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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.
Charcoal produced in kilns or hearths was an important source of energy in many regions of Europe and Northern America until the 19th century, and charcoal production in hearths is still common in many other regions of the world. The remains of charcoal hearths are therefore a widespread legacy of historic land use in forest areas. Soils on charcoal hearth sites are characterized by a technogenic layer rich in charcoal and ash on top of the soil profile, and by a pyrogenic modification of substrates below the former hearth.
The aims of our study are to examine how these alterations to the natural soil profiles affect the soil water regime
and other soil physical properties, and to assess the relevance of these effects on the landscape scale. We present
first results of a mapping of hearth site occurrence in forest areas in the state of Brandenburg, Germany, and of a
characterization of the infiltration behaviour on hearth sites as compared with undisturbed forest soils. Results of mapping small-scale relief features from LIDAR-based digital elevation models show that charcoal hearths occur in a high density in many large forest areas throughout Brandenburg. In the areas studied so far, up to almost 3% of the soil surface were found to be affected by the remains of historic hearths. First analyses of soil physical properties indicate differences in the infiltration characteristics of hearth site soils and undisturbed forest soils: Hood infiltrometer measurements show a very high spatial variability of hydraulic conductivity for hearth site soils, and water-drop-penetration-time tests reflect extremely high hydrophobicity of the technogenic layer on the sites. Results of dye tracer experiment show considerably strong preferential flow and therefore a higher spatial variability of soil wetness below the hearth remains. Overall, our first results therefore indicate that the legacy effects of historic charcoal production might significantly affect overall site conditions in forest areas with a high density of charcoal hearth remains.
Rubefizierte Böden wie die für Nordostdeutschland beschriebenen ‚Fuchserden‘ (WRB: Rhodic Brunic Arenosols oder Chromic Brunic Arenosols) sind nicht nur ein lokales Phänomen. Auch wenn die Genese der ‚Fuchserden‘ bisher nicht abschließend geklärt ist, so widerlegt deren Vorkommen auf post-LGM zeitlichen Sedimenten eine prä-pleistozäne Bodenbildung. Des Weiteren zeigen die bisherigen Untersuchungen in Nordostdeutschland und Polen, dass Fuchserden nicht durch in-situ Verwitterung entstanden sind, sondern dassdie rubefizierten Horizonte durch eine allochthone Anreicherung von Eisen entstanden sind und somit das Relief ein wesentlicher bodenbildender Faktor ist. Darüber hinaus scheint die Textur für die laterale Verlagerung bzw. Anreicherung immanent für die Genese der Fuchserden zu sein, da rubefizierte Horizonte zumindest auf den untersuchten Standorten in Nordostdeutschland bisher ausschließlich auf sandigem Substrat anzutreffen sind. Um die für die Genese der Fuchserden relevanten physiogeographischen und pedochemischen Parameter zu identifizieren, soll mittels einer Kombination aus feldbodenkundlicher Kartierung und nachgestellten Säulenversuchen im Labor die Bildung von Fuchserden unter kontrollierten Bedingungen untersucht werden. Hierfür werden neben bekannten Profilen bisher nicht weiter beschriebene Standorte mit Fuchserden feldbodenkundlich aufgenommen, um eine größere Breite naturräumlicher Daten bzw. verschiedener Entstehungsbedingungen zu erhalten. Varianten mit unterschiedlichen physikalischen und chemischen Eigenschaften von Ausgangssubstraten sowie Reliefpositionen bilden die Basis für einen mehrfaktoriellen Säulenversuch, der unter naturnahen Bedingungen in der Klimakammer stattfindet. Derzeit laufende Vorversuche zeigen, dass eine Ausfällung rötlicher Eisenoxiden aus eisenhaltigen Lösungen im Kapillarbereich sandiger Substrate bereits innerhalb weniger Wochen stattfindet und die Entstehung von rubefizierten Horizonten in Fuchserden möglicherweise durch die Anlieferung eisenhaltiger Lösungen limitiert ist.
Pre- and early industrial charcoal production has left a striking legacy effect on today’s soil landscapes in many forests of Central Europe and the North Eastern USA. Charcoaling in upright standing hearths (also called kilns) resulted in distinct circular micro relief structures, easily identifiable today in the field and on high resolution LiDAR-based digital elevation maps. Soils on these sites are characterized by one or multiple layers of decimetre thick charcoal rich substrate, which makes them Spolic Technosols according to the WRB soil classification. The focus of research on these sites increasingly deals with the difference of their soil physical and chemical properties in relation to unaffected forest soils and the potential implications for changes in vegetation and faunal growth. The controlling factor thereby is the soils large content of charcoal in various particle sizes, ranging from fine dust to large chunks. Studies have repeatedly shown the soils significant increase in total organic- and pyrogenic carbon content. The increase in total carbon stocks is thereby not only caused by pyrogenic carbon, but also by an apparently increased accumulation of non-pyrogenic organic matter. Here we present the latest findings regarding the carbon contents of centennially old charcoal rich technogenic substrates, sampled as part of multiple research projects in Brandenburg, Germany and the Litchfield hills in North-western Connecticut, USA. A focus will be the determination of highly aromatic carbon by the molecular marker Benzene-polycarboxylic acid (BPCA) and its prediction by FTIR-MIR chemometric methods. We discuss the results on forest soil carbon stocks on a site specific to a landscape and regional scale. Furthermore, the potential to use these sites to study the long term effects of charcoal admixture to soils by wildfires or biochar application will be discussed.
