Knowing what we count : a comment on Guo

Guo (2011) points to problems arising from different approaches to estimating the proportions of floras that are native or alien, specifically those across and within various regions. This results in inconsistency of numbers reported from internal administrative units by underestimating the numbers of species that are alien to the region and overestimating native species richness. Resulting species numbers and proportions for smaller units within large countries, or whole continents, can be seriously biased if only species alien to the larger unit as a whole are considered alien, while all other species are considered native

Potential phytotoxic and shading effects of invasive Fallopia (Polygonaceae) taxa on the germination of dominant native species

Two species of the genus Fallopia (F. sachalinensis, F. japonica, Polygonaceae) native to Asia, and their hybrid (F. ×bohemica), belong to the most noxious plant invaders in Europe. They impact highly on invaded plant communities, resulting in extremely poor native species richness. The low number of native species in invaded communities points to the possible existence of mechanisms suppressing their germination. In this study we assessed, under laboratory conditions, whether there are phytotoxic effects of the three Fallopia congeners on seed germination of three target species: two native species commonly growing in habitats that are often invaded by Fallopia taxa (Urtica dioica, Calamagrostis epigejos), and Lepidium sativum, a species commonly used in allelopathic bioassays as a control. Since Fallopia taxa form dense stands with high cover, we included varying light conditions as an additional factor, to simulate the effects of shading by leaf canopy on germination. The effects of aqueous extracts (2.5%, 5.0%, and 0% as a control) from dry leaves and rhizomes of the Fallopia congeners on germination of the target species were thus studied under two light regimes, simulating full daylight (white light) and light filtered through canopy (green light), and in dark as a control regime. Rhizome extracts did not affect germination. Light treatments yielded inconclusive results, indicating that poor germination and establishment of species in invaded stands is unlikely to be caused by shading alone. However, we found a pronounced phytotoxic effect of leaf extracts of Fallopia taxa, more so at 5.0% than 2.5% extract concentration. Fallopia sachalinensis exerted the largest negative effect on the germination of Urtica dioica, F. ×bohemica on that of C. epigejos, and F. japonica had invariably the lowest inhibitory effect on all test species. The weak phytotoxic effect of F. japonica corresponds to the results of previous studies that found this species to be generally a weaker competitor than its two congeners. Although these results do not necessarily provide direct evidence for allelopathic effects in the field, we demonstrate the potential phytotoxic effect of invasive Fallopia taxa on the germination of native species. This suggests that allelopathy may play a role in the impact of Fallopia invasion on species diversity of invaded communities

Potential phytotoxic and shading effects of invasive Fallopia (Polygonaceae) taxa on the germination of dominant native species

Two species of the genus Fallopia (F. sachalinensis, F. japonica, Polygonaceae) native to Asia, and their hybrid (F. ×bohemica), belong to the most noxious plant invaders in Europe. They impact highly on invaded plant communities, resulting in extremely poor native species richness. The low number of native species in invaded communities points to the possible existence of mechanisms suppressing their germination. In this study we assessed, under laboratory conditions, whether there are phytotoxic effects of the three Fallopia congeners on seed germination of three target species: two native species commonly growing in habitats that are often invaded by Fallopia taxa (Urtica dioica, Calamagrostis epigejos), and Lepidium sativum, a species commonly used in allelopathic bioassays as a control. Since Fallopia taxa form dense stands with high cover, we included varying light conditions as an additional factor, to simulate the effects of shading by leaf canopy on germination. The effects of aqueous extracts (2.5%, 5.0%, and 0% as a control) from dry leaves and rhizomes of the Fallopia congeners on germination of the target species were thus studied under two light regimes, simulating full daylight (white light) and light filtered through canopy (green light), and in dark as a control regime. Rhizome extracts did not affect germination. Light treatments yielded inconclusive results, indicating that poor germination and establishment of species in invaded stands is unlikely to be caused by shading alone. However, we found a pronounced phytotoxic effect of leaf extracts of Fallopia taxa, more so at 5.0% than 2.5% extract concentration. Fallopia sachalinensis exerted the largest negative effect on the germination of Urtica dioica, F. ×bohemica on that of C. epigejos, and F. japonica had invariably the lowest inhibitory effect on all test species. The weak phytotoxic effect of F. japonica corresponds to the results of previous studies that found this species to be generally a weaker competitor than its two congeners. Although these results do not necessarily provide direct evidence for allelopathic effects in the field, we demonstrate the potential phytotoxic effect of invasive Fallopia taxa on the germination of native species. This suggests that allelopathy may play a role in the impact of Fallopia invasion on species diversity of invaded communities

Alien plants in urban nature reserves : from red-list species to future invaders?

