The identification of edaphic and biotic parameters influencing diversity and activity of Acidobacteria is a prerequisite to understand their role in soil biogeochemical cycles. Here, Acidobacteria diversity changes in grassland and forest soils of different landuse were assessed by sequencing and community fingerprints (T-RFLP) of 16S rRNA. Differences in Acidobacteria community composition were found between the study regions in Germany, between grassland and forest as well as between soil types and apart from soil moisture, carbon, nitrogen, ammonium and phosphorus content, Acidobacteria were predominantly influenced by soil pH. Furthermore, the diversity of Acidobacteria differed seasonally with highest diversity in October. Stable isotope probing was performed to follow the degradation of wheat residues in microcosms of a grassland and forest soil and to identify the bacteria involved by T-RFLP analysis and (pyro)sequencing of 16S rRNA. The wheat residue degrading microbial community was dominated by members of Actinobacteridae, α- and β-Proteobacteria, whereas Acidobacteria did not play a role in early degradation of plant residues