European Plant Species Research Articles

New Insights on the Estimation of the Anaerobic Biodegradability of Plant Material: Identifying Valuable Plants for Sustainable Energy Production

Based on fifteen European plant species, a statistical model for the estimation of the anaerobic biodegradability of plant material was developed. We show that this new approach represents an accurate and cost-effective method to identify valuable energy plants for sustainable energy production. In particular, anaerobic biodegradability (Bo) of lignocellulosic material was empirically found to be related to the amount of cellulose plus lignin, as analytically assessed by the van Soest method, i.e., the acid detergent fiber (ADF) value. Apart from being theoretically meaningful, the ADF-based empirical model requires the least effort compared to the other four proposed conceptual models proposed, as individual fractions of cellulose, hemicellulose, and lignin do not need to be assessed, which also enhances the predictive accuracy of the model’s estimation. The model’s results showed great predictability power, allowing us to identify interesting crops for sustainable crop rotations. Finally, the model was used to predict Bo of 114 European plant samples that had been previously characterized by means of the van Soest method.

Assessing the risks of non-target feeding by the accidentally introduced ragweed leaf beetle, Ophraella communa, to native European plant species

In 2013, the North American oligophagous leaf beetle, Ophraella communa LeSage (Coleoptera: Chrysomelidae), was found in Europe for the first time. Recent studies in Northern Italy and Southern Switzerland record extensive defoliation by O. communa on its preferred host, common ragweed, Ambrosia artemisiifolia L. (Asteraceae, Tribe Heliantheae), and reductions in its flowering and seeding. In some regions in Northern Italy, this has reportedly led to a > 80% depletion in airborne A. artemisiifolia pollen concentrations. The potential for non-target damage by O. communa to closely related native European plant species was previously unknown. During extensive field surveys covering 18 populations of nine potential non-target species, we found adult O. communa on a single plant individual. In a common garden field experiment in Northern Italy in an area with high O. communa densities, leaf damage was highest on two other Asteraceae species, Dittrichia graveolens (L.) Greuter and Pentanema helveticum (Weber) D.Gut.Larr. (both in the Tribe Inuleae). While adult feeding was observed on most of the test plant species, only D. graveolens, which has recently extended its range and is now an invasive species in Western Europe, sustained all life stages of O. communa in the common garden and in laboratory experiments. We found no evidence of substantial non-target effects by O. communa that could potentially threaten populations of European native plant species that are taxonomically closely related to ragweed.

What happens in Europe stays in Europe: apparent evolution by an invader does not help at home.

Some invasive plant species rapidly evolve greater size and/or competitive ability in their nonnative ranges. However, it is not well known whether these traits transfer back to the native range, or instead represent genotype-by-environment interactions where traits are context specific to communities in the new range where the evolution occurred. Insight into transferability vs. context specificity can be tested using experiments performed with individuals from populations from the native and nonnative ranges of exotic invasive species. Using a widespread invasive plant species in Europe, Solidago gigantea, we established reciprocal common garden experiments in the native range (Montana, North America; n=4) and the nonnative range (Hungary, Europe; n=4) to assess differences in size, vegetative shoot number, and herbivory between populations from the native and nonnative ranges. In a greenhouse experiment, we also tested whether the inherent competitive ability of genotypes from 15 native and 15 invasive populations differed when pitted against 11 common native North American competitors. In common gardens, plants from both ranges considered together produced five times more biomass, grew four times taller, and developed five times more rhizomes in the nonnative range garden compared to the native range garden. The interaction between plant origin and the common garden location was highly significant, with plants from Hungary performing better than plants from Montana when grown in Hungary, and plants from Montana performing better than plants from Hungary when grown in Montana. In the greenhouse, there were no differences in the competitive effects and responses of S.gigantea plants from the two ranges when grown with North American natives. Our results suggest that S.gigantea might have undergone rapid evolution for greater performance abroad, but if so, this response does not translate to greater performance at home.

