Tillage-induced changes in the functional diversity of soil biota - a review with a focus on German data

An assessment of the functional and structural biodiversity in arable soils, considering the impact of different tillage systems, is needed in the interest of conserving biodiversity and the ecosystem services provided by organisms. Thus, a survey of the scientific literature published over the past six decades was conducted. We concentrated on data from agro-ecosystems in Germany as they cover a wide range of different soils representative for temperate regions. The state of knowledge was analyzed with regard to the impact of conventional, conservation and no-tillage management on lumbricids, collembolans, mites, enchytraeids, nematodes and microbiota. Interaction effects between tillage intensity and parameters characterizing the respective system (e.g., soil texture and crop) were considered. Besides the abundance and biomass of soil organisms, species richness and individual densities of taxonomical and functional units, enzyme activities, various quotients indicating microbial-driven soil processes and infestation rates of soil-borne pathogens were included in the analysis. The integrating analysis of the datasets indicates that soil biota responds specifically to tillage systems. Whereas abundances and species diversity of lumbricids increased significantly, individual density and species diversity of collembolans decreased significantly when tillage intensity was reduced. Tillage-driven impacts on lumbricids and collembolans differed depending on soil texture, whereas those on nematodes and microbial communities varied depending on soil depth. Functional groups within certain taxa show differing tillage-induced impacts. Linking several datasets on various indicator organisms clearly show that the decision on which tillage system should be applied must be taken for each individual case considering local soil characteristics.