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Abstracts of volume 85, 2013

Hofmann M., Bütof A., Welk E. & Bruelheide H. (2013): Relationship between fundamental and realized niches in terms of frost and drought resistance. – Preslia 85: 1–17.
The objective of the present study was to relate the fundamental niches of 16 grassland species, defined in terms of their frost and drought tolerance, to their realized macroclimatic niches derived from the geographical distributions of the species. Eight species pairs each consisting of two congeneric species with different distributions and exposed to different levels of frost and drought stress were selected. The ranges of the two species in each genus differed in the degree to which their geographical ranges extended into cold or dry regions. Frost resistance was analysed by measuring electrolyte leakage and expressed as temperature at which 50% leakage occurred (LT50). The genera investigated responded differently to frost stress. In two genera, the species with ranges extending into colder regions showed a lower LT50 than species confined to warmer regions. In two other genera, the opposite pattern was recorded and the species in the remaining genera did not differ in their frost resistance. Responses to drought stress were quantified by recording their responses to different moisture treatments in a glasshouse experiment. No differences in the responses to drought stress were recorded for species with geographical ranges that extended differently into dry regions. In general, there was only a poor match between fundamental and realized niches for only a few genera and only for resistance to frost and not drought. Thus, it is not possible to predict the geographical distribution ranges of two congeneric species based on their performance in experiments, and vice versa. Therefore, it is likely that the assumptions made in modelling species distributions are incorrect and as a consequence the forecasts of future distributions of species based on these models unreliable.
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Krahulcová A., Trávníček B. & Šarhanová P. (2013): Karyological variation in the genus Rubus, subgenus Rubus: new data from the Czech Republic and synthesis of the current knowledge of European species. – Preslia 85: 19–39.
The polyploid agamic complex in the subgenus Rubus is one of the most intricate groups in the European flora. Sources of taxonomic complexity are polyploidy, facultative apomixis, both past and recent hybridization followed by segregation, and ecological plasticity. We present an updated overview of ploidy level/chromosome number in 228 representatives of the subgenus, which are native in Europe and for which there are karyological studies. The first section is focused on new data obtained in the Czech Republic during the last 14 years. These chromosome counts and determinations of ploidy level using flow cytometry mainly concern the 19 species recently described from Europe and 14 earlier described species that were newly recorded in the Czech Republic. The first karyological findings are presented for 27 species, comprising triploids (2n = 21, eight species), tetraploids (2n = 28, seventeen species), pentaploids (2n = 35, one species) and hexaploids (2n = 42, one species). Rubus sendtneri Progel is the first hexaploid species to be recorded in the Czech Republic. Currently known karyological characters of native European species are presented and discussed in the second section. This overview involves data adopted from the recently published Atlas Florae Europaeae, to which the new data we present in the first section was added. Ploidy level is known only for 30% of more than 750 species recognized in Europe. Tetraploids make up 80% of the karyologically examined species. Only three sexual diploid species are native to Europe. Triploids are mainly in the series Discolores and Rubus of the section Rubus, while they are unknown in the evolutionary derived section Corylifolii. Pentaploid species are rather less frequent in the subgenus Rubus, but occur more often in the section Corylifolii than in the section Rubus. The rare hexaploids occur only in the section Corylifolii. Several cytotypes within one species is rare in European brambles. Members of the section Corylifolii are considered to be hybrids and segregation products, which resulted from crosses between species of the section Rubus and tetraploid R. caesius of section Caesii. In this case the pattern in the variation in the ploidy level suggests that unreduced gametes had a role in genesis of the section Corylifolii. Taxonomy in Rubus is almost exclusively based on morphological characters of the respective taxa. An actualized karyological overview may increase our understanding of the processes that shaped the present structure of this polyploid complex, namely the origin of the recent hybrids and genesis of some of the apomictic species.
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Follak S., Dullinger S., Kleinbauer I., Moser D. & Essl F. (2013): Invasion dynamics of three allergenic invasive Asteraceae (Ambrosia trifida, Artemisia annua, Iva xanthiifolia) in central and eastern Europe. – Preslia 85: 41–61.
We analyzed the history of the invasion, spread dynamics and habitat affiliation of three allergenic wind-pollinated species (Ambrosia trifida, Artemisia annua, Iva xanthiifolia; tribe Heliantheae, Asteraceae) in central and eastern Europe (CEE) using distribution data from a wide range of sources. In addition, we used niche-based ensemble modelling techniques to assess current invasion risk of the region studied. We collated 1804 records of A. annua, 1063 of I. xanthiifolia and 324 of A. trifida. All species were first recorded in the 19th century, remained rare until the middle of the 20th century, but have spread rapidly in recent decades. Iva xanthiifolia spread the fastest followed by A. annua. The latter species is now abundant in northern Italy, along the Elbe river in Germany and the Danubian Lowland in Slovakia and Hungary, while I. xanthiifolia occurs most frequently in the warm and continental parts of CEE. Ambrosia trifida spread slowly and its current distribution consists of relatively few and mostly isolated localities in CEE. Ambrosia trifida and I. xanthiifolia occur primarily in ruderal habitats, whereas I. xanthiifolia has also increasingly invaded fields. Initially confined to ruderal habitats, A. annua has expanded its habitat niche during the invasion and has invaded riverine vegetation and (semi-)natural habitats. Ensemble species-distribution models show that the current distribution of A. trifida and A. annua in CEE is closely related to temperature and precipitation, whereas land use is only important for I. xanthiifolia. Under the current climate, substantial fractions of the study area provide suitable habitat for these species: A. trifida (16% of CEE), A. annua (28%) and I. xanthiifolia (26%). Because of their significant potential impact on public health, future spread of these species should be monitored and management strategies (e.g. raising awareness, early control) should urgently be implemented.
