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Important Publications

List of important scientific studies and books written by scientists of the Institute of Botany in the last five years.

2009 l 2008 | 2007 | 2006 | 2005 | archiv

2009

Synergy in plant invasions: fast-growing species experience greater enemy release

This research, based on studying 243 European plant species and their fungal and viral pests both in their native Europe and in the invaded range in the United States (Blumenthal et al. 2009), shows that two key causes of plant invasion, escape from natural enemies and increase in plant resources, act in concert. Fast-growing plant species adapted to moist, nitrogen-rich soils in their native region lost many more fungal and viral pathogens upon introduction to the United States than did other types of plants (Fig.­­ 1). Such enemy release is thought to provide alien species with an advantage over native species still burdened by their enemies. This is the first study, however, to show that the strength of enemy release can be predicted from the type of plant: Alien species that are fast-growing and weedy are likely to benefit most from enemy release. Unfortunately, these are the same species most-favored by global change, because fast-growing weedy species thrive in environments with ample plant resources and global change increases key plant resources, such as carbon dioxide and soil nitrogen, through increases in the greenhouse gases carbon dioxide and nitrous oxide, respectively. Alien fast-growing weedy species therefore have a double advantage in today’s world: Increases in resources enable them to outcompete slow-growing plants and unusually strong enemy release enables them to outcompete even fast-growing native plants. As global change proceeds, continuing increases in resource availability are likely to continue to favor fast-growing weedy species, and exacerbate plant invasion (Blumenthal et al. 2009). The results of the study confirm that distinguishing plant species on the basis of their origin, a principle that is sometimes questioned, is justified by differences in performance and traits among native and alien species (Pyšek & Hulme 2009).

Fig. 1

Blumenthal D., Mitchell C.E., Pyšek P. & Jarošík V. 2009. Synergy between pathogen release and resource availability in plant invasion. Proceedings of the National Academy of Sciences of the United States of America 106: 7899–7904.

Pyšek P. & Hulme P.E. 2009. Invasion biology is a discipline that’s too young to die. Nature 160: 324. 

Biological invasions: Europe on a crossroad?

The rates of introductions of alien plants and animals to Europe have been accelerating in the last decades (Fig. 2) and costs associated with invasive organisms are increasing, currently reaching at least 12 bio. € annually (Hulme et al. 2009a). Alien plant invasions threaten native species diversity at various spatial scales, as exemplified by the results of two studies. One of them shows that at the community level, the reduction of diversity of native resident species is associated with the relative dominance of the invader compared to that of the dominant species of the original uninvaded community (Hejda et al. 2009). The second study indicates that plant invasions suppress not only taxonomic but also phylogenetic diversity of regional floras. Despite the huge taxonomic diversity of plants imported into European and American cities, the strong environmental filters imposed by cities constrain the functional diversity of urban floras, which is reflected in their generally low phylogenetic diversity. Urban alien floras are mainly composed of phylogenetically related species that are well adapted to anthropogenic habitats, although these filters are stronger for groups of alien species present for a longer time (Ricotta et al. 2009). The fact that some invasive species provide economic benefits cannot be taken as a strong incentive to their further introduction, despite the potential ecological risks. Economic benefits are often gained by one sector of society while the costs are borne by the wider public. Therefore precautionary approach to biological invasions is necessary in Europe (Hulme et al. 2009b). European data and knowledge, recently acquired during the DAISIE and ALARM projects, provide a strong platform on which to build a European strategy on invasive species, and Europe can therefore serve as a model example for other parts of the world (Hulme et al. 2009c). A possibility to establish a pan-European agency (European Centre for Invasive Species Management) that would integrate all invasion related activities across Europe was suggested; such agency, with a mission to identify, assess and communicate current and emerging threats to the economy and environment posed by invasive species, would help to reduce the influx of invasive organism to Europe and decrease economic costs associated with biological invasions in Europe (Hulme et al. 2009a, d).

Fig. 2

Hulme P., Pyšek P., Nentwig W. & Vilà M. 2009a. Will threat of biological invasions unite the European Union? Science 324: 40–41.

Hejda M., Pyšek P. & Jarošík V. 2009. Impact of invasive plants on the species richness, diversity and composition of invaded communities. Journal of Ecology 97: 393–403.

Ricotta C., La Sorte F.A., Pyšek P., Rapson G.L., Celesti-Grapow L. & Thompson K. 2009. Phyloecology of urban alien floras. Journal of Ecology 97: 1243–1251.

Hulme P.E., Nentwig W., Pyšek P. & Vilà M. 2009b. Biological invasions: benefits versus risk. Response. Science 324: 1015–1016.

Hulme P.E., Nentwig W., Pyšek P. & Vilà M. 2009c. A standardized response to biological invasions. Response. Science 325: 146–147.

Hulme P.E., Nentwig W., Pyšek P. & Vilà M. 2009d. Common market, shared problems: time for a coordinated response to biological invasions in Europe? Neobiota 8: 3–19.

Ecological, taxonomic and evolutionary consequences of genome duplication

Genome duplication is widely acknowledged as a key force in plant evolution. Polyploids differ from their diploid counterparts in several phenotypic, ecological or life-trait characteristics. The former studies of diploid-polyploid plant groups were, however, hampered by non-representative sampling. This limitation was only overcome by the advent of flow cytometry. The prerequisite for comparative studies of polyploid groups is the knowledge of overall ploidy variation and cytotype distribution at various spatial scales. Targeted cytotype screening in several plant groups both in Europe and Africa has markedly changed our perception of ploidy variation and dynamics under natural conditions. Our data showed that genome duplication is much more prolific even in regions traditionally considered to be polyploid-depauperate. An illustrative example is the Cape flora where both genome-wide (e.g., variation in genome copy number and genome size) and chromosomal variation (e.g., different basic chromosome numbers) were detected (Suda et al. 2009; Fig­­. 3). Cytotype distribution is controlled by the synergistic effect of different ecological and evolutionary mechanisms. Evolutionary history (such as the number of independent polyploidization events and place of polyploid's origin) together with the migration ability largely shape the distribution at large spatial scales (Kolář et al. 2009). On the other hand, ecological preferences (e.g., microhabitat sorting, biotic and abiotic interactions) and competitive abilities of different cytotypes drive ploidy segregation at fine spatial scales (Hülber et al. 2009). Together with molecular markers, flow cytometry represents a powerful tool for gaining insight into the evolutionary history of polyploids, especially allopolyploids combining genomes of different parental taxa. Intraspecific differences in genome size allowed us to identify putative parental species in an important component of the high-altitude Alpine flora (Dixon et al. 2009).

