Spessart Mountains Research Articles

Changes of vegetation in coniferous monocultures in the context of conversion to mixed forests in 30 years – Implications for biodiversity restoration

The understorey vegetation of temperate forests harbours a major proportion of terrestrial biodiversity and fulfills an important role in ecosystem functioning. Over the past decades, temperate forest understoreys were found to change in species diversity and composition due to several anthropogenic and natural drivers. Currently, the conversion and restoration of even-aged coniferous monocultures into more diverse and mixed broad-leaved forests are major objectives of sustainable forest management in Central Europe. This forest conversion alters understorey communities and abiotic site conditions but the underlying patterns and processes are not yet fully understood. Therefore, we investigated changes in the Bavarian Spessart mountains in southwest Germany, where we re-sampled 108 semi-permanent plots from four different coniferous stand types (i.e., Norway spruce, Scots pine, Douglas fir, European larch) about 30 years after the initial assessment. On these plots, we recorded understorey vegetation and forest structure, and derived abiotic site conditions based on ecological indicator values of understorey vegetation, followed by multivariate analysis. We found changes in plant communities that point towards a decrease of soil acidity and a “thermophilization” of forest understoreys. Understorey species richness remained constant, while understorey's Shannon and Simpson diversity increased. The observed changes in forest structure explained the temporal shifts in understorey species composition. The understorey species composition did not experience a significant floristic homogenization since the 1990s. However, plant communities exhibited a reduction in species characteristic of coniferous forests and a simultaneous increase in species associated with broad-leaved forests. The increase of specialist species (closed forests and open sites) may have compensated for the detected decrease in generalist species. We conclude that the forest conversion towards mixed broad-leaved forest in the Spessart mountains of the past decades might have masked homogenization trends that are increasingly reported from Central European forest understoreys.

Is Douglas Fir [Pseudotsuga menziesii (Mirbel) Franco] Invasive in Central Europe? A Case Study From South-West Germany

Worldwide, forestry must face several challenges during the UN Decade on Ecosystem Restoration. The decline of biodiversity and ecosystem services, ongoing deforestation, climate change, and biological invasions must be mitigated with forest restoration and by applying sustainable forest management. Experiences with the integration of non-native tree species into forest management in many parts of the world show benefits but also trade-offs regarding sustainability. In Central Europe, Douglas fir [Pseudotsuga menziesii (Mirbel) Franco], originating from Northern America, has been introduced by forestry and managed for more than one and a half centuries. Growth characteristics, drought tolerance, and timber quality are major reasons which make this tree species attractive for forestry and wood industry. Whether Douglas fir might be invasive with potential trade-offs regarding biodiversity, uncontrolled regeneration, and spread is not yet fully understood and controversially debated. We investigated the regeneration of Douglas fir in the Spessart mountains, a vast woodland in south-western Germany which has a considerable cover of anthropogenic coniferous afforestations. We sampled the regeneration of Douglas fir by differentiating height growth classes in various forest-stand types, taking the distance from mature mother trees, abiotic site conditions (e.g., water balance and soil properties), light supply, forest-stand characteristics, ground vegetation, and browsing pressure into account. Also integrating the individual regeneration of the accompanying tree species, we applied multivariate analyses. Most of our investigated variables did not show a significant correlation with Douglas fir regeneration. However, results point to a positive relationship of spontaneous Douglas fir regeneration at moist and light sites as well as in close distance to potential seed trees. The analysis of the current invasion potential did not reveal a major risk under the given site conditions in the study area.

Regionalized dynamic climate series for ecological climate impact research in modern controlled environment facilities.

