BackgroundSoil microbiomes play an important role in the services and functioning of terrestrial ecosystems. However, little is known of their vertical responses to restoration process and their contributions to soil nutrient cycling in the subsurface profiles. Here, we investigated the community assembly of soil bacteria, archaea, and fungi along vertical (i.e., soil depths of 0–300 cm) and horizontal (i.e., distance from trees of 30–90 cm) profiles in a chronosequence of reforestation sites that represent over 30 years of restoration.ResultsIn the superficial layers (0–80 cm), bacterial and fungal diversity decreased, whereas archaeal diversity increased with increasing soil depth. As reforestation proceeded over time, the vertical spatial variation in bacterial communities decreased, while that in archaeal and fungal communities increased. Vertical distributions of the soil microbiomes were more related to the variation in soil properties, while their horizontal distributions may be driven by a gradient effect of roots extending from the tree. Bacterial and archaeal beta-diversity were strongly related to multi-nutrient cycling in the soil, respectively, playing major roles in deep and superficial layers.ConclusionsTaken together, these results reveal a new perspective on the vertical and horizontal spatial variation in soil microbiomes at the fine scale of single trees. Distinct response patterns underpinned the contributions of soil bacteria, archaea, and fungi as a function of subsurface nutrient cycling during the reforestation of ex-arable land.Electronic supplementary materialThe online version of this article (10.1186/s40168-018-0526-0) contains supplementary material, which is available to authorized users.

1. Uncovering the plant-soil feedback mechanisms underlying the assembly of belowground microbial communities is essential for terrestrial biodiversity conservation. However, little is known about the small-scale spatial assembly processes of distinct soil microorganisms, especially during natural restoration of ex-arable ecosystems.2. We examined the spatial structure of soil microbiomes in arable land and reforested soils to elucidate the underlying assembly processes at a small spatial scale.The analysis was based on a MiSeq sequencing database, detecting the diversity of archaeal, bacterial and fungal communities, simultaneously, from 300 soil samples along vertical and horizontal profiles during 30-year reforestation.3. Compared with environmental filtering, dispersal limitation made crucial contributions to microbial community assembly. Archaeal and bacterial communities with a wider niche breadth were governed more by dispersal limitation than were fungal communities.4. The effect of dispersal limitation on archaeal and bacterial communities increased first and then decreased over time, while the effect on fungi temporally increased. Synthesis and applications.Our results highlight the variation of assembly processes governing distinct soil microbiomes during reforestation, with dispersal limitation playing a prominent role. This finding suggests that the increase in soil microbial diversity during natural restoration is mainly due to the stochastic influx and dispersal of microorganisms. This greater understanding of microbial community assembly can contribute to more targeted and efficient environmental management practices for the restoration of terrestrial ecosystems, for example, by promoting the restoration practices and shortening the restoration period. These practices may thus be incorporated into policies developed for effective biodiversity conservation, especially the restoration and maintenance of subsurface soil microbial diversity and associated functions. K E Y W O R D S community assembly, dispersal limitation, ecological restoration, reforestation, small spatial scale, soil microbial diversity, subsurface microbiomes, terrestrial ecosystems | 403 Additional supporting information may be found online in the Supporting Information section. How to cite this article: Chen W, Jiao S, Li Q, Du N. Dispersal limitation relative to environmental filtering governs the vertical small-scale assembly of soil microbiomes during restoration. J Appl Ecol. 2020;57:402-412. https ://doi.

No abstract

Soil microbial communities are crucial for regulating the stability and degradation of contaminated land. However, the temporal response strategies of particular microbial groups to biotic introductions and their contributions to ecosystem functions and services (i.e., ‘multifunctionality’) in contaminated soils have yet to be investigated. Here, we present results from a 90‐day microcosm experiment aiming to evaluate the temporal changes in bacterial communities and functions in response to microbial and plant additions in a contaminated agricultural soil. In addition, we quantified the contributions of specific bacterial taxa with different response strategies over time to alterations in ecosystem multifunctionality in pollutant degradation (polyphenol oxidase) and the cycling of carbon (dehydrogenase), nitrogen (urease and available nitrogen), phosphorus (available phosphorus), and potassium (available potassium). Results showed that native bacterial communities exhibited strong resilience to the introduced microbial consortium and were altered by plant growth. Plant‐enriched bacterial taxa were located in the core and central positions of the co‐occurrence networks and had considerable influence on the other nodes. Plant growth substantially influenced soil multifunctionality, in a process driven by specific bacterial taxa with different response strategies. The more tolerant taxa contributed most to multienzyme activities, whereas the more affected taxa largely determined multinutrient levels in the soil. These results provide a new perspective in disentangling the roles of plant‐associated bacteria in the assembly of community interactions and ecosystem multifunctionality of contaminated agricultural soils.