Dry grassland plant diversity conservation using low-intensity sheep and goat grazing management: case study in Prague (Czech Republic)

After abandonment, dry grassland (Festuco-Brometea) areas decline due to gradual overgrowing by woody species and the expansion of perennial tall grass species. Dry grassland vegetation was formed by extensive livestock grazing, thus grazing is considered one of the most natural methods for managing this type of vegetation. Six years after introducing low-intensity sheep and goat grazing in seven nature reserves in Prague (Czech Republic), the following impact of this management on dry grassland vegetation was observed: The cover of expansive woody species, particularly Ligustrum vulgare, and to a smaller extent Cornus sanguinea and Prunus spinosa declined. In addition, a significant, long-term declining trend of the expansive species Arrhenatherum elatius was also observed. Also the cover of Pimpinella saxifraga and Allium senescens declined significantly with regard to statistical evaluation. On the contrary, the cover of Achillea millefolium, Centaurea stoebe, Securigera varia, Elytrigia repens, Erysimum crepidifolium, Falcaria vulgaris, Fallopia convolvulus and Verbascum lychnitis increased. The cover of species characteristic of dry grasslands (Festuco-Brometea) increased significantly. No changes were observed in the number and cover of the Red List species. In addition, the presence of nitrophilous and ruderal species increased. Species diversity also significantly increased. From our findings we can conclude that managing dry grasslands with low-intensity grazing can help to keep dry grassland vegetation in good condition and conserve its plant diversity. Nomenclature: Kubát et al. (2002) for taxa and Moravec et al. (1995) for syntaxa.     

Type specimens of centipedes (Myriapoda,Chilopoda) in the National Museum,Prague (Czech Republic)

The centipede collection in the National Museum in Prague contains type material of 16 taxa (14 species and two subspecies), of which 15 were described by Luděk J. Dobroruka and one by Karl W. Verhoeff: Allothereua wilsonae Dobroruka, 1979; Chinobius alenae Dobroruka, 1980; Lithobius corrigendus Dobroruka, 1988; Lithobius creticus Dobroruka, 1977; Lithobius erythrocephalus mohelensis Dobroruka, 1959; Lithobius evae Dobroruka, 1958; Lithobius magurensis Dobroruka, 1971; Lithobius purkynei Dobroruka, 1957; Lithobius tatricus Dobroruka, 1958; Lithobius tatricus monounguis Dobroruka, 1958; Monotarsobius homolaci Dobroruka, 1971; Monotarsobius krali Dobroruka, 1979; Pachymerium dilottiae Dobroruka, 1976; Pachymerium hanzaki Dobroruka, 1976; Scolopendra aztecorum Verhoeff, 1934 and Strigamia olympica Dobroruka, 1977. Of these 16 taxa, five were described from the Czech Republic, three from Slovakia and eight from other countries (Greece, Iraq, Kyrgyzstan, Mexico, Nepal, Russia and Uzbekistan). The eight taxa described from the Czech and Slovak Republics are now considered as junior synonyms but the eight taxa described from the other countries are still valid.     

Late holocene history and vegetation dynamics of a floodplain alder carr: A case study from eastern Bohemia, Czech Republic

Vegetation development in the lowland floodplain alder carr “Na bahně” (eastern Bohemia, the Czech Republic) has been studied by means of pollen and macrofossil analyses and combined with vegetation analysis performed over the last 70 years. Local successional changes started with an oxbow lake (160 cal BC) which has later terrestrialised (630 cal AD). Then it changed from a typical alluvial fen into aSphagnum-dominated spring mire (950 cal AD) supplied by water arising from a river terrace surrounding the locality from three sites. In the centre of this wetland a small patch of alder carr developed (100 cal. AD), showing some tendency towards cyclic succession. The alder carr alternated several times with an openCarex fen (1100 cal AD to recent). The last fen-to-alder carr transition has been documented by direct observation during this century. Possible autogenic and allogenic factors driving the succession are discussed. The model of autogenic cyclic succession corresponds well with direct field observations and can be used to interpret alder carr structure, its dynamics, and function.     

