The maturity index applied to soil gamasine mites from five natural forests in Austria

In this study, we tested the performance of the gamasine mites maturity index of (Ruf, A., 1998. A maturity index for gamasid soil mites (Mesostigmata: Gamsina) as an indicator of environmental impacts of pollution on forest soils. Appl. Soil Ecol. 9, 447–452) in five natural forest reserves in eastern Austria. These sites were assumed to be stable and undisturbed reference habitats. The maturity indices of the gamasine communities were near their maximum in the investigated stands, and thus performed well towards the “high end” of the total range of the index. An occasionally inundated floodplain forest yielded much lower values. However, the correlation of the index with humus type, as proposed by Ruf et al. (Ruf, A., Beck, L., Dreher, P., Hund-Rienke, K., Römbke, J., Spelda, J., 2003. A biological classification concept for the assessment of soil quality: “biological soil classification scheme” (BBSK). Agric. Ecosyst. Environ. 98, 263–271) for managed forests, was not found. This indicates that the humus form is not a good predictor of the index over its entire range and is inappropriate to assess the fit of test communities. Fourteen percent of the species in this study were omitted from index calculation because adequate data for their families are lacking. They partly belonged to frequent and abundant soil families which urgently need to be included in the scheme. Our results indicate that the gamasine mites maturity index is a promising bioindicative tool, since data collection is comparatively inexpensive and fail-save (individuals must be sorted but not identified, presence/absence data are sufficient) and the results are easily understood and communicated.