses to relate them with R. ponticum 's cover. We ran RLQ and fourth‐corner analyses to explore the relationships between R. ponticum invasion, environmental variables, species traits, and vegetation composition.
Results
Independent of its abundance, R. ponticum invasion was associated with lower light arrival at the forest floor and increased litter thickness. Concomitantly, species richness and diversity and trait diversity were reduced. The major driver of species assemblages was soil pH, which strongly interacted with the invasion gradient. R. ponticum did not sort species according to traits associated with shade tolerance and thick‐litter tolerance. However, tree and shrub saplings were more abundant in invaded than uninvaded stands, at the expense of graminoid and fern species.
Conclusions
As R. ponticum becomes the dominant shrub, it exerts new selection forces on life‐history traits of extant species, mostly via reduced light availability, increased litter thickness, and physical competition, thereby reducing taxonomic and functional diversity of the herb layer, without impeding tree and shrub self‐regeneration, at least in the short term.
