ORIBATID MITES ENHANCE THE RECOVERY OF THE MICROBIAL COMMUNITY AFTER A STRONG DISTURBANCE

The effects of panphytophagous oribatid mites on the recovery of the m icrobial community in F-layer materials from beech, spruce and mixed ( beech and spruce) stands after strong disturbance (freezing and heatin g) were investigated in a laboratory microcosm experiment. Generally, oribatid mites enhanced the recovery of the disturbed systems by accel erating (1) the recolonization of litter materials by fungal species, (2) the restoration of the microbial biomass and basal respiration and (3) the stabilization of nutrient pools in the litter, i.e. minimizin g nutrient leaching. It is concluded that the accelerated recovery of the microbial metabolism was caused by dispersal of spores by oribatid mites and by grazing on microbial populations. The stimulation of the microbial metabolism enabled microorganisms to grow, thereby immobili zing nutrients in microbial biomass. However, the duration of the expe riment was too short for complete recovery of the microbial community and at the end of the experiment microbial biomass was only one third of its initial size, and heat-resistant or opportunistic fungi still d ominated. Overall, it is concluded that fungal feeding microarthropods are of significant importance for the resilience of forest soil syste ms. (C) 1998 Elsevier Science B.V.