Developmental responses of subdominant grassland species to current weather conditions and their relevance for annual vegetation changes

Year-to-year vegetation changes have been observed many times in temperate grasslands. Ordinarily, variation in annual weather patterns is considered responsible for these changes. However, the exact mechanisms of vegetation dynamics have seldom been studied. In order to analyse the direct response of plants to distinct weather situations, the shoot growth rates of three subdominant grassland species were determined during three growing seasons and tested for significant relationships to meteorological variables measured simultaneously in the study site. Half of the shoots grew in the natural community with competition from neighbouring plants. For the other half, above-ground interference was avoided by regularly clipping the surrounding vegetation. The results lead to the distinction of three different impact patterns of current weather conditions on the growth of subdominant grassland species: (i) As a consequence of extraordinary weather conditions, e.g. lasting periods of drought in the summer, plants die completely or partially or pass into secondary dormancy. Such weather situations may cause quantitative or even qualitative changes in species composition by altering the density and frequency of the species involved. (ii) Major divergences from average weather conditions, such as unusually warm or cold periods in the spring, affect the growth of subdominant species and may therefore lead to quantitative annual variation of the species involved in terms of cover or biomass. (iii) Average weather conditions with slight deviations from the long-term means of the weather variables do not produce detectable direct growth responses and therefore average weather conditions are not key factors for year-to-year variations in the quantitative or qualitative performance of subdominant species.     

15. Brve (Czech Republic): Vegetation development over the last about 2.5 millennia in the Bohemian Lowland close to Prague

Two Burkard seven-day recording traps have been in operation in the cities of Johannesburg and Pretoria since 1987. Pollen calendars average data for 1987 and 1988. Grass pollen is the most significant contributor in absolute and relative terms. This taxon comprises 52% of total regional pollen for the study period. Pollen of alien northern hemisphere trees is abundant, relative to that of native trees. This is attributed partly to the paucity of trees in the natural vegetation, and partly to their entomophilous nature. The flowering season for exotics is very short, possibly due to the short spring season. The greatest proportion of pollen, 58,8%, is nonseasonal. Species in this category flower throughout the year. 28.4% of taxa are spring-flowering. Annual variability is marked for most taxa.     

Vegetation changes in a shallow African Lake: Response of the vegetation to a recent dry period

This paper shows how the bed of Lake Chilwa in Malawi was colonised by plants during a recent dry period. Aeschynomene pfundii and Diplachne fusca were the principal colonising species on the alkaline mud flats. The subsequent changes in the vegetation after the lake refilled are described. Aeschynomene pfundii survived the flooded conditions for four years and eventually died out as seed germination could not occur underwater. The salinity of the lake during the low water and drying period prevented the lake bed from being extensively colonised by Typha domingensis.     

Palaeoecology of a medieval fishpond system (Vajgar, Czech Republic)

A palaeoecological investigation of a sediment core obtained from an artificial lake — the fishpond Vajgar (40 ha) near the town of Jind?ich?v Hradec, southern Bohemia, has been carried out in connection with extensive multidisciplinary research preceding the removal of its sediment. Samples from selected standard profile were subjected to chemical, pollen, and palaeoalgological analyses in order to study the chronology of vegetation development, anthropogenic impact on the landscape, and the development of an artificial fishpond ecosystem. The palaeoecological record under study comprises the period of extensive change from pre-cultural, silver fir-dominated forest vegetation into managed, agricultural landscape dominated by cereal fields and pastures. After Medieval colonization, the proportion between wooded and open landscape changed, and the composition of original forests shifted to pine. Pollen spectra from the High Middle Ages are characterized by high percentages of anthropogenic indicators and closely resemble the results from urban deposits (cesspits, wells, communication horizons, etc.). This period can be subdivided into a first phase correlated with the High and Late Middle Ages and a second phase correlated with the post Medieval period and partly maybe also with the agricultural collectivization of the 20th century. The earlier phase has a rather uniform character with a significant presence of grazing indicators and cereal weeds. After the collectivization of the 1950s and later, a substantial change in agricultural practices can be detected: the large-scale use of herbicides affecting the composition of agricultural ruderal species (e.g. decline of cornflower (Centaurea cyanus), rye (Secale), etc.). The development of the aquatic system of the fishpond Vajgar was studied by means of chemical and palaeoalgological analyses. On the basis of observed changes in the composition of subfossil algal communities, the fishpond history can be split into four distinct phases. It is assumed that the progression over individual phases was caused by changes in water chemistry that can be interpreted as shifts in water quality caused by the urbanization of the surrounding areas as well as by changes in agricultural practices. The results of the investigation of some chemical elements (especially heavy metals) show stratigraphic patterns that can be related to historical events. These results show that the mixing and bioturbation of the sediment was not so significant as might be expected.     