Fig. 3 - Oxalis obtusa

Suda J., Loureiro J., Trávníček P., Rauchová J., Vít P., Urfus T., Kubešová M., Dreyer L.L., Oberlander K.C., Wester P. & Roets F. 2009. Flow cytometry and its applications in plant population biology, ecology and biosystematics: new prospects for the Cape flora. South African Journal of Botany 75: 389.

Kolář F., Štech M., Trávníček P., Rauchová J., Urfus T., Vít P., Kubešová M. & Suda J. 2009. Towards resolving the Knautia arvensis agg. (Dipsacaceae) puzzle: primary and secondary contact zones and ploidy segregation at landscape and microgeographic scales. Annals of Botany 103: 963–974.

Hülber K., Sonnleitner M., Flatscher R., Berger A., Dobrovsky R., Niessner S., Nigl T., Schneeweiss G.M., Kubešová M., Rauchová J., Suda J. & Schönswetter P. 2009. Ecological segregation drives fine scale cytotype distribution of Senecio carniolicus (Asteraceae) in the Eastern Alps. Preslia 81: 309–319.

Dixon C.J., Schönswetter P., Suda J., Wiedermann M. & Schneeweiss G.M. 2009. Reciprocal Pleistocene origin and postglacial range formation of an allopolyploid and its sympatric ancestors (Androsace adfinis group, Primulaceae). Molecular Phylogenetics and Evolution 50: 74–83.

Timing of flowering is an non-trivial result of selection pressure from pollinators and herbivores

The timing of reproduction influences how organisms interact with the environment and can have important effects on fitness. In plants, the evolution of flowering phenology is often interpreted as a response to the selection from mutualists, although antagonistic interactions may also be important. We examined direct and indirect phenotypic selection on the start of flowering via mutualistic and antagonistic interactions in the perennial herb Lathyrus vernus over seven years. Flowering start influenced seed set, predispersal seed predation, and risk of grazing. These effects acted in opposite directions and partly influenced different components of fitness. Combining information on the effects on fitness components with that on links between fitness components and average life-time fitness, in terms of population growth rate, showed that earlier flowering was associated with a higher life-time fitness in all years. These relationships were, however, mediated largely by the variation in flower number, and the direct selection on the date of first flowering was more variable among years. Thes results point that long-term studies correcting for indirect selection and environmental covariance are needed to understand selection on reproductive phenology and that demographic approaches are necessary to assess selection mediated by several agents and influencing several components of fitness (Ehrlén & Münzbergová2009).

Ehrlén J. & MünzbergováZ. 2009. Timing of flowering: Opposed selection on different fitness components and trait covariation. American Naturalist 173: 819–830.

Survival strategies of plants in disturbed environments

Plants, as sedentary organisms, are daily coping with unfavourable conditions of the environment. The study of plant adaptations to stress can contribute to understanding of their ecology and evolution. Plants possess two main systems of dealing with severe disturbances: they either do not survive and the population survival relies on regeneration from seed, or they tolerate the disturbance by means of vegetative regeneration from intact or fragmented parts of their body. Our research focused on mechanisms related to the varying success of regenerative strategies in different environments. We demonstrated that vegetative regeneration after disturbance plays an important role not only in perennials but also in short-lived species, such as widespread weeds (Sosnová & Klimešová 2009; Latzel et al. 2009). Such regeneration ability of weeds should be taken into account in conducting their mechanical removal, especially in organic farming. The mechanical removal of weeds is likely to be less efficient if target weeds are capable of vegetative regeneration. The nutrient level of the environment affects plants’ regenerative strategies in a different way (Latzel & Klimešová 2009), being an important factor determining preference for either seeding or resprouting strategy under given conditions. A novel result is that the success of individual regeneration strategies depends not only on ambient conditions of disturbed plants (e.g. nutrients) but also on the quality of environment experienced by preceding generations (Latzel et al. 2009). We have demonstrated that maternal plants affect the photosynthesis of their progeny (Fig­­. 4a), the growth of which therefore depends on nutrient levels experienced by their mothers. Due to maternal effects, the progeny of mothers that experienced severe disturbance grew better in nutrient-poor conditions whereas that of not disturbed mothers in nutrient-rich conditions (Fig. 4b). This indicates that maternal effects play an important role in different success of seeding and resprouting strategies after disturbance, hence also in the evolution of plant populations.

Fig. 4a

Fig. 4b

Sosnová M. & Klimešová J. 2009. Life-history variation in the short-lived herb Rorippa palustris: The role of carbon storage. Acta Oecologica 35: 691–697.

Latzel V., Dospělová L. & Klimešová J. 2009. Annuals sprouting adventitiously from the hypocotyl: Their compensatory growth and implications for weed management. Biologia 64: 923–929.

Latzel V. & Klimešová J. 2009. Fitness of resprouters versus seeders in relation to nutrient availability in two Plantago species. Acta Oecologica 35: 541–547.

Latzel V., Hájek T., Klimešová J. & Gómez S. 2009. Nutrients and disturbance history in two Plantago species: maternal effects as a clue for observed dichotomy between resprouting and seeding strategies. Oikos 118: 1669–1678.