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Lepší M., Lepší P., Sádlo J., Koutecký P., Vít P. & Petřík P. (2013): Sorbus pauca species nova, the first endemic species of the Sorbus hybrida group for the Czech Republic. – Preslia 85: 63–80.
We describe a newly distinguished apomictic tetraploid (2n = 4x = 68) species Sorbus pauca M. Lepší et P. Lepší. We classify this new species as a member of the Sorbus hybrida group because we presume that it has originated from a cross between S. danubialis and S. aucuparia. Sorbus pauca, a stenoendemic that occurs on Bezděz and Malý Bezděz hills (Doksy region, northern Bohemia), is the first species of the S. hybrida group to be described for the Czech Republic. Multivariate morphometrics and elliptic Fourier analyses reveal that it is distinct from the morphologically close S. danubialis. The new taxon is phenotypicaly homogenous, morphologically well separated from the sympatrically occurring S. danubialis and European taxa of S. hybrida agg. It does not show any karyological variation. Apomixis was detected as the species’ sole mode of reproduction. The two known populations of S. pauca consist of 14 adult individuals. The species is restricted to rocky grasslands, rocky scrub and open woodlands on rocks with Festuca pallens and Cotoneaster integerrimus.
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Hoták Z., Štěpánek J., Plačková I. & Jarolímová V. (2013): Poa riphaea, an endangered stenoendemic species in the Hrubý Jeseník Mts (Eastern Sudetes). – Preslia 85: 81–96.
The taxonomy, nomenclature, geographic distribution, karyology, morphology and isozyme variation in Poa riphaea, a supposed endemic species in central Europe, were studied. We especially focused on resolving the long-standing uncertainty about its relationship with P. laxa by assessing morphological and isozyme data. Attention was also paid to the morphological differention between P. riphaea and P. nemoralis from the highest parts of the Hrubý Jeseník Mts. Our isozyme analysis did not reveal any within-population genetic variability in the last remaining population of P. riphaea at the summit of Mt Petrovy kameny. The reasons for the variability in its morphology are discussed in the context of environmental conditions. The octoploid chromosome number of P. riphaea has been, probably, for the first time, reliably determined to be 2n = 56. We also present a map of the species’ historical and recent distribution. In addition to the sole recent locality at Mt Petrovy kameny, we have confirmed two historical localities (Tabulové skály rock and Velká Kotlina glacial cirque). We have selected a neotype for the name P. riphaea.
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Klaus V. H., Hölzel N., Boch S., Müller J., Socher S. A., Prati D., Fischer M. & Kleinebecker T. (2013): Direct and indirect associations between plant species richness and productivity in grasslands: regional differences preclude simple generalization of productivity-biodiversity relationships. – Preslia 85: 97–112.
Plant species richness of permanent grasslands has often been found to be significantly associated with productivity. Concentrations of nutrients in biomass can give further insight into these productivity- plant species richness relationships, e.g. by reflecting land use or soil characteristics. However, the consistency of such relationships across different regions has rarely been taken into account, which might significantly compromise our potential for generalization. We recorded plant species richness and measured above-ground biomass and concentrations of nutrients in biomass in 295 grasslands in three regions in Germany that differ in soil and climatic conditions. Structural equation modelling revealed that nutrient concentrations were mostly indirectly associated with plant species richness via biomass production. However, negative associations between the concentrations of different nutrients and biomass and plant species richness differed considerably among regions. While in two regions, more than 40% of the variation in plant species richness could be attributed to variation in biomass, K, P, and to some degree also N concentrations, in the third region only 15% of the variation could be explained in this way. Generally, highest plant species richness was recorded in grasslands where N and P were co-limiting plant growth, in contrast to N or K (co-) limitation. But again, this pattern was not recorded in the third region. While for two regions land-use intensity and especially the application of fertilizers are suggested to be the main drivers causing the observed negative associations with productivity, in the third region the little variance accounted for, low species richness and weak relationships implied that former intensive grassland management, ongoing mineralization of peat and fluctuating water levels in fen grasslands have overruled effects of current land-use intensity and productivity. Finally, we conclude that regional replication is of major importance for studies seeking general insights into productivity-diversity relationships.
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Kowarik I., von der Lippe M. & Cierjacks A. (2013): Prevalence of alien versus native species of woody plants in Berlin differs between habitats and at different scales. – Preslia 85: 113–132.
