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The formation of dunes in central Europe reflects ample sediment supply during the last deglacial hemicycle. A Quaternary inland dune complex in southern Brandenburg, Germany, was studied to frame the duration of pedogenesis in two outcrops containing buried paleosols. An integrative approach, which combined geomorphological, sedimentological, pedological and chronological methods was used to identify aeolian deposition events, ensuing pedogenesis and anthropogenic remobilization. At the outcrops, which were situated approximately 2 km apart from each other, a total of twelve samples of the aeolian sands were dated using optically stimulated luminescence (OSL) and a further six samples using 14C dating. Although the dunes have similar morphological features, these forms have a different history of aeolian sand deposition and pedogenesis. At the older dune (Gl 1) the surface soil is a well developed Podzol, whereas soil development of the younger dune (Gl 2) is clearly in an initial state. The studied sites of the dune complex also differ in grain size distribution and in the presence of buried soils, thereby indicating a climatic impact on aeolian remobilization.
Organic matter from biological soil crusts induces the initial formation of sandy temperate soils
(2014)
Different development stages of algae-dominated and moss-dominated biological soil crusts (BSCs) were sampled on a natural sand dune (b17 years old) and on an experimental sand dune (b8 years old) along a catena, including gradients of vegetation cover, location on the slope, as well as composition and thickness of BSC organisms in northeastern Germany. The accumulation of BSC-derived organic carbon (OC)was determined for bulk materials and fractions less than 63 μm. The OC composition was characterized by solid-state 13C NMR spectroscopy and the carbohydrate-C signature. 14C contents were determined to assess the origin and dynamics of OC. From the radiocarbon contents, two OC pools were differentiated: recent BSC-derived and lignite-derived “old” OC. Downward movement of OC into the underlying substratewas found only undermoss-dominated BSCs at the old sand dune. BSC-derived OC was mainly composed of carbohydrate-C and, to a lesser extent, alkyl C and N-alkyl C, with considerably higher contributions of alkyl C in the young dune, indicating differences in the composition of extracellular polymeric substances produced by the BSCs with age. This is consistent with higher proportions of water-soluble OC of moss-dominated BSCs at the old dune, which is leached in the underlying substrate and initiates soil formation. Because of the channeling effect of mosses, OC depth translocation along with suspended colloidal substances contribute to OC accumulation in substrates.
Holocene Dune Formation and Human-Induced Aeolian Remobilisation in South Brandenburg, Germany
(2008)
In the Mid Latitudes form and function of the earth surface are mainly affected by Pleistocene periglacial processes such as solifluction, cryoturbation and aeolian deposition. On the other hand, human impact on landscapes in Central Europe may date back to the earliest farmers from the Neolithic Period (c. 5500 a cal BC). At least since the Middle Ages intense land-use produced wide deforested areas. In the sand-rich North German Lowland these human-induced deforestation often resulted in the remobilisation of Late Pleistocene to Early Holocene sand dunes. Especially in the vicinity of former mining sites or glassworks the dune landscapes possess quite young stratigraphic disturbances (fossilized horizons, weak developed top soils). Within the scope of the Transregional Collaborative Research Centre (SFB/TRR) 38, funded by the Deutsche Forschungsgemeinschaft (DFG), inland dunes in South Brandenburg were used as comparison sites to study structures and processes of the initial ecosystem development phase in an artificial water catchment. Here, we present first results of the pedostratigraphy and the age of two dune systems near Glashuette which is about 50 km south of Berlin. Based on twelve Optical Stimulated Luminescence (OSL) and six radiocarbon (14C) datings a chronology of the landscape development for the last c. 10000 years is derived. Data prove that both dune systems - even though they are just c. 1 km apart and have similar morphological features such as height, width, and orientation - have a completely different history in aeolian sand deposition and pedogenesis. At dune 'Glashuette 1' a well established podsol forms the topsoil. At dune 'Glashuette 2' soil development is clearly in a more initial state showing only some humus accumulation and weaker podsolization processes. OSL and 14C ages of sand from 'Glashuette 1' range between about 11.4 ka cal. BC (3.9 m below surface) and 9.4 ka cal. BC (0.7 m below surface). Against that, the sands in 'Glashuette 2' are mainly dated to about 0.8 ka cal BC (3.4 to 0.7 m below surface). On the basis of our findings further analyses can be planned more accurately to study the impact of initial processes on the later state of ecosystems characteristics.