 2008

Knowledge of biological invaders in Europe is used for setting future research priorities

The DAISIE project of the EU 6th Framework Programme was aimed at collating existing data about invasive organisms in Europe into a pan-European database; this data has been up to now scattered in grey literature and unpublished. The resulting open-access database (www.europe-aliens.org) includes information about 11,000 non-native species of vascular plants, fungi, invertebrates and vertebrates in terrestrial, freshwater and marine ecosystems of Europe. The data was analysed in a monograph, which summarizes historical, geographical and ecological trends in particular taxonomic/environmental groups and evaluates the impact of biological invaders on invaded ecosystems and presents a complete list of alien species in Europe; this list captures status quo of biological invasions in Europe and will serve as a reference data set for evaluating future trends and effectiveness of adopted measures against invasive species. The results of the DAISIE project revealed that the number of naturalized alien species in Europe is much higher than previously thought. A warning signal is that in the dynamics of increase in alien species numbers shows deccelaration in none of the taxonomic groups considered; rather the opposite is trues (DAISIE 2009). The Botanical Institute took major part in the plant part of the project. Alien flora of Europe consists of 5789 species, of which 3749 species are naturalized; 1780 naturalized species arrived from other continents (the remaining are native to part of Europe and invading in another part outside their native distribution range). Currently, six new naturalized species are recorded each year in Europe (Lambdon et al. 2008, Pyšek et al. 2009; Fig. 1). The data from DAISIE project were used as a reference data set in a study assessing geographical biases in research on bilogical invasions (Fig. 2). Some regions, such as Africa and Asia, are disproportionally little studied (related to the actual number of plant invaders), which leads to the lack of information on invasions occurring in regionally specific habitats. Taxonomic bias is minor (all major taxonomic groups of invaders are fairly well covered) but most information on mechanisms of invasions comes from case studies of a limited number of highly invasive species. Therefore, it seems plausible to shift the research focus more towards naturalization, i.e. the part of the process which determines successful establishment of a species in a new regions; this phase is also crucial for our understanding of how invasions work (Pyšek et al. 2008). Thanks to the DAISIE initiative, Europe has become a continent with the most comprehensive knowledge of its alien species, and the results has become an information basis for the recently released European Commision policy options for EU strategy on invasive species (press release no. IP/08/1890).

DAISIE 2009. Handbook of alien species in Europe. Springer, Berlin (ed. W. Nentwig, P.E. Hulme, P. Pyšek & M. Vilà); Pyšek P., Lambdon P., Arianoutsou M., Kühn I., Pino J. & Winter M.: Alien vascular plants of Europe. In: DAISIE (eds), Handbook of alien species in Europe, p. 43–61, Springer, Berlin (2009).

Lambdon P.W., Pyšek P., Basnou C., Hejda M., Arianoutsou M., Essl F., Jarošík V., Pergl J., Winter M., Anastasiu P., Andriopoulos P., Bazos I., Brundu G., Celesti-Grapow L., Chassot P., Delipetrou P., Josefsson M., Kark S., Klotz S., Kokkoris Y., Kühn I., Marchante H., Perglová I., Pino J., Vilà M., Zikos A., Roy D. & Hulme P.E.: Alien flora of Europe: species diversity, temporal trends, geographical patterns and research needs. Preslia 80: 101–149 (2008).

Pyšek P., Richardson D.M., Pergl J., Jarošík V., Sixtová Z. & Weber E.: Geographical and taxonomic biases in invasion ecology. Trends in Ecology and Evolution 23: 237–244 (2008).

New ecologically sustainable measures for the management of cyanobacterial water blooms in aquatic ecosystems

We tested 31 phtalocyanines, (patented in medicine for photodynamic treatment of carcinomes, some of them we already proved as potential algicides before). Cationic phtalocyanonides with substituted heterocycle were selected as the most promising (Jančula et al. 2008a). The experiments focused on the virioplankton proved that viral particles are an abundant and dynamic group of pelagic communities in river ecosystems (Fig. 1). There is a long way to practical use of viruses for management of cyanobacterial blooms, but the first step was to set up methods of their detection. We are the only lab in the Czech Republic, where virioplankton can be detected. Mutual correlations between virioplankton, its host and nutrient contents in the rivers studied indicate that the abundance and dynamics of virioplankton communities can be affected by phospohorus (Slováčková & Maršálek 2008). Our previous research showed that silvercarp was not an efficient tool for the direct management of cyanobacterial water blooms, but recent experiments with nile tilapia show, that photosynthetic activity of cyanobacteria decreased to zero by passing through the gut of this fish (Jančula et al. 2008b). Integrated toxicity assessment of sediments is a useful tool for the ecotoxicological evaluation of sediment quality and should be used in cases, where aquatic ecosystems are to be restored by sediment dredging. We developed a direct test of sediment toxicity, which is sensitive and more reliable than tests based on sediment extraction (Smutná et al. 2008).

Fig. 3. The abundance of virioplankton in river ecosystems is about one order higher than that of bacterioplankton (from Slováčková & Maršálek, Aquatic Sciences 2008).

Jančula D., Drábková M., Černý J., Karásková M., Kořínková R., Rakušan J. & Maršálek B.: Algicidal activity of phthalocyanines-screening of 31 compounds. Environmental Toxicology 23: 218–223 (2008a).

Jančula D., Míkovcová M., Adámek Z. & Maršálek B.: Changes in the photosynthetic activity of Microcystis colonies after gut passage through Nile tilapia (Oreochromis niloticus) and silver carp (Hypophthalmichthys molitrix). Aquaculture Research 39: 311–314 (2008b).

Slováčková H. & Maršálek B.: Virioplankton and microbial communities in two Czech rivers (Svratka and Morava Rivers). Aquatic Sciences 70: 282–291 (2008).

Smutná M., Hilscherová K., Pašková V. & Maršálek B.: Biochemical parameters in Tubifex tubifex as an integral part of complex sediment toxicity assessment. Journal of Soils and Sediments 8: 154–164 (2008). 

