Soil Associations 2020

Methodology

Developing the First City-wide Map of Soil Associations

Starting Point

Aey (1991) wrote a guide on how to prepare a Concept Map of Soil Associations for the entire city. This guide was based on the method described by Grenzius (1987) for developing a Soil Association Map for West Berlin, and the Map of Soil Associations by Grenzius, which was transferred into the spatial reference system of the Urban and Environmental Information System (Informationssystem Stadt und Umwelt, ISU) by Fahrenhorst, Haubrok, and Sydow (1990). No soil association map of this or a similar kind had existed for East Berlin up to this point. The bases for the development of the Map Soil Associations of West Berlin were the trenches dug and borehole impacts conducted in all of West Berlin. These were carried out in forest plantations and agricultural areas under consideration of geomorphological-hydrological conditions, and, in populated areas, under consideration of land use. All occurring parent materials and most land uses, with the exception of those in industrial areas, were surveyed several times, and an appropriate soil-scientific mapping was carried out. Based on the analysis of this mapping, conclusions were derived for soil conditions in unmapped areas.

Many areas of the Map of Soil Associations in West Berlin have been confirmed by comprehensive soil-scientific studies, such as forests and farmland. The soil map is therefore verified for those areas. For areas with only few soil-scientific studies, the map is only partially verified. In East Berlin, sufficiently detailed soil mappings only existed for forest areas. The map in question is therefore only confirmed for these areas and serves as a concept map for all remaining areas. Mappings for further individual areas were added at a later stage. All derivations and classifications of soil associations for East Berlin, excluding the forests, had to rely on analogical inferences and any existing information. This included geological and topographic maps, soil maps, and data on land use, all of which varied greatly in accuracy, substance and age.

More precise classification models for soil associations, as well as the definition of new soil associations not described by Grenzius, were enabled both by maps and soil studies conducted in West Berlin after the publication of the West Berlin Soil Association Map, and the existing soil maps for East Berlin, especially those covering forest areas.

Due to the limitations of representing the spatial distribution of individual soil types in sufficient detail at a scale of 1:50,000, the methodology of soil associations proposed by Grenzius was maintained. This methodology involves selecting overarching geomorphological units to group spatially and materially connected soils into soil associations.

In conclusion, the whole map now serves as a Concept Map with some verified areas (partially verified concept map), which exclusively focuses on pervious soils.

Naming

The naming of the soil associations was based on the interactions of characteristic soils. The first and last soil of each soil association were specified, along with a soil typically indicative of material translocation (Grenzius 1987). In the map legend, soils of largely near-natural areas are connected by a “-“ to illustrate their relationship and linkage.

Near-natural soils are now found only in sparsely populated areas.

The structures of soils in populated areas have sometimes been heavily altered by human intervention. These anthrosols appear irregularly side by side and are connected in the legend by a “+”.

The legend is organised according to the degree of anthropogenic influence on and alteration of the soil. Near-natural soil associations are listed at the beginning; terrestrial soils are followed by semi-terrestrial soils. Soil associations of anthropogenic aggradations and erosion are listed at the end. (Translator’s note: “aggradation” describes soils and materials which have been placed somewhere by natural processes (glaciers, water flows) or human actions. Anthropogenic aggradations include deep landfills (waste and debris depots, etc.), and shallow landfill of upper layers (playgrounds, building construction sites, street construction, etc.))

Boundary Delineation

Soil associations were delineated based on the terrain features of ridges and sinks. Neighbouring units may therefore share the same starting and concluding elements. The area delineation of soil associations also had to conform to the Berlin Digital Spatial Reference System based on block and block segment areas of homogeneous use. If this method resulted in significant information loss, particularly in non-built-up and sparsely developed areas such as forests, agricultural areas, and settlement areas with low degrees of impervious soil coverage, these areas were subdivided further within the spatial reference of the Urban and Environmental Information System (ISU5) adhering to the boundaries of soil associations. Key factors in this subdivision included the boundaries of the geomorphological and geological units, contour lines, detailed soil type mappings, and boundaries of aggradations. Anthropogenic soil associations were delineated based on land use and the boundaries of aggradations or erosions. This additional subdivision of soil associations thus directly influences the formation of block segment areas within the spatial reference of the Urban and Environmental Information System (ISU5), and their regular updates.

Near-natural and Anthropogenic Soil Associations

Determining factors for soil development are parent material, prevailing soil type, relief (slope, sink, channel, gradient etc.), water and climate conditions as well as the degree of human influence. Anthropogenic influences are characterised by aggradation of natural soil material and non-natural materials (e.g. war debris, construction debris, slag and cinders), and erosion of natural soil. Important measures for anthropogenic alterations in soil include present and previous use, and the degree of impervious soil coverage. The map only shows pervious soils, independent of the degree of impervious soil coverage. The latter is used only to support the analysis of the degree of anthropogenic alterations of pervious soils in this area.

