Oribatid (Acari: Oribatida) diversity in natural and altered open arid ecosystems of South-Eastern Caucasus

Data was collected in arid and semi-arid areas of Kakheti Region (south western Georgia), which is characterized by low annual precipitation (600mm on average), cold winters and hot, dry summers. Field sampling was conducted in November 2017, and April and June of 2018 in three geographic units – Shiraki and Eldari valleysand Gareji semi-desert. These territories are (or have been) used for intensive agriculture like tillage and grazing for a long historical time. Only small patches (usually hardly accessible areas of the region) are preserved more or less in a natural condition either with domination of wormwood or saline semi-deserts. Semi-desert ecosystems are generally distributed on 150-700 m altitudes, while dry grassland vegetation can be found at foothills of 300-700 m a.s.l. (Sakhokia 1958). Oribatid mite communities were studied in three types of ecosystems with different disturbance class: (1) Arable lands with severe (ASE) and moderate (AME) erosion; (2) Pasture lands with heavy (PH) and moderate (PM) overgrazing; (3) Natural grasslands with severe (NSE), medium (NME) and no (N) erosion. For each disturbance class (7 in total) nested in three geographic unit (Shiraki, Eldari and Gareji) three sites of 50 m2 were established, and in each site three soil samples of 10cm3 volume were taken. In total 63 sites were investigated and 189 soil samples were collected three times seasonally.