Spontaneous succession or technical reclamation as tools for restoration of vegetation in disturbed habitats

 Vegetation development was studied in gravel-sand pits, spoil heaps from brown coal mining, abandoned fields and spruce forests attacted by bark-beetles. The results contributed to answering the question if we can rely on spontaneous succession or a technical restoration is needed. The most disturbed sites exhibit a high potential to recover by spontaneous succession. This may be applied not only to disturbed sites in the Czech Republic but probably to others in the temperate climate. Vegetation development is influenced predominantly by the presence of target vegetation in a close vicinity (up to 100 m), land use in the surrounding landscape and local site factors, especially moisture, nutrients and pH. Reaching a target stage by spontaneous succession is limited if the surrounding vegetation largely differs and local site factors are altered. Spontaneous succession is not very effective either in highly productive sites where establishment of target species is restricted by a strong competitor. Under such situations, technical reclamation may be preferred. Preferrence for spontaneous succession or technical reclamation is to a large extent determined by the position of a disturbed site along the productivity-stress gradient (Fig­­. 1).

Fig. 1. Relative preference of spontaneous succession and technical reclamation along the productivity-stress gradient (from Prach & Hobbs, Restoration Ecology 2008).

Jonášová M. & Prach K.: The influence of bark beetles outbreak vs. salvage logging on ground layer vegetation in Central European mountain spruce forests. Biological Conservation 141: 1525–1535 (2008).

Frouz J., Prach K., Pižl V., Háněl L., Starý J., Tajovský K., Materna J., Balík V., Kalčík J. & Řehounková K.: Interactions between soil development, vegetation and soil fauna during spontaneous succession in post mining sites. European Journal of Soil Biology 44: 109–121 (2008).

Prach K., Lepš J. & Rejmánek M.: Old field succession in central Europe: local and regional patterns. In: Cramer V.A. & Hobbs R.J. (eds), Old fields: dynamics and restoration of abandoned farmland, p. 180–201, Island Press (2007).

Prach K. & Hobbs R.J.: Spontaneous succession vs. technical reclamation in the restoration of disturbed sites. Restoration Ecology 16: 363–366 (2008).

Řehounková K. & Prach K.: Spontaneous vegetation succession in gravel-sand pits: a potential for restoration. Restoration Ecology 16: 109–121 (2008). 

Checklist and Red List of lichens of the Czech Republic

In the published Red List, the threat of the Czech lichen flora is classified for the first time by using international criteria (IUCN version 3.1). The Red List serves also as a new version of the checklist, with changes to the previously published Catalogue of the Czech lichen flora (Vězda & Liška 1999) indicated. In total, 1497 species are included. More than a third of all species (37.4%) are threatened, almost a quarter of these (8.7% of the total number of species) critically. Almost one tenth of the total number of species is considered extinct in the Czech Republic, and only about one eighth are not endangered. The published work will make it possible to focus future research on the most threatened lichens, and the application of international criteria will allow to compare the situation in the Czech Republic with other European countries (Liška et al. 2008). Besides this complex evaluation of the Czech lichen flora, field studies are carried out aimed at the assessment of stress factors damaging to the lichen flora and at ongoing changes in its composition. Air pollution, mainly by sulphur dioxide, and eutrophication are the most important among these factors. The results of an 18 years lasting monitoring of 139 trees representing sites of epiphytic lichens, which are most susceptible to air pollution, made it possible to evaluate the effects of the distance from pollution source, type of substrate, altitude, and bark eutrophication on the susceptibility of lichen species to air pollution. Changes over time in species composition depended on the position of the tree in landscape and on the initial species composition. The lichen flora on trees affected by eutrophication exhibited less changes; this indicates that the effect of eutrophication (mainly increased bark pH) may reduce the damaging effect of air pollution (Liška & Herben 2008). Research also aims at case studies of individual species; for example, the distribution of Physcia aipolioides has been revised in cooperation with Slovak and Hungarian lichenologists (Lisická et al. 2008).

Liška J., Palice Z. & Slavíková Š.: Checklist and Red List of lichens of the Czech Republic. Preslia 80: 151–182 (2008).

Liška J. & Herben T.: Long-term changes of epiphytic lichen species composition over landscape gradients: an 18 year time series. Lichenologist 40: 437–448 (2008).

Lisická E., Lackovičová A., Liška J., Lőkös L. & Lisický M. J.: Physcia aipolioides – ein Beispiel einer invasiven Flechte oder einer unterschätzten Verbreitung? Sauteria 15: 303–318 (2008).

2007

Invasion of giant hogweed (Heracleum mantegazzianum) in Europe

Giant hogweed (Heracleum mantegazzianum), native to Caucasus, is a serious invasive species in Europe. Since 2002, various aspects of this species’ biology, ecology, genetics, biogeography and management were addressed within the GIANT ALIEN project of the 5th Framework Programme of EU. In 2007, the results were summarized in a monograph reviewing current knowledge of the invasion of this species in Europe (Pyšek et al. 2007). Three species of large hogweeds (H. mantegazzianum, H. sosnowskyi, H. persicum) invade in Europe and their distribution in the continent reflects different germination requirements and seed bank characteristics; Central Europe is invaded by Heracleum mantegazzianum. A high genetic variation was found in the invaded range, most likely due to repeated introductions of all three species to Europe (Jahodová et al., Diversity & Distributions 2007). Genetic studies identified suitable markers for Heracleum mantegazzianum (Henry et al. 2007). The invasive success of this species is determined by a combination of several traits, mostly related to reproduction: high fecundity, extremely high germination rate, short-term persistent seed bank, reproductive assurance through self-pollination, efficient dispersal and high regeneration ability); these traits are described, quantified and analysed in the monograph chapters (Pyšek et al. 2007). A comparison of theoretical simulations of population dynamics with real data, obtained from aerial photographs, suggests that about 2.5% of seed are subject to long-distance dispersal, which results in a dynamic spread and colonization of new sites (Nehrbass et al. 2007). Because of extremely high regeneration of giant hogweed plants, control measures aimed at preventing it from seed production need to be based on appropriate timing. If conducted too early, plants regenerate, if too late, seeds ripe on cut umbels (Pyšek et al., Biological Invasions 2007). The results are important for control and management of giant hogweed in Europe.