Modern controlled environment facilities (CEFs) enable the simulation of dynamic microclimates in controlled ecological experiments through their technical ability to precisely control multiple environmental parameters. However, few CEF studies exploit the technical possibilities of their facilities, as climate change treatments are frequently applied by static manipulation of an inadequate number of climate change drivers, ignoring intra‐annual variability and covariation of multiple meteorological variables. We present a method for generating regionalized climate series in high temporal resolution that was developed to force the TUMmesa Model EcoSystem Analyzer with dynamic climate simulations. The climate series represent annual cycles for a reference period (1987–2016) and the climate change scenarios RCP2.6 and RCP8.5 (2071–2100) regionalized for a climate station situated in a forested region of the German Spessart mountains. Based on the EURO‐CORDEX and ReKliEs‐DE model ensembles, typical annual courses of daily resolved climatologies for the reference period and the RCP scenarios were calculated from multimodel means of temperature (ta), relative humidity (rh), global radiation (Rg), air pressure (P), and ground‐level ozone and complemented by CO2. To account for intra‐annual variation and the covariability of multiple climate variables, daily values were substituted by hourly resolved data resampled from the historical record. The resulting present climate Test Reference Year (TRY) well represented a possible annual cycle within the reference period, and expected shifts in future mean values (e.g., higher ta) were reproduced within the RCP TRYs. The TRYs were executed in eight climate chambers of the TUMmesa facility and—accounting for the technical boundaries of the facility—reproduced with high precision. Especially, as an alternative to CEF simulations that reproduce mere day/night cycles and static manipulations of climate change drivers, the method presented here proved well suited for simulating regionalized and highly dynamic annual cycles for ecological CEF studies.

<p class="HeadingRunIn"><strong>Gene expression profiling in the aquatic caddisfly larvae <em>Micropterna lateralis</em> (Insecta: Trichoptera) in relation to stream drying</strong></p>

Aquatic ecosystems can be either permanently wet or be subject to seasonal or intermittent drying. Insect species inhabiting temporally dry streams have evolved behavioural, morphological and/or life history traits to ensure their persistence. The limnephilid caddisfly Micropterna lateralis (Stephens 1837) has a life cycle that is tailored to the temporal dynamics of periodically dry streams where adults usually hatch before drought commences. Their aquatic larvae are, however, also able to survive stream drying, but the mechanisms driving this survival ability have not been studied to date. We conducted an experiment to simulate drying conditions, using samples from a M. laterialis population taken from an intermittent stream in the Spessart Mountains of the central German highlands. The experiment simulated three hydrological conditions: wet, moist and dry. In a first test of our system we compared gene expression profiles of three individuals (one per condition) using Illumina-based Massive Analysis of cDNA Ends MACE-Seq. Our first results show large differences in gene expression between the studied phases with many genes exhibiting gradual up- or down-regulation across the three experimental hydrological conditions. Under drought stress, up-regulation was primarily found in genes controlling production and mobilization of desiccation protectants, mainly sugars, whereas down-regulated genes were related to cuticle organisation and lipid metabolism. These preliminary results give valuable insights into genetic and physiological responses of aquatic insects to stream drying.

Okruschite, Ca2Mn2+

The new mineral okruschite (IMA No. 2013–047), the arsenate analogue of roscherite, was discovered in a hydrothermal vein cross-cutting rhyolite exposed in the Fuchs quarry, near Sailauf, Spessart Mountains, Bavaria, Germany. Associated minerals are braunite, Mn-bearing calcite and arseniosiderite. Okruschite forms tabular aggregates up to 0.15 × 0.3 × 0.3 mm in size of curved and somewhat misaligned laths. It is white, semitransparent; lustre is vitreous. D meas = 3.33(2), D calc = 3.340 g/cm 3 . Okruschite is optically biaxial (−), α = 1.671(3), β = 1.682(2), γ = 1.687(3), 2 V meas = 65(5)°. The infrared spectrum is given. The chemical composition is (electron microprobe, B and Li by ICP MS, H 2 O by gas chromatography of ignition products, wt. %): Li 2 O 0.04, BeO 7.70, MgO 1.68, CaO 8.28, MnO 16.27, FeO 4.89, Al 2 O 3 0.22, As 2 O 5 51.11, H 2 O 11.0, total 101.19. The empirical formula based on 34 O atoms is: Ca 1.99 (Mn 3.09 Fe 0.92 Mg 0.56 Al 0.06 Li 0.04 ) ∑4.67 Be 4.15 (AsO 4 ) 5.99 (OH) 3.64 · 6.40H 2 O. The simplified formula is Ca 2 Mn 2+ 5 Be 4 (AsO 4 ) 6 (OH) 4 · 6H 2 O. Okruschite is monoclinic, C 2/ c , a = 16.33(4), b = 12.03(3), c = 6.93(1) A, β = 94.84(5)°, V = 1357(4) A 3 , Z = 2. The strongest lines of the powder X-ray diffraction pattern [ d , A ( I , %) ( hkl )] are: 9.68 (39) (110), 4.95 (34) (310), 4.17 (34) (−311), 3.25 (100) (−202, 330), 3.11 (32) (−421), 2.841 (27) (240), 2.711 (26) (600), 1.726 (26) (461, −552, 004). Okruschite is named after Professor Martin Okrusch, from Germany. Type material is deposited in the collections of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.

