Historical land use has long-term effects on microbial community assembly processes in forest soils

Frank O. Aylward,Ernest D. Osburn,J. E. Barrett

doi:10.1038/s43705-021-00051-x

Abstract

Land use change has long-term effects on the structure of soil microbial communities, but the specific community assembly processes underlying these effects have not been identified. To investigate effects of historical land use on microbial community assembly, we sampled soils from several currently forested watersheds representing different historical land management regimes (e.g., undisturbed reference, logged, converted to agriculture). We characterized bacterial and fungal communities using amplicon sequencing and used a null model approach to quantify the relative importance of selection, dispersal, and drift processes on bacterial and fungal community assembly. We found that bacterial communities were structured by both selection and neutral (i.e., dispersal and drift) processes, while fungal communities were structured primarily by neutral processes. For both bacterial and fungal communities, selection was more important in historically disturbed soils compared with adjacent undisturbed sites, while dispersal processes were more important in undisturbed soils. Variation partitioning identified the drivers of selection to be changes in vegetation communities and soil properties (i.e., soil N availability) that occur following forest disturbance. Overall, this study casts new light on the effects of historical land use on soil microbial communities by identifying specific environmental factors that drive changes in community assembly.

Highlights

Soil microbial communities play key roles in terrestrial ecosystems, facilitating essentially all ecosystem processes [1]
These changes in microbial communities are linked to differences in community assembly processes among land uses [7], which, in turn, are driven by specific environmental factors that influence soil microorganisms [3, 4]
We predicted that changes in key soil properties following historical management would serve as an environmental filter, thereby increasing the importance of homogenous selection in structuring bacterial and fungal communities in historically managed soils

Summary

BRIEF COMMUNICATION OPEN

Land use change has long-term effects on the structure of soil microbial communities, but the specific community assembly processes underlying these effects have not been identified. All methodological details regarding sampling, lab methods, and statistical analyses are provided in the Supplementary Information For both bacteria and fungi, communities were structured primarily by neutral processes, with stochastic drift important in bacterial communities (Fig. 1). The greater influence of homogeneous selection on disturbed soil bacterial communities (Fig. 1B) likely reflects consistent bacterial responses to increased N availability, e.g., increased abundance of r-selected and nitrifying taxa [4] These increases in N availability, in turn, are likely linked to vegetation changes following disturbance, e.g., increased abundance of tulip poplar (L. tulipifera) and the historical dominance of N-fixing Robinia pseudoacacia in the disturbed sites (Table 1, S1) [19]. Ecosystem processes associated with specific fungal taxa may recover slowly or not at all following forest disturbance, as these taxa will not be quickly recruited from

Total N

Findings

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