Sites In Central Europe Research Articles

SPATIAL BEHAVIOR OF EUROPEAN ROBINS DURING MIGRATORY STOPOVERS: A TELEMETRY STUDY

We studied the movement patterns of European Robins (Erithacus rubecula) at stopovers during spring and fall migration on the southeastern Baltic Coast, Russia. On the 1st, and sometimes the 2nd, day after arrival at a stopover site, robin movements were less aggregated than those made on subsequent days. Search/settling time varied between several hours and 2 days. During this period, migrants either occupied a defined stopover area or left the site. Stopover duration was 1 to 12 days in spring (mean = 2.4 days ± 0.31 SE) and 1 to 14 days in fall (mean = 3.4 days ± 0.50). The home-range size of European Robins on the southeastern Baltic Coast did not differ between seasons (spring: 4,320 m2 ± 545, n = 15; fall: 3,562 m2 ± 598, n = 15) and was similar to that at a central European site in fall (4,264 m2 ± 241, n = 14). These home ranges were not defended territories. We found no relationship between the robins' spatial behavior and their fat stores on arrival, although in spring more lean than fat robins stopped for >2 days. The pattern of movements at the stopover was variable, both in birds that arrived lean and those that arrived with much more fat. Stopover duration estimates based on radio-tagging are superior to those based on capture-mark-recapture.

Perpetuation of the Lyme Disease Spirochete Borrelia lusitaniae by Lizards

To determine whether the Lyme disease spirochete Borrelia lusitaniae is associated with lizards, we compared the prevalence and genospecies of spirochetes present in rodent- and lizard-associated ticks at a site where this spirochete frequently infects questing ticks. Whereas questing nymphal Ixodes ricinus ticks were infected mainly by Borrelia afzelii, one-half of the infected adult ticks harbored B. lusitaniae at our study site. Lyme disease spirochetes were more prevalent in sand lizards (Lacerta agilis) and common wall lizards (Podarcis muralis) than in small rodents. Although subadult ticks feeding on rodents acquired mainly B. afzelii, subadult ticks feeding on lizards became infected by B. lusitaniae. Genetic analysis confirmed that the spirochetes isolated from ticks feeding on lizards are members of the B. lusitaniae genospecies and resemble type strain PotiB2. At our central European study site, lizards, which were previously considered zooprophylactic for the agent of Lyme disease, appear to perpetuate B. lusitaniae.

Effect of different agronomical measures on yield and quality of autumn saved herbage during winter grazing - 1<sup>st</sup> communication: Yield and digestibility of organic matter

The objective of this paper was to obtain information about the effect of interactions and different agronomical measures on autumn saved herbage of different sites in Central Europe (Czech Republic, Germany, Hungary, Poland). Within the different sites, the effect of the factors pre-utilisation (accumulation since June, July or August) and winter harvest date (November, December or January) on dry matter (DM) yield and digestibility of organic matter (DOM) was investigated over three consecutive years. All results were examined by analysis of variance and least-significance differences (LSD) were calculated (with P < 0.05). For all years, date of winter harvest was the most important source of variance. The highest yields were attained in November (varied from 2.3 to 0.8 t/ha), the lowest in January (from 1.5 to < 0.2 t/ha). The highest DOM concentration (from 70.4 to 52.4% of dry matter) was reached in November, and it decreased until January (from 59.6 to 35.2% of dry matter). Predominantly caused by the prevailing climatic conditions, the DM yields of the sites varied considerably during winter, showing a significance for the interaction winter harvest date × site as well as for the factor site. The utilisation of autumn saved herbage, pre-utilised in July, might be the best opportunity providing an adequate quantity and DOM for suckler cows until the end of the year, but the prevailing climatic conditions at different sites inCentral Europe finally decide on the practicability of winter grazing.  