Pyšek, P., Cock, M. J. W., Nentwig, W. & Ravn, H. P. (2007): Ecology and management of Giant Hogweed (Heracleum mantegazzianum). – CAB International, Wallingford, 331 pp.

Jahodová, Š., Trybush, S., Pyšek, P., Wade, M., Karp, A.: Invasive species of Heracleum in Europe: an insight into genetic relationships and invasion history. – Diversity and Distributions 13: 99–114.

Pyšek, P., Krinke, L., Jarošík, V., Perglová, I., Pergl, J., Moravcová, L. (2007): Timing and extent of tissue removal affect reproduction characteristics of an invasive species Heracleum mantegazzianum. – Biological Invasions 9: 335–351.

Nehrbass, N., Winkler, E., Müllerová, J., Pergl, J., Pyšek, P., Perglová, I. (2007): A simulation model of plant invasion: long-distance dispersal determines the pattern of spread. – Biological Invasions 9: 383–395 (2007).

Henry, P., Provan, J., Goudet, J., Guisan, A., Jahodová, Š., Besnard, G. (2008): A set of primers for plastid indels and nuclear microsatellites in the invasive plant Heracleum mantegazzianum (Apiaceae) and their transferability to Heracleum sphondylium. – Molecular Ecology Resources 8: 161–1633.

Jahodová, Š., Fröberg, L., Pyšek, P., Geltman, D., Trybush, S., Karp, A. (2007): Taxonomy, identification, genetic relationships and distribution of large Heracleum species in Europe. – In: Pyšek P. et al. (eds), Ecology and management of giant hogweed (Heracleum mantegazzianum), CAB International, Wallingford, p. 1–19; Pyšek, P., Müllerová, J., Jarošík, V.: Historical dynamics of Heracleum mantegazzianum invasion on regional and local scales. – Ibid., p. 42–54; Perglová, I., Pergl, J., Pyšek, P.: Reproductive ecology of Heracleum mantegazzianum. – Ibid., p. 55–73; Moravcová, L., Pyšek, P., Krinke, L., Pergl, J., Perglová, I., Thompson, K.: Seed germination, dispersal and seed bank in Heracleum mantegazzianum. – Ibid., p. 74–91; Pyšek, P., Perglová, I., Krinke, L., Jarošík, V., Pergl, J., Moravcová, L.: Regeneration ability of Heracleum mantegazzianum and implication for control. – Ibid., p. 112–125; Moravcová, L., Gudžinskas, Z., Pyšek, P., Pergl, J., Perglová, I.: Seed ecology of Heracleum mantegazzianum and H. sosnowskyi, two invasive species with different distributions in Europe. – Ibid., p. 157–169; Pyšek, P., Cock, M. J. W., Nentwig, W., Ravn, H. P.: Master of all traits: Can we successfully fight giant hogweed? – Ibid., p. 297–312.

Diversity and evolution of Hieracium (Asteraceae)

The genus Hieracium belongs to most diverse and taxonomically intricate plant groups in Europe. The extreme diversity is caused by a combination of various breeding systems (sexuality, apomixis, vegetative spreading), common hybridization and polyploidy. Just study of groups with different modes of reproduction is an important contemporary issue. A series of papers comprising various new approaches was published in 2007. Phylogenetic reconstruction of Hieracium subgen. Pilosella based on selected molecular traits is of crucial importance for assessment of evolution in this group. Sequencing of selected segments of chloroplast DNA revealed two groups of haploide genotypes (haplotypes), incongruent with the recently accepted classifications. On the other hand, result of nuclear DNA (ITS) sequencing correspond with morphology and most likely reflect the real evolution (Fehrer et al. 2007). A review summarizing the sources of variation in Hieracium subgen. Pilosella appeared in 2000. Due to accelerated development in this field, research team of IB summarized recently gathered data, scattered in many publications (Fehrer et al. 2007). Recent development of flow cytometry allowed the estimation of genome size (DNA content) in a large set of basic species and both field and experimental hybrids of Hieracium subgen. Pilosella. Considerable interspecific differences were detected, which enable, besides others, to infer genome constitution (putative parental combination) in hybrids (Suda et al. 2007). Within Hieracium subgen. Hieracium, taxonomic treatment of a mountain apomictic group Hieracium nigrescens was finished. Morphological and geographical approaches were accompanied by isozyme analysis and a relation between isozyme phenotypes and morphologically defined types was confirmed (Chrtek et al. 2007, Chrtek & Mráz 2007).

Fehrer J., Gemeinholzer B., Chrtek J. Jr & Bräutigam S. (2007): Incongruent plastid and nuclear DNA phylogenies reveal ancient intergeneric hybridization in Pilosella hawkweeds (Hieracium, Cichorieae, Asteraceae). – Molecular Phylogenetics and Evolution 42: 347–361.

Circulation of cyanobacteria, algae and bacteria in the catchment area of Werenskoilbreen glacier, Svalbard

The succession of the algae, cyanobacteria and bacteria was studied in the catchment area of the Weresnkoildbreen glacier at Svalbard. The study was performed in four different habitats- subglacial sediments, proglacial sediments, in deglaciated soil and in wetlands. The main focus was laid on the circulation of the microorganisms among these different habitats, and their ability to survive the transfer to the subglacial systems and if they can participate on the primary colonization of newly deglaciated soils. It was found that the phototropic microorganisms can survive in the sediments under the glacier (subglacial systems) and that they can participate on the colonization of deglaciated soil. The most important sources of the inoculum for colonization are cryoconite sediments from proglacial area and microorganisms from wetlands. The transport is done by water in the summer season and by wind in the late autumn.
Other part of study was the seasonal and diurnal dynamics of the physiological state and photosynthetic activity of the snow alga Chlamydomonas nivalis. Photosynthetic activity was measured using pulse amplitude modulation fluorometry. Three types of cell (green biflagellate vegetative cells, orange spores clustered by means of mucilaginous sheaths, and purple spores with thick cell walls) were found, all of them photosynthetically active. The photosynthetic activity had seasonal and diel dynamics. The Fv/Fm values ranged between 0.4 and 0.7, and generally declined over the course of the season. A dynamic response of Fv/Fm to the irradiance was recorded.

