Soil microbiome of wetland plant species. Context dependency of soil microbes in mesocosm

Soil microbes are an important component of the tightly connected plant-soil-microbe (PSM) systems. PSM systems in general, and the soil microbial community in particular, are influenced by both biotic and abiotic factors, which are known to greatly influence the abundance, community structure, and activities of soil microbes. The objectives of this study were to determine the effect of 1) changing environmental conditions (= context dependence), namely differences in soil type, hydrology and nutrient levels, and 2) the presence or absence of plants on soil microbial community structure. Based on the results from our previous field study as well as literature sources, we hypothesized that: 1) soil microbial composition would be most impacted by nutrient addition, with the other environmental factors, water level and soil type, having secondary impacts; 2) interactions between these environmental factors will have greater influence on microbial community structure than individual effects; 3) there will be a context-dependent shift in the dominance of r and k strategists, with r strategists favored in nutrient-richer, moist but not saturated conditions; and 4) since the field study showed that the wet grasslands are plant-dominated systems, plant growth promoting microbes will be the dominant groups in most if not all of the different treatment combinations.