Impact of late frost events on radial growth of common beech (Fagus sylvatica L.) in Southern Germany

Phenological, temperature, and tree-ring data were used in order to identify and quantify the impact of late frosts on common beech (Fagus sylvatica L.) at different altitudes in Southern Germany during the last century. For this intention, dendroecological investigations were made upon trees at the Meteorological Observatory Hohenpeisenberg as well as from seven stands in the Bavarian Forest and 17 stands at the northern fringe of the Alps. From these locations, a considerable number of severe growth minima in the tree-ring series could be related to late frost in the days of or immediately after leaf unfolding. The frequency of frost-related growth minima increases with altitude. In individual years, radial growth can be reduced by more than 90% (stand mean) in relation to the average growth of the ten previous years. Hence, late frosts are considered as important ecological events that strongly affect beech vitality and competitiveness especially at high altitudes. Evidence of significant impacts on radial growth by late frosts distinct before leaf unfolding or with temperatures above −3°C was not found. Also, increasing frequency and intensity of late frosts during recent decades were not ascertained. Hence, the recently observed decreased vitality of common beech accompanied by growth depressions especially at high altitude sites in Central Europe cannot be explained as a consequence of late frost damage.

Quantitative reconstruction of mid-Holocene climatic variations in the northern Alpine foreland based on Lake Morat (Swiss Plateau) and Lake Annecy (French Pre-Alps) data

Vegetation and lake-level data from the sites of Lake Morat (Switzerland) and Lake Annecy (eastern France) are used to provide quantitative estimates of climatic variables over the period 6600-5500 cal.yr BP in the nor-them Subalpine zone, and to test the method of climate reconstruction based on modern pollen analogues constrained by lake-level data. The results obtained from both sites suggest: (1) that phases of higher lake level coincided with a cooling and a shortening of the growing season and an increase in annual precipitation, and (2) that during climatic reversals summer was more affected than winter. They also provide evidence of a sensitive method of reconstruction of climatic variables capable of capturing minor climatic oscillations such as reflected by weakly pronounced lake-level fluctuations. However, comparison of results obtained at Lake Morat and Lake Annecy, with each other and with results from other sites in central Europe, also clearly indicates that either anthropogenic disturbances of the vegetation cover or an overrepresentation of taxa due to particular site exposition can bias the reconstruction of variations in climatic parameters. In addition to pluri-centennial climatic oscillations, both the Lake Morat and Lake Annecy records show a general trend toward temperature cooling over the period considered. This may be related to a reduction in summer insolation induced by orbital factors. Finally, the quantitative estimates of climatic parameters reconstructed at Lake Morat and Lake Annecy help to increase our understanding of the possible impact of climatic oscillations on ancient agricultural communities.

Estimation of uncertainty of direct radiative forcing of the aerosol for a rural site in central Europe

Direct climate forcing due to scattering and absorption of the main aerosol components (ammonium sulfate and total carbon) was estimated seasonally in Hungary by a box model. Ammonium sulfate played an important role in the direct forcing while the carbonaceous aerosol contributed significantly to the development of extinction. In summer, the scattering effect of both species showed a maximum (ammonium sulfate: −2.21±1.73 W m −2, total carbon: −0.88±0.73 W m −2), while the absorption of carbon was the most significant in autumn (+0.40±0.41 W m −2). Uncertainty of these data was obtained by using the theory of error propagation and by taking into consideration the standard deviation of the experimental parameters. The relatively high values of the calculated relative standard deviations of the climate forcing data were attributed partly to the large number of the model parameters (9 and 11) and partly to their large uncertainty. The calculated uncertainties of various forcings were found to be in between the factors of 1.7 and 2.1 which were lower than those generally applied in forcing calculations. Parameter sensitivity analysis of the model equation proved that the reliability of the calculated data could be improved if attention is paid to the measurement of certain parameters such as: mass concentration, cloud coverage, surface albedo, upscattered fraction, single-scattering albedo and the fractional transmittance of the atmosphere.

Re‐interpretation of the Meikirch pollen record, Swiss Alpine Foreland, and implications for Middle Pleistocene chronostratigraphy

AbstractThe Meikirch drilling site in the Swiss Midlands north of Bern is re‐interpreted using a combination of sedimentological logging, pollen analyses and luminescence dating. The sedimentary sequence comprises about 70 m of lacustrine deposits, overlain by about 39 m of coarse glacial outwash interpreted to represent at least two independent ice advances. Pollen analyses of the apparently complete limnic sequence reveal a basal late glacial period followed by three warm phases that are interrupted by two stadial periods (Meikirch complex). The warm periods were previously correlated with the Holsteinian and Eemian Interglacials. According to luminescence dating, and with consideration of evidence for Middle Pleistocene climate patterns at other central European sites, a correlation of the Meikirch complex with marine isotope stage (MIS) 7 is now proposed. If this correlation is correct, it implies the presence of three intervals with interglacial character during MIS 7. However, the late Middle Pleistocene vegetational features of the Meikirch complex show significant differences when compared with the pollen record from the Velay region, central France. Possible explanations for this discrepancy are distinct Middle Pleistocene patterns of atmospheric circulation over central Europe and a different distribution of vegetation refugia compared to the Eemian Interglacial and the Holocene. Copyright © 2005 John Wiley & Sons, Ltd.