Cities are hotspots for plant invasions and woody plants that have escaped from cultivation contribute significantly to this phenomenon. Yet whether the richness of alien species in the floras of woody plants in urban areas also corresponds to a prevalence of alien species at the habitat and population levels is an open question. To explore the scale and context dependence of invasions by woody plants of urban environments, we analysed the occurrence of alien and native species of trees, shrubs and vines at the city, habitat and community scales in Berlin, Germany. The percentage of alien species in the flora of spontaneously occurring woody plants increased from 16% at the end of the 18th century to 67% two hundred years later. Of the 181 species of alien woody plants in Berlin’s flora 32% have become naturalized. Species from other parts of Europe, the Mediterranean and western Asia escaped and became naturalized more frequently than species from other areas. Escape from cultivation did not increase the share of evergreens in the total flora of woody plants. All habitats other than wetlands had more alien than native species, and the percentage of alien species was significantly higher in green spaces, wastelands and residential areas than in forests and wetlands. However, native species were more frequent at the habitat scale. Overall, the trees most likely to be found in all habitats were native Acer platanoides, Betula pendula, Quercus robur and alien Robinia pseudoacacia, Acer negundo and Prunus serotina, and the most frequent shrubs the native Sambucus nigra and alien Mahonia aquifolium. At the community scale, counts of the numbers of individual trees in two selected study areas revealed that native species prevailed in residential areas and alien species in urban wasteland. The results demonstrate that invasion success of alien woody species in urban environments is strongly scale- and context-dependent. The clear dominance of alien species in the total urban species pool was not similar at both the habitat and community scales, particularly when the frequency of species is considered. In conclusion, assemblages of woody species in urban areas are not only characterized by high numbers of aliens but also by an increase in the abundance of native species such as the formerly rare Acer platanoides and A. pseudoplatanus, which now prevail due to enhanced propagule pressure and the eutrophication of urban ecosystems.
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Kučera J., Turis P., Zozomová-Lihová J. & Slovák M. (2013): Cyclamen fatrense, myth or true Western Carpathian endemic? Genetic and morphological evidence. – Preslia 85: 133–158.
Cyclamen fatrense is described as a narrow endemic of the Western Carpathians, but because of its uncertain morphological distinction from the closely allied C. purpurascens it is not generally accepted as a separate species. Genetic, morphological and karyological analyses were used to revise the taxonomic status of the Western Carpathian populations of C. fatrense and explore potential differentiations in the widely distributed C. purpurascens. Our results show that the Western Carpathian populations are genetically and morphologically separate from those of C. purpurascens and should be considered a separate endemic subspecies (C. purpurascens subsp. immaculatum). The most important diagnostic characters discriminating it from the nominate subspecies include the absence of ornamentation on the upper leaf surface, the shape of the leaves and sepals, the width of the petals and the position of the widest part of the leaf lamina. All populations studied are karyologically uniform and diploid (2n = 2x = 34) with negligible differences in their absolute DNA content (2C = 6.63–6.92 pg).
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Lepší M., Lepší P. & Vít P. (2013): Sorbus quernea: taxonomic confusion caused by the naturalization of an alien species, Sorbus mougeotii. – Preslia 85: 159–178.
Sorbus quernea, a hybridogenous species described in 1996 as an endemic in two places in Prague (Czech Republic), is revised. A wide range of contemporary biosystematic techniques, including molecular (nuclear microsatellite markers) and karyological analyses (chromosome counts, DAPI flow cytometry) along with multivariate morphometric and elliptic Fourier analyses, were used to assess its taxonomic status. The revision revealed that S. quernea is taxonomically identical to S. mougeotii, a western-European hybridogenous species with a large distribution area, which was described from the Vosges Mts in France in 1858. Plants from localities given in the protologues of both taxa and from the German Alps, French Alps, the Massif Central and those of unknown origin planted in the Czech Republic, were shown to be taxonomically, karyologically and genetically consistent. A negligible variation in the microsatellite pattern partly combined with variation in leaf shape was recorded only at Grand Ballon Mt. (Vosges Mts). This variability is probably caused by introgressive hybridization with diploid S. aria s. str. Specimens of S. mougeotii from woodland show more deeply lobed and broader leaves compared with those from subalpine areas. This variability is ascribed to the ecologically conditioned plasticity of the species. The type material of S. mougeotii deposited in Nancy is regarded as taxonomically consistent. At the Prague localities, S. mougeotii (the populations erroneously described as S. quernea) is considered to be an escaped and recently naturalized alien species. Sorbus mougeotii is occasionally planted in the Czech Republic and also in other European countries as a roadside, street or garden tree. In Europe, several other species of Sorbus that were planted escaped and became established in (semi-)natural, often relict (rocky) vegetation, which when combined with poor knowledge of taxonomy of the planted species, may give an impression of a natural origin for an escaped population and lead to serious taxonomic misinterpretations. An overview is provided of alien and often or occasionally cultivated hybridogenous Sorbus species in European countries.