Throughout the northeastern United States (U.S.) and Europe, relict charcoal hearths (RCHs) are regularly being discovered in proximity to furnaces once used for the extraction of metal from ore or quick-lime production; charcoal produced in hearths was used as a furnace fuel. Given previous research has shown that topographic and subsurface disturbance can be great when a hearth is constructed, we hypothesize that hearth construction alters surface hydrology and soil chemistry in environments in and near hearths. We used a landscape classification process to identify 6758 hearths near furnaces at Greenwood and Pine Grove Furnace State Park, central and southcentral Pennsylvania, U.S. Two types of digital elevation model wetness indexes were used to quantify surface hydrology effects in and around hearths. Modeled wetness conditions were compared to field soil volumetric water content in RCHs near Greenwood Furnace State Park. Modeled wetness indexes indicate that RCH interiors are significantly wetter than RCH rim areas; RCHs are acting as a landscape moisture sink. Results also indicate that RCHs on slopes result in downslope drier conditions below RCHs. Field measured volumetric water content indicates that as distance from the center of the hearth increases, soil moisture significantly decreases. Geomorphic position was found to not be related to RCH wetness. Soil from RCHs, compared to nearby native soils, has significantly higher total C, a lower Mehlich 3 extractable acidity, higher Ca and P. No trend was evident with RCH soil chemistry and geomorphic position. The high frequency of RCH occurrence, in proximity to the furnace's RCHs supported, suggests that RCHs today could locally be an important niche for understory flora and fauna. Further research could explore how RCHs might be affecting surrounding plant populations and how within RCH patterns, especially on hillslopes, might represent a distinctly different scale of physical and chemical variability.
Relict charcoal hearths (RCHs) are sites of former charcoal production that are an increasingly well documented anthropogenic feature in forests of the temperate climate zone. However, the type and extent of a possible legacy effect from RCHs on soil physical and chemical properties is still largely unknown. In the Litchfield Hills in west Connecticut, RCH sites are located mainly on slopes and therefore differ in their architecture from lowland sites found in Europe. One of the striking characteristics of a RCH site regardless of its architecture is the enrichment of the soil with charcoal in varying particle sizes. In this study, we use chemical digestion coupled with a PLSR-model to quantify organic carbon and pyrogenic carbon in RCH substrate by MIR-DRIFT measurements. Furthermore, we analyse the quality of carbon compounds by MIR-DRIFT measurements on multiple grain size fractions to assess the post-burn enrichment of soil organic matter. Preliminary results show a markedly increase in organic and pyrogenic carbon in RCH substrates in relation to the natural forest soil. Also, our first results suggest that the enrichment of organic carbon is favoured on RCHsites. However, the causality between the enrichment of soil organic matter and site features remains open. Experiments using chemical extraction techniques on our samples hint at an increase of labile organic compounds and/or microbial biomass. This legacy effect of RCHs is however evident and further studies need to focus on how to address them.
Do small landforms have large effects? A review on the legacies of pre-industrial charcoal burning
(2022)
Relict charcoal hearths (RCHs) are small, anthropogenic landforms resulting from past charcoal burning and reaching significant land coverage in pre-industrial mining areas. We review three coupled legacies linked by RCH development: (i) a landscape-scale geomorphic effect, (ii) a unique soil fingerprint, and (iii) an evolving novel ecosystem. The history and technique of charcoal production are described to clarify legacy effects. Applying a recently presented morpho-genetic catalogue is useful for classified mapping of RCH findings. The RCH numbers and calculated RCH densities per study region vary greatly and impose uncertainties due to insufficient methods causing over- or underestimations. Areas with high RCH densities between 50 and 500 RCH/km2 seem reasonable. Machine learning-based remote sensing techniques are promising approaches with which to better assess the full scale of charcoal burning legacies. RCH soil properties feature dark charcoal-rich technogenic substrate layers classified as Auh horizons according to the World Reference Base with significantly increased C contents. These Auh horizons can also exhibit specific physical and chemical properties, such as relatively low bulk density, high porosity, high plant available water content, low thermal conductivity and differences in cation exchange capacity or nutrient status. However, relevant studies are rare, and thus, the effects may differ by study region. Regarding vegetation, there seem to be four main effects: changes in forest structure, species composition, recruitment pattern and productivity. The number of studies on this issue is, however, also very limited. Even fewer studies have examined the soil fauna in RCHs; thus, the reported effects cannot be used to draw general conclusions. Notably, RCH research has made considerable progress in the last five years, especially in the Light Detection and Ranging-based mapping of these small landforms and identification of RCH-specific soil properties, but ecological legacies are not well understood; thus, more interdisciplinary and integrative studies are needed.
The mining region of Upper Silesia has a long tradition with international significance. In 2017, the historic silver mine in Tarnowsky Gory was recognized as a UNESCO World Heritage Site. With the mining of galena (PbS), the region developed into one of the most important industrial centers in Central Europe in the 16th century. In addition to the underground galleries, the historical mining has left thousands of mining shafts as small relief forms, which have not been systematically investigated so far. Partly the mining shafts are associated with Relict Charcoal Hearths (RCH), another small form which is a result of charcoal production. In the Mala Panew River valley, north of Tarnowsky Gory, several tens of thousands of these RCH are found, which could be mapped by LiDAR in recent years. More detailed pedological investigations, which would allow a systematic comparison with other known RCH sites, are missing so far.
Within the framework of a Polish-German cooperation project, we started in 2021 to investigate the mining shafts and the RCH in Tarnowsky Gory and in the Mala Panew River valley from a pedological-sedimentological point of view. At the RCH sites on the Mala Panew River, we focused on the following questions: How was the soil stratigraphy changed by the RCH construction? What are main processes of soil development before and after RCH construction? What was the role of the pits surrounding the RCH? How do the sites differ from the RCHs at Tarnowsky Gory especially with respect to soil properties and soil genesis? In Tarnowsky Gory, where a RCH was excavated directly next to a mining shaft, the following questions were in focus: How did the mining activity change soil distribution and soil properties? What are main processes of soil development on the different parts? What is the origin of the pit infill? What is the origin of the shaft rim deposits?
