Plant communities mediate the interactive effects of invasion and drought on soil microbial communities

Abstract

Soil microbiomes could play a major role in ecosystem responses to escalating anthropogenic global change. However, we currently have a poor understanding of how soil microbes will respond to interacting global change factors and if responses will be mediated by changes in plant community structure. We used a field experiment to assess changes in soil fungal and bacterial communities in response to plant invasion, experimental drought, and their combination. In addition, we evaluated the relative importance of direct versus indirect pathways of invasion and drought through changes in associated plant communities with structural equation models. We found that fungal communities were interactively structured by invasion and drought, where fungal richness was lowest with invasion under ambient conditions but highest with invasion under drought conditions. Bacterial richness was lower under drought but unaffected by invasion. Changes in the plant community, including lower plant richness and higher root biomass, moderated the direct effects of invasion on microbial richness. Fungal and bacterial functional groups, including pathogens, mutualists, and nitrogen metabolizers, were also influenced by plant community changes. In sum, plant communities mediated the effects of interacting global change drivers on soil microbial community structure, with significant potential consequences for community dynamics and ecosystem functions.

Leaf δ15N, δ13C and Their Associations with Soil Fungal Biodiversity, Ectomycorrhizal and Plant Pathogenic Abundance in Forest Ecosystems of China

“…However, precipitation is an important factor in the dry north. High soil moisture can inhibit rhizomicrobial activity (Song et al 2018), high fungal diversity can help plants to resist the adverse effects of drought (Fahey et al 2020), thus causing the fungal Shannon index to decrease signi cantly as MAP increased (Preece et al 2019). Furthermore, the fungal Shannon index decreased signi cantly with longitude from the dry west to the wet east in North China in the present study.…”

“…Furthermore, the fungal Shannon index decreased signi cantly with longitude from the dry west to the wet east in North China in the present study. Similarly, the relative abundance of ectomycorrhizas decreased as longitude increased, which may be due to the lack of soil moisture for microbial activity and biodiversity in low MAP zones (Song et al 2018;Preece et al 2019;Fahey et al 2020). As the soil becomes more waterlogged in the east, trees rely more on mycorrhizal fungi to protect their roots against the adverse effects of excessive soil moisture (Erlandson et al 2016), which explains why the relative abundance of EMF increased as longitude increased in high MAP zones in the present study.…”

Microbial’s Effects on Invasive Grass’ Response to Water and Nutrient Stress

“…Despite research focus has shifted to below-ground mechanisms of invasion, which has provided valuable insights into the role of soil microbes in invasion (20), the eld is still in the early stage. One possible mechanism is the alterations in soil microbial communities, which can be exacerbated by climate change (21,22). For instance, shifts in microbial community composition and bacterial diversity under drought could be linked to changes in biogeochemical processes that in uence the availability of resources (23), whereas current ndings are inconsistent (24,25).…”

“…An experiment in semi-arid grasslands showed that soil microbial community structure is unaltered by plant invasion and nitrogen fertilization (26). Conversely, another study showed that plant communities mediate the interactive effects of invasion and drought on soil microbial communities (21).…”

Invasive grass dominance over native forbs is linked to shifts in the bacterial rhizosphere microbiome

“…Although Fibrobacteraceae is typically lower in abundance in soils with high heavy metal content [74], this family is also positively associated with invasive grass dominance [78].…”