The soil microbial community as a whole: compositional changes in soil bacterial and eukaryotic communities through time and in times of perturbations

Ondertitel:compositional changes in soil bacterial and eukaryotic communities through time and in times of perturbations

Korte inhoud:Soils are without a doubt among the most important habitats on Earth, supporting an extraordinary diversity of microbial life. These soil microbial communities play a crucial role in maintaining ecosystem functions, soil health, and fertility. Despite growing interest and research into the soil microbiome, key questions remain unanswered. Notably, It is currently still unclear how a given soil microbial community composition is determined after initial colonisation, and whether this composition changes according to seasons or over longer time periods. Furthermore, it is also unclear how soil microbial communities react to drastic and repeated changes in the environment. Solving these knowledge gaps is necessary if we are to predict soil microbial responses in the future, especially in the context of ongoing climate change. This thesis is divided into two main parts. The first part explores spatial and temporal variation in soil microbial communities and investigates the extent to which these changes are driven by soil variables. Using unique datasets from global sampling efforts and long-term monitoring programs, we examined seasonal patterns and microbial stability over time. Remarkably, only a small subset of microbes displayed consistent seasonal cycles, and overall community composition was not stable across a three-year period. Furthermore, temporal changes in bacterial, fungal, and protist communities were correlated, suggesting potential intergroup interactions. We also observed a strong link between spatial distance and microbial community composition. The second part of the thesis focuses on biotic interactions and the impact of repeated drought events. Through a controlled experiment, we assessed the role of arbuscular mycorrhizal fungi (AMF) and drought stress on plant performance and microbial communities. While AMF generally promoted plant growth and survival under normal conditions, their presence during droughts led to unexpected outcomes. Plants exposed to repeated droughts adapted better than those facing a single event, whereas soil microbes showed minimal response to a single drought but significant shifts after repeated ones. Surprisingly, AMF presence during droughts negatively affected plant performance and caused greater changes in bacterial communities. In conclusion, our findings demonstrate that true seasonality of soil microbial communities may be very rare, and that soil microbial communities may never truly stabilize. Moreover, while plant symbionts like AMF are typically beneficial, their role under stress conditions may be more complex. As climate change intensifies, understanding soil microbial dynamics becomes increasingly urgent, reinforcing the importance of soil ecology as a global research priority.

Jaar van publicatie:2025

Trefwoorden:Biology

Toegankelijkheid:Open