Summary:

The aim of the research was to determine the population density and group composition of soil mites (Acari), and in particular the species composition of oribatid mites (Oribatida), on strawberry plantations mulched with wood chips. Field studies were conducted in the experimental field of the Institute of Horticulture in Skierniewice in 2011-2012. The plots selected for examination were mulched with wood chips as follows: ZC - chips without additives, ZT - chips with the addition of the biopreparation TSB (unidentified Gram-negative rod bacteria), ZG - addition of the biopreparation 7GII (unidentified Actinobacteria). The control plot was a patch of grass near the experimental plots.
On the plots examined, the most abundant were oribatid mites, 16.11-18.84 thousand indiv.∙m-2. They accounted for 64.3% of all the mites in the grass patch, but significantly more of them (86.8-89.5%) were found on the strawberry plantations mulched with wood chips. A total of 17 species of oribatid mites were identified on the strawberry plots, but only 9 in the nearby patch of grass. Punctoribates punctum dominated in the grass-covered soil, while the dominant species in the mulched soil were Ramusella mihelcici or Tectocepheus velatus (depending on the experimental combination) .
The high abundance and species diversity of oribatid mites were a result of the mulching treatments, but the biopreparations used in the experiment did not affect these indicators. Mulching with wood chips improved the microclimate, protected the soil from excessive drying, and provided organic matter necessary for the life of saprophagans and development of micro-organisms (bacteria and fungi), which are also an important part of the diet of oribatid mites. Abundant occurrence of the Oribatida in soil can be of practical importance as they can be vectors for a number of beneficial microorganisms, such as saprotrophic and mycorrhizal fungi, which in turn stimulate the yield of crops.