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Krahulcová A., Krahulec F., Bräutigam S. & Chrtek J. Jr. (2013): Chromosome numbers and reproductive systems of selected representatives of Pilosella from the Krkonoše Mts (the Sudetes Mts). Part 3. – Preslia 85: 179–192.
Chromosome counts/DNA ploidy level (DNA-PL) and modes of reproduction of the following species, hybridogenous species and hybrids of Pilosella from the Krkonoše Mts (Czech Republic) are reported: P. aurantiaca (2n = 36, 2n = 45, DNA-PL tetraploid, pentaploid, all apomictic); P. bauhini subsp. bauhini (2n = 45, with a long hemizygous marker chromosome – MC, apomictic); P. caespitosa (2n = 36, 2n = 45, apomictic, both cytotypes MC); P. cymosa subsp. vaillantii (2n = 45, MC); P. lactucella (2n = 18, DNA-PL diploid); P. officinarum (2n = 36, sexual); P. blyttiana (2n = 36); P. floribunda (2n = 36, MC); P. glomerata (DNA-PL tetraploid, 2n = 45, MC, apomictic, 2n = 46, MC); P. iserana (2n = 35 + fragment, MC, 2n = 36, MC, DNA-PL tetraploid,, apomictic); P. piloselliflora (2n = 36, DNA-PL pentaploid); P. rubra (2n = 54); P. schultesii (2n = 36); P. rothiana (2n = 36, apomictic); P. scandinavica (2n = 36, MC, apomictic). In addition, a heptaploid plant (2n = 63, apomictic), probably a hybrid between P. rubra (2n = 54, reduced gamete) and P. aurantiaca (2n = 36, unreduced gamete) and a rare hybrid corresponding morphologically to P. fusca (2n = 36, apomictic), which is probably a hybrid between P. aurantiaca and P. blyttiana, were found. The latter hybrid has not been previously reported from the Krkonoše Mts or the Czech Republic. New data for P. cymosa subsp. vaillantii, P. fusca, P. rothiana and P. scandinavica for this mountain range are presented. It is shown that tetraploid and pentaploid P. aurantiaca differ in the number and shape of their stem leaves, which makes it easier to identify them in the field.
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Takács A., Schmotzer A., Jakab G., Deli T., Mesterházy A., Király G., Lukács B. A., Balázs B., Perić R., Eliáš P. jun., Sramkó G., Tökölyi J. & Molnár V. A. (2013): Key environmental variables affecting the distribution of Elatine hungarica in the Pannonian Basin. – Preslia 85: 193–207.
Elatine hungarica Moesz is a small wetland ephemerophyte that occurs and is classified as extinct, data deficient or a very rare and endangered taxon in most countries in eastern and central Europe. Based on literature and herbarium data, supplemented by 160 field records collected between 1998 and 2011, we present the currently known distribution of this species in the Pannonian Basin, which mostly but not exclusively includes Hungary. Within the Pannonian Basin this species is distributed throughout Hungary, with sporadic occurrences in Romania, Serbia and Slovakia. The temporal distribution of floristic records is very uneven. This species was recorded only in 27 years during the last 213 years (1798–2011). When examining presence/absence data for most of the 20th century, we found a significant correlation between the number of records of this species in a given year and two key, but not independent, environmental variables: rainfall and the extent of the area inundated in the same year. In the more intensively documented period between 1998 and 2010, there is only a significant correlation between the numbers of records of this species and the extent of flooding, which is because there is a delay in the effect of an increase in rainfall. The peak occurrence of records in the 1940s and 1950s is associated with extensive rice production in Hungary. Today, most records are for agricultural fields that are subject to flooding and becoming temporary wetlands. The comparison of recent and past distributions of E. hungarica reveals a consistent and marked regional difference; whereas this species is not rare along the Tisza river and its tributaries, it is markedly scattered in similar habitats near the Danube.
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Birks H. H. & Birks H. J. B. (2013): Vegetation responses to late-glacial climate changes in western Norway. – Preslia 85: 215–237.
How fast can vegetation respond to rapid climate change? To answer this question, we require long-term vegetational data and an independent climate record. Both can be obtained from multi-proxy palaeoecological studies involving pollen analysis and plant macrofossil analysis (vegetational data) and chironomid analysis (climate record). Late-glacial climate changed rapidly and passed critical vegetation thresholds in western Norway. The interstadial (Allerod) vegetation at Krakenes on the west coast was analogous to low- or mid-alpine vegetation in the west Norwegian mountains today. There was a marked vegetational response over ~10 years to the Younger Dryas cooling, even though mean July air temperature, as inferred from the independent fossil chironomid record, only decreased by about 2 °C. Together with the prevailing precipitation, this was sufficient to allow a cirque glacier to develop above Krakenes Lake during the Younger Dryas. As summer temperatures increased rapidly at the opening of the Holocene, plants responded immediately. Warmth-intolerant arctic-alpines rapidly succumbed. Warmth-tolerant arctic-alpine species expanded until declining as a result of increasing competition. Successional processes proceeded through to damp and dry grassland, the development of tall-fern vegetation, and the expansion of Empetrum-dominated dwarf-shrub heath. Tree-birch Betula pubescens showed a migrational lag of ~500 years before forming birch woodland. This study illustrates how floristic and vegetational patterns recorded in sedimentary sequences can be interpreted in terms of ecological processes if an independent palaeoclimate record is available; here, from fossil chironomid assemblages from the same sediment core.
