Can enemy release explain the invasion success of the diploid Leucanthemum vulgare in North America?

Enemy release is a commonly accepted mechanism to explain plant invasions. Both the diploid Leucanthemum vulgare and the morphologically very similar tetraploid Leucanthemum ircutianum have been introduced into North America. To verify which species is more prevalent in North America we sampled 98 Leucanthemum populations and determined their ploidy level. Although polyploidy has repeatedly been proposed to be associated with increased invasiveness in plants, only two of the populations surveyed in North America were the tetraploid L. ircutianum. We tested the enemy release hypothesis by first comparing 20 populations of L. vulgare and 27 populations of L. ircutianum in their native range in Europe, and then comparing the European L. vulgare populations with 31 L. vulgare populations sampled in North America. Characteristics of the site and associated vegetation, plant performance and invertebrate herbivory were recorded. In Europe, plant height and density of the two species were similar but L. vulgare produced more flower heads than L. ircutianum. Leucanthemum vulgare in North America was 17 % taller, produced twice as many flower heads and grew much denser compared to L. vulgare in Europe. Attack rates by root- and leaf-feeding herbivores on L. vulgare in Europe (34 and 75 %) was comparable to that on L. ircutianum (26 and 71 %) but higher than that on L. vulgare in North America (10 and 3 %). However, herbivore load and leaf damage were low in Europe. Cover and height of the co-occurring vegetation was higher in L. vulgare populations in the native than in the introduced range, suggesting that a shift in plant competition may more easily explain the invasion success of L. vulgare than escape from herbivory

Dark side of the fence: ornamental plants as a source of wild-growing flora in the Czech Republic

Ornamental plants constitute an important source of alien, and potentially invasive species, but also include a substantial part of native flora and consist of taxa that occur both in the wild and in cultivation; yet garden floras are largely ignored in ecological studies.We studied ornamental plants in the Czech Republic in order to provide detailed information, based on field sampling, on the diversity of taxa grown in cultivation in private gardens. Sampling was done in accessible public areas, private gardens and private areas in villages, town- and city neighbourhoods, garden allotments, cemeteries, areas of dispersed farmhouse settlements not accessible to the public, and in new urban sprawl. The data can be used to estimate the propagule pressure of individual taxa, measured in terms of the frequency with which they are planted in the gardens. To make the data comparable across sites, we adopted a two-level approach that resulted in producing a detailed list (including all the taxa recorded) and an aggregated list (merging closely related and similar taxa, which was necessary in order to assess the frequency of planting across sites). Each species on the detailed list was assigned an origin, status, life history and cultivation requirements. Comparing the field records with national checklists of both native and alien vascular plants we quantified particular components of the ornamental flora. The floristic inventories for 174 sites yielded 1842 taxa on the detailed list, consisting of 1642 species (standard binomials), 9 cultivars assigned to genera, 147 hybrids and hybridogenous taxa, and 44 taxa identified at higher than species level. Of these taxa 1417 (76.9%) were alien and 420 (22.8%) native. The ornamental flora consisted of not-escaping aliens, escaping aliens and cultivated natives. Of the recorded taxa, 841 (45.6%) occur both in cultivation and the wild. The aggregated list comprised 1514 taxa and resulted from merging 533 taxa from the detailed list into 205 taxa. Most alien ornamentals are native to Asia and Americas. The proportion of escaped and not-escaping aliens significantly differed from wild aliens in the spontaneous flora with underrepresentation of escaped, which originated from Australia, Africa and the Mediterranean area. Taxa from Africa and anecophytes were overrepresented and those from Australia, the Mediterranean and other parts of Europe underrepresented among not escaping aliens. The assessment of planting frequency revealed that 270 taxa were found at more than 25% of the sites, while 584 (40%) occurred at only one or two sites.Winter annuals and shrubs are most represented among the commonly planted aliens; the only native species with comparably high planting frequencies among the aliens, are Vinca minor, Hedera helix and Aquilegia vulgaris. Related to the invasion potential of ornamental garden flora we analysed the recorded taxa with respect to the transient/persistent character of their occurrence. The core (persistent) part of the flora comprised 599 taxa (32% of the total number of taxa) and the transient 240 (13%) taxa. The “grey zone” between the two included 1003 taxa (55%). The results reported here provide quantitative insights into the role of horticulture as a major pathway of plant invasions

Catalogue of alien plants of the Czech Republic (2nd edition): checklist update, taxonomic diversity and invasion patterns