Mit dieser Arbeit wurde der Einfluss von biologischen Bodenkrusten auf die Benetzungshemmung / Hydrophobizität auf sandigen, anthropogen geschütteten, rekultivierten Böden der Tagebaufolgelandschaft und auf sandigen, sich mehr oder weniger natürlich entwickelnden Böden in Flugsandarealen und Dünengebieten Südbrandenburgs untersucht. Gezeigt wurde, dass sich in der Bergbaufolgelandschaft auf dem sandigen anthropogen geschütteten Substrat andere Krustenarten auf der Substratoberfläche ansiedeln als auf der Substratoberfläche von Flugsandgebieten und Dünen. Der Effekt der Benetzungshemmung ist bei den Krustenarten der rekultivierten Bergbauflächen stärker ausgeprägt als bei den natürlichen Flugsandgebieten und Dünen, wo die Benetzungshemmung im Krustentstadium mit Einfluss von Moosen wieder zurückgeht. Gerade Flechten haben in Bergbaufolgelandschaften negativen Einfluss auf die Infiltration von Niederschlag. Auch die Bindungskräfte zwischen den Partikeln spielen bei der Betrachtung des Einflusses der Benetzungshemmung / Hydrophobizität eine Rolle, denn es zeigt sich bei Betrachtung der Korngrößenverteilung, dass das Substrat in den Rekultivierungsgebieten der Bergbaufolgelandschaft unsortiert ist und hohe Anteile an Feinmaterial (Schluff und Ton) aufweisen kann. Auf den Flugsandgebieten findet eine natürliche
Sortierung der Partikel durch Wind und Wasser statt, wobei das Substrat meist locker lagernd vorkommt und lediglich im Lee von höheren Pflanzen zur Ruhe kommen kann. Dort übernehmen dann biologische Bodenkrusten und andere Mikroorganismen die Bindung und Festigung der Partikel z. B. durch extrazelluläre polymere Substanzen. Es wurde deutlich, dass die Akkumulation organischer Substanz bei Bewuchs mit Laubgehölzen in größerem Maße stattfindet als bei Bewuchs mit Nadelgehölzen. Jedoch weisen die Chlorophyll a-Gehalte auf mehr Biomasse durch biologische Bodenkrusten bei den Nadelgehölzen hin. Insgesamt ist festzuhalten, dass jeder untersuchte Standort separat für sich betrachtet werden muss und nicht von einer Chronosequenz im Sinne einer eindeutig zeitlichen Abfolge bei Betrachtung der Alter der Standorte ausgegangen werden kann. Lediglich die Standorte in der Bergbaufolgelandschaftfür sich sowie die Standorte in den relativ natürlich entwickelten Flugsand- und Dünengebieten können gemeinsam betrachtet werden. Wie gezeigt wurde, beeinflussen biologische Bodenkrusten gerade schon in der Initialphase der Bodenbildung den Wasserhaushalt durch Porenverschluss, durch hydrophob wirkende Exsudate,
aber auch durch Rhizoide der Moose, insbesondere im brandenburgischen Übergangsklima vom maritimen zum kontinentalen Klima. Durch die Regulierung des Wasserhaushalts des Bodens durch die biologischen Bodenkrusten wird die Bodenentwicklung in bestimmte Richtungen gelenkt. Hierfür sind allerdings Langzeitbeobachtungen und eine möglichst gewissenhafte Auswahl an Chronosequenzen notwendig.
The influence of biological soil crusts in natural ecosystems on structures and processes is well investigated. However, in South-Brandenburg (Germany), it is possible to study the development of biological soil crusts (BSC) during initial ecosystem genesis on two artificial water catchments with well-known ages and under differing starting conditions. The two experimental sites are located in the recultivation area of the lignite open-cast mining district of southern Brandenburg with a distance of approximately 1 km between them. Two different topographies were constructed at the experimental sites: the experimental plot at the catchment Neuer Lugteich was shaped like a dune, whereas the artificial water catchment Hühnerwasser was modelled as an inclined slope. The catchment Neuer Lugteich is four years older than Hühnerwasser. The original substrate at Neuer Lugteich is more sandy and carbonate-free compared to the original substrate dumped at Hühnerwasser. At both sites geomorphological differentiation and crust development were compared and the importance of substrate-dependent water availability and crust type clarified. Once settled, the crusts influenced the water regime of the soils by delaying infiltration through enhanced water repellency, and by limiting water infiltration. Chlorophyll analysis revealed that all crusts were at early stages of development. At Neuer Lugteich, the establishment of the biological soil crusts was closely associated with the vegetation succession, whereas no clear succession of the crusts could be observed at Hühnerwasser. The mosaic-like pattern of the biological soils crusts is associated with the distribution of fine-grained material here.zeige weniger