Corticolous microarthropod communities have been analyzed in 3 sites located in Belgian Lorraine and related to their microhabitat (epiphytie cover), to phorophytes and sites. Oribatida represent ca 34 OJo of corticolous arthropods and 36 species were recorded out of a total of nearly 19000 oribatid mites. At the population level, six common species are studied in relation to seasons and habitats. At the community leve!, the structure and composition of oribatid taxocenoses are analyzed in relation to habitat and compared with the community properties observed by studying Arthropoda as a whole.