THE EFFECT OF COLLEMBOLAN GRAZING ON FUNGAL ACTIVITY IN DIFFERENTLY MANAGED UPLAND PASTURES - A MICROCOSM STUDY

Laboratory microcosms containing litter from three tussock grasslands were used to assess the impact of grazing by a collembolan, Onychiurus procampatus, on the abundance, nutrient release, and respiration of t he saprotrophic fungus, Phoma exigua. The fungal biomass and respirati on rate were significantly reduced only when Collembola were present i n excess of mean field densities but perhaps more typical of spatial a ggregations in the soil. A high efficiency of nutrient immobilization by P exigua was demonstrated but nutrient release was not significantl y affected by the fauna. Problems associated with the use of microcosm s in the simulation of field conditions are discussed.