Soil microbial communities are highly complex ecological units responsible for a wide range of terrestrial ecosystem functions, most notably nitrogen fixation and the decomposition/recycling of large amounts of senesced plant tissue. Due to their close association with the soil environment, they may be particularly impacted by anthropogenic changes to this environment. Agricultural practices are of particular note due to their invasive methods of changing aboveground plant communities and various physiochemical characteristics of the soil itself. However, in many areas, farming has declined and has to an abundance of abandoned farm land. This has allowed for the recolonization of native plant communities and potential restoration of soil microbial communities. The research reported here focused on determining the impact that agricultural land use history has on soil fungal and bacterial communities. We hypothesized that the length of time since abandonment of agricultural fields will play a large role in determining soil microbial community composition. To test this hypothesis, soil samples were taken from the A horizon of various field sites in Erie Bluffs State Forest in Western Pennsylvania on the coast of Lake Erie. The sites sampled included: no longer in use agricultural fields (abandoned for either 4 or 11 years), native forest, a modified sandy ridge, and actively farmed agricultural fields. Fungal and bacterial genomic DNA was extracted from each soil sample and then sent off for next generation sequencing of the bacterial 16s rDNA V4 region and the fungal ITS region. Sequences were classified to the family level for bacteria and order level for fungi.
Results/Conclusions
Upon analysis of taxon counts, it was found that bacterial communities clustered together into two groups. One group that included still actively farmed fields and 4-year abandoned fields; and the other made up of 11-year abandoned farms and unfarmed land. N2 fixing bacteria and acetic acid bacteria were found to be more associated with abandoned farmland, while myxobacteria was more associated with actively farmed fields. However, no clear patterns could be observed for fungal communities. Further analysis will be performed on soil samples to characterize physiochemical characteristics to understand how the environment influences soil microbial communities. In addition, fungal and bacterial OTUs will be placed into functional groups, to investigate the role that land use change influences ecosystem function.