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Využívání listového opadu hrálo v minulých staletích v mnoha regionech střední Evropy významnou roli. Chudé rolnictvo odnášelo na podzim z lesů opad ve velkých pytlích nebo nůších, aby bylo na čem v zimě ustájit dobytek. To se dělo zejména tam, kde byla nouze o slámu nebo jiný materiál vhodný pro podestýlku. Na jaře se pak tato materie promíchaná s exkrementy využila jako hnojivo na pole. Dnes o listí v lese není zájem žádný; odbyt je nulový a vrstva dost vysoká na to, aby bránila slunečním paprskům dosáhnout na obnažený povrch půdy a podpořit v klíčení všudypřítomná semena, následný růst semenáčků nebo vegetativní šíření rostlin. Listí je také nezanedbatelným zdrojem živin, které přispívají k eutrofizaci stanoviště. Tento článek je shrnutím našich poznatků získaných na základě monitoringu vlivu každoročního odstraňování opadu na bylinné patro světlých lesů ze třech lokalit v NPR Karlštejn v Českém krasu. Na jejich základě se vám pokusíme demonstrovat, jaký vliv mohla mít tato činnost na utváření charakteru tehdejších lesů a jaké uplatnění může najít v současné době při ochraně biologicky cenných fragmentů světlých lesů a při stále narůstajících aktivitách kolem jejich obnovy., Tato studie byla financována Technologickou agenturou České republiky a Norskými granty 2014-2021, číslo grantu TO01000132. Článek vyšel v Živě 2023/2.

Species contributing high proportions to community biomass strongly influence ecosystem processes within the community. Studies have shown that dominant species may serve as nurse plants, helping to ensure biomass stability of the subordinate species under stress conditions. The question is widely debated as to whether either niche differentiation or neutral processes drive the net outcome of plant interactions within a subordinate plant community. To answer this question, requires precise estimates of individual variation in functional traits and performance. In a 5‐year mesocosm experiment, the functional responses of a subordinate plant community to the removal of the dominant species were evaluated across two drought‐stress scenarios. Small‐scale (i.e. large pots) wetland communities were constructed comprising one dominant species Carex elata and three subordinate species. Removal of the dominant species allowed evaluation of the net effects of drought and interspecific interactions. We estimated the functional divergences for three traits (SLA, leaf dry matter content and allocation to height growth) and compared these with performance differences quantified individually. This enabled distinctions to be made between deterministic (i.e. niche differentiation) and neutral processes driving the drought response of the subordinate community. We showed that the dominant species decreased relative performance differences within the subordinate plant community under conditions of permanent drought stress. These changes were associated with the convergence of traits related to resource acquisition and growth. The dominant species equalized species performance differences by supressing relatively drought‐tolerant species with low competitive ability and by supporting the less drought‐tolerant species with relatively high competitive ability. Meanwhile, under conditions of inter‐annual drought, the subordinate species likely coexisted due to differentiation in resource‐use strategies and the interaction with the dominant species. Inclusion of individual variation in performance with a functional trait approach provides valuable insights into the processes structuring plant communities. Ours is the first study to provide evidence that subordinate species exposed to drought may coexist via neutral processes arising from their interactions with the dominant species, leading to functional convergence of traits associated with the trade‐off between stress tolerance and competitive ability. A free Plain Language Summary can be found within the Supporting Information of this article.