A plant-geographical study of the genusDorycnium MILL. (Fabaceae) in the Czech Republic

Two species of the genusDorycnium with the most northern distribution reach the absolute northern limit of their distribution areas in the Czech Republic.Dorycnium germanicum, a less ecologically plastic and more xerothermic species, covers a compact area in south Moravia, connected with its occurrence in Lower Austria.Dorycnium herbaceum, and ecologically more tolerant species, has its primary distribution area in south-east Moravia; this is connected with the Slovak part of the area of this species; secondary occurrences are scattered throughout other parts of Moravia and Bohemia. The distribution of both species was evaluated, using 23 herbarium collections. Climatic characteristics are provided for 54 climatic and ombrometric stations from the distribution area of both species. In the Czech RepublicD. germanicum represents the Illyrian-Noric migration element whileD. herbaceum represents the Carpathian one. There is a clear climatic differentiation between the localities of both species:D. germanicum occurs in dryer and warmer regions thanD. herbaceum. An introgression, zone was identified in the vicinity of the twon of Uherské Hardi?tě and the area south-east of this town. This zone coincides with the area where most of the identification problems with these species occurred.     

A study of habitat conditions of the macrophytic vegetation in selected river systems in western Lower Saxony (Federal Republic of Germany)

In connection with a phytosociological survey of running water macrophytes in Lower Saxony, ecological investigations were carried out in selected river systems. Within these systems, 43 sampling sites were studied. The vegetation of the sampling sites was classified by means of cluster analysis into 7 groups, 3 of which occurred on the diluvial plains and 2 in the coastal marsh area only. Forty-one parameters were measured 3–7 times covering 2 vegetation periods. In the first instance, the structure of the data was carefully studied by bivariate correlation analysis and factor analysis. A high number of significant correlations was detected, which indicates difficulties in ecological interpretation. Temporal variation of the parameters measured was also studied, and they were classified into 3 groups according to stability. For a study of the relationships between the vegetation and the ecological parameters, the data set was split into 5 subsets (physical data, water chemical data, interstitial water chemical data, sediment characteristics, and a mixed set of simple field data). The relationships of each subset to the vegetation was studied separately using cluster analysis. The mixed data set FIELD showed the highest degree of similarity to the vegetation clustering. Analysis of variance was carried out in order to find out which variables differ most among the vegetation types. The best differentiation qualities were shown by some physical and water chemical parameters (oxygen content, turbitity, current velocity, acidity, calcium). This result can only be interpreted ecologically in connection with the intercorrelations observed. The ecological behaviour of some species of medium frequency was also studied in detail by means of analysis of variance. The means of all parameters for occurrence and non-occurrence were compared. In the case of Ranunculus peltatus Schrank, Myriophyllum alterniflorum DC and Elodea canadensis Michx., several differentiation variables could be detected. Finally, the zonation of two rivers was studied in detail by comparing the vegetation sequence with important physical and chemical parameters. The interaction between these parameter groups is clearly shown. Physical parameters like current velocity are responsible for the basic zonation, whilst chemical parameters can modify the zones to a large extent. The necessity for a comprehensive approach to such types of data sets, including profound structural data analysis, is stressed in the discussion. The special problem of relating phytosociological and ecological data is discussed. The methods used are explained and possible objections are noted. The difficulties of using the habitat ecological results for bioindication purposes are outlined. Spatial autocorrelation, vegetation dynamics, interactive processes between the system parameters and the genetic variability of species have to be considered as the main problems in this special application. Nevertheless, the study produced some results which indicated the significance of physical, chemical and sediment parameters for macrophyte growth in the type of waters under investigation, and suggested subject areas for future research.     

Seasonal development of planktonic rotifers in Slapy Reservoir (Czech Republic)

The rotifer community of the canyon shaped Slapy Reservoir was studied over four years, from 2000 to 2003. A total of 38 rotifer taxa were identified in the pelagial zone. The dominant species, Keratella cochlearis, K. quadrata, Polyarthra dolichoptera, P. vulgaris, Synchaeta lakowitziana and Pompholyx sulcata, were similar to other reservoirs in the same area. Tychoplanktic species, which are typical for communities of upstream reservoirs, are reduced in the Slapy Reservoir. The seasonal fluctuation of rotifer abundance is characterized by a significant spring peak, clear water depression, summer peak and sometimes a lower peak in autumn. Fluctuation of the rotifer species shows a highly unified trend through the years with very low variation through the years. It results from the input of hypolimnetic water from an upstream reservoir, which erased a large part of the effect of year to year climatic fluctuations.     

