Oribatid mite species richness and soil organic matter fractions in agricultural and native vegetation soils in Western Australia

We contrasted oribatid species richness and the distribution of carbon (C) and nitrogen (N) in organic matter (OM) density and size fractions in agricultural fields with the closest area of native vegetation at three locations in the Western Australian wheat belt. Few studies have quantified oribatid richness in WA soils and none has investigated the impact of agriculture on these animals. A total of 22 oribatid species was identified from the samples, of which 8 were found in agricultural fields. A maximum of 5 species was found in individual agricultural fields, and a minimum of 11 species was found in the individual native vegetation areas. There were few differences in the mass of C and N in OM fractions between native and agricultural areas, and no correlation between mite abundance and mass of C in the density and size fractions of soil OM assessed. Therefore, soil disturbance, and not soil OM levels per se, is the likely cause of the low species richness at the agricultural sites.