Formation and transformation of Pleistocene periglacial slope deposits in the Spessart Mountains (Hesse, Germany)

The bedrock of the Spessart Mountains is covered by Pleistocene periglacial slope deposits (PPS- Ds). These slope deposits are supposed to have formed in a periglacial environment by a variety of processes. For this study soil profiles in the Spessart Mountains were analyzed with respect to features elucidating processes forming and transforming PPSDs. Field and laboratory analyses were complemented by micro- morphological investigations to gain more detailed information. The results verify aeolian sedimentation, solifluction and cryoturbation as most important formation processes. Furthermore, several findings sug- gest the influence of additional genetically active processes. PPSDs provide the parent material for Holocene soil formation. In addition, they experience alteration by bioturbation and anthropogenic influence on relief and soil. Pedogenic transformation is dependent on the PPSDs material composition. Particularly the content of silt-sized allochthonous material controls the efficacy of silicate weathering and depth of soil development. The coincidence of pedogenic boundaries and layers often reported in the literature is partly falsified: Eluviation and illuviation of clay is not separated at the boundary between upper and intermediate layer. PPSDs experience strong alteration by bioturbation: This process may transform characteristics that could point to formation processes. Furthermore, thin sec- tion analyses support the distinction of Holocene colluvium and PPSDs.

The processes and timing of sediment delivery from headwaters to the trunk stream of a Central European mountain gully catchment

Gully systems determine downstream water quality and sediment loads since they are located where streams begin. They are often only considered as a sediment source, and the degree to which gully systems also store sediment, and the timescales of this storage, have received less attention. Gully sediment storage is important because many sedimentary archives, such as floodplains and lakes, have recorded increases in sedimentation rates particularly in Medieval times, which are interpreted as the result of increased slope erosion and gully activity. At present there is insufficient evidence directly linking such other sedimentary archives and gully systems. There is also a lack of long term records which may indicate how the major external controls, climatic or anthropogenic, might determine gully responses. To address this, we analysed sediment sources and sinks within a small (43ha) gully catchment in the Spessart Mountains, Germany. We found five main phases of erosion and deposition since ~13ka, which revealed catchment vegetation significantly controlled geomorphic responses. A loss of vegetation due to climate deterioration (e.g. Younger Dryas) or deforestation (e.g. Medieval period) caused widespread slope instability and the aggradation of the gully thalweg. In contrast, well forested conditions before the Medieval period, and again in recent years, re-stabilised the slopes, leading to gully incision with knickpoint retreat. This result differs from previous interpretations of gully activity in Central Europe that gully erosion mostly occurred in Medieval times. Our results also demonstrate that only the initial phase of knickpoint retreat is significant for supplying sediment to the gully fan and trunk stream. Then knickpoint retreat leads to a relative increase in the thalweg storage capacity downstream, which limits further sediment export. This has important implications for the interpretation of floodplain ages, since the initial supply of gully sediment to trunk streams may not coincide with human impact. Instead, there will be a lagged response between catchment reforestation and the onset of gully incision, which in this study is up to ~150years. Therefore, the assumption of a direct causal link between increases in floodplain sedimentation and slope erosion may not always be valid.

Sailaufite, (Ca, Na,)2 Mn3O2(AsO4) (CO3)3H2O, a new mineral from Hartkoppe hill, Ober-Sailauf (Spessart mountains, Germany), and its relationship to mitridatite-group minerals and pararobertsite

