The Influence of Soil Fauna on Decomposition by Micro-organisms in Blanket Bog Litter

SUMMARY (1) Two different methods were used to assess the influence of the enchytraeid Cognettia sphagnetorum Vedj. and the tipulid Molophilus ater (Meigen) on the decomposition of blanket bog litter. The litter and the animals were confined within bags of nylon mesh sufficiently fine to prevent significant loss of particulate matter. Loss of weight over a period of 3 months in the field was measured and also the rate of uptake of oxygen at 10 °C by the contents of the bags at the end of the field experiment. (2) The experimental results were analysed using analysis of variance and stepwise multiple regression to assess the effects of litter-type, densities and combinations of animal species, and season, on the processes of weight loss and respiration rate and also on the change of standing crop of the animals used. (3) Season, litter-type, number of enchytraeids and number of tipulids used in the experiment were all shown to have a significant influence on weight loss. One M. ater appeared to have approximately five times the influence of one Cognettia sphagnetorum of one third of its body weight. (4) The rate of uptake of oxygen by the litter bags was shown to be influenced by season and by the type of litter. The rate of respiration of bags with animals was higher than the controls but these differences were not significant. (5) The type of litter had a significant effect on the change in standing crop of C. sphagnetorum. Survival of Molophilus ater was poor except for winter 1971/2 and litter-type and the presence of Cognettia sphagnetorum had a marked effect on change in standing crop. (6) It was concluded that the experiments demonstrated that C. sphagnetorum and Molophilus ater increased the rate of weight-loss of litter and that this was due to increased microbial activity as a result of the feeding activity of the animals.