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Petr L., Žáčková P., Grygar T. M., Píšková A., Křížek M. & Treml V. (2013): Šúr, a former late-glacial and Holocene lake at the westernmost margin of the Carpathians. – Preslia 85: 239–263.
There is a unique palaeolimnological record of the late-glacial and Holocene periods in the former lake Šúr near Bratislava in western Slovakia. The aim of this study was to reconstruct the development of the environment in the locality of the lake, including the gradual infilling of the lake. We reconstructed the development of the lake environment by combining results of a geochemical analysis with analyses of diatoms and plant macrofossils. We also carried out a pollen analysis to assess the changes in the surrounding terrestrial vegetation. The results reveal how the character of the lake has changed over time. At the peak of the glacial period, water flowed through the lake and deposited sand there. Later on the flow of water through the lake ceased and a vast oligotrophic lake developed. During the Holocene, the lake gradually became eutrophic. The pollen record contains evidence of the occurrence of woody species of broad-leaved forest in the late-glacial period in the Carpathians and of the expansion of mixed forests of Fagus and Carpinus in the Holocene around 4500 BP. The development of the vegetation in the locality of lake Šúr is more similar to that at localities in Hungary than those situated north and west of the Western Carpathians.
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Jankovská V. & Pokorný P. (2013): Reevaluation of the palaeoenvironmental record of the former Komořanské jezero lake: late-glacial and Holocene palaeolimnology and vegetation development in north-western Bohemia, Czech Republic. – Preslia 85: 265–287.
The main goal of this article is to summarize results of palaeoecological investigations of a classical and iconic site in the Czech Republic, the former Komořanské jezero lake. This lake persisted in north-western Bohemia from at least the Weichselian Late Glacial until quite recently. Pollen and palaeoalgological analyses of coccal green algae were carried out on several sedimentary sequences sampled within the framework of palaeobotanical and archaeological salvage research from 1970s to 1990s. The results are published here jointly for the first time. They make it possible to reconstruct both the lacustrine environment and upland vegetation in the wider surroundings of the lake. The Komořanské jezero lake in the late-glacial period was cold and oligotrophic. Its nutrient status gradually changed and became mesotrophic and dystrophic locally in the early Holocene and eutrophic from the Middle Holocene onwards. Unfortunately, big differences in geomorphology and environmental conditions together with long-distance (and likely even fluvial) transport of pollen make the reconstruction of upland vegetation somewhat difficult. Immigration of climatically demanding species into the area started already in the Preboreal period (before 8200 uncal. yr BP). Maximum expansion of broadleaved forests occurred in the Atlantic period (between 6000 and 7000 uncal. yr BP). At the same time, afforestation spreading from the lowlands (200 to 400 m altitude) up to the mountain ridges (around 1000ma.s.l.) of the Krušné hory Mts attained its maximum level. Based on continually increased presence of non-arboreal pollen we hypothesize that open grassland biotopes (continental-type steppe vegetation) persisted in the wider region from the late glacial throughout the entire Holocene. First clear evidence of a human effect on vegetation in promoting expansion of secondary grasslands is dated in pollen diagrams to around 4000 uncal. yr BP (i.e. the Subboreal period).
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Hájková P., Jamrichová E., Horsák M. & Hájek M. (2013): Holocene history of a Cladium mariscus-dominated calcareous fen in Slovakia: vegetation stability and landscape development. – Preslia 85: 289–315.
There are very few palaeoecological studies of thermal springs in central Europe, despite the fact that they are extreme but stable habitats that enabled the long-term survival of certain species and are located in areas for which there is little data about landscape history. In western Slovakia, close to Malé Bielice village at the northern margin of the Pannonian-Carpathian boundary, a peat-forming warm spring is uniquely preserved, and it still harbours a rare plant, Cladium mariscus. This site is located in a region that is noteworthy for the occurrence of many rare, light-demanding species that have disjunct distributions or are at the limits of their distributions, which may indicate a long history of treeless habitats there. The geographical position of this study site thus provides a great opportunity to address the perennial debate about in situ relicts and the continuity of grasslands throughout the forest optimum. We analysed a Holocene sediment core for macrofossils of vascular plants, bryophytes and molluscs, and for pollen, which were surprisingly preserved in rather high diversity, which enabled a detailed reconstruction of the landscape history. We further reviewed the archaeological evidence. Using this multi-proxy approach, we were able to confirm (i) the early expansion of mesophilous trees (Ulmus, Fraxinus, Tilia and Quercus) in northern parts of the Carpathian-Pannonian boundary, but the onset of this expansion could not be dated precisely, (ii) the continual persistence of the Cladium mariscus population in the fen, and (iii) existence of open steppes and/or dry grasslands and open wetlands in this region throughout the Holocene. Since the Bronze Age, there are coincidences in the history of human settlement, local development of the fen and regional changes in the representation of particular habitats, including managed wet, mesic and semi-dry grasslands.