Sailaufite, a new mineral with idealized composition CaNaMn 3+ 3 O 2 (AsO 4 ) 2 (CO 3 ).3H 2 O, has been found at the locality Hartkoppe hill near Ober-Sailauf (Spessart mountains, Germany), associated with hausmannite, arseniosiderite, kutnahorite, dolomite, quartz, calcite, and Mn-calcite. It occurs as strongly intergrown, dark red-brown to black tabular crystals, often forming mammillated coatings on calcite and arseniosiderite. Mohs9 hardness is ∼3.5, the cleavage is perfect parallel (001), the tenacity is brittle with an uneven to conchoidal fracture. Crystals are optically biaxial negative, at 616 nm n α = 1.757(5), δ β,γ = 0.004(1), 2V = 32(3)°, nβ(calc) = 1.806, nγ(calc) = 1.810. The strongest lines in the X-ray powder diffraction pattern are (d obs , I, hkl): 8.807, 100, 001; 5.654, 27, 130; 5.544, 17, 200; 2.936; 75, 003; 2.885, 19, 331; 2.816, 20, 332; 2.772, 36, 400; 2.514, 20, 133; 2.202, 55, 004. UV-VIS-IR spectroscopic measurements confirm the presence of AsO 4 and CO 3 groups as well as the absence of transition metal ions other than Mn 3+ in sailaufite. The crystal structure of a small untwinned crystal fragment could be solved by direct methods from X-ray CCD data [monoclinic, space group Cm , a = 11.253(1), b = 19.628(1), c = 8.932(1) A, β = 100.05(1)°, Z = 6] and was refined on 8650 F 2 o to w R2 = 0.079 and R1 = 0.045. The structure contains characteristic nonamer rings of edge-sharing Mn 3+ O 6 octahedra forming compact pseudotrigonal [Mn 3+ 9 O 6 (AsO 4 ) 6 (CO 3 ) 3 ] 9− sheets which are linked by layers composed of (Ca,Na,□)O 5 (H 2 O) 2 polyhedra and isolated water molecules. The octahedral nonamer rings correspond to those occuring in the Fe 3+ -phosphate mitridatite and bear strong similarities to the arrangement of Z-shaped octahedral chains in the Mn 3+ -phosphate pararobertsite.

Mineralogy of complex Co-Ni-Bi vein mineralization, Bieber deposit, Spessart, Germany

AbstractPost-Variscan vein-type Co-Ni-Bi ores of the Bieber deposit, Spessart mountains, Germany, which are related to the Permian Kupferschiefer, have been investigated by ore microscopy, X-ray powder diffraction and electron-probe microanalysis. The samples contain a variety of ore minerals, notably skutterudite, native bismuth, cobaltite, alloclasite, niccolite, maucherite, gersdorffite, rammelsbergite/pararammelsbergite, safflorite, loellingite and emplectite. The ores display structures indicative of multiple brecciation and complex zoned arsenide assemblages. Three sequential stages of deposition are identified, which are (1) the Cu stage, (2) the main Co-Ni-Bi stage, and (3) the late stage. The arsenide minerals, notably skutterudite, diarsenides and sulpharsenides, show a large range of compositional variation in Co-Ni-Fe space. A relatively limited number of skutterudite and diarsenide compositions lie outside the compositional fields established in the literature. Skutterudite and diarsenides are characterized by a significant substitution of As by S up to 0.44 a.p.f.u. and 0.31 a.p.f.u., respectively, which is larger than the range previously reported for these minerals. Sulpharsenide compositions can be grouped into three populations, which conform to cobaltian arsenopyrite, cobaltite and gersdorffite. They display highly variable As/S ratios between 0.95:1.00 and 1.29:0.73, consistent with experimental data. Estimates of the formation temperatures, based on the presence of dendritic native bismuth and emplectite, are in the range 100–300°C, similar to different post-Variscan mineralization styles widespread in Central Europe. Comparison of the Co-Ni-Bi vein assemblage with the framework of available paragenetic information and radiometric age data for regional mineralization events indicates an age of mineralization of ~150–160 Ma for the Bieber deposit.

Food selection by beavers (Castor fiber albicus) in relation to plant chemicals and possible effects of flooding on food quality

AbstractThe goal of this study was to investigate whether or not beavers Castor fiber albicus improve the quality of their food plants by dam construction, resulting in periodic flooding associated with the deposition of mud and nutrients on their feeding grounds. For this, food selection of beavers was studied in relation to plant chemicals in the Spessart mountains (central Germany). The concentrations of the preferred plant chemicals were compared between individuals of the same plant species growing in areas that were flooded periodically and areas that were edaphically dry. Plants eaten by beavers contained higher concentrations of nitrogen and lower concentrations of neutral detergent fibre and hemicellulose than neighbouring plants that were not eaten. Neither nitrogen concentrations nor neutral detergent fibre contents differed significantly between plants from the dry and wet sites. Thus, beaver activities did not improve the chemical quality of their food plants.