Our work program included the construction of excavator trenches across the mining remains, construction, description and sampling of soil profiles along the trenches, schematic drawing of the soil stratigraphy, and laboratory analyses for the determination of texture, Munsell color, pH (CaCl2, H20), CaCO3 content, Ctotal & Ntotal and total elements by FPXRF. We present the first results of the ongoing investigations.
Recent findings of several thousand relict charcoal hearths (RCHs) in the Tauer Forest (Brandenburg, Germany) raise questions about the legacy effects of historical charcoal production on soil properties. RCH sites are characterized by the admixture of charcoal fragments to the natural forest soil, constituting an anthropogenic addition of carbon. Dendrochronological dating of large charcoal pieces has identified RCH ages ranging from 1709 AD to 1823 AD for a subarea in the Tauer Forest, which allows for assessing century old effects of charcoal application on forest soils. We measured the geometry and soil organic matter (SOM) content of 20 RCH sites in a selected part of the forest. The results provide a basis for estimating RCH SOM stocks on a 40-ha forest plot with 120 RCH sites. We also assessed the accuracy of RCH mapping based on digital elevation models (DEMs) with results from a ground survey. Over 50 % of sites were not detected by the DEM-based mapping. In the range of statistical uncertainties, RCHs add between 18 % and 32 % of SOM to the stock of the natural forest soil in the study area. This equals an additional 4.9 – 8.9 Mg of carbon per hectare of forest soil. These substantial amounts of SOM are so far not recognized by any survey or forest soil SOM inventories. Considering recent studies, which uncovered tens- and hundreds- of thousands of RCHs throughout Europe and the USA, we conclude that further knowledge of RCH SOM is important for quantifying anthropogenic SOM stocks on a global scale.
Open-cast lignite mines in Lower Lusatia provide unique insights into human-induced environmental changes in the Northern European Lowland and improve our understanding of Quaternary landscape dynamics. The excursion will focus on soils and sediments of Late Pleistocene and Holocene age that have been modified by land use since the Slavic Middle Ages. In the vicinity of the open-cast mine Jänschwalde and in the Tauer forest north of Cottbus characteristic remains of historical charcoal production, a ridge-and-furrow system and late Quaternary rubification in soils are presented.
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.
An initiative for a morphologic‐genetic catalog of relict charcoal hearths from Central Europe
(2020)
Human land use often leads to distinct modifications of soils within small, clearly delimited areas. Legacy effects of past land use are also abundant in recent forest areas, but are hardly considered in ecosystem assessment and soil mapping. The soils on relict charcoal hearths (RCHs) are a widespread example for such land use legacy soils in forests. Soils on RCHs differ clearly from surrounding forest soils in their stratigraphy and properties, and are most prominently characterized by a technogenic substrate layer with high contents of charcoal and thus soil organic matter (SOM). Although RCH soils can clearly contribute to the SOM stocks of forest soils, their relevance on the landscape scale has hardly been quantified. In this paper we analyze and discuss the distribution and effects of RCH soils across scales for forests in the state of Brandenburg, Germany, with a focus on SOM stocks. Our analysis is based on a large-scale mapping of RCHs from digital elevation models (DEMs), combined with a linear regression model of SOM stocks in RCH soils. The spatial distribution of RCH soils in the study region has a scale dependent heterogeneity. The large-scale variation in site densities is related to the concentration of charcoal production to specific forest areas while the small-scale variation is related to the irregular distribution of single RCHs within the charcoal production fields. Up to 1.5 % of the surface are covered by RCH soils in the forest areas within the study region. The results also show that RCHs can significantly contribute to the SOM stocks of forests, even where they cover only a small fraction of the soil surface, with up to 18 % additional SOM for forest areas. Because of the heterogeneous distribution of RCHs, the SOM stock additions depend on the scale of observation. Our results suggest that RCH SOM additions can be overestimated when sites in small areas (< 1 km²) are analyzed; and that characteristic spatial concentration patterns of RCHs are even observable when values are aggregated to large areas (25 km² and more). Aggregating effects to irregularly-sized forest administrative units resulted in maps that well represent the spatial distribution of RCH soils and SOM. The study highlights that considering land use legacy effects can be relevant for the results of soil mapping and inventories; and that prospecting and mapping land use legacies from DEMs can contribute to improving such approaches.
Charcoal-rich Technosols on century-old relict charcoal hearths (RCHs) are the subject of ongoing research regarding potential legacy effects that result from historic charcoal production and subsequent charcoal amendments on forest soil properties and forest ecosystems today. RCHs consist mostly of Auh horizons that are substantially enriched in soil organic carbon (SOC), of which the largest part seems to be of pyrogenic origin (PyC). However, the reported range of SOC and PyC contents in RCH soil also suggests that they are enriched in nonpyrogenic SOC. RCH soils are discussed as potential benchmarks for the long-term influence of biochar amendment and the post-wildfire influences on soil properties. In this study, we utilised a large soil sample dataset (n = 1245) from 52 RCH sites in north-western Connecticut, USA, to quantify SOC contents by total element analysis. The contents of condensed highly aromatic carbon as a proxy for black carbon (BC) were predicted by using a modified benzene polycarboxylated acid (BPCA) marker method in combination with diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy-based partial least square regression (r2 = 0.89). A high vertical spatial sampling resolution allowed the identification of soil organic matter (SOM) enrichment and translocation processes. The results show an average 75% and 1862% increase in TOC and BPCA-derived carbon, respectively, for technogenic Auh horizons compared to reference soils. In addition to an increase in aromatic properties, increased carboxylic properties of the RCH SOC suggest self-humification effects of degrading charcoal and thereby the continuing formation of leachable aromatic carbon compounds, which could have effects on pedogenic processes in buried soils. Indeed, we show BPCA-derived carbon concentrations in intermediate technogenic Cu horizons and buried top/subsoils that suggest vertical translocation of highly aromatic carbon originating in RCH Auh horizons. Topmost Auh horizons showed a gradual decrease in total organic carbon (TOC) contents with increasing depth, suggesting accumulation of recent, non-pyrogenic SOM. Lower aliphatic absorptions in RCH soil spectra suggest different SOM turnover dynamics compared to reference soils. Furthermore, studied RCH soils featured additional TOC enrichment, which cannot be fully explained now.
