Siebengebirge – im Saum der Großlandschaften. Die Exkursion

The Siebengebirge Mountains, facing Bonn and situated between the Lower Rhine Bight and the well known Middle Rhine valley, cover an area of only some 4800 ha, but represent a fairly unusual complex with respect to landscape and nature. Already some famous exploring travellors of the 18th century such as Georg Forster, Johann Wolfgang von Goethe, and Alexander von Humboldt consistently emphasized the striking diversity and natural beauty of this area. No other part of Germany has hitherto been dealt with by a comparable array of special (geologically as well as biologically centered) investigations and compiling contributions. An excursion proposal recommends a closer inspection of that fascinating landscape.     

Die Fossilfcührung des erdfalls von nieheim (se-westfalen) und seine bedeutung für die paläogeographie imcampan und miozän das nordwestdeutsche tertiärbecken,nr. 27

A landfall in the east Westphalian-Lippean area contains a breccia of Keuper, Liassic and Miocene (marine Reinbekian) sediments. Within the Reinbekian sediments calcareous nannoplankton, diversified foraminiferal assemblages, ostracods, lamellibranchiates and gastropods, including a new subspecies ofAlvania (A.) curta, were found. Furthermore, foraminiferal and calcareous nannoplankton assemblages of Santonian to Campanian age are present. On the basis of these occurrences, the paleogeographic conception of the past coastline of the Westphalian Upper Cretaceous sea as well as of the southern extension of the boreal Middle Miocene sea can be revised. A gulf, stretching to the South, may have connected the North Sea basin with the basin of Mayence and the upper Rhine valley through the Hessian depression for certain periods during the Middle Miocene.     

Gas permeable deep reaching fracture zones encourage site selection of ants

Difficulties with geological mapping of fault patterns occur frequently due to missing outcrops and typically fault mineralization (e.g. crystalline quartz and ore mineralization). Alternatively, in addition to other analyses, soil gas measurements (e.g. helium) can be carried out. Due to fault zone complexity, geologists must often rely on other, in some cases, easier indications of their existence. Geological studies in several areas of central Europe especially in the Middle Rhine Region (Rhenish Massif) indicate that active gas permeable fracture zones are linked to linear distributions of nests of hill-building forest ants. Therefore, the possibility of using formicines as indicators of gas permeable fault patterns was investigated. These preliminary data indicated the possible interaction of site selection and active gas permeable fracture zones. Consequently, regions in the Alps, the Black Forest, the Lower Rhine Embayment, Bavaria, Hesse and South Sweden were chosen, ant nests were mapped, and their sites subsequently compared to geological structures. Most of the investigated ant nests were located on or near active gas permeable faults. Additionally, in the Middle Rhine Region variations in population size of formicines on fault zones and inter fault zones have been observed. These primary data suggest formicines can be applied successfully as an aid to fault pattern location.     

Strong genetic exchange among populations of a specialist bee, <Emphasis Type="Italic">Andrena vaga</Emphasis> (Hymenoptera: Andrenidae)

Habitat fragmentation is believed to be a key threat to biodiversity, with habitat specialists being stronger affected than generalists. However, pioneer species might be less affected by fragmentation, as their high colonization potential should increase gene flow. Here, we present an analysis of the genetic structure of populations of the solitary bee Andrena vaga, which naturally occurs in sandy habitats and is specialized on willow (Salix) pollen as larval food and sandy soils as nesting sites. While the species is widespread in the young sandy landscapes of our main study area (Emsland, northwestern Germany), it occurs less frequently in the Lower Rhine valley. Our analyses of six polymorphic microsatellites show that the populations are only slightly differentiated, suggesting a relatively strong gene flow. No genetic structure corresponding to the geographic origin was found as the variability within populations accounted for the major proportion of variation. F_ST values were higher and allelic richness was lower in the Lower Rhine valley, supporting the hypothesis that habitat availability affects the degree of genetic exchange between populations. Inbreeding coefficients were generally high and nearly all populations had a heterozygote deficiency, which could be explained by the breeding strategy of A. vaga, which nests in aggregations.     