Comparing Early to Middle Miocene floras and probable vegetation types of Oberdorf N Voitsberg (Austria), Bohemia (Czech Republic), and Wackersdorf (Germany)

The Early Miocene vegetation of western Styria, Austria, is reconstructed on the basis of detailed investigations of leaves and diaspores from the mining area Oberdorf N Voitsberg. In this paper, the flora and probable vegetation are compared with other assemblages of similar age from the Czech Republic and Germany to elucidate the diversity of wetland and mesophytic plant communities. The floristic composition and the vegetational units represented in Oberdorf are compared to the middle part of the Most Formation (M Most Fm), Cypris Shale, Mydlovary Formation (Mydlovary Fm) of Bohemia, and the Wackersdorf mining area of Bavaria. Among these sites, Oberdorf is extremely poor in hydrophytes and reed-like monocotyledons, indicating rare pond-like habitats as well as possibly more closed swamp forest conditions than, e.g. in the M Most Fm. In Oberdorf, relatively high pH-values in the lignite-forming swamps and the possible scarcity of acidic, nutrient-poor (sandy) soils have probably influenced the floristic composition of the azonal communities. The peat-forming associations in all regions share the abundance of Glyptostrobus europaeus. However, distinct differences in the accompanying elements, such as Taxodium dubium (present and abundant only in the M Most Fm) indicate even stronger floristic variability of Early(/Middle) Miocene peat-forming and riparian plant communities than previously expected. The virtual absence of Pinus, Engelhardia, Comptonia, and probably also of Quercus kubinyii/Quercus drymeja in the megafossil record of Oberdorf can possibly be explained by the edaphic conditions. The abundance of Sequoia abietina (absent in all the other compared sites), which we assign to riparian (and mesophytic) forests in Oberdorf, may have been favoured by rich alluvial soils.In the mesophytic associations, thermophilous elements of the Lauraceae, Mastixiaceae, Symplocaceae, and Rutaceae are diverse. Usually they include Trigonobalanopsis rhamnoides/Trigonobalanopsis exacantha, an evergreen Fagaceae. This assemblage type corresponds with the Younger Mastixioid Flora sensu Mai. The Younger Mastixioid Flora is best developed in Wackersdorf, less distinct in Oberdorf, and likely in the Cypris Shale and Mydlovary Fm. It is not traceable in the M Most Fm.     

DNA-adducts and atherosclerosis: a study of accidental and sudden death males in the Czech Republic

Atherosclerosis and carcinogenesis may share some common mechanisms of the genotoxic action of exogenous compounds, such as polycyclic aromatic hydrocarbons (PAHs). The main objective of this study was to test the hypothesis that "bulky" aromatic DNA-adducts in smooth muscle cells (SMCs) of thoracic aortas taken at autopsy from sudden and accidental death male subjects, aged between 30 and 60 years (N=133), are associated with the stage of atherosclerosis. The subjects with severe atherosclerotic damage were treated as "Cases" (N=66). The subjects meeting diagnostic criteria for slight and moderate total atherosclerotic body damage were treated as "Controls" (N=67). An additional objective of the study was to evaluate the effect of known atherogenic risk factors and possible modifiers of atherosclerotic changes, such as age, smoking, plasma lipid and antioxidant vitamin levels and some genetic susceptibility markers, e.g. polymorphisms of GSTM1, GSTT1, NAT2, CYP1A1 or apolipoprotein E (APO E) genes. We found significantly higher DNA-adduct levels in "Cases" as compared with "Controls" (2.11+/-1.07 adducts/10(8) nucleotides versus 1.49+/-0.55 adducts/10(8) nucleotides, P<0.001). "Cases" were significantly older and had elevated heart weight and plasma cholesterol levels and a higher frequency of overweight subjects as compared with "Controls". No significant differences in DNA-adduct levels between smokers and non-smokers within either group were detected. Multivariate logistic regression revealed that the "bulky" aromatic DNA-adducts, which are the most likely related to environmental exposure to genotoxic chemicals, remain a statistically significant predictor of the stage of atherosclerosis (OR=3.76, 95% CI=1.54-9.18, P=0.004) even after adjustment for age, smoking, obesity, heart weight and genetic susceptibility markers (GSTT1 and CYP1A1-MspI polymorphisms) that were also significant predictors. The fact that the "bulky" aromatic DNA-adduct levels predict the progression of atherosclerosis independently of smoking indicates that the formation of atherosclerotic plaques may also be initiated by environmental exposures other than tobacco smoke.     