Soil and geomorphic patterns within relict charcoal hearths could represent unique ecosystem niches
(2023)
Hearths used for 19th and 20th century charcoal manufacturing have been found to have unique plant communities or to produce unique growth characteristics for some species but not others. Given known differences in hearth morphology, within hearth physical and chemical differences may exist and result in unique ecologic niches. We examined soil stratigraphy across 8 relict charcoal hearths (RCH) and control soils on different landforms near a 19th century furnace complex (Greenwood Furnace, northcentral Appalachians USA). Soils
were analyzed for particle size, total and trace elements, and fertility. Platform creation resulted in soils from upslope RCH positions mixed with subsurface materials on the downslope side to create a stabilized platform. The thin, uniform thickness of charcoal surface horizons (Ac) indicate that RCHs were not used more than once
for charcoal manufacturing or that charcoal was always removed very efficiently. While rubification of soil or rock from high heat was seen in 6 of 8 sites sampled, it was not extensive across sampled areas of any one hearth, which indicate hearth use may not be frequent, hot enough, or spatially disparate. Soil fertility characteristics change within RCHs but also by landscape position. Downslope RCH positions are enriched in some parameters compared to control soils (total C, Mehlich 3 Mg, Ca, and Aquia Regia digestion Mn) and that enrichment often is from the surface downward. Downslope enrichment within RCH soils may have occurred from charcoal and
released ions, slope erosion and accumulation, or transportation of constructed materials during RCH creation. Landscape position may accentuate or mute soil chemistry differences. Greenwood Furnace RCHs have unique patterns of chemistry, which could result in unique niches for flora and maybe fauna within RCH. Future research could more closely investigate whether hearths support unique species assemblages and how they may play a role in enhancing today’s forest biodiversity.
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.
Occurrence, soil parameters and genesis of Rhodic Arenosols (‘Fuchserden’) in northeastern Germany
(2018)
In the Tauer Forest, a woodland area north of the city of Peitz (Brandenburg, Germany), extensive charcoal burning was carried out from the mid-16th century to the mid-19th century resulting in numerous Relict Charcoal Hearths (RCHs). The most prominent feature of the soils on RCHs is the anthropogenically modified 20-30 cm thick RCH substrate that buries the former forest soil. The RCH substrate is a quite heterogenous mixture of mineral and organic compounds which were modified through heat during charring. It is characterized by its black color resulting from charcoal fragments (from fine dust to decimetre size pieces), lower bulk density, and higher porosity.
After their use, the charcoal production sites were abandoned and soon became overgrown. Soil formation could commence in this anthropogenically modified RCH substrate. During recently conducted field work on RCHs in the Tauer Forest we detected features of initial podzolisation (bleaching of quartz grains) within this RCH substrate. To further investigate initial processes of soil formation (acidification, podzolisation, accumulation of soil organic matter) on RCHs, two different RCH sites were selected in the Tauer Forest: one RCH site in the forest district Tannenwald and one RCH site in the forest district Kleinsee.
The Tannenwald site (RCH no. 29958) is situated in the western part of the Tauer Forest. It is an inland dune area with a coniferous forest (Scots pine, Pinus sylvestris L.) plantation. The forest soils are Podzols and the soils on the RCHs are classified as Spolic Technosols. The dense undergrowth consists of mainly blueberry (Vaccinium L.). Dendrochronological ages (determination by K-U Heußner, DAI Berlin) of charcoal pieces proof, that the charcoal hearth was used after 1655.
The Kleinsee site (RCH no. 29424) is situated in the eastern part of the Tauer Forest. The parent material is sand from glaciofluvial sediments of the Weichselian glaciation. The forest soils are Brunic Arenosols (Protospodic) and the soils on the RCHs are classified as Spolic Technosols (Arenic). The deciduous forest is dominated by sessile oak (Quercus petraea (Matt.) Liebl.). The undergrowth is only scarce with some ferns (sporadic), blueberry (Vaccinium L.), some shoots of rowan (Sorbus aucuparia L.) and some moss. There is no dendrochronological age available from the RCH, but RCHs nearby were dated from the 18th to the 19th centuries.
At both sites, three soil monoliths were sampled on the RCH platform and three monoliths from the natural forest soil as reference soils. The soil monoliths were sampled continuously in 3 cm vertical spacings. Following lab analyses were carried out: pH (CaCl2), pH (H2O), total carbon (TC), total nitrogen (TN), CECeff and total concentrations of selected elements. Analyses of pedogenic Fe are in progress. First results of these study will be presented and discussed.
Spatial heterogeneity of buried and recent soils in a drift sand area in North-Eastern Germany
(2022)
In the North European Lowland, on the sandy deposits of the Weichselian glaciation, soils developed during periods of landscape stability are often conserved under windblown sand. However, small-scale changes of sediments and other soil forming factors can result in high spatial variation of soil properties in these landscapes; and relocation of soil material by geomorphic processes further increases the spatial heterogeneity of the soil landscape. These spatial variations in soil properties and conservation need to be considered in order to correctly decipher and interpret the buried soils as records of past environmental conditions.
