PS 49-51
Chronic nitrogen deposition alters the functional potential of soil microbial communities in northern hardwood forests
The extent to which terrestrial ecosystems function as a sink for anthropogenic carbon dioxide is, in part, contingent on their response to future rates of atmospheric nitrogen deposition. Soils store ~30% of carbon in terrestrial ecosystems, where the cycling and storage of soil carbon is mediated by litter decay processes. Our study utilized a metagenomics approach to explore the functional potential of microbial communities and to give insight into how these communities may respond to future levels of atmospheric nitrogen deposition. To examine this, we collected forest floor samples from four replicated experimental northern hardwood forest stands receiving N deposition for the past 20 years. Illumina shotgun libraries were created from DNA extracted from the forest floor.
Results/Conclusions
Between 26,000 and 38,000 sequences were generated from each sample. MG-RAST hierarchical classification clustering analysis on functional subsystems demonstrated that the metagenomes of microbial communities exposed to experimental nitrogen deposition differed in functional attributes from those under ambient nitrogen deposition. Across site clustering analysis and KEGG mapping revealed differences between metagenomes under ambient conditions. Our analyses imply that chronic nitrogen deposition has impacted the physiological diversity in the soil microbial communities, a change that has occurred in concert with a reduction in decay, the accumulation of soil organic matter and enhanced leaching of phenolic dissolved organic carbon.