Forschungszentrum Landschaftsentwicklung und Bergbaulandschaften (FZLB)
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Institute
BTU
The spatial variability of soil physical properties on the landscape scale is often increased by anthropogenic land occupation, not only by current land use but also through the legacies of past land use systems. The remains of historic charcoal hearts are an example for such a disturbance of the soil landscape by former forestry. Such relict charcoal hearths (RCH) exhibit a clearly altered soil stratigraphy, most prominently characterized by a technogenic substrate layer on the soil surface, and their soil physical properties can considerably differ from those of surrounding forest soils. The aim of our study is to characterize the soil water and temperature regime on RHC in a pre-industrial charcoal production area in Brandenburg, Germany, as compared with the surrounding sandy forest soils. Soil properties were analyzed in profiles on and around hearth sites and are monitored in a sensor transect equipped with soil
moisture sensors and pF-meters. Results of soil sample analyses show differences in density and porosity between the RCH soils and surrounding forest soils, not only in the technogenic layer but also in the buried soil layers on hearth sites. The soil water characteristic curves determined in the laboratory indicate a modified pore size distribution and lower plant available water contents in the RCH soils. Preliminary results of the ongoing soil water monitoring, however, show increased soil wetness in the RCH soils, along with lower soil moisture tensions. Furthermore, the measurements show higher variations of soil temperature in RCH soils. The results affirm that the legacies of historic charcoal production can increase the spatial variability of soil physical properties and therefore also of ecological site conditions in forest areas. The results of soil moisture monitoring suggest that a determination of soil physical parameters in the laboratory is not sufficient to characterize the spatio-temporal variations of the soil water regime.
Historical charcoal production has long been an unconsidered type of forest utilization in lowland areas. The archaeological discovery of a large charcoal burning area in the forefield of the active opencast lignite mine J€anschwalde in SE Brandenburg (North German Lowlands) has highlighted the need for multidisciplinary research in the study of the dimensions of historical charcoal burning. The charcoal produced in our study area, the former royal forest district Tauer, provided energy for the nearby Peitz ironworks during its operation from the mid-16th to the mid-19th century. Here, we aimed to record the amount, size and distribution of relict charcoal hearths (RCHs) to examine their context with respect to the ironworks and to better understand the potential impacts on late Quaternary landscape change. The applied methods combined archaeological research with shaded-relief mapping of RCHs. To evaluate the detection success of RCHs in the shaded-relief maps (SRMs), we compared the results with the results from specific archaeological surveys and conventional forest site mapping. Furthermore, we analyzed our dataset with descriptive, comparable and spatial statistics. Additionally, dendrochronological dating of charcoal fragments from selected RCHs was used to investigate the temporal relationships among the RCHs. Approximately 6000 circular RCHs were manually digitally identified in the SRMs of the 109-km2 evaluable area. However, ground truthing showed that the shaded-relief maps could not completely capture all RCHs in our study area due to local conditions. At the regional scale, two focus areas with high RCH site densities were found. Statistical analysis revealed that the diameters of the RCHs range widely from 4 to 30.5 m. Spatial statistics were applied to the RCH diameters to aggregate areas with larger or smaller RCHs. At the small scale, no systematic arrangement of RCHs was obvious in the SRMs. Dendrochronological dating of selected RCHs lying close together could not detect significant spatiotemporal relationships or patterns. The dating results also showed that some areas have been preferentially used for charcoal production for over 300 years. Due to the homogeneity of the physiogeographical location factors, we assume that these factors are not superficially responsible for site selection. Instead, economic location factors and contemporary regulations are more likely responsible for the distribution of RCHs.