In the forefield of the open-cast mine Cottbus-Nord, archaeological excavations in a dune and drift sand area revealed widespread buried soils of different characteristics. The densely spaced excavation trenches give exceptionally good insights into the pedosphere, allow for reconstructing the distribution of fossil and recent soils in a high spatial resolution, and offer good opportunities to improve the understanding of spatial and temporal patterns of soil formation. Remains of postpleistocene hunter-gatherer campsites were documented in archaeological excavations and found to be associated with a buried soil horizon.
We recorded the stratigraphy of soil profiles along more than 15 trenches within an area of about 20 ha, and additionally described the position of buried soils from GPR surveys and microdrone photogrammetry. In a recently opened, 455 m long trench, all characteristic soils and sediments of the study region could be observed and stratigraphically connected. Within this trench, four profiles were identified for further research. Each profile was classified and described according to WRB and German Guidelines for Soil Mapping; and was sampled and investigated through laboratory analyses including determination of organic matter, total carbon and nitrogen contents, soil colour identification, texture analysis, magnetic susceptibility measurement, metal content analysis using X-ray fluorescence analyzer and pH measurement. The compaction and cementation of soil horizons was assessed in situ with a pocket penetrometer.
Results show a small-scale mosaic of soils developed on fluvio-aeolian, limnic and aeolian sediments, high spatial variations in pedogenesis due to varying groundwater influence and intensity of horizontal and vertical leachate transport, and high variations in the erosion or conservation of fossil soils. The soil and sediment stratigraphy reflects several phases of landscape development: i) the formation of a Late Pleistocene soil on fluvio-aeolian deposits, ii) a fossilization by aeolian sands, iii) a stability phase with intensive podsolization and peat formation, and iv) a land use-induced aeolian remobilization of the sands.
Understanding how present-day abrupt change may alter forest ecosystem services is becoming more important due to ever-growing anthropogenic stresses. Forest managers trying the adapt to anthropogenic stress can benefit from the study and quantification of past abrupt changes in forests, especially when the legacy of past disturbance is still evident. Across the United Kingdom, Europe, and recently the northeastern United States, the examination of historic forest change due to charcoal manufacturing for the firing of iron or lime furnaces is yielding new insights relative to landscape stability, anthropogenic vs natural soil genesis, and forest evolution.
A landscape classification process was used in the Central Appalachians (Pennsylvania) to identify 6,758 RCHs near Greenwood Furnace (Greenwood Furnace State Park) and Pine Grove Furnace (Pine Grove Furnace State Park). Topographic wetness index (TWI), and SAGA wetness index (SWI) were created using ~1m LiDAR data for two study areas to quantify surface hydrology effects and were compared to field soil volumetric water content (VWC) measurements. Modeled TWI and SWI values were different for RCH areas when compared to surrounding non-hearth areas indicating that RCHs were acting as a moisture sink. We also found that RCH platforms have different TWI and SWI values than rim areas. Using field measured volumetric water content, we found that as distance from the center of the RCH increases, the drier the soil becomes. Geomorphic position did not affect wetness.
Surface soil samples were collected at 51 RCHs in the Greenwood Furnace study area. Laboratory analyses revealed that RCH soils have higher C content than surrounding native soils. Furthermore, while the pH of RCH soils is like native soils, the acidity is greater in RCHs. RCH soils at Greenwood Furnace were found to have lower Mehlich 3 P concentrations and lower K potentially effecting plant growth. RCH soils were found to have higher Ca concentration when compared to native soils.
To examine within RCH differences in soil chemistry and morphology more closely, 8 of the 51 RCHs were sampled intensely along a topographic gradient. Control pits were excavated directly upslope from the RCHs. The RCHs were sampled in 5 positions across the hearth from the upslope to down slope position (A upslope rim of the RCH; B halfway point between A and C; C RCH center; D halfway C and E; E downslope rim of the RCH). Soil profiles were described and sampled at each position. The soil samples were analyzed for trace and rare earth element content (Aqua Regia digestion), soil pH (water) and fertility (Mehlich 3 extraction). Results indicated that RCHs are potentially a unique location of refugia for forest flora and perhaps fauna due to the unique geochemistry with higher bases and C and some concentrated metals and a higher soil water content hypothesized to be due to an observed restrictive morphology. Future research should more closely investigate whether RCHs support unique species assemblages and how they may play a role in enhancing today’s forest biodiversity.
Soils on relict charcoal hearths (RCHs), i.e. aged charcoal rich Technosols, feature documented legacy effects regarding their physical and chemical soil properties. These forest soils result from the pre-/early-industrial production of charcoal in upright standing hearths. Today, RCHs are found in forested areas as circular microrelief structures with average diameters of about 10 meters that contain technogenic soil horizons of about 20 cm thickness. RCH soils are most distinctly characterized by their large content of pyrogenic soil organic matter and consequently increased total carbon contents. The resulting changes in the soils’ cation exchange capacity, soil acidity, total nitrogen contents and total element stocks are often significant. Furthermore, changes in soil physical properties like a lower bulk density and a higher porosity result in changed soil-water- and temperature regimes. Combined, these effects potentially result in unique soil microhabitats that are restricted to relatively small, clearly defined areas in many forest ecosystems.
Recent studies on RCH soils increasingly focus on potential changes in microbiological and vegetational composition and abundances and report diverse effects. Here, we study the effects of century old charcoal rich Technosols on the drought sensitivity of Scots pine (Pinus sylvestris L.) on three RCH sites located in Lower Lusatia, Saxony (Germany). Through dendrochronologial analysis of increment cores and historical climate data, we study climate-growth relationships for trees on RCH soils and reference forest soils for two periods (AD 1963-1992 & AD 1990-2019). Furthermore, we determine pointer years and components of resilience to quantify the trees’ reaction to extreme weather conditions. This analysis was accompanied by soil sampling and analysis on the RCH sites and adjacent reference forest soils. Here, we present preliminary results and discuss them in the context of findings from other studies on RCH soils.