Changes in the composition of the European snake fauna during the Early Miocene and at the Early / Middle Miocene transition

The members of the ‘modern’ snake families Colubridae, Viperidae and Elapidae (representatives of the family Colubridae appeared in Europe as the first) might have penetrated into the areas of Central Europe probably across the Mazury -Mazowsze continental bridge. The ‘modern’ families penetrated into West Europe across the Rhine Graben by several immigration waves. Based on the known marine incursions into the Rhine Graben and adjacent areas, a total of four distinct waves of dispersal of both the Asiatic and North American immigrants can be discerned within the Early Oligocene — Middle Miocene time span. The Early Miocene (MN 1–MN 2a) and the Early / Middle Miocene (MN 3–MN 4/5) dispersals of snakes are responsible for the final displacement of representatives of the ‘ancient’ family Boidae out of West and Central Europe. The Early and the Middle Miocene migrations have likewise initiated the evolution of the modern European snake fauna.     

Comparison of landscape diversity in forests of the upper Rhine and the middle Loire floodplains (France)

Traditional measures of biotic indices (, , ) from phytosociological relevés are used to compare diversity at three scale-levels in the upper Rhine valley (Alsace, northeastern region) and the middle Loire (Bourgogne, central region), France. Both study areas included a tributary. The Ill, which is the Rhine tributary in this sector, has no forest communities in common with the main river because of opposite hydrological and edaphic characteristics. This is not the case in the Loire valley, in which the fluvial characteristics are close to those of its tributary, the Allier.Nearly all forest communities (12/14) were shown to be species-rich, due to the role of natural disturbances. Species richness peaks in late-successional forests of the Rhine valley (for example, up to 50 woody species in Querco-Ulmetum). Sixty per cent of the forest-communities are comon to the two floodplains, which explains why 85% of the families, 65% of the genera and 55% of the species are in common. Compared to the Loire valley, the Rhine valleys shows higher biotic diversity. This was related first to its geographical situation, and second to higher landscape heterogeneity. Human disturbance through river management is responsible for changes in species composition as shown by floristic comparison of flooded and unflooded sites. Insularity of natural forests among man-made landscapes is involved in species diversity. In order to preserve the natural diversity of such rich landscapes, floodable areas should be recreated and the attitudes of foresters should evolve accordingly.     

Crossing the Rhine: a potential barrier to wildcat (<Emphasis Type="Italic">Felis silvestris silvestris</Emphasis>) movement?

The European wildcat (Felis silvestris silvestris) underwent a severe decline across Europe in the early twentieth century. Remaining populations are often very small and isolated, though there are indications that wildcat populations are currently expanding their range. However, linear landscape elements such as rivers and roads are thought to present barriers to dispersal, inhibiting gene flow and, thus, affecting the recolonization process. In this study, we investigated the fine-scale genetic structure of wildcats in the Upper Rhine Valley. We specifically analysed wildcats on both sides of the Rhine River by genotyping 55 individual wildcats, using 20 microsatellite loci. Genetic differentiation was weak and positive spatial autocorrelation was found up to a distance of 10 km (females: 5 km, males: 10 km) indicating substantial gene flow among sampling sites. High levels of gene flow, even across the Rhine River, indicated that the water body itself does not necessarily have a strong barrier effect, which is in contrast to other studies. Our findings could best be explained by the populations’ history, a local extinction east of the River Rhine and a current ongoing population expansion. Our study highlights that potential barriers, such as rivers, may have different effects in different local wildcat populations and that the history of the populations is important to interpret genetic results. As many wildcats still occur in isolated and patchy forest fragments, maintaining connectivity between populations is crucial to ensure their viability in the long term.     

Ecological classification of the climate of the Rhine catchment

An ordination and classification it carried out on the climate of the Rhine catchment based on data from meteorological stations. The objective of the classification is to provide an ecological interpretation of climate data. The climate of northern France, Belgium, Luxemburg, the Netherlands, the Federal Republic of Germany and northern Switzerland is divided into five classes, of which two, the Atlantic and the subcontinental are subdivided further into subclasses. The climate classes can be interpreted ecologically and are correlated with floristic and vegetation data. The Rhine valley has a distinctive and characteristic climate. Interpolation of the classification is not carried out, because of the uneven geographical spread of the sites in the dataset.     

