The loss of biodiversity is leading to cascades of negative effects throughout many ecosystems. In terrestrial systems, plant diversity is observed to be decreasing rapidly due to global climate change. Plant community diversity determines community assembly across multiple trophic levels. Increased interactions between species and genetic diversity in communities can lead to increased productivity and functionality of that ecosystem. Previous studies have shown that there are positive interactions between plant diversity and microbial ecosystem functions. However, the mechanisms driving changes in microbial communities and their functions are unclear. One possible explanation could be attributed to plant diversity having a positive effect on microbial diversity, resulting in higher functionality. Below-ground microbial communities provide key ecosystem functions such as soil stability, nutrient fixation, decomposition, and plant symbiosis. We predicted that an increase in genetic and species diversity would increase the richness and diversity of microbial communities. To test the effects of plant genetic and plant diversities on bacterial community diversity, we conducted a common garden experiment at Sleeping Bear Dunes National Lakeshore on Lake Michigan. We fully crossed three levels of genetic diversity within the dominant species (1, 3, or 6 source populations) with three levels of species diversity (1, 3, or 6 species) in 2x2m plots. After two years, soil from the rhizosphere was collected and processed for DNA extraction. We used high throughput pyrosequencing of the 16s rRNA for each sample and processed the metagenomic sequence data using Quantitative Insights into Microbial Ecology (QIIME) to determine bacterial community richness and diversity.
Results/Conclusions
We analyzed bacterial diversity and richness data using a two-way analysis of variance. Preliminary review has shown Shannon Diversity Index of bacterial communities increased significantly (P < 0.04) in result of the interaction between plant species and genetic diversity. Our results suggest that plant genetic diversity and plant species composition play a significant role in increasing microbial diversity and structuring bacterial communities. Changes in the microbial communities can alter effects on below-ground ecosystem functions. Our results provide further evidence for the importance for the preservation of biodiversity in order to prevent cascading declines in ecosystem function.