Effects of cattle and industries on oribatid mite communities of grassland soil in the Basque Country (Spain)

The effect of industrial and cattle activities on oribatid mite communities of grassland soil was studied in the Basque Country of Spain. Environmental and community variables were studied in three grassland areas: (1) an industrial site with heavy metal pollution, (2) a cattle farming site with medium and high fertilizer inputs and (3) a natural site - the last one as control. Although the industrial areas presented high concentrations of heavy metals, they showed high biodiversity, perhaps because the metals were bound to the high clay content. Concentrations of Cd, Pb, Cu and Mg at the industrial site were positively correlated with the abundance of Oribatula tibialis, Lauroppia similifallax, Tectocepheus minor, Scheloribates minifimbriatus, Oribatella quadricornuta, Ceratozetes conjunctus and Xenillus tegeocranus. In contrast, the cattle area had poor soils with very low oribatid diversity, which was inversely correlated with the fertilizer input. The high-input cattle grassland had a fewer and less uniformly distributed species compared to the medium-input site. Species positively associated with cattle grasslands are Zygoribatula undulata, Microppia minus minus, Ceratozetes armatus, Peloptulus montanus, Scheloribates latipes and Minunthozetes reticulatus. The natural grasslands had the highest oribatid mite diversity, with species being well distributed.