We used existing metagenomics data from eight geographically distributed soils at opposing ends of a landscape soil pH gradient and evaluated its functional differences. The large differences in soil bacterial taxonomic richness at opposite ends of a pH gradient were not strongly reflected in functional richness. However, consistent changes in the abundance of related functional genes were observed, characteristic of differential ecological and nutrient acquisition strategies between high pH and anaerobic low pH soils (figure 1). Our assessment at opposing ends of a landscape soil gradient encapsulates the limits of soil functional diversity in temperate climates, and identifies key pathways which may serve as indicators for soil element cycling and C storage processes in other soil systems. These results have been published in an open access journal ‘mBio’.
Soils collected from across Britain were used for a landscape scale assessment of microbial functional traits that were then linked to soil C. A subset of 3 sites with a land use contrast in each was used in a small-scale experiment aimed at examining the temporal trends of microbial functional traits. Results from these experiments are quite novel and will be published in a highly-reputed journal very soon. We discern two distinct pH-related mechanisms of soil carbon storage and highlight that the response of these mechanistic indicators is shaped by the environmental context. Land use intensification in low pH soils that increases soil pH above a threshold value (~ 6.2) leads to loss of carbon due to increased microbial degradation as a result of lower acid retardation of plant organic matter decomposition. On the contrary, the loss of carbon through intensification in high pH soils was linked to decreased microbial biomass and reduced microbial growth efficiency. This was in turn linked to tradeoffs with stress alleviation and resource acquisition. We conclude that more extensive land management practices at higher soil pH have greater potential for soil carbon storage through increased microbial metabolic efficiency, whereas in organic acidic soils abiotic factors exert a greater influence.
