The aim of the study was to analyze the presence of mites (Acari), with special focus on indicator oribatid mites (Oribatida), in control pine wood chips and pine wood chips enriched with peat and lignite inoculated with forest litter and irrigated. The study was conducted in 2013 on microplots (1 x 1 m) located within a belt of trees in a nursery in Białe Błota. The experiments included the following variants: C - pine wood chips, Ec - pine wood chips inoculated with forest litter, Ec+Pe - pine wood chips enriched with deacidified high peat (20%) (pH 5.5-6.5) and inoculated with forest litter, Ec+Ca - pine wood chips enriched with granulated lignite (20%) (granule size 1-10 mm) inoculated with forest litter.
The addition of forest litter caused an increase in total number of mites in the control pine wood chips and those enriched with peat. Mites belonging to Mesostigmata order prevailed in control chips and those enriched with forest litter and peat, while Oribatida were dominant mites in the other variants. Considering the results for the entire year, 20% addition of peat and lignite negatively affected the presence of oribatid mites, thus indicating a reduced biological activity of the substrates. The populations of oribatid mites on all microplots were clearly dominated by Oribatula tibialis, and Tectocepheus velatus and Adoristes ovatus were slightly less common.