Large differences in biomass quantity and quality between invasive Reynoutria japonica and resident vegetation are not reflected in topsoil physicochemical properties

Biological invasions are an important element of ongoing global change. Reynoutria japonica is one of the most invasive plant species in Europe and North America, potentially affecting recipient ecosystems. However, little is known about the relationships between its senescing biomass and element concentrations/pools in soil. The aim of this study was to compare the quantity and quality of aboveground and belowground plant biomass, and the quality of topsoil between plots with invasive R. japonica and resident plant communities. The study was conducted at 25 paired R. japonica-native plots in southern Poland. Harvested biomass was dried and weighted, and characterized in terms of C, Ca, K, Mg, N and P concentrations and pools, as well as C/N and C/P ratios. These parameters were also measured in soil along with texture, bulk soil density, moisture and pH. R. japonica produced greater amounts of aboveground and belowground biomass relative to resident species. The concentrations and pools of most elements in plant biomass were affected by invasion (R. japonica vs. resident), biomass type (aboveground vs. belowground) and/or their interactions. Senescing aboveground biomass of R. japonica was characterized by poor quality – lower N, P, K, greater C, Ca concentrations and greater C/N, C/P ratios compared to resident vegetation. Belowground R. japonica biomass had either greater or similar element concentrations (with the exception of P) or ratios. Element pools were greater in R. japonica than in resident species, with the exception of N and P in aboveground biomass. Despite these differences, topsoil generally did not differ in physicochemical properties when analyzed across all study sites; only total N and H2O-extractable K pools were lower under R. japonica than resident vegetation. Our data suggest that ecosystem response to invasion may be site-specific and depend on initial ecosystem properties.

Does an invader have a bright side? Floral reward in two Solidago species

The knowledge of nectar secretion and pollen production is important for understanding the biology of invasive species. In the present paper, the floral reward in Solidago canadensis and S. gigantea (Asteraceae), two invasive plant species in Europe, were investigated. Flowers of Solidago species are protandrous. The floral nectar was found to be rich in hexose (sucrose/fructose/glucose – 13.8/32.7/53.5% in S. canadensis and 18.3/35.1/46.6% in S. gigantea). The per-flower rewards (sugars/pollen) in the Solidago species were not abundant; however, due to the formation of dense populations and massive floral display, high amounts of resources were produced at the community level. The mean sugar output was 482.3 kg/ha in S. canadensis and 121.6 kg/ha in S. gigantea. The mean pollen yield was 30.7 kg/ha (S. canadensis) and 6.5 kg/ha (S. gigantea). In the landscape with limited floral resources, the nectar and pollen available in Solidago flowers are important and can provide additional (or even exclusive) food resources for pollinators during summer/late summer. In particular, areas invaded by Solidago species may be attractive to beekeepers, as >80.0% of visits were performed by Apis mellifera. However, a broad spectrum of wild insect visitors (including Bombus spp., Vespula spp., Diptera, Lepidoptera, Coleoptera) deserves further studies to assess the impact of mass flowering in Solidago species on the native plant species-insect interactions.

Chemical Composition of Essential Oil from Flower Heads of Arnica Chamissonis Less. under a Nitrogen Impact.

Chamisso arnica (Arnica chamissonis Less.) is a valuable plant species used in the pharmaceutical industry due to the content of many pharmacologically active substances and the similarity of its chemical composition to that of Arnica montana—a medicinal plant commonly used in pharmacy and cosmetics. The similarity of the two plant species implies that chamisso arnica can be a pharmaceutical substitute for the mountain arnica, i.e., an endangered and endemic plant species in Europe. Chamisso arnica extracts exhibit anti-inflammatory and antiradical activity and possesses high antioxidant properties that might be helpful in preventing or delaying the progress of free radical dependent diseases. The attributes of A. chamissonis are mainly related to the content and chemical composition of essential oil. Therefore, the objective of this study was to characterize the chemical composition of essential oil derived from A. chamissonis flower heads under a nitrogen impact. The experiment was performed on experimental fields in mid-eastern Poland on two soil types (sandy and loamy soils). The nitrogen fertilizer was applied as ammonium sulfate (control, 30, 60, 90, and 120 kg N ha−1). Collection of flower heads was carried out in the full flowering phase, which was characterized by the highest content of essential oil. The chemical composition of essential oil was examined using GC-MS. Among the 75 ingredients of the volatile oil of chamisso arnica flower heads, alpha-pinene, cumene, p-cymene, germacrene D, spathulenol, decanal, caryophyllene oxide, beta-pinene, and benzene acetaldehyde were present at relatively high levels. Both the nitrogen application and the soil type had an effect on the oil concentration and the yield of the main constituents (alpha-pinene and germacrene D) with pharmacological value. Different levels of nitrogen application could be considered as a relevant way to modify the chemical composition and to increase the essential oil production.

