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Abstrakty/Abstracts

Zprávy České botanické společnosti 51/2, 2016


Abstrakty/Abstracts

Pokorný P., Jankovská V. & Horáček I.
České Hercynikum versus Západní Karpaty: Klíčové biogeografické rozhraní Evropy v posledním glaciálu
Bohemian Hercynides versus Western Carpathians: A crucial biogeographic boundary of Europe during the last glacial epoch

Abstract

The Last Glacial Maximum (LGM, MIS2) and subsequent Late Glacial are with no doubt the key periods for an interpretation of the post-glacial history of biota. During the last decades, several ground-breaking hypotheses have been proposed in order to provide historical arguments for the biogeographic patterns which are observed elsewhere in the Word. Among these, the "microrefugia" or "cryptic refugia" hypothesis is the most influential and, at the same moment, probably the most relevant for the central part of Europe. Nevertheless, this hypothesis remains hardly verifiable without the support of reliable and well-dated fossil evidence. In this review we have collected and newly interpreted fossil evidence currently available for plants, snails and small vertebrates in the area of the present Czech and Slovak Republics. In the light of such evidence, the boundary between the Bohemian Hercynides and the Western Carpathians appears to be a particularly important area in which the present biogeographic patterns in temperate Europe have largely emerged.

Pokorný P., Sádlo J., Chytrý M., Juřičková L., Novák J. & Ložek V.
Nelesní vegetace české nížiny: reliktní původ a kulturní transformace
Non-forest vegetation of Bohemian Basin: relict origin and anthropogenic transformation

Abstract

A fundamental question for the biogeographical interpretation of central European lowlands is whether the Early Holocene steppe and its biota survived the period of maximum afforestation in the mid-Holocene. So far, our knowledge was limited by the lack of fossil pollen records from dry lowland areas. The scarce analyses of fossil pollen and the more common analyses of molluscs from sedimentary series led to the contrasting interpretations of closed-forest landscape (pollen data) and partly open landscape (mollusc data) in the mid-Holocene. We performed parallel analyses of pollen and molluscs from sedimentary sequences in the dry lowland area along the lower Ohře river in northern Bohemia (Zahájí and Suchý potok). Both analyses provide strong support for the hypothesis of continuous local occurrence of steppe grasslands throughout the Holocene. At the beginning of the Neolithic period this area was probably covered by forest-steppe with pine and birch woodlands supporting many light-demanding species which later found their habitat in secondary grasslands. These secondary grasslands have been developed from ca. 5000 yrs BP due to anthropogenic deforestation and grazing by domestic livestock. For the first time both pollen and mollusc data provide consistent evidence that these grasslands and their biota, although supported and maintained by humans, are a direct continuation of Late Pleistocene and Early Holocene natural steppes.

Roleček J., Hájek M., Karlík P. & Novák J.
Reliktní vegetace na mezických stanovištích
Relict vegetation on mesic sites

Abstract

Vegetation is a dynamic system of interacting plant populations. In spite of this dynamism, different vegetation types exhibit a variable amount of inertia in species composition. For this reason, the current vegetation of Central Europe is a heterogeneous mixture of plant communities of different age, depending not only on site conditions, but also on the history of vegetation development. We use the term "relict vegetation" for vegetation with an extraordinarily high proportion of species or species combinations which used to be more abundant in the past and may thus be considered as remnants of their wider past distribution. Although there is an almost infinite number of unique local histories of plant populations and their sites, within which a number of milestones might be identified, only two kinds of vegetation relicts are frequently distinguished in Czech botanical literature: 1) Glacial and Early Holocene relicts, i.e. remnants of plant communities widespread during the last Glacial period or the subsequent period of the Early Holocene but retreated mostly due to the spread of shady forests during the mid-Holocene; and 2) cultural relicts, i.e. vegetation types shaped by human activities which used to be more common in the past but have recently been abandoned. In this study we focus on relict vegetation on mesic sites at lower altitudes in the Czech Republic. Here, natural vegetation is represented mostly by oak-hornbeam and beech forests (Carpinion, Fagion) and semi-natural vegetation mostly consists of nutrient-rich mesic grasslands (Arrhenatherion) and relatively species-poor types of semi-dry grasslands (Bromion erecti). Although mesic lowland and upland sites were predominantly intensively managed in the past, we suggest that in some places ancient vegetation types were preserved both in forest and non-forest habitats. We assume that most relict vegetation types of mesic sites are derived from communities which used to be widespread before the mid-Holocene. Based on palaeoecological evidence, these were open-canopy forests dominated mainly by Betula and Pinus, whose total species composition is unknown but may be approximated using recent analogues from continental regions of Eurasia. Hemiboreal Brachypodio pinnati-Betuletea pendulae forests, distributed from the Southern Urals to southern Siberia, include many central European species which we suggest are characteristic of relict communities of both forest and non-forest vegetation in central European lowlands and uplands. These communities mostly include extensively managed species-rich mesic, dry-mesic and wet-mesic grasslands on base-rich to moderately rich but nutrient-poor to moderately rich soils (Cirsio-Brachypodion, Molinion and mesotrophic variants of Arrhenatherion) and open-canopy mesic to dry-mesic oak forests on base-rich to moderately rich soils. Characteristic species include Betonica officinalis, Brachypodium pinnatum, Potentilla alba, Galium boreale, Viola hirta, Carex montana, Inula salicina, Peucedanum cervaria and Primula veris. Many sites of these communities harbour some rare species with disjunct distribution ranges, which we interpret as another indication of relict origin of this vegetation. Besides hemiboreal forests we discuss several vegetation types whose historical analogues could be ancestors of recent relict communities of mesic sites: continental forest meadows (Carici macrourae-Crepidetalia sibiricae), steppe meadows (Galietalia veri), and also some types of alluvial and fen grasslands. Open-canopy forests of the Southern Urals (Lathyro-Quercion roboris), whose understorey is almost identical to that of hemiboreal Brachypodio-Betuletea forests, represent a hypothetical analogue of mid-Holocene mixed oak forests (Quercetum mixtum) from which the current subcontinental oak forests (Potentillo-Quercetum sensu lato) in Central Europe have been derived. We also provide detailed characteristics of several vegetation types occurring in the Czech Republic which we consider as vegetation relicts. We identified several factors possibly important for their preservation: long history of human influence, which was relatively intensive in the more distant history (and thus could have facilitated the survival of heliophilous communities at the expense of shady forests) and relatively low-intensive in recent history (and thus could have prevented the spread of competitive species or complete destruction by human activities). This vegetation frequently survives at remote and poorly manageable sites, yet with a long history of human influence.