Floodplain forests offer a diversity of habitats and resources for a very wide range of plant and animal species. They also offer many benefits to humankind and are considered essential to the mitigation of the effects of climate change. Nevertheless, throughout the world they are suffering the most intense of anthropogenic pressures so are, of all ecosystems, among the most endangered. Here, we bring together and synthesise existing ecological understanding of the mechanisms underlying the high heterogeneity and diversity of temperate floodplain forests and of the pressures threatening their high biological value due to habitat homogenisation. Floodplain forests depend on the periodic disturbances under which they evolved, including fluvial dynamics, traditional management practices and the activities of herbivores. However, they have been heavily degraded by climate change, invasion of exotic species, river-flow regulation, landscape fragmentation, eutrophication and the cessation of traditional management. We can now observe two general trends in temperate floodplain forests: (1) Due to intensive landscape exploitation, they are now more open and thus prone to the spread of competitive species, including of invasive exotics and (2) Due to the cessation of traditional management, along with modified hydrological conditions, they are composed of species in the later successional stages (i.e., more shade-tolerant and mesic) while light-demanding species are quickly vanishing. Restoration practices have brought about contrasting results when restoration of floodplains to their natural states has been problematic. This is likely because of interplay between various natural and artificial processes not previously taken into proper consideration. We would like to draw attention to the fact that restoration projects or the preservation of existing floodplain forest ecosystems should combine the restoration of watercourses with the mitigation of other important threats acting at different scales of the landscape (spread of invasive species, eutrophication of watersheds and inappropriate forest management).

AIM: The Holocene history of annual plant species is at best shadowy because, for most, the palaeobotanical data are scarce or absent. Hence, there is limited information on their glacial refugia and postglacial colonization pathways. Also, little is known on how human activity has affected their expansion. Here, we outline the joint influences of postglacial colonization and recent expansions on the genetic diversity of the continental, sub‐halophyte species Atriplex tatarica during the late Pleistocene and the Holocene. LOCATION: Europe. TAXON: Atriplex tatarica (Amaranthaceae). METHODS: We analysed 780 individuals from 80 populations throughout the current European distribution range, employing chloroplast DNA sequences and microsatellite markers. RESULTS: Five haplotype lineages were recognized based on the results of the cpDNA phylogenetic analyses. These lineages originated 0.43–0.22 myr BP. Bayesian clustering analyses divided populations of A. tatarica into two clusters: (a) populations in the Pannonian Basin and the Bohemian Massif and (b) populations in the North European Plain, the Balkan Peninsula, the Carpathian Arc and the Pontic region. The ABC approach provided the strongest statistical support for a model proposing refugia in the Balkan Peninsula and the Pannonian Basin. Expansions from these refugia occurred around 7,000 yr BP. MAIN CONCLUSION: Atriplex tatarica represents a continental species growing exclusively in man‐made habitats. It serves as a phylogeographic model for annual ruderal taxa currently spreading in central Europe along highways and representing a large group of alien plant species, the so‐called archaeophytes. Atriplex tatarica survived the last glaciation in both a southerly located Balkan refugium and in a more northerly refugium in the Pannonian Basin. From these, the species has colonized Europe as a result of expansion of humans and the anthropogenic climate change. The massive colonization of central north Europe is very recent, with the expansion estimated to have occurred only hundreds of years ago.

Studies of perennial plants generally search for a seed size vs. seed number trade-off. Surprisingly, the fact that perennials may replace an investment in large seeds by the allocation to vegetative propagation has not yet been investigated as an additional pathway enabling species coexistence. We focused on the mechanisms of coexistence in Carex elata and C. elongata, two co-occurring clonal sedges dominant in European swamp alder forests. We asked the following questions: i) Is the number of germinated seeds a better predictor of species coexistence than the total number of seeds? ii) What recruitment conditions and competition rules determine vegetative sprouting to be an alternative to large, competitively superior seeds? We measured several species functional traits related to the colonisation and fitness of perennials. To examine the competitive hierarchy between species and microsite species preferences, we analysed the effects of environmental factors and plant densities on fitness-related traits using Structural Equation Modelling (SEM). Then, using a series of spatially explicit simulations partly parameterised based on the field measurement, we evaluated the importance of seed and ramet propagation and recruitment conditions for long-term species coexistence. SEM indicated a competitive hierarchy and a large overlap in microsite preferences between species. As a response to our initial questions we found that: i) Only differences in the numbers of germinated seeds, allowed the two species to coexist. If we consider only differences in the total number of seeds, the superior competitor (Carex elata) outcompeted the inferior competitor (C. elongata) in all scenarios. This is because the former produced about three-times as many seeds as the latter. ii) We show that vegetative sprouting represents an additional pathway for the seed size-number trade-off when the competitive superiority of species is attributed to vegetative propagation. This is another way that a species deals with the omnipresent seeds of other species. Taken together, our study demonstrates that differences in seed performance, coupled with differences in vegetative propagation related to competitive ability, are an additional mechanism allowing the coexistence of perennial plants.