Postglacial change of the floristic diversity gradient in Europe

Climate warming is expected to cause a poleward spread of species, resulting in increased richness at mid to high latitudes and weakening the latitudinal diversity gradient. We used pollen data to test if such a change in the latitudinal diversity gradient occurred during the last major poleward shift of plant species in Europe following the end of the last glacial period. In contrast to expectations, the slope of the gradient strengthened during the Holocene. The increase in temperatures around 10 ka ago reduced diversity at mid to high latitude sites due to the gradual closure of forests. Deforestation and the introduction of agriculture during the last 5 ky had a greater impact on richness in central Europe than the earlier climate warming. These results do not support the current view that global warming alone will lead to a loss in biodiversity, and demonstrate that non-climatic human impacts on the latitudinal diversity gradient is of a greater magnitude than climate change.

Draft Genome Sequence Resources of Three Strains (TOS4, TOS5, and TOS14) of Xylella fastidiosa Infecting Different Host Plants in the Newly Discovered Outbreak in Tuscany, Italy.

An outbreak of Xylella fastidiosa was discovered in late 2018 in northern Italy affecting several plant species. Multilocus sequence typing analyses detected the presence of strains clustering in X. fastidiosa subsp. multiplex and harboring a hitherto uncharacterized sequence type, ST87. Three cultured strains (TOS4, TOS5, and TOS14) were subjected to high-throughput sequencing and the draft genomes assembled. Phylogenetic analysis conclusively indicated that they belong to the subspecies multiplex. The genetic information generated for these newly discovered strains further supports the evidence that sequence types are associated with the emergence of X. fastidiosa in Europe, posing major challenges for predicting the main threatened European and Mediterranean crops and plant species.

Assessing sampling coverage of species distribution in biodiversity databases

AbstractAimBiodiversity databases are valuable resources for understanding plant species distributions and dynamics, but they may insufficiently represent the actual geographic distribution and climatic niches of species. Here we propose and test a method to assess sampling coverage of species distribution in biodiversity databases in geographic and climatic space.LocationEurope.MethodsUsing a test selection of 808,794 vegetation plots from the European Vegetation Archive (EVA), we assessed the sampling coverage of 564 European vascular plant species across both their geographic ranges and realized climatic niches. Range maps from the Chorological Database Halle (CDH) were used as background reference data to capture species geographic ranges and to derive species climatic niches. To quantify sampling coverage, we developed a box‐counting method, the Dynamic Match Coefficient (DMC), which quantifies how much a set of occurrences of a given species matches with its geographic range or climatic niche. DMC is the area under the curve measuring the match between occurrence data and background reference (geographic range or climatic niche) across grids with variable resolution. High DMC values indicate good sampling coverage. We applied null models to compare observed DMC values with expectations from random distributions across species ranges and niches.ResultsComparisons with null models showed that, for most species, actual distributions within EVA are deviating from null model expectations and are more clumped than expected in both geographic and climatic space. Despite high interspecific variation, we found a positive relationship in DMC values between geographic and climatic space, but sampling coverage was in general more random across geographic space.ConclusionBecause DMC values are species‐specific and most biodiversity databases are clearly biased in terms of sampling coverage of species occurrences, we recommend using DMC values as covariates in macro‐ecological models that use species as the observation unit.

Comparison of the understory vegetation of native forests and adjacent Robinia pseudoacacia plantations in the Carpathian-Pannonian region

Information about invasive alien species and their interactions with the environment and native ecosystems is very important to prevent widespread loss of original habitats and biodiversity. Black locust (Robinia pseudoacacia) is one of the most widespread alien plant species in Europe and has become a dominant forest tree species, which is frequently planted. We analysed how environmental factors (light, temperature and humidity), species composition and level of invasion changed in black locust stands compared with those in different neighbouring native forest types (floodplain, oak and mixed oak-hornbeam forests). The aims of this study were to determine (i) how the microclimatic conditions of the native forests changed after replacing the native trees with black locust, (ii) how black locust changed species composition and level of invasion of the understory and (iii) whether black locust equally influenced the three types of native forests. The results showed that compared with those of the other forest types, the conditions of black locust stands were always warmer and drier with more light from the sparse canopy of trees. In the black locust forests, we recorded more non-forest and ruderal species with significantly higher percentage number and cover of alien species in the understory vegetation than in the native forest stands. Different native forest types and their black locust twins were mutually influenced in a different way. The mixed oak-hornbeam forest was the type most influenced by replacement with black locust, whereas floodplain forest changed the least. Black locust plantations replacing native forests cause decreasing native species biodiversity, because of the occurrence of alien, ruderal and non-forest species. The dry and warm character of black locust stands contributed to an acceleration of microclimate change. This information can be useful for forest managers and planners participating in the replacement of native forest stands by alien tree species, which has ecological and economic impacts with consequences for nature and society.