Moisture conditions and the presence of bryophytes determine fescue species abundance in a dry calcareous grassland

Festuca ovina is the abundant matrix-forming species and F. rubra a subordinate species in shallow-soil calcareous grasslands. F. pratensis is a transient species, occurring sparsely in this community. We hypothesised that the different abundances of these three species are primarily due to the differential effect of moisture conditions on their germination and early establishment, and that the effect of the pattern of rainfall intensity depends on the presence or absence of a bryophyte layer. We studied the dependence of the germination and establishment of the three fescue species on the moisture conditions both in the laboratory and in the patches of intact grassland community (microcosms). In a laboratory germination experiment, F. pratensis showed the highest, F. rubra , the intermediate and F. ovina, the lowest drought tolerance. In microcosms, the establishment of F. ovina was the highest. At the same time, the annual mortality of seedlings of F. ovina was the lowest. All three species responded positively to an increasing irrigation level. Differently from F. ovina, F. rubra showed a positive response only in plots from which the bryophyte layer had been removed, while F. pratensis responded positively to both irrigation and bryophyte removal. We conclude that moisture conditions have a differential effect on the three fescue species mainly in the seedling establishment, not in the germination phase. For the successful establishment of F. rubra and F. pratensis, the coincidence of high rainfall and local disturbance, removing bryophytes, is required. The presence or absence of bryophytes had no effect on establishment in dry years, while in rainy years the removal of bryophytes has a clear positive effect.     

Quantifying the role of vegetation in slope stability: A case study in Tuscany (Italy)

Vegetation significantly affects hillslope hydrological and mechanical properties related to shallow landslide triggering. In view of the complexity of soil plant hydrological interactions, the quantification of root mechanical reinforcement remains a challenge. Herein we present a back analysis of mechanical stability criteria related to a well-characterized vegetated shallow landslide in Italy, focusing on the quantification of lateral and basal root reinforcement. Lateral root reinforcement is included in slope stability estimates by adding a stabilizing force proportional to the scarp surface and root distribution. This stabilizing force is added to the force balance equation for the infinite slope model for different landslide shapes and dimensions. To quantify root reinforcement, we use the Wu model and the fiber bundle model (WM and FBM, respectively). Implementation of the latter model allows the quantification of the stress–strain behaviour of a bundle of roots for different root distributions and mechanical properties. Results of these models are compared highlighting key differences between the two approaches. Calculations using the FBM can explain the overestimation of lateral root reinforcement using WM and the commonly observed overestimation in the factor of safety. The model also quantifies the displacement-dependent behaviour of root reinforcement on vegetated slopes. Lateral root reinforcement can strongly influence the stability of slopes up to a certain area (1000–2000 m²). The magnitude of this stabilizing effect depends on parameters such as inclination, soil mechanical properties, and root distribution.     

The potential of pollen analyses from urban deposits: multivariate statistical analysis of a data set from the medieval city of Prague, Czech Republic

In the 12th and 13th centuries, the land which is now the Czech Republic underwent deep social and landscape changes, defined by historians and archaeologists as a transitional period between the early and late medieval periods. This study aims to analyze this transition as reflected by 142 pollen spectra from urban deposits so far excavated in the city of Prague. Multivariate statistics and critical assessment of the results has brought general conclusions on the potential of pollen analysis for urban archaeological research. They reveal an early medieval urban environment as a fine mosaic formed by extensive management, and composed of many habitats without sharp borders between them. Since human impact increased with time and the use of land became more rationalized and intensive, this mosaic developed a relatively coarser structure in the high medieval period. Our results support findings of the earlier subjective and uncertain characteristics of two differing types of medieval pollen spectra (Cerealia-dominated ones with low pollen diversity versus those with a higher proportion of arboreal and wild herbal pollen and high pollen diversity) obtained from various archaeological sites.     

Macrozoobenthos response to environmental degradation in a heavily modified stream: Case study the Upper Elbe River,Czech Republic

Benthic macroinvertebrates are an important indicator of river health. However, their response upon water quality development downstream the pollution outlets considerably depends on the environmental habitat characteristics. Three successive stretches, each of them providing three different mesohabitats in stillwater (S), torrential (T) and riparian (R) zones were selected for evaluation of the impact of altered metapotamal river bed morphology (channelization) and chemical determinants of water quality on the Upper Elbe River. In downstream direction, the stretches are separated by weirs and characterized as a low polluted low modified natural stream (N), a low polluted channelized stream (C) and a channelized polluted stream (CP). Altogether, 111 benthic macroinvertebrate taxa were recorded in the Pardubice hotspot between Němčice and Přelouč. Despite different levels of stream bed and water quality degradation, micro- and mesohabitat characteristics appeared to be the most important factors determining the diversity of macrozoobenthos in riffle (substrate size structure) and in shoreline (macrophyte community composition and structure) mesohabitats. The diversity of macroinvertebrate communities was highest in riparian mesohabitats compared to stillwater and torrential ones. Saprobic indices increased in downstream direction, thus indicating the decline of water quality.