Studie se zabývá pravěkým vývojem oblasti Bezdězska – Dokeska v severních Čechách se zvláštním zřetelem na výzkum laténského sídliště Okna, které je s opatrností připisováno kobylské skupině. Sídliště je posuzováno s ohledem na fakta získaná paleobotanickým, geobotanickým a sedimentologickým výzkumem lokality i celého zkoumaného regionu, který je z velké části tvořen boreálním lesem. Jsou diskutovány možnosti jeho využívání v pravěku a důvody pozdní kolonizace zemědělských půd v jeho bezprostředním okolí, která nastává až v pozdně laténském období a následně ve středověku. Výzkum nivy Robečského potoka zachytil dvě erozní události, které jsou následkem odlesnění a vzniku polí, první v době existence laténského sídliště a druhá nejspíše po založení středověké vsi Okna. and The study deals with the prehistoric development of the Bezděz – Doksy region in Northern Bohemia, with special regard to the excavation of the La Tène settlement at Okna that is cautiously ascribed to the Kobyly group. The settlement is assessed according to the data obtained by palaeobotanic, geobotanic and sedimentologic research of the site as well as the whole studied region which is largely comprised of boreal forest. Its possible use in prehistory and the reasons of late colonization of agricultural lands in its immediate vicinity, which occurs only in late La Tène period and subsequently in the Middle Ages, are discussed. Survey of the alluvial plain of the Robečský brook revealed two erosion events which may be results of deforestation and establishment of fields, first during the existence of the La Tène settlement and the last probably upon foundation of the medieval village of Okna.
A syntaxonomical synthesis of calcicolous forests dominated by Fagus sylvatica (Cephalanthero-Fagenion suballiance) in the Czech Republic was carried out using the Braun-Blanquet approach. Relevés included in the analyses were selected following formalized approach by using an expert-delimited group of 38 calcicolous and/or xerothermophilous species. Only one association Cephalanthero-Fagetum was distinguished, which usually occurs on limestone, calcareous sandstone and calcareous sandy marlite; however, can be found also on base-rich siliceous bedrock (e.g. basalt, phonolite). Based on TWINSPAN analysis, three subassociations were recognized within the Cephalanthero-Fagetum: (i) Cephalanthero-Fagetum seslerietosum caeruleae on shallow rocky soils with frequent dominance of Sesleria caerulea and presence of petrophytes, (ii) Cephalanthero-Fagetum typicum on dry, shallow soils with a significant presence of light-demanding, thermophilous, and calcicolous species, and (iii) Cephalanthero-Fagetum actaeetosum spicatae on deeper, sufficiently moist soils with an abundance of mesophilous, nitrophilous and acidophilous species. The name Cephalanthero-Fagetum actaeetosum spicatae is a new nomenclatural combination. The relationships between Cephalanthero-Fagetum and similar forest vegetation types containing xerothermophilous and/or calcicolous species in the Czech Republic are discussed. The main gradients in species composition of Cephalanthero-Fagetum subassociations were revealed by gradient analysis. The Ellenberg indicator values, altitude, slope, and ‘southness’ were used to interpret these gradients. Using unconstrained ordination analysis (DCA) the syntaxonomical interpretation indicated three relatively distinct groups. Moreover, further DCA analysis revealed the well-defined position of Cephalanthero-Fagetum within Czech beech forests. The results of the above delimitation of Cephalanthero-Fagetum were compared with the results based on Cocktail-defined species groups improved by similarity-based assignment of relevés (using frequency-positive fidelity index). When the Cocktail-based formulas for beech forests were applied to the relevés selected by our 38-species diagnostic group, the correspondence between these two approaches was only 36%. However, at the lower subassociation level, the highest correspondence occurred for Cephalanthero-Fagetum seslerietosum (84%). The reason for this high correspondence is that the species composition includes many specialists (i.e. good diagnostic species) and it occurs at the end of an ecological gradient. To sum up, it is possible to define vegetation units accurately using strict formulas, as opposed to the less rigorous ‘soft’ traditional approach. However, both approaches fail when defining central units.