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Ammann B., Wright H. E., Stefanova V., van Leeuwen J. F. N., van der Knaap W. O., Colombaroli D. & Tinner W. (2013): The role of peat decomposition in patterned mires: a case study from the central Swiss Alps. – Preslia 85: 317–332.
A number of hydrological, botanical, macro- and micro-climatological processes are involved in the formation of patterned peatlands. La Grande Tsa at 2336 m a.s.l. is probably the highest bog in the central Swiss Alps and is unique in its pattern. In two of five pools there is in the contact zone between the basal peat and the overlying gyttja an unconformity in the depth-age models based on radiocarbon dates. Palynostratigraphies of cores from a ridge and a pool confirm the occurrence of an unconformity in the contact zone. We conclude that deepening of the pools results from decomposition of peat. The fact that the dated unconformities in the two pools and the unconformity in the ridge-core all fall within the Bronze Age suggest they were caused by events external to the bog. We hypothesize that early transhumance resulted in anthropogenic lowering of the timberline, which resulted in a reduction in the leaf-area index and evapotranspiration, and in higher water levels and thus pool formation.
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Dítě D., Hájek M., Hájková P. & Eliáš P. Jr. (2013): The occurrence of the relict plant, Trichophorum pumilum, in the Western Carpathians in the context of its distribution and ecology in Eurasia. – Preslia 85: 333–348.
Vascular-plant relict species Trichophorum pumilum has a disjunct distribution range and in Europe (not considering Caucasus and South Ural Mts) it currently occurs only in the Alps, Norway and a small area in the Western Carpathians. This study reviews all available data on the distribution and ecology of this species in Europe, provides vegetation and ecological characteristics of recent populations in the Western Carpathians and compares them with that found in other European regions. In the Western Carpathians this species is found in a small area in an Inner-Carpathian basin in northern Slovakia, the Liptov, Poprad and Hornád Basin, and rarely reaches the margins of adjacent mountains. It is currently present at 10 sites in this area. This species is therefore classified in the IUCN category “endangered”. Occurrence of Trichophorum pumilum is associated with calcareous fens, usually those initiated during the late glacial and surrounded by extremely mineral-rich active travertine springs. Finds of macrofossils suggest that the species was more widespread in Europe and Slovakia during the last glacial. Currently this species occurs in communities of the Caricion davallianae alliance, associations Glauco-Trichophoretum pumili and Caricetum davallianae. Habitat and vegetation affinity differ substantially from that found at most other European localities of this species. The reasons for this difference are the specific ecological conditions of travertine springs and surrounding fens, which enabled the postglacial survival of this species at rather low altitudes in the temperate zone. One of the most important differences is the occurrence of halophytic and subhalophytic species at the Western-Carpathian localities, which makes their vegetation somewhat analogous to that of T. pumilum fens found in the Russian Altai Mts. We demonstrate this similarity by detrended correspondence analysis of all available individual relevés from the Carpathians, the Alps and Altai.
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Pawlikowski P., Abramczyk K., Szczepaniuk A. & Kozub Ł. (2013): Nitrogen:phosphorus ratio as the main ecological explanation of the differences in species composition in brown-moss rich fens of north-eastern Poland. – Preslia 85: 349–367.
The species composition of 22 mires (brown-moss rich fens) was surveyed in north-eastern Poland, located in continental boreo-nemoral Europe. Detailed analyses of the water chemistry, biomass N, P, and K content, productivity and water level were made. Two floristically different types of richfen vegetation occur in this area, one with numerous Caricetalia davallianae (calcicole) species such as Scorpidium cossonii, Campylium stellatum, Carex lepidocarpa and Eriophorum latifolium (Cd fens) and the other with a few Caricetalia davallianae species and mainly Hamatocaulis vernicosus, Marchantia polymorpha, Plagiomnium ellipticum, Carex diandra and C. rostrata (non-Cd fens). In these two rich-fen types surface water chemistry and water levels were similar, but the Cd fens characteristically had higher pHs and lower PO43– concentrations. N and P availability revealed by the N:P ratio is the ecological factor that best accounts for the differences in species composition of the two rich-fen types: the non-Cd fens are N-limited while the Cd-fens are usually P-limited. Moreover, the Cd fens differ from the non-Cd fens in a higher productivity of the bryophyte layer. In the case of P and K concentrations, there is a correlation between that in vascular plants and bryophytes, while N concentrations are not correlated. We believe that in the case of low productive ecosystems the use of the broad “nutrient availability gradient” should be replaced by a (from) N-(to) P-limitation gradient with N:P ratio as a useful measure. Natural N-limited, low-productive rich fens and their ecological conditions can be a phenomenon typical of continental-eastern temperate European areas, which have been poorly surveyed and need further research.
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Hettenbergerová E., Hájek M., Zelený D., Jiroušková J. & Mikulášková E. (2013): Changes in species richness and species composition of vascular plants and bryophytes along a moisture gradient. – Preslia 85: 369–388.
