The bacterial biogeography of British soils

Abstract

Despite recognition of the importance of soil bacteria to terrestrial ecosystem functioning there is little consensus on the factors regulating belowground biodiversity. Here we present a multi-scale spatial assessment of soil bacterial community profiles across Great Britain (> 1000 soil cores), and show the first landscape scale map of bacterial distributions across a nation. Bacterial diversity and community dissimilarities, assessed using terminal restriction fragment length polymorphism, were most strongly related to soil pH providing a large-scale confirmation of the role of pH in structuring bacterial taxa. However, while α diversity was positively related to pH, the converse was true for β diversity (between sample variance in α diversity). β diversity was found to be greatest in acidic soils, corresponding with greater environmental heterogeneity. Analyses of clone libraries revealed the pH effects were predominantly manifest at the level of broad bacterial taxonomic groups, with acidic soils being dominated by few taxa (notably the group 1 Acidobacteria and Alphaproteobacteria). We also noted significant correlations between bacterial communities and most other measured environmental variables (soil chemistry, aboveground features and climatic variables), together with significant spatial correlations at close distances. In particular, bacterial and plant communities were closely related signifying no strong evidence that soil bacteria are driven by different ecological processes to those governing higher organisms. We conclude that broad scale surveys are useful in identifying distinct soil biomes comprising reproducible communities of dominant taxa. Together these results provide a baseline ecological framework with which to pursue future research on both soil microbial function, and more explicit biome based assessments of the local ecological drivers of bacterial biodiversity.

Links between soil microbial communities and plant traits in a species‐rich grassland under long‐term climate change

“…We found evidence of links between plant traits and soil microbial communities despite the breadth of microbial functional groups included in our community fingerprints; the seemingly small effect sizes in our study are unsurprising, given the high microbial diversity and the potential influence of numerous soil physical and chemical properties. Soil pH in particular has an overriding effect on soil bacteria (Fierer, Bradford, & Jackson, 2007; Griffiths et al., 2011), and it is conceivable that some of the observed differences in bacterial community structure are a result of lower soil pH in the drought plots and deep microsites (Fridley et al., 2011) or a direct effect of differences in soil depth. Nevertheless, plant C:N ratios explained a greater proportion of the variation in soil bacteria compared to microsite characteristics (soil depth and pH) and the carbon construction costs of plant material explained an equivalent amount of variation in both bacterial and fungal community structures.…”

Turnover of soil bacterial diversity driven by wide-scale environmental heterogeneity

“…0.02), even in large areas of contiguous habitats, suggesting that communities of both bacteria and macroorganisms are structured by analogous processes 31 . Recent microbial biogeography studies have revealed that the main environmental filters shaping spatial microbial diversity distribution are soil physico-chemical characteristics, land use and plant cover, whereas climatic and geomorphologic filters are less important 9,11,15,37 . Similar filters were also reported to explain soil bacterial community distribution in contrasted ecological regions at the scale of France 27,34 .…”

Soil organic carbon and soil structure are driving microbial abundance and community composition across the arid and semi-arid grasslands in northern China

“…Despite the large number of studies focusing on the driving factors of microbial distribution under a specific environmental gradient at regional or local scale, studies of microbial biogeography at large spatial scales have only been initiated recently (Fierer and Jackson, 2006;Drenovsky et al, 2010;Griffiths et al, 2011;Dequiedt et al, 2011). A notable example was the investigation of bacterial biogeography in British soil (Griffiths et al, 2011). Nevertheless, few of these studies have simultaneously considered climate, vegetation and soil properties as predictors of the microbial community structure.…”

“…Wakelin et al (2008) found that soil pH was the dominant driver of microbial community structure and function in a range of Australian agricultural soils. Despite the large number of studies focusing on the driving factors of microbial distribution under a specific environmental gradient at regional or local scale, studies of microbial biogeography at large spatial scales have only been initiated recently (Fierer and Jackson, 2006;Drenovsky et al, 2010;Griffiths et al, 2011;Dequiedt et al, 2011). A notable example was the investigation of bacterial biogeography in British soil (Griffiths et al, 2011).…”