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12. Flowering phenology and reproductive effort of the invasive alien plant Heracleum mantegazzianum

Creator:
Perglová, Irena, Pergl, Jan, and Pyšek, Petr
Type:
article and TEXT
Subject:
alien plant, andromonoecy, Apiaceae, Czech Republic, fecundity, flowering, fruit production, invasive plant, phenology, protandry, and self-pollination
Language:
English
Description:
Heracleum mantegazzianum is one of the most invasive species in the Czech flora. The present study describes its flowering phenology and assess the effectiveness of protandry in preventing selfing in this self-compatible species, describes the timing of flowering in a heavily invaded area of Slavkovský les (Czech Republic) and estimates fruit set in a large sample of plants, which provides reliable data on the often exaggerated fecundity of this species. The study of flowering phenology revealed that protandry is always effective only within individual flowers, where male and female flowering phases are completely separated. In contrast, anther dehiscence in some flowers can occasionally overlap with stigma receptivity in other flowers in the same umbel, providing an opportunity for geitonogamous (i.e. between-flower) selfing. Nevertheless, the potential for selfing in H. mantegazzianum is determined mainly by an overlap in the male and female flowering phases between umbels on the same plant; at least a short overlap between some umbels was observed in 99% of the plants at the Slavkovský les. Although the degree of protandry in H. mantegazzianum favours outcrossing, the opportunity to self may be of crucial importance for an invasive plant, especially if a single plant colonizes a new location. At Slavkovský les, flowering started within one week (from 20 to 27 June 2002) at all 10 sites. The duration of flowering of an individual plantwas on average 36 days,with maximum of 60 days, and increased significantly with the number of umbels on a plant. In the second half of August, the majority of the fruits were ripe and had started to be shed. The beginning of flowering of a plant was significantly negatively correlated with the number of umbels it had – the earlier a plant started to flower the more umbels it had produced. A significant negative relationship was also found between basal diameter and beginning of flowering; plants with large basal diameters started to flower earlier. An average plant at Slavkovský les produced 20,671 fruits. Of these, 44.6% were produced by the terminal umbel, 29.3% by secondary umbels on satellites, 22.6% by secondary umbels on branches and only 3.5% by tertiary umbels. The estimated fruit number of the most fecund plant was 46,470 – compared to an average plant, the proportional contribution of tertiary umbels increased relative to the primary umbel. This study revealed a significant positive relationship between fecundity and plant basal diameter. Although the results of this study indicate that the fecundity of this species is often overestimated in the literature, the number of fruits produced by H. mantegazzianum provides this invasive species with an enormous reproductive capacity.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/

14. History of the invasion and distribution of Reynoutria taxa in the Czech Republic: a hybrid spreading faster than its parents

Creator:
Mandák , Bohumil, Pyšek, Petr, and Bímová , Kateřina
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
alien plants, Czech Republic, distribution, Fallopia, history of invasion, hybridization, habitat preferences, Polygonaceae, rate of spread, Reynoutria ×bohemica, R. japonica, and R. sachalinensis
Language:
English
Description:
The distribution of four alien Reynoutria taxa (R. japonica var. japonica, R. japonica var. compacta, R. sachalinensis and R. ×bohemica), native to East Asia, and history of their introduction to and spread in the Czech Republic was studied. The most widely distributed representative of the genus, R. japonica var. japonica, was first recorded in 1883 by A. Weidmann in cultivation in S Bohemia. The first record outside cultivation is from N Bohemia in 1902. Up to 2000, it has been recorded in 1335 localities, most frequently in riparian and human-made habitats. The dwarf variety R. japonica var. compacta is of a limited distribution that depends on rare cultivation and subsequent escape. The first herbarium specimen was collected in 1948 and the first record out of cultivation is from 1995. R. sachalinensis was recorded in 261 localities. It was first collected in 1921 in Central Bohemia. A herbarium specimen of a plant cultivated in the Botanical Garden of the Charles University in Prague, collected in 1950, has been re-determined as R. ×bohemica, the hybrid between R. japonica var. japonica and R. sachalinensis, and represents the earliest record of the hybrid in the Czech Republic. Since then, this taxon was observed in 381 localities. Herbarium records were used to compare the rate of spread among the three common taxa in 1952–1995, i.e. since when the hybrid started to appear in herbaria. R. japonica var. japonica has been spreading significantly faster than R. sachalinensis and the hybrid exhibits twice the rate of invasion of its parents.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