Phylogeography of a widespread eastern North American shrub, Viburnum lantanoides.

There have been relatively few phylogeographic studies of eastern North American plants, especially of animal-dispersed shrubby species, and this leaves a significant gap in our understanding of how such species were affected by glacial events. Here, we analyzed the phylogeography of the widespread understory shrub Viburnum lantanoides. We generated RADseq data and paleoclimatic species distribution models (SDMs) to identify the locations of refugia where V. lantanoides may have survived the Last Glacial Maximum (LGM) and how its range expanded as glaciers receded. Genetic diversity falls off with increasing latitude and longitude, indicating that range expansion likely occurred via serial founder events from southern source populations. Samples from the southern Appalachians form a grade, while those from the north form a clade, suggesting that a single genetic lineage recolonized the north. SDMs indicate that V. lantanoides probably survived the LGM in refugia on the mid-Atlantic Coastal Plain and/or the interior Gulf Coastal Plain. Our analyses indicate that V. lantanoides survived the LGM in refugia south of the glacier but north of the extensive refugium along the Gulf Coast. Following the LGM, a single population expanded northward along the Appalachian Mountains and eventually into eastern Canada. The patterns observed here suggest that range expansion occurred in a stepwise manner, similar to postglacial dynamics observed in a number of European plant species.

A Comprehensive Model for the Quantitative Estimation of Seed Dispersal by Migratory Mallards

Long-distance seed dispersal is an important ecosystem service provided by migratory animals. Plants inhabiting discrete habitats, like lakes and wetlands, experience dispersal limitation and rely heavily on zoochory for their spatial population dynamics. Granivorous waterbirds may disperse viable seeds of wetland plants over long distances during migration. The limited knowledge of waterbird migration long hampered the evaluation of the importance of waterbirds in seed dispersal, requiring key metrics such as realistic dispersal distances. Using recent GPS tracks of mallards on spring migration, we built a mechanistic seed dispersal model to estimate realistic dispersal distances. Mallards are abundant, partially migratory ducks known to consume seeds of >300 European plant species. Based on the tracking data, we informed a mallard migration simulator to obtain a probabilistic spring migration model for the mallard population wintering at Lake Constance in Southern Germany. We combined the spring migration model with seed retention curves to develop seed dispersal kernels. We also assessed the effect of pre-migratory fasting and the availability of suitable deposition habitat for aquatic and wetland plants. Our results show that mallards at Lake Constance can disperse seeds in northeastern direction over median distances of 293 and 413 km for seeds with short and long retention times, respectively, assuming departure immediately after foraging. Pre-migratory fasting strongly affected the dispersal potential, with only 1-7% of ingested seeds left for dispersal after fasting for 12 h. Availability of suitable deposition habitat was generally <5% along the migratory flyway. High probability of seed deposition in freshwater habitat during the first stopover, after the mallards completed the first migratory flight, makes successful dispersal most likely to happen at 204-322 km from Lake Constance. We conclude that the directed long-distance dispersal of plant seed realized by mallards on spring migration may contribute significantly to large scale spatial plant population dynamics, including range expansion in response to shifting temperature and rainfall patterns under global warming. Our dispersal model is the first to incorporate detailed behavior of migratory waterbirds and can be readily adjusted to include other vector species when tracking data are available.

HPTLC Autography Based Screening and Isolation of Mushroom Tyrosinase Inhibitors of European Plant Species.

In the course of this project, 133 plants were evaluated on their ability to inhibit tyrosinase, a key enzyme in melanogenesis. The screening was performed by means of a HPTLC autographic assay, resulting in the selection of three plants, Asplenium trichomanes, Pinus uncinata, and Scutellaria altissima, with promising tyrosinase inhibiting activities. With the aid of the HPTLC assay, it was not only possible to select the most interesting plant extracts, but also to monitor the activity-guided fractionation which, in a relatively short time period, led to the isolation of active principles. Benzoic acid, roseoside, and dihydrovomifoliol-O-β-d-glucopyranoside could be identified as tyrosinase inhibitors present in P. uncinata. Globularin turned out to be the active principle of S. altissima, and 4-ethenylphenyl 6-O-(6-deoxy-α-l-mannopyranosyl)-β-d-glucopyranoside was detected as tyrosinase inhibitor of A. trichomanes. The pure compounds were tested also in a 96 well-plate assay in order to determine their IC50 values. The lowest IC50 value (42 μm) could be obtained for globularin, whereas the other compounds, e. g., benzoic acid exhibited a rather high IC50 value (IC50 =552 μm). This stood in clear contrast to the autographic assay, but is has to be taken into account that the outcome of the autography assay is not only depending on the IC50 value of a compound, but also on the content of the respective constituent in the extract.