Near-natural soil associations are characterised by their distinctive soil types, geomorphological formation, substrate/ soil types, and the influence of water. They are minimally altered by humans.

The soil structure and soil associations of anthropogenic soil associations are not influenced by the topographical relief but rather by the type of use as well as the occurrence and type of aggradations. Certain transitional forms bear traces of various influences, including those from the parent material, geomorphology, groundwater levels, and partially natural soils. This is the case for soils at military training areas, former surface mining sites, cemeteries, and levelled sewage farms.

Table 4 presents the effects of human intervention on soils. It classifies the urban area into various soil association categories (anthropogenic soil associations) under consideration of historic and current land uses, damage to buildings in the Second World War, the type of construction, and the degree of impervious soil coverage.

Tab. 4: Landscape segments, land uses and their effects on soils

Soil Associations/ Collective Soil Associations/ Concept Soil Associations

Grenzius’ classification of near-natural and anthropogenic soil associations for West Berlin was applied to East Berlin using available data and drawing parallels for similar regions, considering factors such as geomorphology, land use, and water conditions. Challenges arose for areas where soil associations could not be clearly derived based on the data available, or where new combinations of land use and geomorphology appeared that were not present or previously unidentified in West Berlin. Examples of these areas are former sewage farms, sinks in plateaus, and mapped end moraines podzols. Besides the soil associations included in the Soil Association Map of West Berlin, the availability of appropriate mapping was used to develop new soil associations. In the case of insufficient information, concept soil associations and collective soil associations were developed. The soil associations used in the map thus exhibit three distinct levels of differentiation and designation:

1. Soil Associations (SA) – Soil associations in dependence on geomorphology and land use. These can be verified by field studies in the form of detailed maps, key profiles, and soil profile studies.
2. Collective Soil Associations (CSA) – These are groups of soil associations, as insufficient data for East Berlin does not allow for a differentiated categorisation of individual soil associations within the collective soil association.
3. Concept Soil Associations – Combinations of land use and geomorphology (e.g. levelled sewage farms) previously unidentified or absent in West Berlin at the time they were first recorded for East-Berlin. They have not yet been verified by soil studies.

Fig. 1: Diagram demonstrating the classification process of soil associations

Categorisation of Soil Associations

The categorisation of soil associations was carried out in several steps:

1. The actual use of each area was extracted from the land use data record. Each type of use category was linked to a specific decision tree on which the categorisation of soil associations was based (cf. Fig. 1).
2. Areas were defined as having mainly naturally developed soils or highly anthropogenic soils. Land use and degree of impervious coverage were used as criteria to pinpoint the extent of anthropogenic alterations of the soils. Other key factors included available data such as the Cadastre of Old Contaminated Sites, geological and topographic maps of various ages, building damage maps, etc. (cf. Tab. 5).
3. For areas with hardly altered soils without aggradations or erosion, and a degree of impervious coverage of < 35 %, soil associations were categorised into near-natural soils according to the decision aid in Table 6.
4. Areas with a degree of impervious coverage of >/= 35 % were classified as highly anthropogenic soil associations, depending on the type of land use and the type of development (cf. Tab. 5).

Tab. 5: Classification guidelines for soil associations based on land use and degree of impervious coverage

The classification rules presented in the figures and tables are general guidelines. It was often impossible to classify soil associations precisely, due to insufficient information on current land use or the degree of impervious coverage. Decisions hence had to be made on a case-by-case basis. The classification of soil associations in residential areas considered the development type as well as previous land uses. Residential areas located on sites formerly used for industrial purposes were considered industrial areas, e.g. the Thälmannpark residential unit. Waste disposal sites, military locations, sewage farms, and other aggradations were analysed also based on information such as maps, the Cadastre of Old Contaminated Sites, aerial photography, and expert opinions.

For soils that were confirmed not to have been heavily altered by humans, near-natural soil associations were assigned according to the process outlined in Table 6.

Tab. 6: Classification of soil associations of natural lithogenesis

Typical landscape segments with characteristic soil types, key profiles and their most important ecological properties have been defined for almost all soil associations.

Presentation on the map

Groups with uniform colour schemes were formed from the soil associations, concept soil associations, and collective soil associations for a clear presentation on the map. The grouping of near-natural soil associations was based on geomorphological units, while anthropogenic soil associations were grouped according to land use.

Update of the Map in 2003

Due to changes in the geometry of the initial map (splitting or merging of areas) and updates in land use and impervious soil coverage, the map had to be revised after a decade in 2003.