Stibal, M., Elster, J., Šabacká, M., Kaštovská, K.: Seasonal and dial changes in photosynthetic activity of the snow algae Chlamydomonas nivalis (Chlorophyceae) from Svalbard determined by PAM fluorometry. – FEMS Microbioloy Ecology 59: 265–273 (2007).

Applications of flow cytometry to plant biosystematics, ecology, and population biology

Flow cytometry (FCM), a method of rapidly characterizing optical properties of isolated particles, is advancing research in several areas of cellular biology. However, its routine use in plant sciences was markedly delayed due to methodological difficulties and only the last decade has seen significant increase of FCM applications in plant biosystematics, ecology, and population biology. One of the recent landmarks is the first comprehensive book “Flow Cytometry with Plant Cells” (Doležel et al. 2007). Elucidation of causes and consequences of genome duplication, variation in nuclear genome size and modes of reproduction rank among the most promising research avenues (Kron et al. 2007). FCM offers many advantages over other methods of detecting ploidy, which paves the way for large-scale surveys at the landscape and population levels. Representative sampling allowed gaining novel insights into the extent of intra- and inter-population ploidy variation, niche differentiation, and ecological preferences of particular cytotypes (Suda et al., Amer. J. Bot. 2007). Synergistic use of FCM and molecular analyses proved suitable for unravelling complex low-level taxonomies, detection of cryptic biodiversity (Schönswetter et al. 2007) and colonization history of species/cytotypes (Eidesen et al. 2007). Genome size, another key character of living systems, was used as a species-specific character in plant groups with complex evolutionary history (Leong-Škorničková et al. 2007; Suda et al., Ann. Bot. 2007). A prerequisite of reliable FCM studies is the meticulous methodology (Doležel et al., Nature Protocols 2007). The data obtained will help better understanding of frequency and dynamics of polyploidy and genome evolution in populations of wild plants.

Doležel, J., Greilhuber, J., Suda, J.: Flow cytometry with plant cells: Analysis of genes, chromosomes and genomes. – Wiley-VCH, Weinheim, 455 pp. (2007).

2006

Biogeographical approach to plant invasions and processes underlying the naturalization of alien plants

Integration of hypotheses and theories explaining the ability of plant species to invade and vulnerability of regions/ecosystems to invasion is necessary for achieving progress in the theory of plant invasions; so far, these two facets were mostly considered separately (Richardson & Pyšek 2006, Pyšek et al. 2006). Biogeographical approach is a convenient tool for exploring the principles of naturalization (i.e. the ability of a species to sustain viable populations in the target area without help of humans (Pyšek & Richardson 2006). A global analysis of naturalization patterns shows that temperate mainland areas are more invaded than tropical mainlands, but islands in tropics suffer as much as islands in the temperate zone. Naturalization success decreases with latitude, indicating that for plant species it is easier to become naturalized in warmer climates. So far, studies used the number of naturalized species as a measure of naturalization success in a given region; in paper (Richardson & Pyšek 2006) we were the first who used a relative measure (percentage of the total number of alien plants introduced to the region that became successfully naturalized). This made it possible to reveal patterns that would otherwise remain hidden (Fig. 1).

Alongside with climate, propagule pressure (the number of propagules that are introduced to the target, i.e. invaded region) also crucially affects naturalization success. By using both climatic and propagule pressure variables in the same model (climatic match between source and target area was expressed by means of climate modelling, and the volume of trade and tourism between those two regions was used as a proxy for propagule pressure), we were able to explain present distribution and abundance of plants of South African origin invading in other parts of the world (Thriller at al. 2005).

Working on regional scale allows for a more precise evaluation of factors that determine naturalization as documented by a study considering the effects of propagule pressure and residence time. The approach adopted here was novel in that we worked with a source species pool (a vast majority of studies rely on plants in a target region, recruited from unknown species pool). Further, by focusing on woody plants we reduced potential bias associated with life forms (Křivánek e. Woody plants introduced to the Czech Republic for forestry purposes several centuries ago have significantly higher probability of escape from cultivation and subsequent naturalization than those introduced late (Fig. 2). The relative importance of residence time (i.e. time for which a species has been planted in CR) is significantly higher than that of the extent of planting (i.e. a proxy for propagule pressure). The paper indicates that forestry is an important historical pathways of alien plant invasions. Another study, using 180 woody species planted in the Czech Republic (Křivánek & Pyšek 2006), showed that invasive behaviour can be predicted based on species traits and concluded that a prediction scheme developed in Australia can be successfully used in the temperate zone of Central Europe.

Pyšek P., Richardson D. M. 2006. The biogeography of naturalization in alien plants. J. Biogeogr. 33: 2040–2050.

Richardson D. M., Pyšek P. 2006. Plant invasions: Merging the concepts of species invasiveness and community invasibility. Progr. Phys. Geogr. 30: 409–431.

Pyšek P., Richardson D. M., Jarošík V. 2006. Who cites who in the invasion zoo: insights from an analysis of the most highly cited papers in invasion ecology. Preslia 78: 437–468.

Thuiller W., Richardson D. M., Pyšek P., Midgley G. F., Hughes G. O., Rouget M. 2005. Niche-based modelling as a tool for predicting the risk of alien plant invasions at a global scale. Global Change Biol. 11: 2234–2250.

