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Investigations on intra- and interannual coarse sediment dynamics in a high-mountain catchment
(2011)
Seit 2010 untersucht eine interdisziplinäre Forschergruppe der BTU, des BLDAM und des LBGR die Landnutzungsgeschichte sowie die natürliche und anthropogen induzierte Landschaftsentwicklung in der Niederlausitz, Brandenburg. Systematische archäologische Grabungen des BLDAM im Vorfeld der laufenden Tagebaue sind eine wichtige Grundlage für geopedologische Untersuchungen. Die Arbeiten hatten zunächst ihren räumlichen Schwerpunkt in den Braunkohletagebauen nordöstlich von Cottbus (Tgb. Cottbus Nord, Tgb. Jänschwalde) und wurden dann ausgedehnt auf weitere Forstflächen nördlich von Peitz. Wir geben einen Überblick über die wichtigsten Erkenntnisse der letzten Jahre, präsentieren aktuelle Ergebnisse und zeigen zukünftige Forschungsfelder auf.
Im Tagebau Jänschwalde sind zwischenzeitlich mehr als 1000 Relikte von Holzkohlmeilern (HKM) als Zeugen einer intensiven historischen Holznutzung archäologisch dokumentiert. Mit Stand Januar 2016 liegen Dendroalter von 64 HKM vor. Die Alter schwanken zwischen dem ausgehenden 16. Jahrhundert und der Mitte des 19. Jahrhunderts, was in etwa dem Betriebszeitraum des Hüttenwerks in Peitz entspricht. Die Mehrzahl der Meiler datiert auf den Beginn des 18. Jahrhunderts. Weitere Hinterlassenschaften der historischen Landnutzung sind u.a. Wölbäcker und begrabene Ackerböden. Fossile Böden und ehemalige Landoberflächen sind stellenweise mit äolischen Sedimenten überdeckt. 14C- und OSL-Datierungen an diesen Böden und Sedimenten lassen auf eine Intensivierung der äolischen Aktivität zur slawischen Zeit und im Deutschen Mittelalter schließen. Einige Relikte von HKM sind mit Sand überweht worden, und an einer Stelle konnte das Alter dieser äolischen Sedimentation mittels Dendrodatierung des begrabenen Meilers auf1850 oder jünger bestimmt werden. Allerdings stellt dies die Ausnahme dar. Der weitaus größere Teil der HKM-Relikte liegt direkt an der Oberfläche und ist nicht begraben, was auf eine sehr geringe Winderosion in der Neuzeit schließen lässt. Seit 2015 konnte im Rahmen des DFG-Projekts „Räumliche und zeitliche Dimension der historischen Köhlerei im Tauerschen Forst (Niederlausitz, Brandenburg). Ein Beitrag zur Kulturlandschaftsentwicklung des Norddeutschen Tieflands“ (Az RA 1129/3-1; RA 931/6-1) ein weiteres Gebiet mit hoher HKM-Dichte untersucht werden. Erste Auswertungen der LiDAR-Daten ergeben eine Anzahl von 4449 ehemaligen Meilerstandorten im Tauerschen Forst. 26 Meilerstellen sind beprobt, die Dendroalter hierzu sind in Bearbeitung. Ebenfalls in jüngerer Zeit fanden Untersuchungen zur Verbreitung von HKM-Relikten für das gesamte Land Brandenburg statt. Mit Hilfe eines binären Modells wurden Gebiete mit hoher Wahrscheinlichkeit von HKM-Standorten detektiert. Im Rahmen des im November 2016 beginnenden DFG-Projekts „Die historische Köhlerei in Brandenburg - Analyse der räumlichen Dimension und der Effekte auf bodenhydraulische Eigenschaften“ (SCHN 1349/1-1) sollen nun neben der Verbreitung der historischen Köhlerei auch bodenrelevante Auswirkungen beschrieben und bewertet werden.