Knowledge of the position of archaeological remains in the surface relief provides important basic information for archaeological survey design and interpretation. Geomorphological processes in (pre)history may have resulted in a modification of the local relief around archaeological sites, especially in areas that are prone to sediment erosion and relocation, such as sheet sand and dune landscapes. In this study, we reconstructed and analysed the palaeorelief of an archaeological excavation site in an inland dune area in southern Brandenburg, Germany. The remains of two Mesolithic sites were documented in the archaeological excavations and found to be associated with a buried soil horizon. To gather information on the relief of the buried soil surface, we used a combination of sedimentological and pedological profile descriptions along archaeological survey trenches and geophysical prospection with ground penetrating radar supplemented with microdrone photography and photogrammetry, global positioning system (GPS) surveys, and analysis of LiDAR-based elevation models. A digital elevation model of the buried surface was generated and analysed using a geographical information system (GIS). A comparison of the palaeosurface model with the recent surface elevation model shows that sand remobilization resulted in a considerable reshaping of the relief. Further, an analysis of the buried surface model shows that the relief position of the two archaeological sites in the study area was considerably more prominent in relation to the corresponding buried soil surface than in relation to the recent surface morphology. The results affirm the significance of Holocene sediment relocation for the local surface morphology and the importance of considering such relief modifications in archaeological surveys.
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.
Archaeological excavations have revealed more than thousand charcoal kiln remains (CKRs) in the prefield of
the active opencast lignite mine Jänschwalde, situated about 150 km SE of Berlin (SE Brandenburg, Germany).
The charcoal was mainly produced for the ironwork Peitz nearby, which operated from the 16th to the mid-19th
centuries. In a first approach, to estimate the dimension of the charcoal production, CKRs were mapped on
shaded-relief maps (SRMs) derived from high-resolution LiDAR data (Raab et al. 2015). Subsequently, for a selected test area, identified CKRs on the SRMs were compared with archaeologically excavated CKRs in the
field. This survey showed a considerably number of falsely detected sites. Therefore, the data was critically
re-evaluated using additional relief visualisations. Further, we extended the CKR mapping to areas which are not
archaeologically investigated. The study area, the former royal forest district Tauer, consists of two separate areas: the Tauersche Heide (c. 96 km2 area) N of Peitz and the area Jänschwalde (c. 32 km2 area) NE of Peitz. The study area is characterized by a flat topography. Different former and current anthropogenic uses (e.g., military training, solar power plant, forestry measures) have affected the study area, resulting in extensive disturbances of the terrain surface. The revised CKR abundance in the study area Jänschwalde was considerably smaller than the numbers produced by our first approach. Further, the CKR mapping revealed, that a total record of the CKRs is not possible for various reasons. Despite these limitations, a solid database can be provided for a much larger area than before. Basic statistic parameters of the CKR diameters and all comparative statistical tests were calculated using SPSS. To detect underlying spatial relationships in the CKR site distribution, we applied the Getis-Ord Gi* statistic, a method to test for local spatial autocorrelation between neighbouring sites. The test is available as part of the ArcGis 10.1 spatial statistics toolbox. The outcomes are discussed in consideration of our archaeological, archival and dendrochronological research results.
Automated detection of small-scale anthropogenic relief features from high-resolution ALS-data
(2014)
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.
Conclusions
(2011)
In pre-industrial times, charcoal burning was a common source of energy across Europe. Charcoal production and its related consequences for the upland environment are well known due to historical and palaeoenvironmental research. In recent years, awareness has grown regarding the use of woods in the lowlands for charcoal production. In the last 20 years, a large charcoal-burning field in Lower Lusatia (Brandenburg, North German Lowlands) was discovered by systematic archaeological excavations of the opencast mine of Jänschwalde. However, the excavations are limited to the mine, which only covers a portion of the Jänschwalder Heide and the surrounding forests.
In this paper, we present the results of our study regarding the spatial extension and timing of charcoal production in the Jänschwalder Heide and its surrounding areas. We applied a combined approach using archaeological research results, GIS-analyses of shaded-relief maps (SRMs) and tree-ring dating of selected charcoal kiln remains. Approximately 900 excavated charcoal kiln ground plans were analysed, which provided a solid data basis for our GIS analyses. For an extensive evaluation, we enlarged our study area beyond the limits of the lignite mine. We identified and digitised the remains of the charcoal kilns by creating SRMs from digital elevation models (DEMs) that were based on high-resolution airborne laser scanning data (ALS). The data from the excavated and digitised charcoal kiln remains were analysed in terms of their sizes and spatial distributions. In addition, the dendrochronological ages of 16 selected charcoal kiln remains were determined.
