Impact of biotic and abiotic interaction on soil microbial communities and functions : a field study

Interactions between plants, soils and microbes regulate terrestrial ecosystem functioning. Biotic and abiotic interactions can strongly affect the community structure which in turn will impact on ecological processes. Plant species with different ecophysiological traits can exert strong effects on soil biological properties. Our objective was to investigate and identify the effects of different biotic and abiotic variables on soil microbial community structure and functions and to examine if plant species with different physiological traits support different microbial communities in soils. Here, we show that 3 years of the presence of plants had direct impacts on soil function in terms of total heterotrophic respiration and on microbial biomass and microbial community structure. However, the plant species specific impact on bacterial community structure was weak, and differences were mainly driven by sample field location. The fungal community analysis gave similar results, with soil location being the most important factor driving fungal community structure. The effect of plant species on fungal community structure was weak but statistically significant. There was a strong concordance between bacterial and fungal communities (P < 0.001) which suggested that the bacteria and fungi have an influence on shaping the structure of each other’s community. Among the abiotic factors, moisture had a comparatively higher impact on bacterial communities compared to soil N and C. However, the fungal community was not affected by the soil moisture but soil N and C had a stronger impact than on the bacterial community. These results indicate that the microbial community structure in the natural environment is influenced by interactions between both biotic and abiotic factors