In der Niederlausitz finden sich - meist unter Kiefern- und Eichenforsten versteckt - zahlreiche Relikte der historischen Landnutzung, die bisher kaum bekannt sind. Zu den auffälligsten Formen zählen Wölbäcker und Plätze ehemaliger Kohlemeiler. In einigen Regionen der Niederlausitz ist die Verbreitung der Landnutzungsrelikte so groß bzw. ihre Dichte so hoch, dass sie prägend für die Bodenlandschaft werden. Dieser Beitrag zeigt an repräsentativen Beispielen die charakteristischen Merkmale und Eigenschaften der Böden auf Wölbäckern und Relikten von Holzkohlenmeilern (HKM).
We used a GIS analysis of environmental and historical data to identify potential areas of extensive charcoal
production in Brandenburg. The analysis was based on three assumptions (i to iii). Large charcoal kiln fields can be found in areas that i) are close to historical industrial sites, ii) are close to bog iron ore deposits, and iii) have
been continuously covered by forest during the last centuries. Information on theses parameters was gathered in an archive and literature study and from historical and recent maps. Areas with a high probability of kiln site occurrence were then determined using a simple binary additive model. In the last step, shaded-relief maps (SRMs) were visually checked for clearly visible kiln sites and soil
properties were analysed in the determined areas. In total, eight areas with a high probability of kiln site occurrence are identified for the state of Brandenburg. By visual interpretation of SRMs, high kiln site densities in these areas are confirmed. The analysis of soil maps shows that kiln fields are predominantly located on sandy soils with a low yield potential. Although further parameters and study areas need to be considered in the model in order to explain the spatial distribution patterns of charcoal production, the results indicate correlations between the location of bog iron ore deposits, historic ironworks and charcoal kiln fields.
In the sandy deposits from the Late Pleistocene in the Northern European lowlands, the local appearance of red
subsoils emerges the question of their formation and palaeoenvironmental significance. According to the WRB
this soil is classified as Rhodic Arenosols, but in the German Guidelines for Soil Mapping this soil is still unconsidered because the age and genesis is unclear. Due to the intense red subsoil, the working title of this soil is
‘Fuchserde’. Whereas rubefication is a characteristic feature of soils in regions with warm and dry summers like in the Mediterranean, the occurrence of red subsoil horizons containing hematite in soils in northeastern Germany is not an indicator for tropic or Mediterranean climate conditions. Already the appearance of Fuchserden on sandy
deposits from the last glaciation objects earlier theories that consider these soils as a relictic soil formation from
the last interglacial or even the Palaeogene or Neogene. To characterize the genesis of the Fuchserden, we focused
on four different study sites in northeastern Germany. We present our findings from soil micromorphology and the
identification of the iron(hydr)oxides by FTIR. Our results give new insights on the development of the Fuchserden
and the importance of lateral input of iron for their genesis.
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.
Geoecological legacies of pre-industrial charcoal burning – Research questions and approaches
(2019)
Der Einfluss von Relikten der historischen Köhlerei auf Bodentemperatur und –wärmeleitfähigkeit
(2019)
Die Beimengung von Holzkohle in Böden kann deutlichen Einfluss auf die physikalischen Bodeneigenschaften haben. Solche Effekte treten nicht nur in gezielt mit Holzkohle („biochar“) angereicherten Ackerböden auf, sondern auch auf den Standorten historischer Holzkohlemeiler (HKM), die in vielen Waldgebieten in großer Zahl vorkommen. Die prägendste Eigenschaft solcher Böden auf HKM ist eine technogene, kohlereiche Substratschicht, die über dem natürlich entwickelten Bodenprofil abgelagert ist. In jüngster Zeitwurden in mehreren Studien ein von den umliegenden Waldböden abweichendes Vegetationswachstum und eine abweichende C-Dynamik auf HKM festgestellt. Welche Bodeneigenschaften der HKM solche Unterschiede bewirken, ist aber noch unklar. Ein möglicher, bisher kaum untersuchter Einflussfaktor ist die Bodentemperatur. Ziel dieser Studie war es, den Einfluss von Holzkohlebeimengungen auf die Wärmeleitfähigkeit und das Bodentemperaturregime von HKM-Böden zu charakterisieren. Untersucht wurden HKM auf sandigem Substrat in der Lausitz (Brandenburg). An zwei Standorten wurden Profile auf HKM und benachbarten Waldböden für ein Monitoring der Bodentemperatur über jeweils ein Jahr instrumentiert, die Wärmeleitfähigkeit von HKM-Schicht, Ah-, fAh-und Bv-Horizont wurde im Labor bestimmt. In einem Laborexperiment wurde zusätzlich die Wärmeleitfähigkeit von künstlich hergestellten Proben aus sandigem Substrat und Holzkohlefragmenten in unterschiedlichen Mischungsverhältnissen untersucht. Die Ergebnisse zeigen eine deutlich verringerte Wärmeleitfähigkeit des kohlereichen Substrats. Damit verbunden zeigen sich im Monitoring geringere Schwankungen der Bodentemperatur auf den HKM in tiefen Bereichen des Profils, in den obersten Dezimetern wurden hingegen stärkere Schwankungen der Bodentemperatur festgestellt. Insgesamt zeigt sich damit ein noch über die technogene Substratschicht hinaus wirksamer Einfluss der typischen Eigenschaften des kohlereichen HKM-Substrats auf die Bodentemperatur.