Fog water flux at a canopy top: Direct measurement versus one-dimensional model

Abstract A one-dimensional model [Lovett, 1984. Rates and mechanisms of cloud water deposition to a subalpine balsam fir forest. Atmospheric Environment 18, 361–371] to quantify fog water deposition was compared with results of long term (13 months) measurements of turbulent exchange with the eddy covariance method at a mountainous site in Central Europe. Turbulent exchange is mainly deposition and dominates over sedimentation at that site, therefore eddy covariance is a suitable tool in quantifying fog water deposition. The model can be operated with use of the measured droplet size distribution (DSD), with a DSD as parameterized from liquid water content (LWC) data, or with the measured visibility (VIS) as a quantitative indicator for fog. The latter is the easier measurement and therefore preferable for long-term applications. We compared the fog water deposition on a monthly basis. If VIS data are used as model input, the overall underestimate of the measurement is −23% as compared to the measurements. Using LWC and the parameterized DSD as input, the deviation is +37%. All deviations are highly significant.

The chronology of Neolithic dispersal in Central and Eastern Europe

We analyze statistically representative samples of radiocarbon dates from key Early Neolithic sites in Central Europe belonging to the Linear Pottery Ceramic Culture (LBK), and of pottery-bearing cultures on East European Plain (Yelshanian, Rakushechnyi Yar, Buh-Dniestrian, Serteya and boreal East European Plain). The dates from the LBK sites form a statistically homogeneous set with the probability distribution similar to a single-date Gaussian curve. This implies that the duration of the spread of the LBK is shorter than the available temporal resolution of the radiocarbon dating; therefore, the rate of spread must be larger than 4 km/yr, in agreement with earlier estimates. The East European sites exhibit a broad probability distribution of dates. We identify in these data a spatio-temporal sequence from south-east to north-west, which implies the rate of spread of the initial pottery-making of the order of 1.6 km/yr, comparable to the average rate of spread of the Neolithic in Western and Central Europe. We argue that this spatio-temporal sequence is consistent with an idea that the tradition of the initial pottery-making on East European Plain developed under an early impulse from the Eastern Steppe.

Seasonal changes in the relationship between plant species richness and community biomass in early succession

