Summary:

The study was conducted in the experimental field of the Institute of Horticulture in Skierniewice, on strawberry plantations mulched with wood chips and in a nearby patch of grass. Seasonal dynamics (in spring, summer, and autumn) of the occurrence of soil mites (Acari), especially of oribatid mites (Oribatida), were studied on 6 occasions during the seasons in 2011-2012.
Already in the first season of the study, high numbers of mites - 26.91 thousand indiv. • m-2, were found in the mulched soil of the strawberry plantations. Among these arachnids, the predominant group were oribatid mites (98.2%). The density of mites, especially of the Oribatida, in the wood chips during the vegetative period was more uniform than in the grass patch. The mulch used in the experiment provided favourable environmental conditions for the development of most Oribatida species.
There were 12 species of Oribatida found on the strawberry plantations, and 9 in the nearby grass patch. The number of species in the grass-covered soil ranged from 5 to 8 in the successive seasons. In the wood chips, by comparison, there were 7 taxa at the beginning of the study, and at the end of the cycle the number increased to 11. The differences in the diversity of Oribatida species, calculated using the (s) ratio between the beginning and the end of the test cycle, were statistically significant.
Depending on the time of examination, the following oribatid mites dominated on the strawberry plantations mulched with wood chips: Ramusella mihelcici - season 1, 2 and 4, Tectocepheus velatus - 3 and 5, and Scutovertex sculptus in season 6. Clearly the dominant species in the grass patch (D = 41.4-75.5%) was Punctoribates punctum. The highest density of its occurrence was recorded in the spring of 2011 (35.04 thousand indiv. • m-2).