A complete list of all alien taxa ever recorded in the flora of the Czech Republic is presented as an update of the original checklist published in 2002. New data accumulated in the last decade are incorporated and the listing and status of some taxa are reassessed based on improved knowledge. Alien flora of the Czech Republic consists of 1454 taxa listed with information on their taxonomic position, life history, geographic origin (or mode of origin, distinguishing anecophyte and hybrid), invasive status (casual; naturalized but not invasive; invasive), residence time status (archaeophyte vs neophyte), mode of introduction into the country (accidental, deliberate), and date of the first record. Additional information on species performance that was not part of the previous catalogue, i.e. on the width of species’ habitat niches, their dominance in invaded communities, and impact, is provided. The Czech alien flora consists of 350 (24.1%) archaeophytes and 1104 (75.9%) neophytes. The increase in the total number of taxa compared to the previous catalogue (1378) is due to addition of 151 taxa and removal of 75 (39 archaeophytes and 36 neophytes), important part of the latter being the reclassification of 41 taxa as native, mostly based on archaeobotanical evidence. The additions represent taxa newly recorded since 2002 and reported in the national literature; taxa resulting from investigation of sources omitted while preparing the previous catalogue; redetermination of previously reported taxa; reassessment of some taxa traditionally considered native for which the evidence suggests the opposite; and inclusion of intraspecific taxa previously not recognized in the flora. There are 44 taxa on the list that are reported in the present study for the first time as aliens introduced to the Czech Republic or escaped from cultivation.Práce přináší úplný seznam nepůvodních taxonů zaznamenaných na území České republiky; je aktualizací a doplněním předchozího seznamu publikovaného v roce 2002. Zahrnuje nové údaje shromážděné za poslední desetiletí a přehodnocuje zařazení a status některých druhů, vyplývající z rozvoje taxonomického poznání. Nepůvodní flóra České republiky zahrnuje 1454 taxonů, které jsou uvedeny v Apendixu 2 s informacemi o taxonomické příslušnosti, životní formě, oblasti původu, invazním statusu (zda jde o druh přechodně zavlečený, naturalizovaný avšak neinvazní, nebo invazní), charakteru výskytu v krajině, době zavlečení (archeofyt nebo neofyt), způsobu introdukce do země a u neofytů o datu prvního nálezu. Oproti původnímu katalogu je uveden počet typů biotopů, ve kterých se druh vyskytuje, pokryvnost v rostlinných společenstvech a impakt. Podíl zavlečených druhů v české flóře je značný: tvoří jej 350 (24,1%) archeofytů a 1104 (75.9%) neofytů. Nárůst počtu taxonů oproti původnímu katalogu, který uváděl 1378 taxonů, vyplývá z toho, že bylo přidáno 151 taxonů. Celkem 75 (39 archeofytů a 36 neofytů) bylo naproti tomu vypuštěno; značná část tohoto počtu jde na vrub přeřazení 41 taxonů mezi původní druhy, a to vesměs na základě archeobotanických dokladů. Přírůstky na seznamu představují taxony nově objevené a uvedené v botanické literatuře od roku 2002, taxony zařazené na základě excerpce dříve opominutých zdrojů či revize zdrojů použitých, nebo přehodnocení statusu některých taxonů tradičně považovaných za původní. Vněkterých případech jde o infraspecifické taxony, které nebyly dříve v české flóře rozeznávány. Seznam obsahuje 44 taxonů, které jsou uváděny pro Českou republiku poprvé jako zavlečené, nebo pro něž je podán první důkaz o jejich zplaňování

The role of species charisma in biological invasions

Commonly used in the literature to refer to the "attractiveness", "appeal", or "beauty" of a species, charisma can be defined as a set of characteristics - and the perception thereof - that affect people's attitudes and behaviors toward a species. It is a highly relevant concept for invasion science, with implications across all stages of the invasion process. However, the concept of invasive alien species (IAS) charisma has not yet been systematically investigated. We discuss this concept in detail, provide a set of recommendations for further research, and highlight management implications. We review how charisma affects the processes associated with biological invasions andIASmanagement, including species introductions and spread, media portrayals, public perceptions of species management, research attention, and active public involvement in research and management. Explicit consideration ofIAScharisma is critical for understanding the factors that shape people's attitudes toward particular species, planning management measures and strategies, and implementing a combination of education programs, awareness raising, and public involvement campaigns.Peer reviewe

Arbuscular mycorrhizal symbiosis of herbaceous invasive neophytes in the Czech Republic

I have studied arbuscular mycorrhizal symbiosis of 44 herbaceous invasive neophytes occuring in the Czech Republic. My results show that about 70% of the examined species are capable to form symbiotic association with arbuscular mycorrhizal fungi (AMF) in the field. To my knowledge, mycorrhizal status of 23 invasive species is reported here for the first time. I predicted, based on the hypothesis of Urcelay & Díaz (2003), that the intensity of AMF in the roots of invasive species will be correlated with that of the native dominant species of invaded plant community, but collected data did not support this hypothesis. In addition, the effects of habitat and community characteristics on the intensity of AMF colonization of the invasive species{\crq} roots were tested. My results show that, at the within-species level, plants in the habitats with higher light and temperature conditions have less colonized roots whereas intensity of mycorrhizal colonization increases with habitat moisture. At the among-species level, invasive species occurring in the habitats with elevated nitrogen availability have higher mycorrhizal colonization of their roots. The effect of nitrogen availability is revealed at the among-species level and stays significant even after phylogenetic correction, suggesting this is an evolutionary adaptation rather than a phenotypic plasticity

