Disentangling the relative importance of spatio-temporal parameters and host specificity in shaping arbuscular mycorrhizal fungus communities in a temperate forest

Abstract

Many woody and herbaceous plants in temperate forests cannot establish and survive in the absence of mycorrhizal associations. Most temperate forests are dominated by ectomycorrhizal woody plant species, which implies that the carrying capacity of the habitat for arbuscular mycorrhizal fungi (AMF) is relatively low and AMF could in some cases experience a limitation of propagules. Here we address how the AMF community composition varied in a small temperate forest site in Germany in relation to time, space, two plant host species, and also with regard to the degree to which plots were covered with AMF-associating woody species. The AMF communities in our study were non-random. We observed that space had a greater impact on fungal community composition than either time, mycorrhizal state of the close-by woody species, or the identity of the host plant. The identity of the host plant was the only parameter that modified AMF richness in the roots. The set of parameters which we addressed has rarely been studied together, and the resulting ranking could ease prioritizing some of them to be included in future surveys. AMF are crucial for the establishment of understory plants in temperate forests, making it desirable to further explore how they vary in time and space.

Arbuscular mycorrhizal root colonization depends on the spatial distribution of the host plants

“…However, these processes could have been accelerated in the treatments in which the habitats were in the vicinity of one another and thus have given rise to our observations. Second, we believe that these results match well with a previous study we carried out at a much larger spatial scale which showed that in forest stands with high coverage of AMF-associating trees, the roots of the herbaceous understory were colonized more extensively with AMF than in stands maintaining a low-coverage of AMF-associating trees (Grünfeld et al 2019) even though they did not differ in AMF community composition (Grünfeld et al 2021). Both in Grünfeld et al (2019) and here, we observed that a relatively higher proximity to likely AMF hosts led to AMF more extensively colonizing plant hosts.…”

Temporal variation of mycorrhization rates in a tree diversity experiment

“…While Heklau et al ( 2021 ) described a significant relationship between AM colonization in the root system and OTU richness of Glomeromycota across different tree species, other studies attributed the variation in AM composition more to space than host identity or season. Analyzing the AM community composition of two understory forest plants (the deciduous shrub Euonymus europaea and the evergreen climber Hedera helix ) over different seasons, Grünfeld et al ( 2021 ) found that the physical distance between samples exerted a stronger influence on AM community composition than either sampling time or host specificity. In consequence, they encountered only a low seasonality in AM community composition.…”

“…In consequence, they encountered only a low seasonality in AM community composition. However, Grünfeld et al ( 2021 ) based these conclusions on molecular analyses without testing morphologically if arbuscules and vesicles as structures of active AM were present in the cortex cells of the host organisms.…”

Soil moisture and competition determine soil biota effects on invasive Centaurea stoebe

“…Richardson et al (2000) suggested that AM fungi likely play a small role in invasion outcomes due to the lack of host specificity in this symbiosis. However, AM fungal communities can differ between heterospecific neighbors (Bunn et al, 2014; Eom et al, 2000; Grünfeld et al, 2021; Reinhart & Anacker, 2014), suggesting some degree of host preference. Furthermore, plant species vary inter‐ and intraspecifically in their response to AM fungi (Koch et al, 2017; Reynolds et al, 2006; Walder et al, 2012).…”