Einflüsse der Stauaktivität des Bibers ( Castor fiber albicus) auf physikalische und chemische Parameter von Mittelgebirgs-Bächen (Hessen, Deutschland)

For a valuation of the influence of beavers on a riparian ecosystem a restriction on the constructed beaver ponds is not sufficient. In addition, the whole homerange in its total length must be taken into consideration. In 1995 the geomorphological effects and the chemical and physical alterations during the passing through two beaver homeranges were studied in the Spessart mountains (Hesse, Germany). Inside of the homeranges, the beavers transformed the running waters into series of small beaver pools and ponds. Parallel to the sectors, where riffles got disappeared because of the damming up, secondary brooks developed, which created various wetlands in the riparian ecosystem. Because of the enlargement of the water surface and the distribution of the brook water on adjacent areas, the water-freight of a brook can decrease under certain weather conditions. Thereby beavers can contribute to a higher retention of precipitation and to a diminuation of flood-disasters. The alterations of the measured parameters were bounded mostly on the pond and regenerated quickly below. In comparison of the water conditions entering and leaving the homerange, there was a meagre increase of temperature, pH, oxygen- and NO 2-concentration measured. The concentration of nitrate, NH 4 and o-phosphate decreased, the conductivity kept constant. Extensive effects on the water quality below the homeranges were not proven.

Der Einfluß des Bibers ( Castor fiber albicus) auf die Fauna (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) von Mittelgebirgsbächen in Hessen (Deutschland)

Due to the return of the beaver an increasing number of brooks become restored to a natural condition. It is characterized by an alternation of flowing and standing sectors. In the summer of 1995, different groups of organisms (Odonata, Mollusca, Trichoptera, Ephemeroptera, Diptera) of two brooks in the Spessart mountains (Hesse, Germany) were studied to compare the composition of invertebrates in beaver homeranges and in the non-influenced sectors above. The new living conditions resulted in the disappearance of some species ( Drusus anulatus, Trich., Sericostoma personatum, Trich., Radix peregra, Gastr.). Nevertheless the beaver homeranges accommodate a significant higher number of species of dragon flies and damsel flies, molluscs and caddis flies than the brooks above the homeranges. The heterogeneity of natural river systems make a coexistence of running water and silent water organisms possible. The examinations result in a significant higher group dominance of ephemeras (i.p. Cloeon dipterum) in a beaver pond than in lenitic sectors conditioned by the gradient without beaver influence. Here the dominance of chironomids was much higher. High current sectors with their characteristic organisms are also present in the beaver homeranges. The higher number of insects is the basis of nourishment for predatory insects and fishes. The potential effects of beaver ponds on fishes are discussed.

Studies on algal drift in a small soft-water stream in the Spessart mountains, Germany

Studies on algal drift in a small soft-water stream in the Spessart mountains, Germany

Stomatal uptake of SO2 , NOx and O3 by spruce crowns (Picea abies) and canopy damage in Central Europe.

The stomatal uptake of SO2 , NO2 and O3 by Norway spruce canopies (Picea abies (L.) Karst.) has been integrated at six sites in central Germany (Königstein in the Taunus mountains. Witzenhausen, Grebenau, Frankenberg, Fürth in the Odenwald mountains and Biebergemünd in the Spessart mountains), Results are based on 788000 half-hourly available sets of field data on air pollution and site meteorology measured since 1984 (45 site years). Data on stomatal water conductance are available from statistical response functions obtained in the field at all times of day and seasons of the year. From this, stomatal conductance was calculated fur different atmospheric tract gases. Statistical response functions are presented which allow the separate estimation of annual stomatal net uptake of trace gases in the field if only (i) measured annual means of SO2 , NO2 , and O3 , pollution and (ii) the length of the trunk growth period (defined by temperature) are known. The following specific annual doses of stomatal trace-gas net uptake in the field (μmol m-2 total needle surface d-1 annual trunk growth period/(nPa Pa-1 ) annual mean of trace gas concentration) are obtained; SO2 : (0.157 ± 0.011) μmol m-2 d-1 /(nPa SO2 , Pa-1 ), NOx : (0.4774 ± 0.034) μmol m-2 d-1 /(nPa NO2 Pa-1 ), O3 : (0.474 ± 0.034) μmol m-2 d-1 /(nPa O3 Pa-1 ). There is an apparent NO2 , compensation point at 7 nPa Pa-1 in the field if NOx (=NO2 , + NO) fluxes are integrated; the individual NO2 , compensation point equals c 3.2 nPa Pa-1 . Additionally, a statistical response function is presented, which estimates actual stomatal water transpiration rates in the field on the basis of measured water vapour pressure differences. VPD (mPa Pa-1 ). Complex canopy effects were calculated on the basis of available data using an effective leaf area which is 0×32 times the morphological leaf area index. Results are consistent (i) with available water balance data, (ii) with observed SO2 -dependent sulphate accumulation rates in spruce needles and (iii) with observed epicuticular SO2 , deposition rates. Pollution data are compared with observed damage of spruce canopies in the field. There was a statistically significant correlation between observed damage to spruce canopies.