This study shows that charcoal production was more extensive than initially proven by archaeological excavations. The remains of more than 5000 charcoal kilns were detected on the SRMs across an area that was twice as large as the excavated charcoal-burning field. In the Jänschwalder Heide, considerably more charcoal kiln relicts exist compared with the surrounding communal areas. Furthermore, the charcoal kiln remains in the Jänschwalder Heide have larger diameters, suggesting large-scale charcoal production for supplying energy to the nearby ironworks at Peitz. However, the charcoal production on the communal land was most likely for local crafts. The ages of the charcoal kiln remains indicated that charcoal production occurred between the 17th and 19th centuries, corresponding with the main period of charcoal burning. Overall, our study suggested that charcoal production sites are underestimated in the modern landscapes of the North German Lowlands.
High-resolution digital elevation data from airborne laser scanning (ALS) allow for identification and mapping of so far unknown small-scale relief features that are hidden by forest cover. Especially as a result of historic land use, small anthropogenic landforms can occur, e.g., remains of charcoal kilns on sites that were used for charcoal
production or ridge and furrow systems in former farmland areas. Mapping such relief features and analyzing their spatial distribution patterns can help to understand past land-use systems and their effects on landscapes. To efficiently detect and quantify small-scale relief features from high-resolution DEMs for larger areas, (semi-)
automated mapping routines are required.
South Brandenburg is the central part of the North European Lowland (NEL) extending as a plain landscape from
the North and Baltic Sea to the foothills of the Central European Highlands and reaching from the Netherlands to Poland. Since many decades lignite opencast mines have been operating in this region which is known as the Lusatian mining district. The total land demand in Lusatia is about 852 square kilometres and mining will continue
for many more years or even decades. Large-scale outcrops resulting from these mining activities are excellent archives to study the younger Earth’s history. The scope of our research in open cast mines is to reconstruct the
Late Quaternary landscape development and to distinguishing natural from anthropogenic forcing and processes. In more detail, the aims are to identify and to quantify the impact of past land uses, i.e. changes of vegetation, landforms and soils induced by agriculture and/or forestry. Here, we are presenting latest results from our research and review important findings giving novel insights into man-induced environmental changes in Lusatia within the past thousands years and thus improving the general understanding of Late Quaternary landscape dynamics.
The formation of erosion rills and gullies is a critical step in land surface development, but possibilities to study initial unaffected surface development under natural conditions and with well-defined initial and boundary conditions are rare. The objective of this study was to characterize rill network development from ’point zero’ in the artificially-created catchment ‘Hühnerwasser’. To ensure unaffected development, the study was largely restricted to the analysis of remotely-sensed data. We analyzed a series of photogrammetry-based digital elevation models (DEMs) for 10 points in time, over a period of five years and beginning with the initial state. The evolving erosion rill network was quantitatively described based on mapping from aerial photographs. DEMs and rill network maps were combined to specifically analyze the development of morphometry for different parts of the network and to characterize energy dissipation and connectivity. The restriction to remote-sensing data did not allow for analyzing specific processes governing rill network development, nevertheless, two major development phases could be characterized. We observed a phase of growth of the rill network along with variations in drainage patterns during the first two years of development and a subsequent phase of reduction of its area along with comparably stable patterns. Region-specific analysis of morphometry indicates that, besides effects of changing sediment characteristics and vegetation cover development, locally evolving hydro-geomorphic feedback cycles influenced this development. Results show an increasing similarity of overall statistical characteristics (e.g. drainage density) for two parts of the catchment, but a persistent influence of initial conditions on specific rill geometry. The observed development towards higher orderliness and increased connectivity is consistent with experiments and concepts on drainage network evolution across scales; however, we did not observe major influences of rill piracy and cross grading or a reduction of energy dissipation with network development.