Křivánek M., Pyšek P., Jarošík V. 2006. Planting history and propagule pressure as predictors of invasions by woody species in a temperate region. Conserv. Biol. 20: 1487–1498.

Křivánek M., Pyšek P. 2006. Predicting invasions by woody species in a temperate zone: a test of three risk assessment schemes in the Czech Republic (Central Europe). Diversity Distrib. 12: 319–327.

The role of arbuscular mycorrhiza in contaminated and degraded soils

Symbiosis of plants with arbucular mycorrhizal fungi (AMF) represents an important mechanism how to cope with stresses, e.g. deficiency in mineral nutrients, unfavorable water relations or soil pH, high concentrations of heavy metals etc. To study contribution of AMF to immobilization of cadmium in substrate, tobacco plants were grown non-inoculated or inoculated with AMF (Janoušková et al. 2006). Obtained substrates were amended with Cd and Cd toxicity was than assessed by a series of biotests using growth inhibition of lettuce roots as a sensitive indicator. Tests revealed lower toxicity of Cd in mycorrhizal than non-mycorrhizal substrate, with the difference increasing with concentration of Cd (Fig. 1). In a subsequent experiment, it was found that extraradical mycelium contained ten to twenty fold higher concentrations of Cd per biomass unit than tobacco roots. Hypothesis on immobilization of heavy metals by AMF confirm also results from the experiment conducted in a soil contaminated with lead, where AM inoculation led to higher Pb concentrations in tobacco roots, presumably due to metal accumulation in fungal mycelium (Sudová et al. 2007). These data point to a potential of AMF for fytostabilization of contaminated soils.

Composition of AMF community and length of the extraradical fungal mycelium significantly affected the coexistence of two dominant plant species co-occurring in highly alkaline anthropogenic sediment from PVC factory in Portugal, the shrub Salix atrocinerea and herbaceous Conyza bilbaoana (Fig. 2) (Oliveira et al. 2006). In another experiment focused on biomass production in substrate from a freshly recultivated spoil bank, it was found that dual inoculation with AMF and soil yeasts significantly increased biomass of maize depending on the combination of yeast strain and AMF isolate (Gollner et al. 2006).

Janoušková M., Pavlíková D., Vosátka M. 2006. Potential contribution of arbuscular mycorrhiza to cadmium immobilisation in soil. Chemosphere 65: 1959–1965.

Sudová R., Pavlíková D., Macek T., Vosátka M. 2007. The effect of EDDS chelate and inoculation with the arbuscular mycorrhizal fungus Glomus intraradices on the efficacy of lead phytoextraction by two tobacco clones. Appl. Soil Ecol. 35: 163–173.

Oliveira R. S., Castro P.M.L., Dodd J.C., Vosátka M. 2006. Different native arbuscular mycorrhizal fungi influence the coexistence of two plant species in a highly alcaline anthropogenic sediment. Plant Soil 287: 209–221.

Gollner M.J., Püschel D., Rydlová J., Vosátka M. 2006. Effect of inoculation with soil yeasts on mycorrhizal symbiosis of maize. Pedobiologia 50: 341–345.

2005

Time of introduction still determines the current distribution of alien plants after several millenia of invasion

Historical circumstances play a crucial role in plant invasions, yet they are rarely considered in studies on alien plants, partly due to limited information on the history of particular invasions. A series of papers based on a unique data set of weeds in arable fields, sampled over a period of 50 years by using the same methods, showed that current distribution of so-called archaeophytes (alien plants introduced since the beginning of Neolithic agriculture until the end of Medieval) still reflects the history of plant invasions in Central Europe. Neolithic agriculture, introduced from the Near East in the 6th millenium BC, brought archaeophytes with crops and, by creating intense and continuous propagule pressure and imposing new agricultural management, facilitated their invasion. By contrast, the crops introduced during the past five centuries and their specific agrotechnical management has supported spreading of weed species from overseas (so-called neophytes, introduced after ca. 1500 BC). Archaeophytes are still more common in old crops introduced with the beginning of agriculture (cereals), but are poorly represented in relatively recently introduced crops (rape, maize), where neophytes are most numerous. Archaeophytes respond like neophytes to some variables (climate, seasonal development of crop) and alternatively like native species to other variables (increasing agricultural intensification through time, human population density). In general, species diversity of weeds on arable land decreased from 1955 to 2000; this decrease is due to retreat of native species and archaeophytes, while modern invaders (neophytes) are becoming more numerous.
A global comparative study of residence times of species in alien floras (defined as time for which they have been present in a region) indicates that species that were introduced early have currently wider distribution or are more frequent than those that arrived later. The effect of residence time on current distribution of neophytes is very strong, relative to other factors, and should be taken into account in studies exploring factors affecting invasiveness, to avoid obtaining biased results. Surprisingly, residence time still strongly determines current distributions of archaeophytes after several millenia of invasion and its effect is clearly detectable (see Fig. 1). Comparison of Central Europe with British Isles indicates that both regions were invaded by archaeophytes at a similar rate, reflecting that arable land is ecologically similar in different regions and so was the ancient agricultural management that affected the invasion success of archaeophytes. The invasion by archaeophytes started about 1000 yrs earlier in Central Europe than in UK, which si more distant from Mediterranean, the region from which most archaeophytes originated. This delay corresponds to the later start of the Neolithics in the latter region and indicates that as Neolithic people brought about not only crops but also weeds, the invasion by archaeophytes in both regions started immediately with the beginning of the agriculture.

Fig. 1

Pyšek P., Jarošík V., Chytrý M., Kropáč Z., Tichý L. & Wild. J. 2005. Alien plants in temperate weed communities: Prehistoric and recent invaders occupy different habitats. Ecology 86: 772–785.

Pyšek P. & Jarošík V. 2005. Residence time determines the distribution of alien plants. In: Inderjit (ed.), Invasive plants: ecological and agricultural aspects, pp. 77–96, Birkhäuser Verlag-AG, Basel.