Alien flora of the Czech Republic is presented. In Appendix 1, 1378 alien taxa (33.4% of the total flora) are listed with information on the taxonomic position, origin, invasive status (casual, naturalized, invasive; a new category post-invasive is introduced), time of immigration (archaeophytes vs. neophytes), habitat type invaded (natural, seminatural, human-made), vegetation invaded (expressed as occurence in phytosociological alliances), mode of introduction into the country (accidental, deliberate), and date of the first record. Number of phytogeographical as well as biological and ecological attributes were compiled for each species in the database; its structure is presented in Appendix 2 as a suggestion for similar work elsewhere. Czech alien flora consists of 24.1% of taxa which arrived before 1500 (archaeophytes) and 75.9% neophytes. There are 891 casuals, 397 naturalized and 90 invasive species. Of introduced neophytes, 21.9% became naturalized, and 6.6% invasive. Hybrids contribute with 13.3% to the total number of aliens, and the hybridization is more frequent in archaeophytes (18.7%) than in neophytes (11.7%). If the 184 hybrids are excluded from the total number of aliens, there are 270 archaeophytes and 924 neophytes in the Czech flora, i.e. total of 1195 taxa. Accidental arrivals account for 53.4% of all taxa and deliberate introduction for 46.6%; the ratio is reversed for neophytes considered separately (45.5 vs. 54.5%). Majority of aliens (62.8%) are confined to human- made habitats, 11.0% were recorded exclusively in natural or seminatural habitats, and 26.2% occur in both types of habitat. Archaeophytes and neophytes occur in 66 and 83 alliances, respectively, of the phytosociological system. Flora is further analysed with respect to origin, life histories, life forms and strategies. Only 310 species (22.4% of the total number of all alien taxa) are common or locally abundant; others are rare, based on a single locality or no longer present. The following 19 taxa are reported as new for the Czech alien flora: Agrostis scabra, Alhagi pseudalhagi, Allium atropurpureum, Bromus hordeaceus subsp. pseudothominii, Carduus tenuiflorus, Centaurea ×gerstlaueri, Centaurea nigra ×phrygia, Cerastium ×maureri, Gilia capitata, Helianthus strumosus, Hieracium pannosum, Hordeum leporinum, Oenothera coronifera, Papaver atlanticum subsp. mesatlanticum, Parietaria pennsylvanica, Polypogon fugax, Rodgersia aesculifolia, Sedum pallidum var. bithynicum, Sedum stoloniferum; these represent results of our own field research as well as of herbaria search, and unpublished data from colleagues. Other 44 taxa are reported as escaping from cultivation for the first time. Twenty two archaeophytes are listed in the Red List of the Czech flora.
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: Abies concolor, A. grandis, A. nordmanniana, Avena sterilis subsp. ludoviciana, A. ×vilis, Berberis julianae, B. thunbergii, Bidens ferulifolius, Buddleja alternifolia, Buglossoides incrassata subsp. splitgerberi, Buxus sempervirens, Corispermum declinatum, Cotoneaster dielsianus, C. divaricatus, Euphorbia myrsinites, Gleditsia triacanthos, Helleborus orientalis, Hieracium heldreichii, Koelreuteria paniculata, Lonicera periclymenum, Lotus ornithopodioides, Malus baccata, M. pumila, Miscanthus sacchariflorus, Morus alba, Muscari armeniacum, Paeonia lactiflora, Pennisetum alopecuroides, Pinguicula crystallina subsp. hirtiflora, P. grandiflora subsp. rosea, Podophyllum hexandrum, Pyracantha coccinea, Rhodotypos scandens, Rumex patientia × R. tianschanicus ‘Uteuša’, Salix cordata, Sarracenia purpurea, Sasa palmata ‘Nebulosa’, Scolymus maculatus, Spiraea japonica, Tagetes tenuifolia, Thuja occidentalis, Trifolium badium, Vaccinium corymbosum and Viburnum rhytidophyllum. All added and deleted taxa are commented on. Of the total number of taxa, 985 are classified as casuals, 408 as naturalized but not invasive, and 61 as invasive. The reduction in the number of invasive taxa compared to the previous catalogue is due to a more conservative approach adopted here; only taxa that currently spread are considered invasive. Casual taxa are strongly overrepresented among neophytes compared to archaeophytes (76.7% vs 39.4%), while naturalized but non-invasive taxa follow the reversed pattern (18.8% vs 57.4). However, these two groups do not significantly differ in the proportion of invasive taxa. Of introduced neophytes, 250 taxa (22.6%) are considered vanished, i.e. no longer present in the flora, while 23.3% became naturalized, and 4.5% invasive. In addition to the traditional classification based on introduction–naturalization–invasion continuum, taxa were classified into 18 population groups based on their long-term trends in metapopulation dynamics in the country, current state of their populations, and link to the propagule pressure from cultivation. Mapping these population groups onto the unified framework for biological invasions introduced by Blackburn et al. in 2011 made it possible to quantify invasion failures, and boom-and-busts, in the Czech alien flora. Depending on inclusion criteria (whether or not extinct/vanished taxa and hybrids are considered), alien taxa ever recorded in the Czech Republic contribute 29.7–33.1% to the total country’s plant diversity; taking into account only naturalized taxa, a permanent element of the country’s flora, the figure is 14.4–17.5%. Analysis of the dates of the first record, known for 771 neophytes, indicates that alien taxa in the flora have been increasing at a steady pace without any distinct deceleration trend; by extrapolating this data to all 1104 neophytes recorded it is predicted that the projected number would reach 1264 in 2050. Deliberate introduction was involved in 747 cases (51.4%), the remaining 48.6% of taxa are assumed to have arrived by unintentional pathways. Archaeophytes are more abundant in landscapes, occupy on average a wider range of habitat types than neophytes, but reach a lower cover in plant communities. The alien flora is further analysed with respect to representation of genera and families, origin and life history. and Nevejdou se dvě poslední jména autorů
