Greenhouse gases and the succession of soil microbial community structure and function during recovery from agriculture

Teal, T.K., V. Gomez-Alvarez, and T.M. Schmidt

Presented at the All Scientist Meeting (2011-04-15 to 2011-04-15 )

The acreage of land brought under agricultural management is expanding due to interest in biofuels and increased food production. This land conversion significantly increases atmospheric forcing from greenhouse gases, but little is know about how microbial communities are affected by and influence these fluxes. We have generated metagenomic datasets across a range of successional sites at the Kellogg Biological Station LTER, where sites have been maintained, and measures of soil chemistry and biogeochemical fluxes taken, since 1987. For two biological replicates of each of four treatments – standard row-crop agriculture (AG), early-successional (ES), mid-successional (SF) and deciduous forest (DF) – we have 16S-targeted (V6) and whole community 454 metagenomic data. This dataset allows us to explore the taxonomic and functional composition of the communities across land management practices and correlate composition with its corresponding metadata. Using 16S data, we have found that while diversity between the sites and phylum-level composition does not differ, the composition of the communities at 90% similarity differs significantly between AG, ES, and SF and DF, but not between SF and DF, suggesting an approximately 40 year recovery for microbial communities from agriculture. Additionally, we see that different classes within a phylum are represented in the agricultural sites versus the forest, for example Acidobateria GP4 dominates in agriculture and GP1 and GP6 in forest, demonstrating different niche availability, even within a taxonomic group. The same trends are observed using functional data from whole metagenomic sequencing. Here, we see that denitrification is one factor driving functional differences between communities, and denitrifier community structure is related to increased N2O flux in agricultural soils.

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