We focused on the gradient in moisture along transects of from 8 to 30min length from spring fen to semi-dry grassland vegetation. We selected an area in the calcium-rich part of the Western Carpathian flysch zone (Czech and Slovak Republics) where small spring-fed fens occur in close contact with semi-dry grasslands. Altogether 126 vegetation plots of 75 × 75 cm were sampled along 15 transects (one per locality) that each extended from the wettest part of a spring-fed fen into the surrounding semi-dry grassland. In addition, samples of standing plant biomass and soils were analysed for nutrients (N, P, K, C, Ca) and the upper-soil moisture measured. Using this study system and these sampling methods, we can test directly the effects of moisture and so avoid the confounding effects of different background environmental conditions that occur when data from many distinct sites is used. Data were processed using linear mixed-effect models and other statistical techniques. The trend in the number of species of vascular plants was unimodal with the optimum skewed towards lower moisture values. This response was not caused by an edge effect alone as replacing the moisture gradient with the positions of plots on transects resulted in a much weaker unimodal relationship and there was a group of species that occurred mainly in the species-richest moderately moist plots but did not occur in fens or the driest grasslands. The correlations between species richness and productivity (positive) and soil calcium (negative) differed from most of those reported in the literature, which suggests that the observed relationship between species richness and moisture was probably not greatly confounded by these factors. Species richness correlated negatively and the percentage of endangered species positively with the N:P biomass ratio, which is in accordance with other published results, but their correlations with moisture were stronger. For bryophytes, species richness linearly decreased towards the dry plots and did not correlate with any of the nutrients measured. Most of the species of vascular plants and bryophytes in the wettest patches were fen specialists, while more generalists made up the species richness in grasslands, including the species-richest patches. For bryophytes, the percentage of specialists was very high in fen plots. Although Mantel tests showed that bryophyte and vascular plant species turnovers were similar, we recorded substantial differences in their species richness patterns. Comparison with the results of a previous study on molluscs revealed a greater similarity between bryophytes and molluscs than between molluscs and vascular plants in terms of correlations between species richness and environmental variables. We argue that soil moisture should be taken into account when explaining current patterns in diversity in extremely rich temperate grasslands.
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Patberg W., Baaijens G. J., Smolders A. J. P., Grootjans A. P. & Elzenga J. T. M. (2013): The importance of groundwater carbon dioxide in the restoration of small Sphagnum bogs. – Preslia 85: 389–403.
Essential for successful bog restoration is the reestablishment of Sphagnum mosses. High carbon dioxide availability has been shown to be of great importance for the growth of Sphagnum mosses. In well-developed Sphagnum bogs large amounts of carbon dioxide are produced by (an) aerobic decomposition of the peat layer. In cut-over Sphagnum bogs this carbon source is often greatly reduced. In this study the importance of groundwater-derived carbon dioxide is demonstrated in aquatic environments, where Sphagnum species have started to form floating mats after former cutover activities by farmers. We discuss the results of measures taken to restore one of the largest wet heathland reserves in western Europe. After rewetting, some bogs developed markedly well, whereas others did not. The developmental success of 10 small bogs was quantified by analysing aerial photographs and sampling of surface and groundwater. The analysis of the ground- and surface water samples revealed that in the well-developed bogs there were significantly higher TIC/CO2 concentrations than in poorly developed bogs. It is concluded that in the early stages of bog formation the growth of Sphagnum is better in bog systems that are fed by an inflow of carbon-rich groundwater from outside the bog. The present findings suggest that high carbon dioxide availability is a prerequisite for the successful reestablishment of Sphagnum mosses in peat-bog restoration projects and that carbon-rich groundwater can substitute for the carbon dioxide from decomposing peat.
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Aggenbach C. J. S., Backx H., Emsens W. J., Grootjans A. P., Lamers L. P. M., Smolders A. J. P., Stuyfzand P. J., Wołejko L. & Van Diggelen R. (2013): Do high iron concentrations in rewetted rich fens hamper restoration? – Preslia 85: 405–420.
In this study we address the question of the extent to which iron may be a limiting factor in restoring rich fens in the temperate climate zone of Europe. Rewetted fens that were heavily degraded in the past by draining over a long period, were compared with pristine fens or fens with slightly altered hydrological systems. The chemical composition of peat and of pore water was analysed and related to the composition of the vegetation of the fens. The species composition and chemistry of the topsoil of restored fens differed markedly from that of the other fens, while the chemistry of the pore water from deeper layers showed only minor differences. Multivariate analysis revealed that differences in species composition between both categories were strongly related to the concentration of Fe in the pore water in the topsoil. Restored sites with high iron concentrations in the pore water (> 100 µmol·L–1) lacked many vascular plants and mosses typical of peat forming fens. Iron and inorganic phosphorus pools in the topsoil of most restored fens were much greater than in the reference fens. A higher soil phosphorus pool originated mainly from the iron-bound fraction. We conclude that these differences are strongly governed by local processes and not by regional differences in climate, which were associated with geographical distribution of the different fens studied. The strong accumulation of iron and phosphorus in restored fens is attributed to a long history of drainage, which enhanced the accumulation of oxidized iron in the topsoil and also lowered the concentrations of calcium, magnesium and sulphur through drainage-caused reoccurring oxidation-reduction and leaching processes. A high iron and associated high phosphorous content appears to be an important and possibly irreversible bottleneck to restoring biodiversity and accumulation of peat with a low degree of humification in degraded fens. If a degraded fen has a low iron content then it is more likely to be restorable.