Hradiště Vladař v západních Čechách dlouho unikalo soustředěné pozornosti archeologů. V posledních letech zde probíhá výzkum, jehož podstatným aspektem se stala účast přírodovědců různého zaměření. Důvodem jsou ideální podmínky pro podobnou mezioborovou spolupráci – kromě tradičních archeologických situací můžeme k paleoenvironmentálním analýzám využít výplň umělé vodní nádrže, která se nachází uprostřed hradištní akropole. Nádrž poskytla souvislý sedimentární záznam s množstvím dobře zachovaných biologických pozůstatků, přičemž nejstarší vrstvy vznikly na přelomu 5. a 4. stol. BC. V té době byl zkoumaný prostor téměř zcela odlesněn a intenzivně zemědělsky využíván. Na samém sklonku 3. stol. BC došlo k částečnému opuštění hradiště; doklady předchozího masivního osídlení mizí. Na přelomu letopočtu bylo hradiště opuštěno zcela a proběhla vegetační sukcese k zapojenému lesu. V 6. stol. n. l. nastoupila nová vlna kolonizace, která vyvrcholila později vznikem vrcholně středověké kulturní krajiny. Popsaný proces se podařilo podrobně zdokumentovat přírodovědnými metodami i s některými detailními vhledy do struktury a fungování pravěké krajiny. Datování se opírá výhradně o radiokarbonovou chronologii, doplněnou v některých obdobích o nálezy keramiky. and The large fortified hilltop site of Vladař (W Bohemia, Czech Republic, 50° 05’ N, 13° 13’ E) is being studied intensively during recent years by means of environmental archaeology. Palaeoecological methods play a crucial role in this effort; these include analyses of pollen, green algae, Cladocera and other microfossils, plant macroremains (including charcoal and wood) and chemical analyses. This investigation is enabled due to the existence of an artificial water reservoir situated in the middle of the large acropolis. A continuous sedimentary record in the form of well-preserved biological remains starts ca. 400 BC. Absolute dating is based on radiocarbon chronology and is complemented by archaeological finds in some instances. During the oldest documented period, the hillfort has been settled by a considerable number of permanent inhabitants. The site and the surrounding landscape has been almost completely deforested and used for diverse agricultural practices. The site has been partly abandoned by the end of the 3rd century BC. Total abandonment is dated around 0 BC/AD. Natural succesion started at that time, leading to the development of natural forest communities. During the 6th century AD, a new wave of colonization reached the region, culminating at the onset of the High Medieval period.
Based on a combination of data from the Czech National Phytosociological Database and expert knowledge, a database of vascular plant species pools for 88 habitats, representative of the diversity of Czech vegetation, was compiled. This database contains 1820 native species, 249 archaeophytes and 278 neophytes, each assigned to one or more habitats. Besides the data on species occurrence in different habitats, the database contains information on a species’ ecological optimum in the habitat or its dominance. The largest pools of native species were found in rather rare habitats of dry and warm herbaceous or woody habitats at low altitudes, some of which contain > 530 species (maximum of 695 species for thermophilous forest fringes). These were followed by common habitats on mesic soils. The smallest pools of native species were in saline, aquatic and bog habitats ( 350 native species always contained > 5 archaeophytes and > 5 neophytes, and often many more. Two hundred and thirty two native species, 18 archaeophytes and 30 neophytes were identified as potential dominants in at least one habitat. However, potentially dominant species made up less than 3% of the species pool for 78 out of 88 habitats. Larger percentages (up to 14.6%) of potential dominants were included in habitats with small species pools and species-poor stands (e.g., aquatic, saline and mire habitats). The number of habitats in which a species occurred was used as a measure of its ecological range. Most ecological generalists were found among the native species, less among the archaeophytes and least among the neophytes. Out of the 36 species that occur as dominants in three or more habitats, 34 were native (many are grasses), onewas an archaeophyte (Cirsium arvense) and one was a neophyte (Impatiens parviflora).
Nutrient-rich terrestric habitats form small areas in the peaty alluvial plain of upper stream of the Vltava river. Their vegetation consists of birch and grey alder alluvial woodland, willow and bridewort scrub and tall grassland of sedges, grasses and forbs. A hypothesis that this vegetation is an Early Holocene relic is presented. The relict origin is supported by recent dynamics of habitats and vegetation, findings of palynology, palaeoecology and history of land use, and by the analogical composition and history of relict vegetation of northernmost Europe. The refugial effect of the habitat is suggested by stable conditions on high temporal and spatial scales, and by permanent reclaiming of open gaps along the stream.