Changes in spatial distribution of fungal propagules associated with invertebrate activity in soil

Soil fungal species density and aggregation had changed 6 months after spring burning and raking in a Wisconsin prairie. Fungal species density had increased by 29% in burned relative to raked or undisturbed plots; species density was highest at the soil surface in burned and raked plots, and lowest at the surface in undisturbed plots. Fungal propagules of the same species were less aggregated in burned and raked plots than in undisturbed. These changes imply greater mixing of fungal propagules in soil of burned and raked plots than in undisturbed plots. The physical effects of burning and raking and the properties of fungal spores do not account for the changes. It is argued that soil invertebrates are responsible for the mixing because: (1) at any depth in soil, density of mites and collembola increased concurrently with fungal species density; and (2) path analysis shows that fungal species density is equally associated with microarthropod density and root biomass after burning, but after raking, fungal species density was more strongly associated with root biomass than microarthropods.