Abstract
Bacterial community composition is largely influenced by environmental factors, and this applies to the Arctic region. However, little is known about the role of spatial factors in structuring such communities. In this study, we evaluated the influence of spatial scale on bacterial community structure across an Arctic landscape. Our results showed that spatial factors accounted for approximately 10% of the variation at the landscape scale, equivalent to observations across the whole Arctic region, suggesting that while the role and magnitude of other processes involved in community structure may vary, the role of dispersal may be stable globally in the region. We assessed dispersal limitation by identifying the spatial autocorrelation distance, standing at approximately 60 m, which would be required in order to obtain fully independent samples and may inform future sampling strategies in the region. Finally, indicator taxa with strong statistical correlations with environment variables were identified. However, we showed that these strong taxa-environment associations may not always be reflected in the geographical distribution of these taxa.IMPORTANCE The significance of this study is threefold. It investigated the influence of spatial scale on the soil bacterial community composition across a typical Arctic landscape and demonstrated that conclusions reached when examining the influence of specific environmental variables on bacterial community composition are dependent upon the spatial scales over which they are investigated. This study identified a dispersal limitation (spatial autocorrelation) distance of approximately 60 m, required to obtain samples with fully independent bacterial communities, and therefore, should serve to inform future sampling strategies in the region and potentially elsewhere. The work also showed that strong taxa-environment statistical associations may not be reflected in the observed landscape distribution of the indicator taxa.
Highlights
Bacterial community composition is largely influenced by environmental factors, and this applies to the Arctic region
Results showed that all 35 environmental variables had a significant impact on bacterial community structure, with approximately 73% of the variance explained by environmental factors (Table 1)
While pH was previously identified as the primary driver of bacterial diversity in Arctic soils across the whole Arctic region [19], here, at the landscape scale, total organic content (TOC) was identified as the primary factor influencing bacterial community structure and was tightly linked with soil moisture
Summary
Bacterial community composition is largely influenced by environmental factors, and this applies to the Arctic region. This study identified a dispersal limitation (spatial autocorrelation) distance of approximately 60 m, required to obtain samples with fully independent bacterial communities and, should serve to inform future sampling strategies in the region and potentially elsewhere. Martiny et al [10] further demonstrated the importance of spatial scale for environmental factors identified as influencing community composition in temperate soils They found key environmental drivers differed across spatial scales—ammonia-oxidizing bacterial (AOB) community composition was dependent on distance, moisture, and vegetation cover at the plot scale; at the regional scale, diversity was mainly influenced by water temperature, air temperature, and moisture, while nitrate concentration and air temperature were predominant at the continental scale. The last aim was to identify indicator taxa which were closely associated with environmental variables and map their spatial distribution across the landscape (Fig. S1). Taxa [32] highlight operational taxonomic units (OTUs) with strong environmental associations that may respond to ecological change, we expected their distribution to closely follow that of environmental parameters
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