Response of microannelids to tillage at soil-monitoring sites in Schleswig-Holstein, Germany

Soil decomposer communities of farmland are strongly influenced by a diversity of management practices. Among these, tillage is one principal disturbance factor for soil fauna. Its effects depend on the frequency, depth and type of tillage practices, but also on soil properties like soil texture. A major scope of biological soil monitoring is to detect long-term changes caused by a change in environmental and anthropogenic factors, including management. Therefore, on soil monitoring sites in addition to the measurement of soil chemical and biological parameters, detailed data on management practices are collected. We analysed results from the assessment of microannelids on soil-monitoring sites in Schleswig-Holstein (Germany) in relation to tillage practices. The focus was on the effects of inverting tillage (ploughing) versus non-inverting tillage in the year of sampling and on the impact of the time span between tillage event and sampling of total microannelid abundance, species number and dominance of r-strategists (Enchytraeus-species mainly). The aim was to differentiate short-term effects of tillage from possible long-term effects on which soil-monitoring sites are targeted. Sites were grouped in sandy and loamy sites as varying effects were expected according to soil texture. Grassland sites served as comparison without tillage. They yielded a significantly lower dominance of r-strategists than tilled arable field sites. Concerning the time-span between sampling and tillage, at sandy field sites, the dominance of r-strategists was significantly higher when the soil had been ploughed a few weeks before sampling. Dominance of r-strategists and total abundance of microannelids tended to decrease with increasing time lag since the last ploughing, but this relation was weak. While in sandy soils ploughing seems to be of relative importance for total microannelid abundance and r-strategist dominance, in loamy soils the total number of tillage events seems to be more decisive. No shortterm effects of tillage practices were detected for species number. It was therefore concluded that species number and species composition related parameters are suitable to detect long-term changes of the microannelid population at soil-monitoring sites.