Aged biochar enriched substrate increases SOM stocks of forest soils in the North German Lowland
(2019)
Recentfindings of more than 4000 relict charcoal hearths (RCH) in the forest district Tauer (Brandenburg, Germany) raise the question to what extent soil properties are controlled by a legacy effect of historical charcoal burning. RCH sites are characterized bya substantial admixture of charcoal fragments of varying particle sizes constituting an anthropogenic addition of carbon to the natural forest soil. Ages of about 250 years proven by dendrochronological dating of larger charcoal pieces on RCHs allow for assessing long-term effects of biochar application on forest soils. In this study, we measured the geometry and SOM content of 20 RCH sites in a selected part of the forest district. The results are the basis for a projection of RCH SOM stocks on a 40 ha forest plot with 120 RCH sites. In the range of statistical uncertainties it is shown that RCHs add between 13 % and 32 % of SOM to the SOM stock of the natural forest soil in the studied plot. These substantial amounts of SOM are so far not recognized by any soil survey or forest soil inventories of SOM and SOC stocks. In light of an increasing amount of studies that detect RCH sites in forests of Europe and the USA in the range of tens-and even hundreds of thousands, the question has to be asked how to address this legacy effect in ongoing scientific discussions about soil carbon stocks, carbon sequestration and the long-term effects of biochar application into soils.
As an alternative to the costly wet chemical analysis of soil, Machine Learning (ML) algorithms can be applied for the quantification of soil properties through prediction models. In this study, we evaluate the performances of the Random Forest (RF) algorithm and Partial Least Square Regression (PLSR), in the prediction of soil variables, including CEC, pH, total contents of C and N as wells as other elements (Al, Fe, Ca, Mn, Mg, K, and Na) based on FTIR-spectra of Relict Charcoal Hearth (RCH) soils and reference forest soils (Non-RCH). We investigate the effect of high quantities of charcoal in the soil on the prediction models. Preliminary results suggest that there is no significant difference in the results of prediction models for total N, C, and Fe contents, while the accuracy of PLSR in the prediction of pH, Mg, and Ca, and RF performance in prediction of pH and C decreased for RCH soils. Both algorithms demonstrate higher accuracies in the prediction of Al within the RCH soils. Prediction of CEC, Na, K, Mg (RF) within the RCH soils, Al (PLSR) for Non-RCH soils, and Mn and Ca (RF) for both soil types resulted in lower quality of predictions.
It can be inferred from the results that the performance of FTIR-based prediction models can be affected by the presence of charcoal in soil due to the nature of spectral features reflecting the soil composition. The presence of charcoal in soil likely alters the absorption interference and peak overlaps, which can result in lower accuracy of the prediction models. In addition to the accuracy of the prediction models, we evaluate the reliability of the weighted wavenumbers (as important variables) in each prediction, which provides information about the correlation of spectral features and chemical properties. It can be studied through the Variable Importance Plot in RF and Variable Importance on Projection through PLSR (VIPs), which show high potential for studying soil composition and metal distribution in mineral and organic soil fractions despite the observed weaknesses in weighing wavenumbers in predictions. Therefore, we assess and compare the quality of information gained regarding soil chemical properties from the algorithms besides a sole quantification of soil parameters. Furthermore, we applied the developed prediction models on a large number (n > 600) of FTIR-spectra of RCH soils to investigate the practical application of the models and thereby compare spectral derived chemical properties of the studied Technosols and reference forest soils.
Accumulation patterns of soil organic matter in forests as a legacy of historical charcoal burning
(2021)
Former field systems (FFS) in recent forest areas of Central and Northern Europe are often discernible by their characteristic morphology with slightly flattened slope areas and intermediary ridges formed by tillage and water erosion. Soils of such lynchet systems feature distinctly modified stratigraphy and properties and thereby constitute a memory of past land use. At the same time, the legacies of past agriculture affect recent forest ecosystems. High-resolution digital elevation models (DEMs) allow to identify lynchets over large areas and open up new opportunities to study the spatial distribution patterns and soils of FFS. Within our research on different land use legacy features in forest areas, we study FFS in Northeastern Bavaria (Germany) in a geopedological approach, combining large-scale mapping and spatial analysis with the description and analysis of soil properties for specific sites.
Lynchet areas (and other remnants of pre-industrial FFS) in recent forests were mapped from LIDAR DEMs for an area of 2045 km2 (972 km2 forest area). The mapping results show more than 100 km2 of abandoned field systems within the study area, mostly appearing as lynchet systems. Their spatial distribution patterns differ within the study area, mainly depending on parent material and landform. In the limestone region of the Franconian Jura, FFS occur spatially dispersed, often as considerably small, irregularly shaped parcels, presumably reflecting proceeding abandonment of less productive and accessible fields with intensification of agriculture. In contrast, FFS in the Bohemian Massif in the eastern part of our study area were often found in compounds of many regularly shaped parcels, frequently associated with deserted settlement areas.
Soil stratigraphy and properties were studied for FFS and reference positions (forest areas with no indications of former agricultural use) in six study sites, combining detailed characterization of principal soil profiles and an assessment of spatial variations of soil properties in a near-surface sampling approach. First results show that FFS soils are characterized by truncated profiles over most parts of the treads and accumulation of colluvium confined to relatively small areas upslope of lynchet risers. The depth of soil profile truncation and height of lynchet risers differ, mainly related to slope and erodibility of the initial soils. Stratigraphy of the lynchet soils indicates a gradually proceeding formation. Carbon and nitrogen contents were found to differ between FFS and reference soils and to be more homogeneous within the FFS. Carbon contents were mainly lower in the FFS, while both lower and higher nitrogen contents were observed for FFS soils, presumably related to different duration and intensity of agricultural use.
Overall, the results show that the legacy effects of past agriculture affect large fractions of recent forest areas, and can be of different quality depending on lithology of the soils’ parent material and land use history.