15. Invasions by alien plants in the Czech Republic: a quantitative assessment across habitats

Creator:
Chytrý, Milan, Pyšek, Petr, Tichý, Lubomír, Knollová, Ilona, and Danihelka, Jiří
Type:
article and TEXT
Subject:
archaeophytes, EUNIS, habitat invasibility, level of invasion, neophytes, phytosociological database, species number, and vegetation cover
Language:
English
Description:
Occurrence of alien plant species in all the major habitats in the Czech Republicwas analysed using a data set of 20,468 vegetation plots, classified into 32 habitats according to the EUNIS classification. The plots contain on average 9.0% archaeophytes and 2.3% neophytes; for neophytes, this proportion is much smaller than 26.8% reported for the total flora of the country. Most neophytes are found in a few habitats: only 5.6% of them were recorded in more than ten habitats. By contrast, archaeophytes, and especially native species, tend to occur in a broader range of habitats. Highest numbers of aliens were found on arable land, in annual synantropic vegetation, trampled habitats and anthropogenic tall-forb stands. These habitats contain on average 22–56% archaeophytes and 4.4–9.6% neophytes. Neophytes are also common in artificial broadleaved forestry plantations; they also tend to make up a high percentage of the cover in wet tall-forb stands, but are represented by fewer species there. Entirely or nearly free of aliens are plots located in raised bogs, alpine grasslands, alpine and subalpine scrub and natural coniferous woodlands. Correlations between the number of archaeophytes or neophytes and the number of native species, calculated with habitat mean values, were non-significant, but there was a positive correlation between the numbers of archaeophytes and neophytes. The ratio of archaeophytes to neophytes was high in semi-natural dry and mesic grasslands and low in disturbed habitats with woody vegetation, such as artificial broadleaved forestry plantations, forest clearings and riverine willow stands. When individual plots were compared separately within habitats, the relationships between the number of archaeophytes, neophytes and native species were mostly positive. This result does not support the hypothesis that species-rich communities are less invasible, at least at the scale of vegetation plots, i.e. 10 0–10 2 m2.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/

16. Kam se šíří zavlečené rostliny?

Creator:
Chytrý, Milan and Pyšek, Petr
Type:
article and TEXT
Language:
Czech
Description:
Biologické invaze mohou mít závažné důsledky pro biodiverzitu invadovaných území, mohou působit ekonomické škody i negativně ovlivňovat lidské zdraví. Proto se jejich výzkum v posledních dvaceti letech prudce rozvíjí. První díl seriálu, ve kterém budou představeny nové poznatky z výzkumu invazibility (invasibility) ekosystémů nepůvodními rostlinami, se zabývá rozdíly v invadovanosti (level of invasion) velkých území. Obecně lze shrnout, že ostrovy jsou invadovány více než pevnina, Nový svět více než Starý svět, temperátní a boreální zóna více než tropy a nížiny více než horské oblasti. and Biological invasions can have huge consequences for the biodiversity of invaded areas. They can cause economic damage and have a negative effect on human health. This is why research into them has been highly developed over the last 20 years. The first of this series of articles aiming to present new knowledge from research on the invasibility of ecosystems by alien plants deals with differences in the level of invasion of large areas. On the whole it can be said that islands are invaded more than continents, the New World more than the Old World, temperate and boreal zones more than tropics and lowlands more than mountains.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/

17. Kam se šíří zavlečené rostliny?

Creator:
Chytrý, Milan and Pyšek, Petr
Type:
article and TEXT
Language:
Czech
Description:
Výsledky studií z území s různými přírodními podmínkami, různou skladbou flóry a různou historií vlivu člověka na přírodu dávají tušit, že invazibilita rostlinných společenstev není jevem náhodným, ale je do značné míry řízena obecnými zákonitostmi. Obecná teorie invazibility však může mít velký význam jak pro ekologickou teorii, tak pro praxi. Taková teorie umožní předvídat, kde a za jakých okolností vznikne největší riziko invazí, což by ve spojení s efektivním ochranářským managementem mohlo vést k jejich účinnému předcházení nebo omezování. and Results of study carried out in areas with varying natural conditions and varying floral composition, as well as on the history of man’s influence on nature show that the invasive potential of plant communities is not an accidental phenomenon but that it follows general rules. A general theory on invasibility may be of great importance both for ecological theory and practice. Such theory enables us to foresee where and under which conditions the highest invasion risk occurs, and this can be used in combination with effective conservation management to prevent or reduce risk.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/

18. Kam se šíří zavlečené rostliny?

Creator:
Chytrý, Milan and Pyšek, Petr
Type:
article and TEXT
Language:
Czech
Description:
Znalosti o invadovanosti různých společenstev nebo biotopů byly až donedávna spíše kusé a nepodložené reprezentativními daty, která by srovnávala větší počet společenstev. Teprve koncem 90. let 20. století se objevil vhodný zdroj dat pro hodnocení invadovanosti rostlinných společenstev, a to velké databáze fytocenologických snímků vytvářené v některých zemích, zejména v Evropě. Článek přináší mj. odpověď na otázky, která společenstva jsou nejvíce a nejméně invadována a jaké jsou rozdíly v invadovanosti společenstev archeofyty a neofyty. and Knowledge on the level of invasion in different communities and biotopes has been very scarce until recently and not supported by representative data comparing a higher number of communities. As late as at the end of the 1990s, an important source of data allowing for the evaluation of plant communities’ level of invasion was discovered, namely great databases of phytosociological relevés collected in some countries, especially in Europe. The article answers to such questions as which communities are invaded at the highest and which at the lowest level and which differences exist in invasion level by archeophytes and neophytes.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/