ECOLOGICAL EFFECTS ASSESSMENT OF INDUSTRIAL SLUDGE FOR MICROARTHROPODS AND DECOMPOSITION IN A SPRUCE PLANTATION

Effects of dried, granulated industrial sludge-containing residues of organic pesticides and precursors were assessed for microarthropod fau na and the decomposition of a spruce forest floor. The investigation w as highly realistic, using large plots of about 1/2 ha, and the applic ation was done with professional equipment. The ecological effects of the sludge were compared with the ecological effects of an inorganic f ertilizer, Decreases in abundance of the microarthropods ranged from 2 0 to 80% of the control level after 1 year. Isotoma notabilis Schaffer was the only species that exhibited stimulation at twice the control level due to the sludge. The least affected collembolan species was Le pidocyrtus cyaneus Tullberg, a member of the surface-dwelling life for ms, Sensitive species were Isotoma anglicana Lubbock and Isotomiella m inor Schaffer. In subhabitats with almost no application of sludge due to a heterogeneous horizontal distribution, the microarthropods were still affected to the same degree as those in the zones of maximum app lication. Laboratory tests with Folsomia candida Willem gave results s imilar to the effects on field populations concerning the sludge but r evealed no adverse effects of the fertilizer, Decomposition was stimul ated to the same extent in the field by the two types of fertilizer bu t in the laboratory the sludge caused the largest stimulation. The eff ects on the microarthropod fauna are suggested to be the result of a c ombination of direct toxicity and changes in the microbial community d ue to fertilizers. (C) 1997 Academic Press.