Environmental changes such as global warming and nitrogen deposition are having an impact on microbial communities in forest soils. Discovering the importance of these phenomena is crucial to understanding and predicting the extent of the changes impacting life in the soil.
The soils of several stands were subjected to various experimental treatments such as warming, addition of nitrogen and an increase in the amount of light received under the canopy. Among all the treatments, the history of the plots had the greatest effect on the structure of the microbial community. Old-growth forests have a greater abundance of endomycorrhizal fungi and actinomycetes, both of which form symbioses or commensals with plants, including trees. Microbial and floristic communities are co-constructed in old-growth forests, but not in recent forests. Warming and nitrogen fertilisation have not altered the composition of soil bacterial life. Increased light, on the other hand, has led to some changes.
The results of the study show that the history of forests shapes soil microbial communities. The strong links forged between these communities and the trees in these old-growth forests probably help to improve resilience in the face of environmental change.