Chytrý M., Pyšek P., Tichý L., Knollová I. & Danihelka J. 2005. Invasions by alien plants in the Czech Republic: a quantitative assessment across habitats. Preslia 77: 339–354.

Pyšek P., Jarošík V., Kropáč Z., Chytrý M., Wild J. & Tichý L. 2005. Effect of abiotic factors on species richness and cover in Central European weed communities. Agriculture, Ecosystems & Environment 109: 1–8.

Pyšek P. 2005. Survival rates in the Czech Republic of introduced plants known as wool aliens. Biological Invasions 7: 567–576.

Rejmánek M., Richardson D. M. & Pyšek P. 2004. Plant invasions and invasibility of plant communities. In: Van der Maarel E. (ed.), Vegetation ecology, p. 332–355, Blackwell Science, Oxford.

Population dynamics of plants and its importance for understanding species performance in the landscape

Matrix population models are valuable tools for analyses of population viability. In spite of the fact that these techniques are being used already for several decades, they still suffer many methodological problems. We have also not yet appreciated use of these models for answering various ecological questions. We explored the techniques that are currently available for analyses of population dynamics of species. We demonstrate that current techniques are not very precise and suggest an alternative technique that could significantly improve the predictive power of matrix models (Münzbergová & Ehrlén 2005).
We also show how matrix models can be used to predict the rarity of plant species and their response to habitat fragmentation (Münzbergová 2005, 2006). Results of both studies show, that the approach based on analysing complete life cycle of the species is more realistic than that using single species traits. This suggests that conclusions of previous studies can be misleading and more studies on local population dynamics of species are needed. Our model studies suggest that seed predation can explain species rarity at the landscape level, in spite of the fact that the two species compared do not experience different intensity of seed predation (Fig. 1). On the other hand we show that population size does not affect the long-term survival of species despite of having a strong effect on individual species traits.
Our results also indicate the importance of local population dynamics for understanding the distribution of suitable unoccupied habitats in the landscape (Ehrlén et al. 2006). The results of an 11-year sowing experiment demonstrate that it is difficult to identify to identify such habitats by employing current techniques, especially for long-lived species with low recruitment probability. Knowledge of the population dynamics of the species before establishing such an experiment would allow to take this into account and design more robust experiments. We also show that suitable unoccupied habitats really exist in the landscape. Confirming the existence of such localities is important for demonstrating that species behaves as a metapopulations, i.e. sets of interconnected populations.

Münzbergová Z., Ehrlén J. 2005. How best to collect demographic data for population viability analysis models. J. Appl. Ecol. 42: 1115–1120.

Münzbergová Z. 2005. Determinants of species rarity: Population growth rates of species sharing the same habitat. Am. J. Bot. 92: 1987–1994.

Münzbergová Z. 2006. Effect of population size on prospect of species survival. Folia Geobotanica 41: 137–150.

Ehrlén J., Münzbergová Z., Diekmann M., Eriksson O. 2006 Long-term assessment of seed limitation in plants: results from an 11-year experiment. J. Ecol. 94: 1224–1232. 

A European monograph of oscillatorialean Cyanobacteria

The modern taxonomic classification of cyanobacteria has changed substantially in the last decades of the 20th century. Ecological, ultrastructural and particularly biochemical and molecular approach brough about introduction of new criteria that have radically modified and corrected previous systematic classification. The concept of oscillatorialean (filamentous, non-heterocytous) types have been changed in particular, and numerous genera and species were revised. The molecular basis must be decisive for taxonomic classification, however, the phenotype characters were re-evaluated and applied for identification practice of natural populations and isolated strains in coincidence with the molecular background. Our participation in the modernization of the cyanobacterial system concerned mainly coincidences of morphological, ecophysiological and molecular markers; particularly, we have proved the different evolution of ultrastructural patterns in cells in various evolution lines (Komárek & Kaštovský 2003), and revised the delimitation of taxa on the generic level (Fig. 1).
The European monograph of oscillatorialean cyanobacteria was elaborated and finished by J. Komárek at the Institute of Botany AS CR under the support of the Grant Agency of the Czech Republic (grants no. 206/95/0506 and KSK 6005114). The second co-author, K. Anagnostidis (deceased in 1994), prepared the major part of the literature and revised several genera according to modern criteria up to 1994. The book (759 pp.) was edited as a 2^nd part of Cyanoprokaryotes in the frame of the compendium Sűsswasserflora von Mitteleuropa (edited by Elsevier-Spektrum, Heidelberg). It contains identification keys and descriptions of all cyanobacterial filamentous, non-heterocytous genera (53), keys, descriptions, illustrations and ecological data of almost 590 European oscillatorialean species, and remarks to over 400 species from outside Europe. The book contains 1010 figures, list of literature (58 pages), and index of all mentioned taxa. The modernized cyanobacterial system based on polyphasic (combined) criteria is added. The books were edited in June 2005, and over 80% of edition have been already sold. The previous volume, edited in 1998, was evaluated by the American Phycological Society by the G. W. Prescott Award.

The monograph has resulted from intense work of several years, and numerous papers were published as preparatory studies with taxonomic revisions and nomenclatoric validation of numerous taxa on both, generic and specific levels. Results of our work were demonstrated in several international meetings, oriented to taxonomic or molecular cyanobacterial research (e.g., in four symposia in 2005). This annotation is documented by the monograph itself and one principal study published in 2005.

	Fig. 1

Komárek J. & Anagnostidis K. (2005): Cyanoprokaryota, Part 2: Oscillatoriales. – In: Büdel, B. et al. (eds.), Süsswasserflora von Mitteleuropa, 19/2, Elsevier/Spektrum, Heidelberg, 759 pp.

Hoffmann L., Komárek J. & Kaštovský J. (2005): System of Cyanoprokaryotes (Cyanobacteria) – state in 2004. – Arch. Hydrobiol./Algolog. Studies 117: 265–278.