Infektionsgefahr aus dem Süden. Globale Erwärmung

The import of infectious diseases from the Mediterranean region is a possible effect of global warming. At the moment, vector‐borne diseases represent the most important threat. These include tick‐borne Mediterranean spotted fever as well as visceral Leishmaniasis and Pappataci‐fever, which are transmitted by sand flies. Dogs act as main reservoir hosts for the first two diseases; therefore, these pathogens are constantly imported to Germany with unregulated dog transports. In the same way, the vector of Mediterranean spotted fever, the “Brown dog tick”, is imported and may establish in the future. Sandflies, in contrast, are already endemic in the Rhine valley, the warmest region of Germany. Autochthonous cases of Leishmaniasis and Pappataci‐fever indicate that these diseases are already present in Germany.     

Studies on Annalepis from Middle Triassic Along the Yangtze River and Its Bearing on the Origin of Iso?tes

Specimens of Annalepis have been found from the Middle Triassic Series in the Yangtze River valley and described, including a new species. Annalepis is similar to the living plant, Isoëtes , in many aspects, such as the herb with a corm, more or less clustering sporophylls, presence of a ligule, monolete suture microspores of Aratrisporites -type and trilete megaspores, etc. The similarities of features between the two plants indicate their close affmities and that A. brevicystis might be the ancestry of Isoëtes . Since there is a ligule on the sporophyll of Pleuromeia, the Pleuromeiaceae represented by Pleuromeia could be allied to the Isoëtaceae, and both families should belong to Isoëtales. Isëtales represents a distinct evolutionary sequence and is inferred as being evolved probably from Palaeozoic SigiUaria . In Mesozoic age, two evolutionary lines are proposed: one as a line from Pleuromeia to Nathorstiana in relation to wood-monopolar rhizophore; the other as a line from Annalenis to lsoOtes related to herb-bipolar corm. Annalepis appeared almost simultaneously in the Yangtze River valley in early Middle Triassic, but the distribution of Annalepis was concentrated from east to west during middle-late Middle Triassic, in relation to the marine regression which occurred cyclically from east to west on the Yangtze Platform during that time.     

Nitrate elimination by denitrification in hardwood forest soils of the Upper Rhine floodplain – correlation with redox potential and organic matter

Denitrification in floodplains is a major issue for river- and groundwater quality. In the Upper Rhine valley, floodplain forests are about to be restored to serve as flood retention areas (polders). Besides flood attenuation in downstream areas, improvement of water quality became recently a major goal for polder construction. Redox potential monitoring was suggested as a means to support assessment of nitrogen elimination in future floodplains by denitrification during controlled flooding. To elucidate the relationship between redox potential and denitrification, experiments with floodplain soils and in situ measurements were done. Floodplain soil of two depth profiles from a hardwood forest of the Upper Rhine valley was incubated anaerobically with continuous nitrate supply. Reduction of nitrate was followed and compared with redox potential and organic matter content. The redox potential under denitrifying conditions ranged from 10 to 300 mV. Redox potential values decreased with increasing nitrate reduction rates and increasing organic matter content. Furthermore, a narrow correlation between organic matter and nitrate reduction was observed. Experiments were intended to help interpreting redox potentials generated under in situ conditions as exemplified by in situ observations for the year 1999. Results obtained by experiments and in situ observations showed that monitoring of redox potential could support management of the flooding regime to optimize nitrogen retention by denitrification in future flood retention areas.     

River dynamics as a forest process: Interaction between fluvial systems and alluvial forests in large European river plains

This paper corresponds to an overview of the impacts of the inundations on gallery forest processes, with examples of the upper Rhine valley, France. The geomorphic pattern of big river plains, the particularities of the nutrient cycle, the adaptations of the flora, the specificities of the sylvigenetic cycles are detailed, with examples of the upper Rhine valley.

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Résumé  Cet article se propose de passer en revue les impacts majeurs des rivières sur les forêts riveraines, en s’appuyant sur les écosystèmes alluviaux de la vallée du Rhin, en France. Les adaptations de la flore et les spécificités des cycles sylvigénétiques sont mis en relation avec les particularités géomorphologiques et celles des cycles biogéochimiques particuliers au milieu alluvial tempéré.

