Plant effects on and response to soil microbes in native and non‐nativePhragmites australis

Abstract

Plant–soil feedbacks (PSFs) mediate plant community dynamics and may plausibly facilitate plant invasions. Microbially mediated PSFs are defined by plant effects on soil microbes and subsequent changes in plant performance (responses), both positive and negative. For microbial interactions to benefit invasive plants disproportionately, native and invasive plants must either (1) have different effects on and responses to soil microbial communities or (2) only respond differently to similar microbial communities. In other words, invasive plants do not need to cultivate different microbial communities than natives if they respond differently to them. However, effects and responses are not often explored separately, making it difficult to determine the underlying causes of performance differences. We performed a reciprocal‐transplant PSF experiment with multiple microbial inhibition treatments to determine how native and non‐native lineages of Phragmites australis affect and respond to soil bacteria, fungi, and oomycetes. Non‐native Phragmites is a large, fast‐growing, cosmopolitan invasive plant, whereas the North American native variety is comparatively smaller, slower growing, and typically considered a desirable wetland plant. We identified the effects of each plant lineage on soil microbes using DNA meta‐barcoding and linked plant responses to microbial communities. Both Phragmites lineages displayed equally weak, insignificant PSFs. We found evidence of slight differential effects on microbial community composition, but no significant differential plant responses. Soils conditioned by each lineage differed only slightly in bacterial community composition, but not in fungal composition. Additionally, native and non‐native Phragmites lineages did not significantly differ in their response to similar soil microbial communities. Neither lineage appreciably differed when plant biomass was compared between those grown in sterile and live soils. Targeted microbial inhibitor treatments revealed both lineages were negatively impacted by soil bacteria, but the negative response was stronger in non‐native Phragmites. These observations were opposite of expectations from invasion theory and imply that the success of non‐native Phragmites, relative to the native lineage, does not result from its interaction with soil microorganisms. More broadly, quantifying plant effects on, and responses to soil microbes separately provides detailed and nuanced insight into plant‐microbial interactions and their role in invasions, which could inform management outcomes for invasive plants.

The introduced lineage of Phragmites australis in North America differs from its co-existing native lineage in associated soil microbial structure – A holistic view of plant traits and soil microbiome from a common garden experiment

“…In the present study, rst based on the comparison of α-diversity indices including observed species, chao1, Shannon's diversity index and Simpson's diversity index we found that the soil microbial diversity was similar interlineages while slight differences existed intra-lineages. Several previous studies supported our observations as they commonly found a similar soil microbial diversity between the introduced and native lineages especially in freshwater habitats (Bickford et al 2018(Bickford et al , 2020(Bickford et al , 2022Farrer et al 2021). Second, a different generic structure but a similar functional structure was present for the soil bacteria among the four groups.…”

“…Two speculations were embedded in the effects of plant pathogenic fungi: rst, NAnat is the target of plant pathogenic fungi and plant pathogenic fungi can cause harm to their growth, the bene ts of ectomycorrhizal fungi may be offset by the hurt of plant pathogenic fungi; second, NAnat is not the target of plant pathogenic fungi and plant pathogenic fungi can defend NAnat from the competition from other species (Eppinga et Since the transplanting time is different for the three groups, the fungal structure may differ due to different planting times. From the perspective of interaction between plant traits and soil microbiome, although the soil fungal structure was different among the four groups, the trait discrepancy did not exist for almost all measured traits and the effects of soil fungi on plant traits were likely weak (Bickford et al 2022).…”

“…However, the effects of Phragmites invasion on soil microbiome have been uncertain. Several researchers found that the Phragmites invasion caused slight differential effects on soil microbial composition and the difference in microbial functional composition of the soils derived from different lineages was weak, while the introduced lineage has been certi ed to cultivate higher microbial richness and pathogen abundances compared to native species especially under saline condition (Bickford et al 2018(Bickford et al , 2020(Bickford et al , 2022Farrer et al 2021; Schroeder et al…”

Bacteria common to rhizosphere communities of Asiatic bittersweet across a post-glacial landscape

“…One weakness of this work is that funds were not available to determine the distribution of fungi in these samples. This study now paves the way for future studies to test microbial-plant interactions using controlled greenhouse experiments (Bickford et al, 2022). Elucidating the mechanisms used by invasive plants for a competitive advantage over native species also has broader implications for microbially influenced plant-plant interactions.…”

Characterization of the Plant‒Soil feedback index in alpine meadow degradation and recovery: A field experiment

“…However, there are few studies on the differences in plant-soil feedback during alpine meadow degradation and recovery based on field experiments. Current research on plant-soil feedback is dominated by controlled field and indoor trials (Bickford et al, 2022;Buchenau et al, 2022;Dan et al, 2022;Dudenhöffer et al, 2022;Huberty et al, 2022), which validate the effects of plant-soil feedback mechanisms on population dynamics and community composition, and these studies have provided insight into the important role of plantsoil feedback mechanisms in community development (Kulmatiski et al, 2006). However, most studies on plant-soil feedback relationships have focused on the individual species level, and fewer study have been conducted at the community level, limiting our understanding of plant-soil feedback during community-based alpine meadow degradation and recovery (De Deyn et al, 2004;Kardol et al, 2006;Kulmatiski et al, 2006).…”