Význam biotických interakcí v rostlinných invazích

- ABSTRACT - The loss of co-adapted and gain of novel biotic interactions during the invasion process influence the success or failure of introduced plants. Within the present thesis, I studied diverse biotic interactions, specifically the relationships between plants and their herbivores, pollinators, fungi, and resident plant communities, and how biotic interactions can be utilized in planning effective science-based management. With my collaborators, we combined the community and biogeographical approach with the reciprocal transcontinental comparison between Eurasia and North America, based on primary data collected in the field. Of numerous hypotheses for the striking success of invasive plants, the enemy release hypothesis (ERH) is one of the most frequently tested. It asserts that the greater performance of introduced plants in non-native ranges is due to the absence, or decrease, in regulation by natural enemies that are left behind in the native range. Our results, in a broad sense, supported ERH, but we found that the magnitude of herbivore damage is context-dependent, related to the feeding guild and origin of both herbivores and plant species and that the increased plant performance in a new range might also be related to other factors, such as the shift in plant competition. Of animal-plant...- ABSTRAKT - Během invaze dochází k zániku dlouhodobě ustálených a vzniku nových biotických interakcí, což má vliv na invazní úspěch rostliny v novém areálu. Ve své práci se zabývám různými biotickými interakcemi, zejména vztahy mezi rostlinami navzájem, jejich herbivory, opylovači a mykorhizními houbami, ale i tím, jak lze znalosti o biotických interakcích následně využít při plánování efektivního managementu, který by byl založen na vědeckých poznatcích. S kolegy jsme studovali tyto interakce na úrovni rostlinných společenstev, ale provedli jsme i mezikontinentální srovnání, zejména mezi Evropou a Severní Amerikou. Náš výzkum byl založen hlavně na sběru terénních dat. Z mnoha teorií a koncepcí, které byly doposud zformulovány pro vysvětlení úspěchu invazních rostlin v novém areálu, je nejčastěji studovanou hypotézou "únik před nepřáteli. Jejím předpokladem je, že invazní druhy jsou v novém areálu úspěšné mimo jiné i proto, že částečně či úplně unikly svým přirozeným nepřátelům, které jejich populace regulovali v původním areálu. Naše výsledky podporují tuto hypotézu, ale zjistili jsme, že rozsah poškození je závislý na souhře několika okolností, tj. o jakou funkční skupinu herbivorů se jedná, či zda jsou v daném areálu původní, totéž platí i pro jejich živné rostliny. Asi nejdůležitější interakcí mezi...Department of EcologyKatedra ekologiePřírodovědecká fakultaFaculty of Scienc

The role of biotic interactions in plant invasions

- ABSTRACT - The loss of co-adapted and gain of novel biotic interactions during the invasion process influence the success or failure of introduced plants. Within the present thesis, I studied diverse biotic interactions, specifically the relationships between plants and their herbivores, pollinators, fungi, and resident plant communities, and how biotic interactions can be utilized in planning effective science-based management. With my collaborators, we combined the community and biogeographical approach with the reciprocal transcontinental comparison between Eurasia and North America, based on primary data collected in the field. Of numerous hypotheses for the striking success of invasive plants, the enemy release hypothesis (ERH) is one of the most frequently tested. It asserts that the greater performance of introduced plants in non-native ranges is due to the absence, or decrease, in regulation by natural enemies that are left behind in the native range. Our results, in a broad sense, supported ERH, but we found that the magnitude of herbivore damage is context-dependent, related to the feeding guild and origin of both herbivores and plant species and that the increased plant performance in a new range might also be related to other factors, such as the shift in plant competition. Of animal-plant..

Composition patterns of ornamental flora in the Czech Republic

Ornamental plants are an important component of urban floras and a significant source of alien plant invasions to the surrounding landscapes. We studied ornamental flora across 174 settlements in the Czech Republic, Central Europe. The aims of the study were to (i) identify clusters of sites that are defined as distinctive groups of ornamental taxa reflecting environmental or socioeconomic factors and (ii) apply the classification approach which is traditionally used for spontaneous vegetation in order to evaluate the potential of different settlement types to act as source sites of invasive species. The inventories were classified in a similar manner that is generally applied to spontaneous vegetation using the COCKTAIL method. Diagnostic taxa were classified in a repeatable manner into 17 species groups, forming five distinctive clusters with ~70% of sites attributed to one cluster. The species pools of the clusters differed in their representation of species with native or alien status and different life forms. The following clusters were distinguished, based on the prevailing type of settlement: (1) old villas neighbourhoods of towns, (2) upland settlements, (3) modern neighbourhoods, (4) old rustic settlements and (5) modern rustic settlements. Similar to spontaneous vegetation, the classification of ornamental flora reflects both basic natural gradients (i.e. altitude) and man-made factors (i.e. the preferences for certain plants and associated management practices). Alien taxa associated with modern neighbourhoods are characterised by a relatively higher invasion potential than those from, for example, old rustic settlements. This is especially true for woody species which can spread in ruderal habitats as a result of urban sprawl. Our results showed that the classification method, commonly used to analyse vegetation data, can also be applied to ornamental flora