     

Genetic drift and gene flow in a prehistoric population of the Azapa valley and coast,Chile

The present paper studies the evolutionary process operating on prehistoric groups from the Azapa valley and coast (northern Chile). The sample consists of 237 crania from the Archaic Late, Early Intermediate, Middle, Late Intermediate, and Late periods. Six metric variables were used, which were transformed to eliminate the special environmental component and to increase the proportion of genetic variance. Population structure was assessed using a method based on quantitative genetic theory, which predicts a lineal relationship between average within-group phenotypic variance and group distance to the population centroid. Results indicate that 17.5% of the total variance accounts for special environmental variance. An excess in extraregional genetic flow is observed in the population corresponding to the Early Intermediate period in the valley. A reduced differentiation is observed between Archaic and Early Intermediate coastal groups, as well as between the latter and the inhabitants of the valley in the same period. Genetic differences between both areas increased substantially since the Middle period. Evidence indicates that long-range gene flow was lower on the coast than in the valley, the lowest estimated Fst being 0.0199 for the total population (coast and valley), 0.0111 for the coastal population, and 0.0057 for the valley. Results are discussed in terms of regional archeological and ethnohistorical evidence, and a microevolutionary model is presented to account for the biological history of the population.     

Nine polymorphic microsatellite loci for the parasitic wasp Neotypus melanocephalus (Hymenoptera: Ichneumonidae)

Nine polymorphic microsatellite loci were isolated from Neotypus melanocephalus (Gmelin), a parasitoid of the parasitic large blue butterfly Maculinea nausithous. Allelic diversity and heterozygosity were quantified in samples from the Upper Rhine valley in Southwest Germany.     

La stratigraphie et le Paléolithique du complexe saalien dans la région de la Saale et de l’Elbe

Some sediment sequences were known in the Elbe-Saale region. They enable a subdivision of the Saale complex, that is from Neumark Nord (Geisel valley), from Weimar-Ehringsdorf and Bad Kösen-Lengefeld (Saale valley). According to it, there are two interglacials between the Saalian groundmoraine (s.str.) and the Eemian. They are characterized by a strong subcontinental climatic influence, which could not be observed in the other interglacials of the Elbe-Saale region. The interglacials are connected with find horizons from the Middle Palaeolithic. They are concisely described here with their inventories.     

A late Burdigalian gobiid fish,<Emphasis Type="Italic">Gobius brevis</Emphasis> (<Emphasis Type="SmallCaps">Agassiz</Emphasis>, 1839), in the Upper Hydrobia Beds in the middle Upper Rhine Graben (W-Germany)

Gobius brevis (Agassiz, 1839) was hitherto exclusively based on articulated skeletons. It first appears in the late Early Miocene (late Burdigalian, Karpatian) and is widespread throughout the Middle Miocene. Its previously known zoogeographical distribution was the western Paratethys and the Styrian Basin in Austria. We here report on articulated skeletons ofG. brevis with otoliths in situ from a temporary outcrop at Edenkoben, located in the middle Upper Rhine Graben, Germany. The strata are assigned to the basal part of the Upper Hydrobia Beds. The otoliths in situ are identical with those ofGobius latiformis Reichenbacher, 1992, which is an otolith-based species occurring in the Karpatian and Middle Miocene of the western Paratethys; henceG. latiformis has to be regarded as a younger synonym ofG. brevis (Agassiz, 1839). The skeletons ofG. brevis from Edenkoben differ from other articulated freshwater or brackish water MioceneGobius species in the number of vertebrae, more elongate body shape, and number of fin rays. Also the otoliths ofG. brevis differ in their overall shape from these species. However, the in situ preserved otoliths ofG. brevis in the Edenkoben locality show a more primitive evolutionary stage than the Middle Miocene otoliths ofG. brevis (formerly described asG. latiformis). Thus, the gobiid fishes from Edenkoben belong to the oldest representatives ofG. brevis and must be late Burdigalian in age.Gobius brevis probably migrated into the middle Upper Rhine Graben from the Paratethys area.      