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Kaplan Z., Jarolímová V. & Fehrer J. (2013): Revision of chromosome numbers of Potamogetonaceae: a new basis for taxonomic and evolutionary implications. – Preslia 85: 421–482.
In order to establish a sound basis for systematic and evolutionary research, we determined the chromosome numbers of 181 samples of 47 species and 32 hybrids of Potamogetonaceae from 27 countries and areas, ranging from Greenland in the north to New Zealand in the south and reevaluated previously published counts. The first counts are reported here for 10 species and 25 hybrids of Potamogeton and for 1 species and 3 hybrids of Stuckenia. Both homoploid and heteroploid hybrids were identified, as well as hybrids resulting from the fusion of reduced and unreduced gametes. Three previously undetected hybrids of Potamogeton are described and validated as P. ×drepanoides, P. ×luxurians and P. ×serrulifer. The extensive within-species variation in chromosome numbers sometimes reported in the literature was not confirmed. Chromosome numbers appeared to be generally species-specific in Potamogetonaceae; the only exceptions were two sterile autotriploid plants detected within two otherwise fertile diploid Potamogeton species. Furthermore, chromosome numbers were often uniform even within species groups or genera and to some degree also clade-specific in phylogenetic trees based on nuclear ribosomal markers (ITS and 5S-NTS regions). In the largest genus, Potamogeton, there are two base numbers for diploids (x = 13 and x = 14) and three ploidy levels in species (diploids, tetraploids and octoploids; all polyploids were based on x = 13), in Stuckenia only hexaploids (also based on x = 13) occur and Groenlandia is monotypic with x = 15. A critical evaluation of the published counts revealed three major sources of error: (i) methodological problems due to difficult karyotypes, (ii) approximations based on wrong preconceptions and (iii) poor taxonomic treatments, misidentified species or unrecognized hybrids. We estimate that about 24% of the counts in original publications and up to 41% in chromosome atlases and indices are doubtful or demonstrably erroneous. Most of these were from a relatively few dubious sources whereas the majority of counts reported in the literature correspond to our findings. Two alternative scenarios for the evolution of chromosome numbers in this family are discussed in a phylogenetic context, with either x = 13 or x = 14 as the base chromosome number in the family; the base number of x = 7 suggested by some authors is refuted. In both scenarios, several aneuploid transitions between these karyotypes and a single change towards x = 15 have to be assumed. Polyploidizations are rare in this family and mostly associated with major evolutionary events. A single or a very few events led to a large species group of tetraploids in Potamogeton, and two subsequent rounds of polyploidization can explain the cytotype of Stuckenia, in which speciation took place entirely at the hexaploid level. Three octoploid species of Potamogeton had allopolyploid origins. This study gives an example of how the careful re-examination of chromosome numbers can substantially ameliorate interpretations of systematic and phylogenetic patterns.
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Záveská Drábková L. & Kirschner J. (2013): Oreojuncus, a new genus in the Juncaceae. – Preslia 85: 483–503.
Juncus trifidus and J. monanthos, two species traditionally included in section Steirochloa of the Juncaceae, are shown to differ substantially in their morphology from other members of this section. Their relationships with the other groups in this family based on DNA data of selected regions of plastome, chondriome and nrDNA, were examined using phylogenetic analyses of the combined data set of all these DNA regions. The resultant cladograms place J. trifidus and J. monanthos at a very basal position in the Juncaceae. Both the morphology and the phylogenetic analysis support the exclusion of these two species from Juncus and placing them in a separate genus. This genus is described under the name Oreojuncus Záveská Drábková et Kirschner. A detailed comparison with the other genera of the Juncaceae and a key for identifying these genera are provided.
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Király G., Trávníček B. & Žíla V. (2013): Revision of Rubus ser. Micantes occurring in Hungary and re-evaluation of the neglected Rubus balatonicus. – Preslia 85: 505–526.
Rubus balatonicus Borbás, belonging to ser. Micantes Sudre and a long-neglected apomictic species occurring in Hungary, is herein re-evaluated. This species is a nemophilous bramble occurring in the Transdanubian Mts (central Hungary) and has distinctive morphological features that clearly differ from those of related species. A list of localities and a distribution map are presented in addition to the designation of a lectotype and the description and first complete illustration of this species. As part of a general revision of Rubus ser. Micantes occurring in Hungary, the characteristics, distribution and ecology of three additional species (R. clusii Borbás, R. styriacus Halácsy and R. tabanimontanus Figert) of this series reported from Hungary are also assessed.
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