We analysed the relationship between plant species richness and productivity on first-year-old fields at two similar sites in central Europe. At both sites, a wide range of productivity levels was available resulting from different long-term fertilisation. In order to identify underlying mechanisms of the species richness–productivity relationship we included the seasonal dynamics and the number of individuals of each species in our analysis. We sampled 10 and 21 plots, respectively, at the two sites in May, June and July by harvesting all aboveground parts of vascular plants in 0.25 m2 subplots. Species richness, number of individuals of each species and community biomass as a surrogate of productivity were recorded in each sample. At one site, the relationship between species richness and biomass was significantly positive in the May and June harvest. This relationship disappeared in the July harvest due to a reduction in species richness at high productivity levels. The relations between species richness and number of individuals and between number of individuals and biomass paralleled the species richness–productivity relation but the individual number–biomass relationship remained positive until the last harvest. Between-species differences in individual number–community biomass relationships and their seasonal dynamics revealed “interspecific competitive exclusion” even though the species richness–biomass relationships were not negative or hump-shaped. At the second site, species richness was not related to productivity or to number of individuals. Our study demonstrated the importance of temporal dynamics and regional processes in understanding species richness–productivity patterns. Die Beziehung zwischen pflanzlicher Artenvielfalt und Produktivität wurde in einjährigen Brachen an zwei ähnlichen Standorten in Mitteleuropa untersucht. Innerhalb beider Standorte hatte eine langjährig unterschiedliche Düngung zu grossen Differenzen in der Produktivität geführt. Um die der Artenvielfalt-Produktivitäts Beziehung zugrundeliegenden Mechanismen heraus zu arbeiten, wurden die zeitliche Dynamik und die Individuenzahl jeder einzelnen Art in die Analyse einbezogen. Im Mai, Juni und Juli wurden an beiden Standorten die oberirdischen Teile aller Gefässpflanzen in 10 bzw. 21 Teilflächen von je 0.25 m2 abgeerntet. Für jede Probe wurden die Artenzahl, die Individuenzahl pro Art sowie die Biomasse als Maß für die Produktivität bestimmt. An einem der beiden Standorte war die Beziehung zwischen Artenvielfalt und Biomasse in der Mai- und Juni-Ernte signifikant positiv. Aufgrund einer Verringerung der Artenvielfalt bei hoher Produktivität verschwand dieser positive Zusammenhang jedoch in der Juli-Ernte. Die Beziehungen zwischen Artenvielfalt und Individuenzahl sowie zwischen Individuenzahl und Biomasse verliefen parallel zu der Beziehung zwischen Artenvielfalt und Biomasse, die Individuenzahl–Biomasse–Beziehung blieb allerdings bis zur letzten Ernte positiv. Zwischen den Arten traten große Unterschiede in der Beziehung zwischen Individenzahl und Biomasse pro Teilfläche auf. Auch wenn keine negativen oder unimodalen Beziehungen zwischen Artenvielfalt und Biomasse beobachtet wurden, stellen diese artspezifischen Unterschiede und vor allem ihr zeitlicher Verlauf einen Beleg für den Ausschluss von Arten durch interspezifische Konkurrenz dar. Am zweiten Standort war die Artenvielfalt zu keinem Zeitpunkt mit der Biomasse und der Individuenzahl korreliert. Die vorliegende Arbeit veranschaulicht die große Bedeutung von zeitlicher Dynamik und standörtlichen Unterschieden für das Verständnis der Beziehung zwischen Artenvielfalt und Produktivität.

PREHISTORIC COPPER PRODUCTION IN THE INN VALLEY (AUSTRIA), AND THE EARLIEST COPPER IN CENTRAL EUROPE*

In recent years archaeological finds and scientific analyses have provided increasing evidence for a very early beginning of copper production in the rich mining area of the Tyrolean Alps. The earliest findings derive from an excavation of a multi‐phase settlement on the Mariahilfbergl in Brixlegg, which revealed evidence that a small amount of fahlores, probably of local provenance, was at least heated if not even smelted there in the Late Neolithic Münchshöfen culture (the second half of the fifth millennium bc). However, most copper finds of this horizon consist of low‐impurity copper that most probably derives from Majdanpek in Serbia. This long‐distance relationship is corroborated by typological features that link some aspects of the Münchshöfen culture with the Carpathian basin. Thus it is not yet clear if, at Brixlegg, actual copper production took place or, rather, an experimental treatment of the local ores. The typical fahlore composition, with arsenic and antimony in the per cent and silver and bismuth in the per mille ranges, appears in quantity only in the Early Bronze Age. Many thousands of Ösenringe are known from many central European Early Bronze Age sites, with a chemical composition typical of fahlores. At Buchberg near Brixlegg, a fortified settlement with slags from fahlore smelting proves that the local ores were indeed exploited. The lead isotope ratios of Ösenringe from the Gammersham hoard in Bavaria, which consist of fahlore copper, confirm this and suggest that copper mining and production in the Inn Valley reached a first climax during that period. In the Late Bronze Age, copper was produced at an almost industrial level.

Gas to particle distribution of low molecular weight dicarboxylic acids at two different sites in central Europe (Austria)

Low molecular weight dicarboxylic acids exhibit a semivolatile behavior and partition between gas and aerosol phases in the atmosphere. Here we present an approach for sample collection, which provides information about the gas/particle distribution of the investigated acids, but with less effort compared to commonly used denuder systems. The procedure was applied for the investigation of C2–C9 dicarboxylic acids at a continental background site in central Europe (Mt. Rax) and the urban site Vienna. The averaged gas phase contribution ( n = 12 ) determined for individual low molecular weight dicarboxylic acids varied between 4% (malonic acid) and 37% (glutaric acid) of the total collected amounts. Using the observed gas/particle distributions effective Henry's law constants were estimated. Between the carbon chain length of the investigated dicarboxylic acids and the magnitude of K H * a dependence was observed — showing higher values for C2/C3 dicarboxylic acids (averaged 1.1 × 10 13 mol L - 1 atm - 1 ) and lower values for C4/C5 compounds (averaged 1.6 × 10 12 mol L - 1 atm - 1 ).

