Print PageStudying soil organic matter dynamics is especially important in understanding ecosystem dynamics and carbon and nitrogen cycling in global change. Agricultural management and restoration practices are known to affect the ability of soil to store carbon. Previous studies show soil organic matter dynamics are controlled in part by soil biota. Aggressive invaders like garlic mustard and black locust are known to govern soil nutrient cycling and change microbial community. The objectives of our study are to elucidate the role played by microorganisms in controlling SOM sequestration and their response to different land use practice with or without exotic plants. Soil samples (0-10 cm depth) were collected from two experimental sites located at Sand Ridge State Forest, Illinois and Hoytville, Ohio. The Sand Ridge experiment had five treatments to examine the impacts of different methods of restoring agricultural land to perennial vegetation: pine (P), pine with garlic mustard (P+GM), pine with black locust and garlic mustard (P+BL+GM), black locust with garlic mustard (BL+GM) and prairie (Pr). The Hoytville experimental treatments included native forest (NF), conventional tillage maize (CT) and no tillage maize (NT). Partial ribosomal amplification on extracted DNA with tag encoded primers and 454 FLX titanium pyrosequencing were used to estimate microbial diversity and community composition.
Results/Conclusions
Quality trimmed sequences were clustered into Operational Taxonomic Units using CD-HIT using a 97% identity match threshold. Redundancy analysis was performed to determine whether there was a shift in community composition due to land use treatments. Among Hoytville sites, 65% of the variation in bacterial communities (p=0.015) and 40% of variation in fungal communities (p=0.01) was explained by treatment. NT sites showed greater microbial community variation than CT or NF for both fungi and bacteria. All treatments showed high species diversity (Simpson index ~ 0.99), with no significant difference in diversity among treatments. Among Sand Ridge sites, bacterial community composition was determined by the presence of black locust and garlic mustard. Species diversity was high in all sites with Simpson index of 1 for bacteria and above 0.87 for fungi. Species richness was greater in P+GM and P+BL+GM sites compared to P sites. 57% of the variation among bacterial communities (p<0.005) and 36% among fungal communities (p<0.005) was explained by treatments at Sand Ridge. This study demonstrated that the soil microbial community structure shifts with implementation of different agricultural and restoration treatments known to influence the amount of carbon stored in soil.