Various sources provide information about land use history and landscape transformation. For a variety of reasons, the quality of information differs and is often discontinuous or incomplete. In this interdisciplinary study we take advantage of comprehensive archaeological data gathered by large-scale excavations that were necessary because of opencast lignite mining in Lusatia, Brandenburg, Germany. By using a GIS we integrate these archaeological findings with results from archival and literature studies, from historical maps, from landforms and soils as well as from analyses of shaded-relief maps derived from up-to-date LiDAR data. The long-term aim is to develop a palaeoenvironmental model and thus to reconstruct landscape changes caused by human activities. The focus of the study is the Peitz ironwork in SE Brandenburg, which was a large consumer of commodities for about 300 years. During the time it operated, extensive transformations are supposed to have affected the landscape in the vicinity because of wood consumption and especially charcoal production. Digital datasets about forested areas for different timespans reconstructed from historical maps were made available. In combination with dendrochronological dating of charred trees, the spatiotemporal dimension of charcoal kilns was determined. Also, sites of former bog iron ore mining could be identified. Moreover, the different sources contain further information about other forms of land uses such as agriculture, pastoralism and even viticulture. In conclusion we can highlight that the mosaic of past land use systems is different from the modern structure but that major changes in the forests have been retained.
This study is based on 616 geochronological ages from aeolian
and colluvial sediments as well as paleosols, representing the
largest database of geochronological data from northeastern
Germany available to date. Cumulative probability density functions
for radiocarbon data and kernel density estimates for luminescence
data were created covering the last 15 ka. The data analysis aimed at the identification of changes and their drivers in geomorphodynamics and soil formation. The ages representing
aeolian activity cluster in the Late Glacial, the Early Holocene, and the Late Holocene, where the first two clusters are assumed to
result mostly from climatic impact with only a minor share of
human impact triggering the mobilization of aeolian sediments.
The third cluster is considered to result mainly from human
impact. The Late Glacial to Early Holocene activity phase is interrupted by a phase of surface stability around 11.5–12.7 ka, which is indicated by the occurrence of initial soil formations of Finow and Usselo types. Colluvial sedimentation predominantly occurred during the last 7 ka and clearly accelerated since the last 1000 a. According to the ages of specific paleosol types, related soilforming processes started already in the Late Glacial and were
completed in the Holocene.
In the apron of the active lignite opencast pit Jänschwalde (Brandenburg, Germany), three archaeological survey trenches were investigated in an area where aeolian sand deposits are widespread. The investigated sediment sequences contain evidence of aeolian morphodynamics, soil formation and agricultural land use. To study the age and the causes of sand drifting and surface stabilization, standard soil physical and chemical laboratory analyses as well as optically stimulated luminescence (OSL) and radiocarbon dating (14C) were carried out. Two main sedimentological units were identified: Unit 1 consists of glacio-fluvial and Late Glacial aeolian sands representing the parent material for the native Podsol-
Braunerde, while Unit 2 represents the Late Holocene aeolian deposits. Four periods of Late Glacial and Holocene aeolian activity and three phases of geomorphological stability have been identified: (i) Aeolian sedimentation during the Late Glacial, (ii) Mesolithic reactivation of aeolian processes, (iii) soil formation until Late Roman Iron Age settlers intensified the agricultural land use, (iv) intensive drift sand formation
during the High Middle Ages due to agricultural expansion, (v) stabilization of the drift sands and weak soil formation, (vi) reactivation of aeolian processes due to the increasing wood consumption and charcoal production from the early 17th until the mid-19th century, (vii) surface stabilization and formation of Regosols since the mid-19th century due to afforestation.