Modelling the Neolithic dispersal in northern Eurasia

Comprehensieve lists of radiocarbon dates from key Early Neolithic sites in Central Europe belonging to the Linear pottery Ceramic Culture (LBK) and early pottery-bearing cultures in the East European Plain were analysed with the use of the x2 test. The dates from the LBK sites form a statistically homogeneous set, with a probability distribution similar to a single-date Gaussian curve. This implies the rate of expansion of the LBK in Central Europe being in excess of 4 km/yr. Early potter-bearing sites on the East European Plain exhibit a much broader probability distribution of dates, with a spatio-temporal trend directed from the south-east to the north-west. The rate of spread of pottery-making is in the order of 1 km/yr, i.e., comparable to the average expansion rate of the Neolithic in Western and Central Europe.

Air mass modification over Europe: EARLINET aerosol observations from Wales to Belarus

For the first time, the vertically resolved aerosol optical properties of western and central/eastern European haze are investigated as a function of air mass transport. Special emphasis is put on clean maritime air masses that cross the European continent from the west and become increasingly polluted on their way into the continent. The study is based on observations at seven lidar stations (Aberystwyth, Paris, Hamburg, Munich, Leipzig, Belsk, and Minsk) of the European Aerosol Research Lidar Network (EARLINET) and on backward trajectory analysis. For the first time, a lidar network monitored continent‐scale haze air masses for several years (since 2000). Height profiles of the particle backscatter coefficient and the particle optical depth of the planetary boundary layer (PBL) at 355‐nm wavelength are analyzed for the period from May 2000 to November 2002. From the observations at Aberystwyth, Wales, the aerosol reference profile for air entering Europe from pristine environments was determined. A mean 355‐nm optical depth of 0.05 and a mean PBL height of 1.5 km was found for clean maritime summer conditions. The particle optical depth and PBL height increased with increasing distance from the North Atlantic. Mean summer PBL heights were 1.9–2.8 km at the continental sites of Leipzig, Belsk, and Minsk. Winter mean PBL heights were mostly between 0.7 and 1.3 km over the seven EARLINET sites. Summer mean 355‐nm optical depths increased from 0.17 (Hamburg, northwesterly airflow from the North Sea) and 0.21 (Paris, westerly flow from the Atlantic) over 0.33 (Hamburg, westerly flow) and 0.35 (Leipzig, westerly flow) to 0.59 (Belsk, westerly flow), and decreased again to 0.37 (westerly flow) at Minsk. Winter mean optical depths were, on average, 10–30% lower than the respective summer values. PBL‐mean extinction coefficients were of the order of 200 Mm−1 at 355 nm at Hamburg and Leipzig, Germany, and close to 600 Mm−1 at Belsk, Poland, in winter for westerly flows. Whereas the optical depth for westerly flows was typically <0.35 during the summer halfyear, it increased to values of 0.5–0.7 over most of the central European sites during easterly flows. Compared to aerosol sources in Poland and southeastern Europe, the highly industrialized and populated western European region was found to contribute only moderately to the European aerosol burden. Comparably clean conditions (low particle optical depth) prevailed at the Munich site, indicating a sensitive influence of the orography on haze conditions. Estimates of the mean effective (upward minus downward) aerosol mass flux into the atmosphere along the way from the Atlantic Ocean to central Europe (Leipzig), and from Leipzig to Belsk, that are consistent with the optical depth increase, yield values of 0.11–0.17 μg/(m2s) and 0.25 μg/(m2s), respectively. These values correspond to mean effective aerosol mass fluxes for 50 km × 50 km grid cells of the order of 10000 Mg/year and 20000 Mg/year, respectively. The estimates are in reasonable agreement with EMEP emission data.