Summary Past management practices may continue to influence ecosystem functions and processes for decades, centuries or even longer after they have been abandoned. Until now, few researchers have attempted experiments which test the effects of restoring some of these past management practices on long-term community developmental trajectories. Strong evidence indicates that the diversity of various taxonomic groups declined in European lowland forests in the second half of the 20th century, following the abandonment of some traditional forest management practices. We carried out a five-year field trial in a lowland thermophilous oak forest to describe the effects of restoration of litter raking and grass cutting on the long-term developmental trajectory of species composition and the diversity of understorey vegetation. We used target species groups, that is species specific to thermophilous forests and dry grassland vegetation and plant functional traits to evaluate the restoration success using both compositional and functional outcomes. Dissimilarity in species composition between the managed plots and controls increased significantly during the 5 years of the trial. Litter raking increased the richness and cover of the thermophilous forest and dry grassland species, whereas grass cutting increased the richness and cover of only the dry grassland species. We did not record any overall trends in divergence of functional trait composition between managed and control plots. In the litter raking plots, we recorded increases in community-weighted means of specific leaf area, in lateral spread and in Ellenberg indicator values for nutrients and soil reaction. In contrast, we found little evidence for predictability of species functional trait composition subjected to grass cutting. Synthesis and applications. Following the restoration of traditional forest management practices, we were able to change the community's developmental trajectory towards higher richness and cover of target species. The evaluation of community developmental trajectories using species and functional trait composition supports the idea that restoration of traditional forest management practices should carefully distinguish among possible interventions.

The stress-gradient hypothesis predicts a switch from competition to facilitation, under increasing environmental stress. However, it is unclear how important is the change in competition-facilitation balance (i.e., the net outcome of plant-plant interactions) along the stress gradient in the regulation of community temporal stability (i.e., the inverse of temporal variability in total biomass). Increasing environmental stress may enhance community temporal stability by reduced competition or eventually by leading to facilitative interactions between the dominant and subordinate species. Here, we present the results of a 5-yr mesocosm experiment that demonstrates the effects of interspecific interactions on the temporal stability of a riparian community across different drought-stress scenarios. We constructed artificial communities of dominant species (Carex elata) and three subordinate species to simulate the independent effects of environmental stress and interspecific interactions. Using removal of the dominant species, we evaluated the interplay of various mechanisms regulating the temporal stability of the subordinate species (competition-facilitation balance, species asynchrony, and dominant species stability). By simultaneous testing of these stabilizing mechanisms, we show their importance differs depending on environmental variability and harshness. The predominant role is taken by species asynchrony in a seasonally dry environment, whereas in a permanently dry environment, the importance of reduced competition increases. Reduced competition was stabilizing, in particular through increased total community biomass, whereas species asynchrony increased total community biomass and decreased biomass variation. These results suggest experiments and simulations that exclude interspecific interactions may not offer realistic predictions of the effects of changing hydrological regimes on ecosystem functioning.

