Evaluation of soil biodiversity in Germany

In this project, funded by the German Federal Environment Agency (UBA) we compiled and analysed data on the soil status of permanent sites with regard to the implementation and advancement of the national strategy on biological diversity.

Background According to the German Federal Soil Protection Act (1998), one of the natural functions of the soil is its ability to act as a habitat for organisms (mainly invertebrates and microbes). So far, this function is not considered when assessing the quality of soils, e.g. in the context of landscape planning. The German National Strategy on Biological Diversity presents a vision regarding soil use: “Germany possesses a natural diversity of soils which have evolved over the course of history, are typical of the region, and fulfill a range of functions for man and nature. They offer favorable living conditions for the location-typical species and biotic communities which live in, on and from the soils. Our Aims: By supporting the natural functions, the correct functioning of soils is maintained in the long term. Good soil use practices make allowance for this fact. In consequence soil functions must be protected, e.g. the natural function of soil as one of the foundations of life for humans, animals, plants and soil organisms, as a component of the natural balance, and as a degradation, equalization and reconstruction medium for material influences by virtue of its filtering, buffering and substance conversion properties.” Aims of the project 

• Critical compilation of existing concepts and approaches in the area of biological soil classification and assessment;
• Assembly of a database on soil biodiversity in Germany, in particular collection of data from German Permanent Soil Monitoring Sites (BDF) and from literature (for Collembola, Oribatida, Lumbricidae, Enchytraeidae and microbes);
• Definition of a base-line for a soil organism inventory
• Expression of recommendations for the implementation of soil biological monitoring concepts and methods in Germany.

Concept/Approach At first a database was set up, contain relational data on the collections, organisms (species) and sites. The basis were abiotic data for German Permanent Soil Monitoring Sites (BDF),  complemented by available datasets on soil organisms, such as oribatid mites, collembolans, enchytraeids and earthworms were included. The analyses of all datasets were triggered by the distribution of all investigated sites with respect to biotope types. This was the basic idea to reach relevance at landscape level and to create a reference system. The preferences of the most indicative species of all organism groups in correlation to the dominant soil specific parameters were analyzed and compared. Species composition was analyzed using multivariate statistical methods, such as Detrended Correspondence Analysis (DCA), Principal Component Analysis (PCA) or Correspondence Analysis (CA). To find environmental parameter correlations we used Redundancy Analysis (RDA) or Canonical Corresponndence Analysis (CCA). Results (Report No.: FB 3708 72 201 to UBA, January 2012, to be published by UBA) Soil biological data included abundance or dominance data for Collembola, Oribatida, Lumbricidae and Enchytraeidae, which were analysed with respect to their distribution and relation with site (biotope type, land use) and soil properties (pH, texture, organic matter). As a result, indicator species for several biotopes, representing a specific set of exogenic and endogenic conditions, were extracted and reference values (species richness and composition, abundance) for the most important biotope types were proposed. The biogeographical distribution of selected species from the four invertebrate groups and their distribution in relation to the most important site factors (land use, pH, texture, organic matter) were presented in maps and tables (similar information for additional species was put into an Annex). Since it was not possible to perform a similar evaluation for microorganisms, the work with this group focused on a critical discussion of available methods used for the recording of their diversity. Finally, a deficit analysis concerning the state-of-the-art of soil biodiversity assessment in Germany was performed. A detailed proposal how to improve soil biological monitoring was made, focusing in particular on BDF. In this context, the ecosystem services provided by soil organisms were also considered. Conclusions The ecological classification and assessment of terrestrial field sites, in theoretical approaches as well as in its practical work like landscape planning, nature (soil) conservation or ecotoxicology (from laboratory tests to monitoring methods) lags clearly behind limnology and related sciences including aquatic ecotoxicology. To overcome thia impediment we give recommendations concerning suitable organism groups and standard methods (including – mainly microbial – genetical indicators) for a nation-wide soil biodiversity monitoring program.