Ambient particles at an urban, semi-urban and rural site in Central Europe: hygroscopic properties

Abstract Measurements on hygroscopic properties of sub-micrometer atmospheric particles have been carried out using a tandem differential mobility analyser (TDMA). It measures the growth of initially dry monodisperse particles with sizes of 50 , 100 , 150 and 250 nm at a relative humidity (RH) of 0.85. Measurements have been carried out at an urban, semi-urban and rural location in Bavaria (Germany) each during 1 week in winter, summer and fall. Two fractions of particles are found, hygroscopic and non-hygroscopic particles with mean growth factors of 1.37 and 1.03, respectively. Growth factors are nearly independent of location and season, but increased significantly with initial particle size from 1.31 to 1.47 for 50 and 250 nm particles, respectively. The mean number concentration of non-hygroscopic particles is strongly dependent on location and increases by a factor of 2.4 for the semi-urban site and by a factor of 9 for the urban site, compared to the rural location. The corresponding differences for hygroscopic particles are less than a factor of three, respectively. Individual measurements strongly differ in number concentration from each other. Assuming that the hygroscopic material is ammonium sulphate, the non-hygroscopic particles and the hygroscopic particles contain about 3% and 54% ammonium sulphate, respectively. For the hygroscopic particles the mean increase of ammonium sulphate was 38–74% for 50 and 250 nm particles, respectively.

Relationships of a Novel Lyme Disease Spirochete, Borrelia spielmani sp. nov., with Its Hosts in Central Europe

To determine whether the pathogenic variant of Lyme disease spirochetes, isolate A14S, is perpetuated in a particular reservoir-vector relationship, we screened vector ticks in various Central European sites for a related spirochete and determined its host association. A14S-like spirochetes infect numerous questing ticks in the Petite Camargue Alsacienne (PC). They frequently infect dormice, but no mice or voles. Garden dormice appear to be better reservoir hosts for A14S-like spirochetes than for Borrelia afzelii, because these spirochetes are retained longer and infect ticks more readily. Spirochetes associated with garden dormice in the PC site form a homologous entity with those isolated from a human patient in The Netherlands. Its unique biological relationship together with previous genetic characterization justifies designating this dormouse-associated genospecies as a distinct entity. Garden dormice serve as the main reservoir hosts of a novel genospecies, Borrelia spielmani sp. nov., one of several that cause Lyme disease in people.

Long-distance migration timing of Tringa sandpipers adjusted to recent climate change

Capsule Evidence for earlier spring migration of Tringa sandpipers after warmer winters, but no clear pattern concerning autumn migration timing. Aim To analyse the timing of migration of three Tringa sandpipers between 1966 and 2002 with respect to recent global warming on a local and a hemispheric scale. Methods I analysed long-term migration timing variation in Greenshank Tringa nebularia, Spotted Redshank T. erythropus and Wood Sandpiper T. glareola at four Central European staging sites. Variation in passage onset, median and end per migration period was analysed using stepwise regression with respect to variation in (i) local abundance, residence time and age-dependent abundance as an estimate of breeding success and (ii) climate at the staging sites, snowmelt at the presumed central breeding area and the North Atlantic Oscillation (NAO). Results All three species consistently showed an overall spring migration advance and autumn migration delay. Autumn passage timing varied with both climatic conditions at the breeding area and breeding success, while in 43% of all cases spring passage correlated with local and hemispheric climate variation. Conclusion The distinction between population dynamic and climatic effects on timing of autumn migration requires separate data for local adult and juvenile passage or a larger sample of sites. In spring, the data strongly suggest a flexible response of migration timing to local weather conditions and the hemispheric variation of the North Atlantic Oscillation. This indicates that even long-distance migrants are able to adjust their overall migration pattern to fluctuating environmental conditions on a phenotypic basis.

Long-term variations of the UV-B radiation over Central Europe as derived from the reconstructed UV time series