For all new areas, the soil association of the existing map was adopted, provided that a clear geometric assignment was possible, there had been no major change in land use, and the degree of impervious soil coverage fell within the definition of the previous soil association. In the case of a land use change from built-up to open space use, the previous soil association was also maintained.

If there was a change in land use from open space to built-up, along with an increase in impervious coverage, an ‘anthropogenic’ soil association was assigned. This was also the case if the impervious soil coverage increased and exceeded the category threshold.

All other new areas were assigned a soil association by expert opinion.
An important addition compared to the Soil Association Map from 1998 is the additional differentiation of the Soil Association SA 50 (regosol + calcaric regosol + hortisol) and SA 50a (calcaric regosol + loose lithosols + regosol), depending on the different parent materials including glacial sand, drift sand, fluvial sand and boulder marl. The assignment process was based on the geological overview map of Berlin and surrounding areas 1 : 100,000 (GÜK 100, Geological Overview Map). With this, the number of units in the legend increased to 76. In addition, a four-digit ID was introduced to distinguish the soil associations. The soil associations and their characteristics are stored in the soil database under their ID. The map at hand has a scale of 1 : 50,000 and is an overview map used to determine goals and measures for state planning purposes. Detailed statements about individual lots cannot be inferred, as they would require project-specific detailed maps.

Update of the Map in 2008

Due to changes in the geometry of the base map (splitting and merging of areas – as of December 31, 2005) and updates in land use and impervious soil coverage, the map had to be revised and updated once again in 2008.

The same methods from 2003 were applied here to record new areas, detect changes in land use or in the category of impervious soil coverage.

Soil Association 1251 © (transitional eutric histosol – histo-humic gleysol – dystric gleysol, kettle hole in ground moraine flat upland), an oligotrophic transitional histosol located in the Düppeler Forst area, was newly defined.
Furthermore, the findings of the following large-scale soil-scientific mappings from the Geography Department of the Humboldt University of Berlin were integrated into the map (Makki and Bíró 2008):

• sewage farms Blankenfelde,
• nature protection area and landscape protection area Johannisthal,
• landscape protection area Tiefwerder Wiesen as well as
• Tempelhofer Feld (former Tempelhof airport).

Update of the Map in 2012

Due to the changes in the geometry of the base map (splitting and merging of areas – as of December 31, 2010) and updates in land use and impervious soil coverage, the map had to be revised and updated once again in 2012.

The same methods from 2003 were applied here to record new areas, detect changes in land use or in the category of impervious soil coverage.

Furthermore, the findings of the following large-scale soil-scientific mappings from the Geography Department of the Humboldt University of Berlin were integrated into the map (Kissner 2010):

• Königsheide.

Update of the Map in 2017

Due to the changes in the geometry of the base map (splitting and merging of areas – as of December 31, 2015) and updates in land use and impervious soil coverage, the map had to be revised and updated once again in 2017.

The methods from 2003 were largely applied here to record new areas, detect changes in land use or in the category of impervious soil coverage. See Gerstenberg (2017a) for a comprehensive description of the methods.

In addition, the results of various individual mappings by the Soil Science Department of the Technical University of Berlin and the Chair of the Geography of Soils of the Geography Department of the Humboldt University of Berlin were incorporated (Böhme 2009, Makki et al. 2014a, Makki et al. 2014b, Godbersen 2007, Edelmann 2014). By integrating the results of the research project ‘Berliner Moorböden im Klimawandel’ (Berlin’s peatlands and climate change, Klingenfuß et al. 2015, Gerstenberg 2014), the location/ extent of peat soil associations and their characteristics could be defined in more detail.

The Soil Association 2441 [43a] (calcaric regosol + regosol + loose lithosols on military training area on (glacial outwash plain) moraine area of sand containing war debris and construction debris) was added as a new association. It is a part of the former military training area ‘Parks Range’ in Lichterfelde Süd.

Update of the Map in 2022/23

Due to the changes in the geometry of the base map (splitting and merging of areas – as of December 31, 2020) and updates in land use and impervious soil coverage, the map was revised and updated once again in 2022/23.

The methods from 2003 were largely applied here to record new areas, detect changes in land use or in the category of impervious soil coverage.

In addition, the results of various individual mappings were incorporated (Grottke 2015, Schmalisch 2017, Kayser 2019, Fell und Fell 2020, Hoffmann 2021, Tost 2021). By integrating the results of the NatKEV project (Kaufmann-Boll 2022), the assignment of bog soil associations and their characteristics could be defined in more detail.

The location and extent of operational and levelled sewage farms as well as existing and former war debris hills and waste disposal sites, were revised. Geomorphological units of the soil associations were adjusted based on the GK25. An additional unit, ‘meltwater deposition of the plateau’, was added, and landscape-related soil associations were assigned to it.