Materials on the distribution of plant species which are rare for the Volgograd oblast

The information about the distribution of 28 rare and endangered species of vascular plants under Federal and regional security, registered in 2018 on the territory of the Volgograd oblast under the Federal and regional security is given. Among them, 2 species (Crambe tataria Sebeok и Stipa zalesskii Wilensky ex P. A. Smirn.) are included in the List of Threatened plant species of Europe. Each location is linked to the grid of Atlas Flora Europaea. The obtained materials about the distribution of rare and endangered species of vascular plants represent an important data for long-term monitoring and also for environmental management measures at the regional level.

Habitat requirements and germination performance of some relict populations of Ligularia sibirica (Asteraceae) from Romania

Background and aims – Ligularia sibirica is a glacial relict plant species in Europe. Its populations are rare and endangered in most of the European localities. Studies on glacial relics are insufficient; among them only a few focus on the population characteristics and their reproductive capacity. We aimed to determine the habitat requirements of L. sibirica populations; which factors affect the reproductive output of the populations and how the interaction of ecological and biological parameters influences their germination capacity.Methods – We described habitat conditions in terms of the Ellenberg indicators (for nitrogen availability, moisture, light, soil reaction, and temperature) in each analysed population. To determine which factors affect the population viability we performed a series of regression analyses. Germination experiment was carried under laboratory-controlled conditions at a 14/10 h. photoperiod and 24/16°C temperature, for 32 days, with cold stored seeds (at 4°C), and seeds stored at room temperature on a different substrate (moist filter paper and oligotrophic soil). The parameters influencing population germination rate were determined with general linear models. Key results – We found that the soil humidity, nitrogen availability, temperature, and lighting are the ecological factors influencing the morphological features of L. sibirica populations. The largest seeds are in the middle part of the inflorescence though this parameter has no influence on germination rate. The seeds germinated better on moist filter paper. Cold stored seeds did not show higher germination rate. Germination increased with the altitude of the populations and the seeds mass, whilst higher values of density had a negative influence on it. Conclusions – Our results suggest that habitat conditions and population characteristics are highly related to the germination success of L. sibirica. The prosperity of a population (expressed by the number of individuals) is not a guarantee of reproductive success, the densest populations having the lowest rates of germination.

Assessing the potential distribution of invasive alien species Amorpha fruticosa (Mill.) in the Mureş Floodplain Natural Park (Romania) using GIS and logistic regression

The assessment of invasive terrestrial plant species in the Romanian protected areas is an important research direction, especially since the adventive species have become biological hazards with significant impacts on biodiversity. Due to limited resources being available for the control of the invasive plants, the modelling of the spatial potential distribution is particularly useful in order to find the best measures to eliminate them or prevent their introduction and spread, as well as including them in the management plans of protected areas. Thus, the present paper aims to assess one of the most disturbing invasive terrestrial plant species in Europe – A.fruticosa in one of the most important natural protected area in Romania, i.e. Mureş Floodplain Natural Park (V IUCN category and RAMSAR –Wetlands of International Importance). The current study is a geographical approach seeking to explain the spatial relationships between this invasive species and several explanatory factors (soil type, depth to water, vegetation cover, forest fragmentation and distance to near waters, roads and settlements) and to assess its potential distribution by integrating GIS and logistic regression into spatial simulation. The resultant probability map can be used by the park’s administration in implementing the Management Plan in terms of identifying the areas with the highest occurrence potential of A.fruticosa according to the primary habitats and ecosystems and setting up actions for its eradication/limitation.

Removal of soil biota alters soil feedback effects on plant growth and defense chemistry.