Urban reserves, like other protected areas, aim to preserve species richness but conservation efforts in these protected areas are complicated by high proportions of alien species. We examined which environmental factors determine alien species presence in 48 city reserves of Prague, Czech Republic. We distinguished between archaeophytes, i.e. alien species introduced since the beginning of Neolithic agriculture up to 1500 A. D., and neophytes, i.e. modern invaders introduced after that date, with the former group separately analysed for endangered archaeophytes (listed as C1 and C2 categories on national red list). Archaeophytes responded positively to the presence of arable land that was in place at the time of the reserve establishment, and to a low altitudinal range. In addition to soil properties, neophytes responded to recent human activities with the current proportion of built-up area in reserves serving as a proxy. Endangered archaeophytes, with the same affinity for past arable land as other archaeophytes, were also supported by the presence of current shrubland in the reserve. This suggests that for endangered archaeophytes it may have been difficult to adapt to changing agricultural practices, and shrublands might act as a refugium for them. Forty-six of the 155 neophytes recorded in the reserves are classified as invasive. The reserves thus harbour 67% of the 69 invasive neophytes recorded in the country, and particularly worrisome is that many of the most invasive species are shrubs and trees, a life form that is known to account for widespread invasions with high impacts. Our results thus strongly suggest that in Prague nature reserves there is a high potential for future invasions

Phragmites australis as a model organism for studying plant invasions

© 2016, Springer International Publishing Switzerland. The cosmopolitan reed grass Phragmites australis (Poaceae) is an intensively studied species globally with a substantial focus in the last two decades on its invasive populations. Here we argue that P. australis meets the criteria to serve as a model organism for studying plant invasions. First, as a dominant species in globally important wetland habitats, it has generated significant pre-existing research, demonstrating a high potential for funding. Second, this plant is easy to grow and use in experiments. Third, it grows abundantly in a wide range of ecological systems and plant communities, allowing a broad range of research questions to be addressed. We formalize the designation of P. australis as a model organism for plant invasions in order to encourage and standardize collaborative research on multiple spatial scales that will help to integrate studies on the ecology and evolution of P. australis invasive populations, their response to global environmental change, and implications for biological security. Such an integrative framework can serve as guidance for studying invasive plant species at the population level and global spatial scale

The generic impact scoring system (GISS): a standardized tool to quantify the impacts of alien species

Alien species can exert negative environmental and socio-economic impacts. Therefore, administrations from different sectors are trying to prevent further introductions, stop the spread of established species, and apply or develop programs to mitigate their impact, to contain the most harmful species, or to eradicate them if possible. Often it is not clear which of the numerous alien species are most important in terms of damage, and therefore, impact scoring systems have been developed to allow a comparison and thus prioritization of species. Here, we present the generic impact scoring system (GISS), which relies on published evidence of environmental and socio-economic impact of alien species. We developed a system of 12 impact categories, for environmental and socio-economic impact, comprising all kinds of impacts that an alien species may exert. In each category, the intensity of impact is quantified by a six-level scale ranging from 0 (no impact detectable) to 5 (the highest impact possible). Such an approach, where impacts are grouped based on mechanisms for environmental impacts and receiving sectors for socio-economy, allows for cross-taxa comparisons and prioritization of the most damaging species. The GISS is simple and transparent, can be conducted with limited funds, and can be applied to a large number of alien species across taxa and environments. Meanwhile, the system was applied to 349 alien animal and plant species. In a comparison with 22 other impact assessment methods, the combination of environmental and socio- economic impact, as well as the possibility of weighting and ranking of the scoring results make GISS the most broadly applicable system

When are eradication campaigns successful? A test of common assumptions

Eradication aims at eliminating populations of alien organisms from an area. Since not all eradications are successful, several factors have been proposed in the literature (mainly by referring to case studies) to be crucial for eradication success, such as infestation size or reaction time. To our knowledge, however, no study has statistically evaluated which factors affect eradication success and attempted to determine their relative importance. We established a unique global dataset on 136 eradication campaigns against 75 species (invasive alien invertebrates, plants and plant pathogens) and statistically tested whether the following factors, proposed by others were significantly related to eradication success: (1) the reaction time between the arrival/detection of the organism and the start of the eradication campaign; (2) the spatial extent of the infestation; (3) the level of biological knowledge of the organism; and (4) insularity. Of these, only the spatial extent of the infestation was significantly related to the eradication outcome: local campaigns were more successful than regional or national campaigns. Reaction time, the level of knowledge and insularity were all unrelated to eradication success. Hence, some factors suggested as being crucial may be less important than previously thought, at least for the organisms tested here. We found no differences in success rates among taxonomic groups or geographic regions. We recommend that eradication measures should generally concentrate on the very early phase of invasions when infestations are still relatively smal