Soil physical properties can show high heterogeneity in forest soils, implying a high spatial variability of soil moisture and plant water availability. Legacy effects of past land use, resulting in a small-scale mosaic of anthropogenically modified and unmodified soils in forest areas, further increase this spatial heterogeneity. The soils associated with relict charcoal hearths (RCH), most prominently characterized by a technogenic layer rich in charcoal fragments, are a widespread example for such land use legacy soils in forest areas.
The objective of our study was to characterize the soil moisture regime of forest soils and RCH soils on sandy substrates in the northeastern German lowlands; and in particular to assess the long-term effect of the prolonged summer drought period in 2018 on spatial and temporal variability of soil moisture. We monitored matric potentials, soil water contents and soil temperature from June 2018 in forest soils in the Tauersche Forst (Brandenburg, Germany). Three soil profiles (one reference forest soil profile and two characteristic RCH soil profiles) were instrumented, sampled for laboratory analyses of bulk density, pore size distribution, saturated hydraulic conductivity, and persistence of water repellency; and root density distribution in the profiles was recorded.
The soils in all profiles show low porosity and plant available water contents. On RCH soils, overall porosity is clearly higher compared with the reference soils, mainly related to larger volumes of coarse and fine pores. Soil moisture monitoring shows very high spatial and temporal variability of the recorded data after the prolonged dry period in 2018, with gradual rewetting over the winter periods and only short-term fluctuations of soil moisture in reaction to high-intensity precipitation events in the summer periods. The comparison of in-situ and laboratory-based water retention data shows strong hysteresis effects during the rewetting, with increasingly clear reactions of soil water contents to precipitation events over the years following the dry period, especially in the charcoal-rich substrates. The differences in soil moisture between the dry and the wetter periods were clearly higher in the RCH soils, which, compared with the reference soils, showed higher water contents under wet conditions and lower water contents under dry conditions. The results affirm that land use legacies can clearly increase the spatial and temporal variations of soil moisture in forest areas.
Former field systems (FFS) in sloped forest areas are often discernible by a characteristic morphology with flattened slope areas and intermediary ridges formed by tillage erosion and colluvial redeposition. Soils of such lynchet field systems feature modified stratigraphy and properties and constitute a memory of past land use. At the same time, the legacies of past agriculture affect recent forest ecosystems. High-resolution digital elevation models (DEMs) allow to identify lynchets over large areas and open up new opportunities to study the FFS. Within our research on different land use legacy features in forest areas, we study FFS in Northeastern Bavaria (Germany) in a geopedological approach, combining large-scale mapping and spatial analysis with the description and analysis of soil properties for specific sites.
Lynchet systems (and other remnants of pre-industrial FFS) in recent forests were mapped from LIDAR DEMs for an area of 2045 km2 (972 km2 forest area). The results show more than 100 km2 of FFS, mostly appearing as lynchet systems. Their spatial distribution patterns differ within the study area, mainly depending on parent material and landform.
Soil stratigraphy and properties were studied for FFS and reference positions in six study sites, combining a characterization of principal soil profiles and an assessment of spatial soil property variations. The FFS soils are characterized by truncated profiles over most parts of the flattened slope areas and accumulation of colluvium upslope of lynchet risers. The depth of soil profile truncation and height of lynchet risers differ, mainly related to slope and erodibility of the initial soils. Stratigraphy of the lynchet soils indicates a gradually proceeding formation by tillage erosion. First results of soil property analyses show that carbon and nitrogen contents differ between FFS and reference soils and are more homogeneous within the FFS. Furthermore, physical properties of the FFS soils (bulk density, pore size distribution, hydraulic conductivity) are modified compared to unaffected forest soils through profile truncation and accumulation of colluvium. Overall, the results show that the legacy effects of past agriculture affect large fractions of recent forest areas, and can be of different quality depending on lithology of the soils’ parent material and land use history.
The occurrence, soil parameters and genesis of rubified soils (‘Fuchserden’) of northeastern Germany
(2019)
LiDAR-based high-resolution digital elevation models (DEMs) can now provide a centimetre-accurate image of the Earth's surface. Soil science is still in the early stages of realising how fundamentally this new technology will change our understanding of the formation, properties and functions of the pedosphere and in particular the uppermost part of it, which usually represents A horizons. With the help of high-resolution DEMs, it is possible to identify and classify small topographic features that were previously not considered in soil mapping. Therefore, precise landform analyses will be crucial in assessing variations in soil horizonation and soil stratigraphy and will provide the framework for a new perspective in Geopedology that truly integrates Geomorphology and Pedology from pedon to soil landscapes. In the digital domain, this geopedological approach is growing rapidly by using artificial intelligence (AI) to automatically identify small landforms and visualise the heterogeneity of diverse pedological information. We present the results of the study of different types of relict anthropogenic landforms (RALs) and highlight their characteristics and differences compared to natural, undisturbed soils. The origins of these relict features can vary greatly, as can their distribution, morphology and age. The analysis of high-resolution relief models in Europe and the USA shows that morphological features can be found, particularly in forest that were created in pre-industrial times. Settlement structures (e.g. stone walls, burial sites) or linear relief forms created by soil cultivation (e.g. field terraces, furrow systems) are common. Relict Charcoal Hearths (RCHs), which originate from historic charcoal burning, are usually small circular platforms surrounded by pits or ditches, but can still cover a considerable part of the area. A relatively complex geomorphology can be observed in historic mining areas, which may include different landform types such as mine shafts and spoil heaps, resulting in a very heterogeneous pedological mosaic. To summarise, all studies reveal a high variation of soil properties controlled by small relief structures. Pedology should take this more into account in the future and improve knowledge of the impact of RALs on the pedosphere and other components of ecosystems.