Berlin Environmental Atlas

01.12 Soil Functions (Edition 2009)

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For the evaluation of the soil functions, the key soil values (cf. Map 01.06) derived from the soil-community map (cf. Map 01.01) and the associated dissertation by Grenzius (1987) were the main source. The quality of these basic data decisively determines the quality and authoritativeness of the evaluation of soil functions. From these and other information, criteria were derived (cf. Map 01.11) to permit an evaluation of the soil functions (cf. Figure 1). The method of evaluation was developed in the context of the soil protection conception procedure (Lahmeyer 2000), and later transferred to the whole city (Gerstenberg/Smettan 2001,2005). The maps presented here are based on updated basic data and improved methods of evaluation (Gerstenberg 2009).

Diagram for the evaluation of soil functions
Fig. 1: Diagram for the evaluation of soil functions

The map of soil associations at a scale of 1: 50,000, and thus also the maps for the evaluation of soil functions, are general maps which allow statements for state-level planning. Due to the generalization, necessary at that scale, small-scale differentiation of the soils which occur in reality and are definitely ecologically relevant, can frequently not be shown in the soil map, or, hence, in the functional evaluations derived from it. Detailed lot-precise statements are therefore not possible due to the scale; for this purpose, large-scale detailed mapping is required. However, the present maps are usable in these cases for initial examinations.

The soil units represented in the soil map describe soil associations, i.e., the more or less regular association of various soil types in landscape sections delimited primarily geologically, geomorphologically and/or by their water balance and utilization. With the appearance of different soil types, the ecological qualities of the soils to be evaluated here can therefore show sometimes major margins of fluctuation within a soil association.

To some extent, the evaluation of the soil associations is carried out due to the appearance of single soil types, e.g. for the certification of wet soils as potentially high-quality vegetation locations. It must be taken into account here that such soils may appear in a soil association only in an associate or subordinate position along with other types, in this case in non-wet sites. A spatial delimitation of such different ecological qualities within a soil association is not possible in a map of the scale used here.

Parameters are used in the evaluation of individual soil functions, the expression of which have generally not been measured, but rather ascertained as key values. This is a common method used in soil science even for large-scale investigations, since only in this manner is it possible to arrive at overarching statements for large areas. The main input data for key-value ascertainment are soil species, humus content and pH, which are available in the file of key values for the soil association map in sufficient detail.

The evaluation of the efficiency of the soils for the five soil functions was carried out with the three evaluation stages "high", "medium" and "low." Evaluation variations which arise due to the fact that the soil associations frequently consist of pedologically (soil-scientifically) and functionally different soil types, have been generalized.

Breakdown of the municipal area of Berlin (without roads and bodies of water) by evaluation for various soil functions
Fig. 2: Breakdown of the municipal area of Berlin (without roads and bodies of water)
by evaluation for various soil functions

[Statistical base of Figure 2 is also available as Excel-File (MS-Excel is required).]

In the result, the evaluations of the sections are distributed quite unequally between the individual soil functions (cf. Figure 2). This differing break-down of soils of low, medium and high functional efficacy is derived from the respective function itself:

  • The protection of endangered biotopes is generally viewed as the habitat function of rare near-natural plant communities, which are by definition uncommon, as are their sites.
  • Natural soil fertility is generally rather low in Berlin.
  • The buffering and filtration function in Berlin is considerably better at higher locations. This differentiation and the regional frequency of the plateau and valley-sandy areas are shown in the distribution as many "medium" and "high"-weighted sections. In addition, many near-natural bog and mire sites are included because of their high carbon-storage capacity.
  • The regulatory function for the water balance is evaluated on the basis of the exchange frequency of the soil water, and its similarity to "natural" drainage conditions, which are characterized by high evaporation and a low rate of percolation. This is the case in large parts of the forest and farming areas, so that, thanks to the relatively high share of these uses, many sections are assessed as "medium" or "high."
  • The archival function primarily protects those soil associations which distinguish the region from others and give it its characteristic mark, that which makes it special. This is in turn by definition not the "usual" or the commonplace, so that most sections are assessed as "low" here.

These differences in evaluation are intended, because they correspond to the natural spatial conditions and the differing significance of the functions.

In Map 01.12.6 the five individual maps were combined to a complete map "Efficacy of the Soils in the Fulfillment of the Natural Soil Functions and the Archival Function."

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