The impact of flooding regime on the soil seed bank of flood‐meadows

Abstract. We assessed the significance of flooding for the floristic composition of seed banks in flood‐meadows of the northern valley of the Upper Rhine. We compared three hydrological compartments of the alluvial plain, consisting of the regularly flooded land between the river and low summer dykes (functional flood‐plain), the occasionally flooded land between summer dykes and high winter dykes (hybrid floodplain) and the land behind the winter dykes, which is now only submerged by ascending groundwater (fossil flood‐plain). Due to their different flooding regime, the three compartments should differ with respect to the prevailing conditions of diaspore input. The seed density of soil samples increased with the duration of flooding in the three compartments, while species richness and the proportion of species not occurring in the vegetation was constant. The increase in seed density can be largely attributed to an increase of disturbance indicators, which are present in the above‐ground vegetation and capable of forming a long‐term persistent seed bank. No effects of flooding on the composition of seed banks in the three flood‐plain compartments were found. The differences in seed bank composition can be largely explained by corresponding differences in above‐ground vegetation and former and present‐day meadow management. Seeds of species absent from above‐ground vegetation can be attributed to the local species pool present in the immediate vicinity of the study plots. We discuss consequences of the results for the restoration of species‐rich flood‐plain meadows.     

Variation in vernal species composition in alluvial forests of the Rhine valley,eastern France

Patterns of vernal synusiae in alluvial forests of the upper Rhine valley were analysed phytosociologically. Five synusial types were described. Environmental factors included in the analysis were spring water level, texture, trophic status and soil reaction. A separate environmental study was undertaken in pure stands of six competitive geophytes in the most fertile habitats. In a laboratory experiment effects of water stress and interspecific competition were studied for three competitive geophytes. The vernal species can be grouped into eight groups with respect to species position along the environmental gradients occurring in the floodplain. These groups can be used for bioindication.     

Mobility of iron in the estuaries of the Rhine and the Ems relevant to plant-availability problems

Studies were undertaken to obtain information on the iron mobilization processes in the sediments of the rivers Rhine and Ems, both located in western Europe. On their way from the fresh-water tidal area to the marine environment these sediments loose a considerable amount of their iron. The iron is released from the sediment by means of biodegradation products of the organic matter which dissolve the iron as organic iron complexes. The major functional groups of these organic compounds responsible for the iron mobilization are carboxyls and phenolic hydroxyls. From the sediments of the river Ems greater amounts of organic iron compounds are dissolved than from sediments of the river Rhine. Also fewer organic compounds are released from marine sediments than from fresh-water sediments, which indicates a diminished iron mobility in the marine area of the delta. Besides this the organic compounds from the marine sediments show an impoverishment in their functional groups. The sediments of the rivers Rhine and Ems are also distinguished by a different occupation of functional groups in the organic compounds. On account of a number of experiments the mobilization capacity of these river systems have been discussed.From a viewpoint of plant nutrition the mobility of iron in deposits of different ripening stages was also investigated.     

Genetic analysis of potential postglacial watershed crossings in Central Europe by the bullhead (Cottus gobio L.)

Natural colonizations across watersheds have been frequently proposed to explain the present distributions of many freshwater fish species. However, detailed studies of such potential watershed crossings are still missing. Here, we investigated potential postglacial watershed crossings of the widely distributed European bullhead (Cottus gobio L.) in two different areas along the Rhine–Rhône watershed using detailed genetic analysis. The main advantage of studying bullheads vs. other freshwater fish species is that their distribution has been lightly influenced by human activities and as such, interpretations of colonization history are not confounded by artificial transplantations. The genetic analyses of eight microsatellite loci revealed strong genetic similarities between populations of both sides of the Rhine–Rhône watershed in the Lake Geneva area, giving strong evidence for a natural watershed crossing of bullheads from the upper Rhine drainage into the Rhône drainage in the Lake Geneva area likely facilitated by the retreat of the glaciers after the last glacial maximum some 20 000 years ago. Populations from the Lake Geneva basin were genetically more similar to populations from across the watershed in the upper Rhine drainage than to populations further downstream in the lower Rhône. In contrast, populations from Belfort, an area, which was not covered by ice during the last glacial maximum, showed strong genetic differentiation between populations of the upper Rhine and Rhône drainages. Based on our results on the bullhead, we propose that glacial retreat may have eased the dispersal of numerous European freshwater fish species across several geological boundaries.