Summary We examined how the removal of soil biota affects plant–soil feedback (PSF) and defense chemistry of Jacobaea vulgaris, an outbreak plant species in Europe containing the defense compounds pyrrolizidine alkaloids (PAs).Macrofauna and mesofauna, as well as fungi and bacteria, were removed size selectively from unplanted soil or soil planted with J. vulgaris exposed or not to above‐ or belowground insect herbivores. Wet‐sieved fractions, using 1000‐, 20‐, 5‐ and 0.2‐μm mesh sizes, were added to sterilized soil and new plants were grown. Sieving treatments were verified by molecular analysis of the inocula.In the feedback phase, plant biomass was lowest in soils with 1000‐ and 20‐μm inocula, and soils conditioned with plants gave more negative feedback than without plants. Remarkably, part of this negative PSF effect remained present in the 0.2‐μm inoculum where no bacteria were present. PA concentration and composition of plants with 1000‐ or 20‐μm inocula differed from those with 5‐ or 0.2‐μm inocula, but only if soils had been conditioned by undamaged plants or plants damaged by aboveground herbivores. These effects correlated with leaf hyperspectral reflectance.We conclude that size‐selective removal of soil biota altered PSFs, but that these PSFs were also influenced by herbivory during the conditioning phase.

Linking root exudates to functional plant traits.

Primary and secondary metabolites exuded by plant roots have mainly been studied under laboratory conditions, while knowledge of root exudate patterns of plants growing in natural communities is very limited. Focusing on ten common European grassland plant species, we asked to which degree exuded metabolite compositions are specific to species or growth forms (forbs and grasses), depend on environments and local neighbourhoods, and reflect traditional plant functional traits. Root exudates were collected under field conditions and analysed using a non-targeted gas chromatography coupled mass spectrometry (GC-MS) approach. In total, we annotated 153 compounds of which 36 were identified by structure and name as metabolites mainly derived from the primary metabolism. Here we show by using variance partitioning, that the composition of exuded polar metabolites was mostly explained by plot identity, followed by plant species identity while plant species composition of the local neighbourhood played no role. Total and root dry biomass explained the largest proportion of variance in exudate composition, with additional variance explained by traditional plant traits. Although the exudate composition was quite similar between the two growth forms, we found some metabolites that occurred only in one of the two growth forms. Our study demonstrated the feasibility of measuring polar exudates under non-sterile field conditions by mass spectrometry, which opens new avenues of research for functional plant ecology.

Evaluation of species inter-relations and soil conditions in Arnica montana L. habitats: a step towards active protection of endangered and high-valued medicinal plant species in NE Poland

&lt;em&gt;Arnica montana&lt;/em&gt; L. is a critically endangered and highly valued medicinal plant species in Europe. We show the inter-relationships between arnica and accompanying plant species, as well as soil factors, that promote the persistence of the studied forest arnica populations in terms of active protection of this species in the northeast region of Europe. The population characteristics and plant species composition were assessed during a field study. Additionally, soil samples were taken and analyzed to assess variation in soil conditions in the habitats of arnica populations. Correlations between population characteristics and soil properties were highlighted. The forest habitats of arnica presented in this study differ from those described in other European mountain and submountain areas. The sandy and very poor soils are characterized by a very low content of macro- and microelements, and a strong acid reaction. The positive correlation between population characteristics and Ca and K indicates an important role of these macroelements in flower head production. Acidity, K, Ca, the sum of exchangeable bases, and base saturation play crucial roles in the persistence of arnica populations in pine forests. The level of acidity and its consequences result from soil-forming processes and climatic conditions rather than air pollution. When planning active protection scenarios, special attention should be paid to the frequency and cover of &lt;em&gt;Vaccinium myrtillus&lt;/em&gt;, which can act as a competitor in forest habitats. Assessment of soil conditions that favor the persistence of the studied arnica populations and species relationships is important for improving knowledge of the ecology of the species and for the active protection of endangered plant species.

Influence of seed size on performance of non-native annual plant species in a novel community at two planting densities

Climate warming enables plant species to migrate to higher latitudes and altitudes. Within Europe, the Mediterranean harbours many species that might expand their ranges towards Western Europe. Small seed size may facilitate dispersal, however, it may impair establishment of the range-expanding plant species in the novel vegetation. In a greenhouse experiment, we examined effects of average seed size of Mediterranean plant species on their establishment in a mixed community of Western European plant species. Applying two levels of densities of the natives and a herbivory treatment, we tested how seed size is linked to response in plant growth and fitness in novel vegetation. While all non-native plant species showed a negative response to increased planting density, species with small seeds showed a less negative response. This effect persisted under herbivory. Our data suggest that small-seeded non-native plant species may tolerate competitive pressure from novel plant communities better than large-seeded species, so that small seed size may confer a higher probability of establishment of non-native species in novel communities.