Studies on the macroalgal vegetation of a small soft-water stream in the Spessart mountains, Germany, with reference to algal distribution and seasonality

Studies on the macroalgal vegetation of a small soft-water stream in the Spessart mountains, Germany, with reference to algal distribution and seasonality

Light requirements for photosynthesis and growth in several macroalgae from a small soft-water stream in the Spessart Mountains, Germany

Abstract Fluence rate-response curves (P vs I curves) were measured in several species of stream macroalgae from laboratory culture and from a small soft-water stream. Photosynthesis of laboratory-grown algae was light saturated at 24 μmol photons m−2 s−1 of white light in Klebsormidium rivulare (Kutzing) Morison et Sheath, at 25.51 μmol m−2 s−1 in Batrachospermum helminthosum Bory emend. Sheath et al., at 35 μmol m−2 s−1 in Balbiania investiens (Lenormand) Sirodot (cultivated at 4 μmol m−2 s−1), at 42 μmol m−2 s−1 in Microspora quadrata Hazen, at 60 μmol m−2 s −1 in Vaucheria bursata (O.F. Muller) C. Agardh (= V. sessilis De Candolle), Stigeoclonium tenue (C. Agardh) Kutzing, Audouinella hermannii (Roth) Duby in De Candolle, Balbiania investiens (cultivated at 40 μmol m −2 s−1) and at 67 μmol m−2 s−1 in Cladophora glomerata (Linnaeus) Kutzing. Photosynthesis of algae taken from the Bieber stream was light saturated at significantly higher photon irradiances of 115 μmol m−2 s−1 in Batrachospermum helminth...

Complete texture analysis of a deformed amphibolite: comparison between neutron diffraction and U-stage data

This paper describes a new technique of analysing complex neutron diffraction patterns, allowing the quantitative texture analysis of each rock-forming mineral up to trielinic lattice symmetry in polymineralic rocks. The method is demonstrated using hornblende and plagioclase fabrics in Alzenau amphibolite from the Spessart Mountains (Mid-German Crystalline Rise). Hornblende and plagioclase exhibit a pronounced shape preferred orientation with respect to the macroscopic fabric elements. For control purposes, crystallographic preferred orientations were also determined independently by individual grain measurements using a U-stage. From the neutron texture analyses we obtain only superposed pole figures (hornblende and hornblende, hornblende and plagioclase, and plagioclase with plagioclase) of low-indexed lattice planes. Therefore, the critical crystallographic directions were recalculated by the orientation distribution function (ODF) which is given by texture components. The optical and neutron-derived pole figures are in a good agreement. All pole figures display strong preferred orientation, although the plagioclase texture is less pronounced. The hornblende texture consists of a [001] maximum parallel to the stretching lineation, with [010] showing a tendency to develop a girdle around the lineation. [100]-axes are distributed with a clearly split maximum representing the monoclinic angle between [100] and [001]. The plagioclase texture is a rare one with (001) subparallel within the foliation and [100] oriented subparallel to the lineation. [010] of plagioclase is concentrated normal to lineation within the foliation.The technique outlined here is potentially the most useful one for texture analysis of polyphase rocks, independent of crystal symmetry.

Fundstellen mittelpleistozäner Tephralagen im Randbereich des Kristallinen Vorspessarts. Ein Beitrag zur Schwermineralogie und Stratigraphie quartärer Tephren

Fundstellen mittelpleistozäner Tephralagen im Randbereich des Kristallinen Vorspessarts. Ein Beitrag zur Schwermineralogie und Stratigraphie quartärer Tephren