The use of predatory soil mites in ecological soil classification and assessment concepts, with perspectives for oribatid mites.

Gamasina are the main predators among the soil mesofauna and, therefore, have a crucial position in the soil food web and contribute significantly to energy and matter turnover. Ecological concepts including predatory mites in soil assessment have not yet been established, while standardized sampling, extraction, and conservation methods are available. There are reliable keys for Europe that cover most families. Few species in low dominance ranks correlate well with soil properties like soil texture and pH. Meaningful endpoints for soil assessment are community parameters that are based on the life history of the species (e.g., Maturity Index). It has been shown that the predatory mites, as well as the oribatids as a second common and widespread group of mites, fit well into a soil assessment concept comparable to RIVPACS, which was established for aquatic systems. Perspectives for future research are the development of a computer-aided identification key and the creation of a database with information on the ecology and biogeography of important species.

Considerations for the use of soil ecological classification and assessment concepts in soil protection.

In comparison with other environmental compartments, the protection of soil was identified relatively late as an important issue. Even later, policy makers and the general public considered the ecological functions of the soil. However, recently, the central role of these functions, as well as the importance of the soil organism community, has become obvious in several countries in Europe and in the European Union itself. In this contribution, basic considerations referring to use of ecological endpoints for the classification and assessment of soils are discussed. The article begins with two goals of protection: to protect soil so that it can function and to protect soil as a habitat for organisms necessary for these functions. Afterward, the quality of soil from is discussed from a biological point of view. Finally, on the basis of experience from limnology and botany, recommendations are made for monitoring programs. In other articles of this series, details of the entire approach to ecological classification and assessment are outlined.