Aim: Formalized classifications synthesizing vegetation data at the continental scale are being attempted only now, although they are of key importance for nature conservation planning. Therefore, we aim to provide a vegetation classification and to describe the main biogeographical patterns of floodplain forests and alder carrs in Europe. Location: Europe. Methods: A database of more than 40 000 vegetation plots of floodplain forests and alder carrs across Europe was compiled. After geographic stratification, 16 392 plots were available for classification, which was performed using the supervised method Cocktail. We also searched for new associations using semi-supervised K-means classification. The main biogeographic patterns and climate-related gradients in species composition were determined using detrended correspondence analysis and cluster analysis. Results: Thirty associations of floodplain forests and alder carrs were distinguished, which belong to five alliances. The Alnion incanae includes riparian, seepage and hardwood floodplain forests in the nemoral and hemiboreal zones (dominated by Alnus glutinosa and Fraxinus excelsior) and in the boreal zone (dominated by A. incana). The Osmundo-Alnion represents oceanic vegetation dominated by Alnus glutinosa, Fraxinus angustifolia and F. excelsior distributed mostly on the Iberian Peninsula and composed of species with Atlantic distribution and Iberian endemics. The Populion albae comprises floodplain forests frequently dominated by Fraxinus angustifolia, Populus alba and P. nigra that are widespread in floodplains of large rivers under summer-dry climates in the Mediterranean region. The Platanion orientalis represents eastern Mediterranean floodplain forests dominated by Platanus orientalis. The Alnion glutinosae includes forest swamps dominated by Alnus glutinosa distributed mostly in the nemoral and hemiboreal zones. The main biogeographic patterns within European floodplain forests and alder carrs reflect the climatic contrasts between the Mediterranean, nemoral, boreal and mountain regions. Oceanic floodplain forests differ from those in the rest of Europe. The hydrological regime appears to be the most important factor influencing species composition within regions. Conclusions: This study is the first applying a formalized classification at the association level for a broad vegetation type at the continental scale. The proposed classification provides the scientific basis for the necessary improvement of the habitat classification systems used in European nature conservation.

Heterocarpy enables species to effectively spread under unfavourable conditions by producing two or more types of fruit differing in ecological characteristics. Although it is frequent in annuals occupying disturbed habitats that are vulnerable to invasion, there is still a lack of congeneric studies addressing the importance of heterocarpy for species invasion success. We compared two pairs of heterocarpic Atriplex species, each of them comprising one invasive and one non-invasive non-native congener. In two common garden experiments, we (i) simulated the influence of different levels of nutrients and population density on plants grown from different types of fruits and examined several traits that are generally positively associated with invasion success, and (ii) grew plants in a replacement series experiment to evaluate resource partitioning between them and to compare their competitive ability. We found that specific functional traits or competitiveness of species cannot explain the invasiveness of Atriplex species, indicating that species invasiveness involves more complex interactions of traits that are important only in certain ecological contexts, i.e. in specific environmental conditions and only some habitats. Interestingly, species trait differences related to invasion success were found between plants growing from the ecologically most contrasting fruit types. We suggest that fruit types differing in ecological behaviour may be essential in the process of invasion or in the general spreading of heterocarpic species, as they either the maximize population growth (type C fruit) or enhance the chance of survival of new populations (type A fruit). Congeners offer the best available methodical framework for comparing traits among phylogenetically closely related invasive and non-invasive species. However, as indicated by our results, this approach is unlikely to reveal invasive traits because of the complexity underlying invasiveness.

We investigated 39 previously developed Betula, Alnus ,a ndCorylus simple sequence repeat (SSR) markers for their utility in the cross-generic amplification of two European alder species, i.e., Alnus glutinosa and A. incana. Of these markers, ten loci had successful amplification within Alnus species. Finally, we designed two multiplexes composed of eight and nine loci for A. glutinosa and A. incana, respectively. Multiplexes were tested on 100 samples from five different populations of each species across Europe. The majority of loci had a relatively high genetic diversity, were in Hardy-Weinberg equilibrium, and showed low error rates and low occurrence of null alleles. By comparing sequences of source species and both Alnus species, we concluded that repeat motifs of five of these ten loci differed from those described for the source species. These differences represent mainly the modifications of the original motifs and affected compound or interrupted re- peats as well as pure ones. The repeat motifs of three loci of the two alder species also differed. These mutations could lead to erroneous estimates of allele homology, be- cause alleles with identical lengths will not have the same number of repeat units. Hence, before using microsatellite markers in studies comparing two or more species, they should be carefully examined and sequenced to ensure that allele homology is really stable and not affected by various inserts that change the sequence.