Abstract. The daily doses of the erythemally weighted UV radiation are reconstructed for three sites in Central Europe: Belsk-Poland (1966–2001), Hradec Kralove-Czech Republic (1964–2001), and Tõravere-Estonia (1967–2001) to discuss the UV climatology and the long-term changes of the UV-B radiation since the mid 1960s. Various reconstruction models are examined: a purely statistical model based on the Multivariate Adaptive Regression Splines (MARS) methodology, and a hybrid model combining radiative transfer model calculations with empirical estimates of the cloud effects on the UV radiation. Modeled long-term variations of the surface UV doses appear to be in a reasonable agreement with the observed ones. A simple quality control procedure is proposed to check the homogeneity of the biometer and pyranometer data. The models are verified using the results of UV observations carried out at Belsk since 1976. MARS provides the best estimates of the UV doses, giving a mean difference between the modeled and observed monthly means equal to 0.6±2.5%. The basic findings are: similar climatological forcing by clouds for all considered stations (~30% reduction in the surface UV), long-term variations in UV monthly doses having the same temporal pattern for all stations with extreme low monthly values (~5% below overall mean level) at the end of the 1970s and extreme high monthly values (~5% above overall mean level) in the mid 1990s, regional peculiarities in the cloud long-term forcing sometimes leading to extended periods with elevated UV doses, recent stabilization of the ozone induced UV long-term changes being a response to a trendless tendency of total ozone since the mid 1990s. In the case of the slowdown of the total ozone trend over Northern Hemisphere mid-latitudes it seems that clouds will appear as the most important modulator of the UV radiation both in long- and short-time scales over next decades. Key words. Atmospheric composition and structure (biospheric-atmosphere interaction) – Meteorology and atmospheric dynamics (climatology; radiative processes)

Impact of long-term conventional and organic farming on the diversity of arbuscular mycorrhizal fungi.

Previous work has shown considerably enhanced soil fertility in agroecosystems managed by organic farming as compared to conventional farming. Arbuscular mycorrhizal fungi (AMF) play a crucial role in nutrient acquisition and soil fertility. The objective of this study was to investigate the diversity of AMF in the context of a long-term study in which replicated field plots, at a single site in Central Europe, had been cultivated for 22 years according to two "organic" and two "conventional" farming systems. In the 23rd year, the field plots, carrying an 18-month-old grass-clover stand, were examined in two ways with respect to AMF diversity. Firstly, AMF spores were isolated and morphologically identified from soil samples. The study revealed that the AMF spore abundance and species diversity was significantly higher in the organic than in the conventional systems. Furthermore, the AMF community differed in the conventional and organic systems: Glomus species were similarly abundant in all systems but spores of Acaulospora and Scutellospora species were more abundant in the organic systems. Secondly, the soils were used to establish AMF-trap cultures using a consortium of Plantago lanceolata, Trifolium pratense and Lolium perenne as host plants. The AMF spore community developing in the trap cultures differed: after 12 months, two species of the Acaulosporaceae (A. paulinae and A. longula) were consistently found to account for a large part of the spore community in the trap cultures from the organic systems but were found rarely in the ones from the conventional systems. The findings show that some AMF species present in natural ecosystems are maintained under organic farming but severely depressed under conventional farming, indicating a potentially severe loss of ecosystem function under conventional farming.

Variation in species richness and species pool size across a pH gradient in forests of the southern Blue Ridge Mountains

PARTEL (Ecology 83: 2361-2366, 2002) and EWALD (Folia Geobot. 38: 357-366, 2003) suggest that the relationship between local species density and soil pH is determined by regional species pool size, which in turn reflects the relative abundance of soil types during the evolutionary history of the flora. Ewald observed that calcareous sites in Central Europe have higher species density and larger species pools than acidic sites, and argues that this is the consequence of a Pleistocene bottleneck for acidophiles. The flora of the southern Blue Ridge Mountains USA has always been associated with primarily acidic soils. We used vegetation and soil data from 3328 100 m 2 southern Blue Ridge forest plots to examine the generality of the Partel-Ewald hypothesis. The Blue Ridge flora with less than 20% of species confined to sites above pH 4.7 contrasts dramatically with that of Europe. However, regional species pool size increases with pH. Genus- and family-level pools increase with pH, suggesting an ancient origin for this pattern. Mean species density is also strongly positively correlated with soil pH. Thus, both regional species pool size and plot species density of southern Blue Ridge forests fail to conform to predictions derived from the work of Partel and Ewald. The increase in species pool with increase in pH exhibited by southern Blue Ridge forests appears to reflect broad species distributions and tolerance for high pH conditions among species that grow predominantly under acid conditions. We conclude that richness on higher pH sites is a consequence of generally more favorable conditions for plant growth and/or establishment. Ewald may be correct in asserting that the abundance of high pH specialists in Central Europe is an historical artifact, but our data contradict the assertion of Partel and Ewald that evolution of a flora in a primarily low pH environment will necessarily translate into a negative correlation between pH and species density in local vegetation.