Petr L.
Paleolimnologické lokality Západních Karpat a jejich význam pro rekonstrukci životního prostředí pozdního glaciálu a holocénu
Paleolimnological localities in the Western Carpathians and their importance for a reconstruction of the Late Glacial and Holocene environment

Abstract

The Holocene vegetation development of the Western Carpathians is so far known only fragmentarily from palynologically investigated localities situated in the northern part of the region. Therefore we intended to sample new paleoecological profiles from the entire region. Lake sediments are the most interesting due to their potential for multi-proxy analyses approach. The origin and development of the Western Carpathian lakes are reflected in their geological and environmental diversity. The investigated localities are situated in the southern part of the Carpathian arch on the border with the Pannonian Basin. Lake sediments of the studied localities show global changes at the transition of the Glacial and the Holocene, increasing human impact during the Holocene period.

Hájková P., Hájek M., Horsák M. & Jamrichová E.
Co víme o historii vápnitých slatinišť v Západních Karpatech
Our knowledge of the history of calcareous fens in the Western Carpathians

Abstract

We review and summarise the results of an ongoing project dealing with the Holocene history of calcareous fens in the Western Carpathians. Calcareous fens in the Inner Western Carpathians harbour a higher number of rare fen specialists than those in the Outer Western Carpathians even though the abiotic conditions are nearly the same. In order to identify the possible causes, we have studied the history of calcareous fens in the Western Carpathians using multi-proxy analyses including pollen, macrofossils of bryophytes, vascular plants and molluscs and radiocarbon dating. So far, we have dated the basal layers of 72 calcareous fens, 50 of which we have also analysed for biotic proxies. In addition, we analysed 12 profiles in detail to trace their Late Glacial and Holocene history. Most the of analysed calcareous fens are relatively young and originated largely in the Middle Ages and particularly after the Wallachian colonisation. The old fens are mainly located in the Inner Western Carpathians, where we reconstructed various succession pathways. Most of these fens contained open-fen plant and snail communities in the Late Glacial and Early Holocene, but were encroached by alder and spruce carrs in the Middle Holocene. Small open fen patches could probably persist during these forest phases, but we have documented them only rarely - in one case by means of plant macrofossils, and in another one htrough fossil mollusc shells. Only two of the studied calcareous fens (one in a lowland, the other in an inter-mountain basin) were sufficiently documented to be completely open throughout the Holocene, suggesting continuous persistence of fen communities. In one case, we revealed a unique case of reversed succession from an early-Holocene Sphagnum fuscum bog to a late-Holocene calcareous fen. Further, we recorded a number of rare calcareous-fen specialists in old fen deposits. We discuss the possibility of their persistence over the Holocene forest optimum. More profiles need to be analysed to obtain more detailed information on the historical distribution of particular fen species and possibilities of their surviving the Middle Holocene.

Douda J., Havrdová A. & Mandák B.
Co nám říkají molekulární data o glaciálních refugiích středoevropských dřevin?
What do molecular data tell us about glacial refugia of Central-European woody plants?

Abstract

The current species distribution in Europe was influenced by Quaternary climatic and environmental changes when alteration of glacial and interglacial periods was the most important factor. The traditional view was that European trees survived unfavourable times in glacial refugia on southern European peninsulas. With growing paleoecological knowledge, many discrepancies in this theory have appeared and evidences about possible survival of trees in northern cryptic refugia have emerged. The development of molecular techniques has made it possible to verify the results of palynological studies, but have also provided new insights into refugia and colonisation routes of European trees. Our review aims at: summarising the usability of molecular markers in phylogeographical studies, describing the results of available molecular studies on this topic and finding common characteristics of postglacial histories of European trees.

Kočár P., Pokorná A. & Komárková V.
Synantropní flóra pravěkých sídlišť ve světle makrozbytkové analýzy
Anthropogenic flora of prehistoric settlements according to macro-remain analysis

Abstract

The aim of this article is to outline our recent knowledge of the history of anthropogenic flora based on data from archaeobotanical investigations of prehistoric sites. It is based on 207 archaeological sites (301 settlement phases) investigated in the Czech Republic. We aimed at tracing both successive changes of anthropogenic flora, as well as the spreading history of alien plants (using computation of the immigration rate of archaeophytes). Moreover, our data reflect the origin of anthropogenic non-forest vegetation (segetal and ruderal plant communities, and also semi-natural communities such as pastures, meadows, and wet meadows). Above all, we depict the specific features of archaeobotanical analysis, and emphasise some limitations of this method when used for botanical interpretations.