Nejstarší nálezy bolševníku velkolepého (Heracleum mantegazzianum) v Čechách

V herbáři Maďarského přírodovědného muzea (BP) byl objeven herbářový doklad bolševníku velkolepého (Heracleum mantegazzianum), který pořídil v roce 1871 při léčebném pobytu v Teplicích v Čechách Lajos Haynald, kaločský arcibiskup a významný mecenáš kultury, vědy a vzdělání v historických Uhrách. Sběr pochází pravděpodobně z kultury. Nejstarší dosud známý sběr bolševníku velkolepého pochází z roku 1877; je to sběr zplanělé rostliny z blízkosti Mariánských Lázní. Haynaldův sběr z Teplic tak představuje nejstarší fyzický doklad o přitomnosti tohoto druhu v Čechách. Při analýze starších floristických prací se ukázalo, že datace intrudukce, příp. zplanění bolševníku velkolepého v zámeckém parku v Kynžvartě nad Ohří rokem 1862 je nesprávná a je založena na chybně interpretovaném údaji o výskytu jedné morfologických variant domácího bolševníku obecného (H. sphondylium) na okraji Mariánských Lázní. Podle textů na internetu se dostal bolševník velkolepý do Čech už v roce 1815, a to jako dar ruského cara Alexandra I. knížeti Metternichovi během Vídeňského kongresu. Tento údaj se nám však nepodařilo ověřit v tištěných pramenech.A herbarium specimen of Heracleum mantegazzianum collected in 1871 in the spa of Teplice in northern Bohemia by Lajos Haynald, archbishop of Kalocsa-Bács in Hungary, was recently found in the Hungarian Natural History Museum in Budapest (herbarium BP). To our knowledge, this is the earliest preserved specimen of this invasive species from the territory of the current Czech Republic. It is assumed to have been collected in ornamental plantations in the town. Until recently, a specimen of an escaped plant of H. mantegazzianum collected in 1877 on the outskirts of the spa of Mariánské Lázně (formerly Marienbad)was considered the earliest herbarium record from this country. Examining the earliest record in this country of H. mantegazzianum from the town of Kynžvart (formerly Königswart) dated to 1862 and variously interpreted as relating either to cultivated or to escaped plants, we have arrived at the conclusion that this information is erroneous and misplaced as it is based on the misinterpretation of the name H. elegans, which certainly refers to a morphological variant of H. sphondylium recorded next to the nearby spa of Mariánské Lázně. In newspapers and in various texts found on the internet, H. mantegazzianum is reported to have arrived in Bohemia as early as in 1815 as a present of Russian tsar Alexander I for Austrian foreign minister Prince Metternich during the Congress of Vienna. Reportedly, the seeds were handed over to the minister in one of the malachite vases that are still on display in the Chateau of Kynžvart. However, we failed to find the primary source of this information and, therefore, the exact year of introduction into the chateau park of Kynžvart remains uncertain. Still, this is a plausible report, because Prince Metternich had at least some interest in natural history and established a small natural history museum in his Kynžvart Chateau, which he opened to the public

A vision for global monitoring of biological invasions

Managing biological invasions relies on good global coverage of species distributions. Accurate information on alien species distributions, obtained from international policy and cross-border co-operation, is required to evaluate trans-boundary and trading partnership risks. However, a standardized approach for systematically monitoring alien species and tracking biological invasions is still lacking. This Perspective presents a vision for global observation and monitoring of biological invasions. We show how the architecture for tracking biological invasions is provided by a minimum information set of Essential Variables, global collaboration on data sharing and infrastructure, and strategic contributions by countries. We show how this novel, synthetic approach to an observation system for alien species provides a tangible and attainable solution to delivering the information needed to slow the rate of new incursions and reduce the impacts of invaders. We identify three Essential Variables for Invasion Monitoring; alien species occurrence, species alien status and alien species impact. We outline how delivery of this minimum information set by joint, complementary contributions from countries and global community initiatives is possible. Country contributions are made feasible using a modular approach where all countries are able to participate and strategically build their contributions to a global information set over time. The vision we outline will deliver wide-ranging benefits to countries and international efforts to slow the rate of biological invasions and minimize their environmental impacts. These benefits will accrue over time as global coverage and information on alien species increases

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