Analysing the spatial distribution of anthropogenic relief structures can contribute to the understanding of past landuse systems. With automated mapping routines, small relief forms can be detected efficiently from high-resolution digital terrain models (DTMs). In this study, we describe an approach for the automated mapping of charcoal kiln sites from an airborne laser-scanning DTM. The study site is located north of Cottbus, Germany, where an exceptionally large historic charcoal production field has been documented in previous archaeological surveys. The goal of this study was to implement, evaluate and improve an automated GIS-based routine for mapping these features based on the template-matching principle. In addition to the DTM, different morphometric variables were evaluated for their suitability to detect kiln sites. The mapping results were validated against a comprehensive database of kiln sites recorded from archaeological excavations and via manual digitization. The effects of irregular kiln-site geometry and DTM noise were evaluated using synthetic DTMs. The results of the synthetic DTM mapping show that the template-matching results differed depending on the morphometric variable used for the mapping process. In accordance with this observation, a validation of the mapping procedure for the field site suggests that feature mapping can be improved. In particular, the number of false detections can be reduced using a combination of morphometric variables. For the validation area, the kiln sites with diameters of at least 10m were mapped using the automated routine, with detection rates that were close to those of manual digitization. Therefore, the described method can considerably facilitate the mapping and distribution analysis of kiln sites or similar small relief forms that are prominent in a specific landscape.
In der Niederlausitz finden sich sehr unterschiedliche Beispiele für junge Bodenbildungen, die oftmals durch menschliche Eingriffe ausgelöst wurden. In dem Beitrag werden neben den jüngsten Bodenentwicklungen auf Bergbaufolgestandorten auch jüngere Böden auf seit dem Mittelalter mit Flugsanden überdeckten Standorten vorgestellt. Obwohl die Genese der auf diesen Flugsanddecken anzutreffenden Böden bereits seit bis zu 1 000 Jahre andauert, sind hier erst Böden der Klasse der Ah/C-Böden entwickelt. Auf den Bergbaufolgestandorten wird versucht, die Bodenbildung durch spezielle Meliorationsmaßnahmen zu fördern. Untersuchungen an diesen besonders jungen Böden lassen gut die Prozesse der initialen Bodenentwicklung erkennen.
Modern lignite mining in southern Brandenburg (East Germany) causes the destruction of entire landscapes. To date, research concentrated on the reclamation of areas affected by mining-related activities, but the significance of prehistoric and historic cultures on land use changes is disregarded. Recently, a joint research project was launched for interdisciplinary long-term palaeoenvironmental research and to study anthropogenic landscape change in southern Brandenburg. The project partners are geoscientists from the Brandenburg University of Technology (BTU) Cottbus and archaeologists from the Brandenburgisches Landesamt für Denkmalpflege und Archäologisches Museum (BLDAM), within the scope of this project pedological and geomorphological investigations are carried out to reconstruct Holocene landscape and land use change in the apron of the opencast pit Jänschwalde (Lower Lusatia), c. 100 southeast of Berlin and c. 15 km northeast of Cottbus. By law large-scale surveys and excavations have to be carried out in the forefield to document all archaeological findings. In combination with the excellent outcrop situation the archaeological investigation offers ideal conditions to study the soil geomorphology on a landscape scale.
Fieldwork includes topographical surveying by differential GPS. Soils and sediments are described along cross-sections (up to 140 m long, up to 2 m deep). Field-portable XRF analyzes (FPXRF) is used for a quick characterization of total element concentrations of the substrates. Standard analytical methods (e.g., soil texture, contents of pedogenic oxides) are carried out in the laboratory. To obtain chronological information, radiocarbon and OSL (optically stimulated luminescence) dating are applied on suitable material.
Evidence of different land use and land use change in the study area is abundant. For example, at several cross-sections agricultural soil horizons are covered with up to 150 cm thick eolian sands, proving that deforestation and agricultural use induced eolian soil erosion. In addition, remnants of charcoal piles buried under up to 150 cm thick eolian sands indicate remobilization of Quaternary sands as a consequence of clearing for charcoal production.
The ongoing investigations will concentrate on fieldwork. Preliminary results are presented.