Factors affecting the distribution and community structure of fungi in a mixed temperate forest

Background/Question/Methods

The spatial distribution of microbial taxa in the environment is a result of two main processes: dispersal and the availability of suitable microhabitat for establishment. Microbial taxa differ widely with respect to both of these factors. Studies have shown the importance of microhabitat properties such as nitrogen content, pH and dominant vegetation on fungal communities, however no study has systematically addressed spatial dependency within these relationships. Furthermore the extent to which current theoretical principles of community ecology explain these distributions. To address these knowledge gaps we designed a hierarchical series of experiments to explore the importance of spatial distribution and microhabitat suitability on structuring fungal communities in the landscape. Here we discuss the first of these experiments where we focus on the effects of dominant vegetation and spatial distribution.

Soil fungal communities were analyzed under replicated stands of spruce, beech and oak across a mixed temperate forested region (~100km²). Samples were collected seasonally with litter and soil horizons analyzed separately. Soil nutrient analysis (C, N, P, OM), fungal biomass (ergosterol) and enzyme potentials were measured for each of the horizons. The replicate sites encompassed the natural variation of parent rock types, slope, aspect and elevation of the region.

Results/Conclusions

Results from 454 pyrosequencing indicate that fungal community structure and general edaphic conditions across the replicates were most affected by the dominant tree species, suggesting the large influence of tree species on shaping soils abiotically and biotically. Litter and soil horizon samples differed considerably. Deciduous tree stands (beech and oak) show a tendency towards greater seasonal variation in both horizons, likely due to the large seasonal variation in root exudate abundance and litter quality. Fungal taxa with different dispersal strategies showed varying patterns of spatial distribution.