The ability of a species to adapt to sub-optimal conditions at the margin of its distribution range and to cope with environmental stress is considered to be important for its successful geographic expansion. To ascertain the roles of phenotypic differentiation and plasticity in the expansion of the annual Atriplex tatarica, we compared plants from populations found in Marginal and Central areas of the species’ range. We grew these plants under marginal climatic conditions in pots with different types of substrate. We assessed the population genetic structure at five putatively neutral allozyme loci to evaluate whether there was any evidence of reduced genetic diversity in Marginal populations compared to Central ones. We used the QST vs. FST approach (while FST gives a standardised measure of the genetic differentiation among populations for a genetic locus, QST measures the amount of genetic variance among populations relative to the total genetic variance) to ascertain the roles of adaptive vs. non-adaptive processes on phenotypic differentiation. Plants native to the Marginal area of the species’ range flowered earlier and had a lower shoot mass and a higher reproductive allocation than plants native to the Central part of the species’ range. The Marginal populations of Atriplex tatarica showed lower genetic diversity at allozyme loci and higher phenotypic differentiation than the Central populations. We recorded similar plastic responses to substrates in plants native to both regions. Our results indicate that Marginal populations of expanding A. tatarica maintain the ability to adapt locally and to elicit a plastic response to environmental stress, despite loss of genetic diversity.

BACKGROUND/AIMS: Recently, new palaeoecological records supported by molecular analyses and palaeodistributional modelling have provided more comprehensive insights into plant behaviour during the last Quaternary cycle. We reviewed the migration history of species of subgenus Alnus during the last 50,000 years in Europe with a focus on (1) a general revision of Alnus history since the Last Glacial Maximum (LGM), (2) evidence of northern refugia of Alnus populations during the LGM and (3) the specific history of Alnus in particular European regions. METHODOLOGY: We determined changes in Alnus distribution on the basis of 811 and 68 radiocarbon-dated pollen and macrofossil sites, respectively. We compiled data from the European Pollen Database, the Czech Quaternary Palynological Database, the Eurasian Macrofossil Database and additional literature. Pollen percentage thresholds indicating expansions or retreats were used to describe patterns of past Alnus occurrence. PRINCIPAL FINDINGS: An expansion of Alnus during the Late Glacial and early Holocene periods supports the presence of alders during the LGM in southern peninsulas and northerly areas in western Europe, the foothills of the Alps, the Carpathians and northeastern Europe. After glaciers withdrew, the ice-free area of Europe was likely colonized from several regional refugia; the deglaciated area of Scandinavia was likely colonized from a single refugium in northeastern Europe. In the more northerly parts of Europe, we found a scale-dependent pattern of Alnus expansion characterised by a synchronous increase of Alnus within individual regions, though with regional differences in the times of the expansion. In southern peninsulas, the Alps and the Carpathians, by contrast, it seems that Alnus expanded differently at individual sites rather than synchronously in whole regions. CONCLUSIONS: Our synthesis supports the idea that northern LGM populations were important sources of postglacial Alnus expansion. The delayed Alnus expansion apparent in some regions was likely a result of environmental limitations.

It has been suggested that a heterogeneous environment enhances species richness and allows for the coexistence of species. However, there is increasing evidence that environmental heterogeneity can have no effect or even a negative effect on plant species richness and plant coexistence at a local scale. We examined whether plant species richness increases with local heterogeneity in the water table depth, microtopography, pH and light availability in a swamp forest community at three local spatial scales (grain: 0.6, 1.2 and 11.4 m). We also used the variance partitioning approach to assess the relative contributions of niche-based and other spatial processes to species occurrence. We found that heterogeneity in microtopography and light availability positively correlated with species richness, in accordance with the habitat heterogeneity hypothesis. However, we recorded different heterogeneity–diversity relationships for particular functional species groups. An increase in the richness of bryophytes and woody plant species was generally related to habitat heterogeneity at all measured spatial scales, whereas a low impact on herbaceous species richness was recorded only at the 11.4 m scale. The distribution of herbaceous plants was primarily explained by other spatial processes, such as dispersal, in contrast to the occurrence of bryophytes, which was better explained by environmental factors. Our results suggest that both niche-based and other spatial processes are important determinants of the plant composition and species turnover at local spatial scales in swamp forests.