Many processes in a developing catchment can only be fully understood if the spatial
heterogeneity is adequately described. Process-based modeling allows reproducing
specific key structural elements of catchments. Constructed catchments are ideal test
objects because of the well-known spatial conditions. In our study, we (i) modeled the
entire process chain of catchment construction, (ii) established a consistent sediment mass/
volume balance between the excavated outcrop and the generated catchment model, and
(iii) provided consistent three-dimensional distributions of texture and bulk density for
deriving soil hydraulic properties. Data are from the 6 ha Hühnerwasser catchment (Chicken
Creek, Lower Lusatia, Germany), which was constructed from overburden sediments in an
open-cast lignite mine. Uncertainty about the parent material origin was captured in a
multiscenario approach based on a geological model of the outcrop site and the simulation
of excavation procedures. Generated distributions are incorporated in a gridded threedimensional
volume model (GOCAD), and results were evaluated by semivariogram
analysis and by quantifying point-to-point deviations. Filling and compaction are modeled
based on three-dimensional volume analysis and mass balances of dumped sediments.
Heterogeneities reflect both the batch-wise sediment variation and the succession of
excavated geological units. The scale of the generated spatial models can be adjusted for
three-dimensional hydrological catchment modeling while three-dimensional sediment
mass balances can be used for analyzing soil and ecosystem development processes.
A structure model describes the boundary geometries and the three-dimensional solid phase distributions of the catchment. In contrast to an established ecosystem, feedback relations can be assumed for an initial geosystem between the development of spatial structures and the water and element fluxes. The objective was to develop a hydrological catchment model as a three-dimensional spatial database of the solid phase that allows an integrative analysis, a periodical mass balance, and the generation of distributed model parameters for the developing system. Data were from the constructed catchment “Chicken
Creek.” The initial texture and bulk density distributions were generated by imitating sediment dumping, segregation, and compaction. Boundary geometries and changes in surface topography due to erosion and sedimentation processes were quantified on the basis of digital elevation models (DEMs) derived from aerial photographs. The catchment was visualized with the three-dimensional software GoCad; the “emergence” of the water table and other structures (e.g., soil horizons, root zone) could be spatially assigned and quantified to identify regions with specific processes. A combination of three-dimensional catchment with time-dependent two-dimensional surface models allowed generating the development of spatially distributed erosion–deposition patterns that formed new initial surfaces. The three-dimensional distributed solid phase structure of the catchment allowed for a more direct comparison with observations using minimal invasive methods. The mass balance of the solids could be related with pedologic development and transfer to other geopedologic systems achieved by adapting sediment transport and deposition in the descriptions of the model. This model may help improve the integrative analysis of hydrological catchments.
Bilanzierung der Sedimentmassen eines künstlichen Wassereinzugsgebiets mit einem 3D-Strukturmodell
(2009)
Reproducing the initial internal structural heterogeneity of an artificially created catchment
(2010)
For systems such as soils or watersheds, the initial distribution of sediment mass and composition at the starting point of the development are mostly not well-known. The development of such systems, however, has frequently been assumed to depend on boundary and initial conditions including the solid phase. Here, an experimental watershed of about 6 ha surface area was artificially-created in order to imitate an initial stage just at the beginning of the geo-ecosystem development. However, sediment homogeneity could not be achieved for this large-scale field experiment, and the 3D spatial distribution of structures and components remained uncertain. The objective of this study was to quantify and reconstruct the initial sediment distribution and the first development stages using aerial photographs, point information, and a 3D model. The watershed was made of coarse-textured sediments of quaternary origin with a low permeable clay liner as the bottom boundary. A 2D horizontal digital elevation model (DEM) of the surface and a DEM of the subsurface clay layer are used to construct a 3D triangulated numerical grid of the catchment’s initial spatial structure using the 3D-GIS software GOCAD. Physical and chemical soil properties obtained from borehole samples are assigned to this model and interpolated onto the 3D grid. The volumetric changes in space and time are quantified and related to material properties to obtain the mass changes. Correlations between terrain attributes, sediment properties, and mass changes are explored specifically in regions of differing source materials. A temporal sequence of surface DEMs is obtained from photogrammetric, high-precision ground based laser scanning and airborne laser scanning data. 3D models of elevation change are constructed from these DEMs. The processes following the initial state are mainly characterized by runoff-induced erosive mass relocations related to the distribution of surface and subsurface structures and sediment properties. The results suggest that both sediment structures and mass translocations differ between the western and eastern parts of the watershed and that correlations between initial surface structures and subsequent mass changes exist.