Continental scaling of bacterial, archaeal and fungal communities: Preliminary results from the NEON soil microbe prototype

Background/Question/Methods

The National Ecological Observatory Network (NEON) is a national-scale research platform for analyzing and understanding the impacts of climate change, land-use change, and invasive species on ecology. Little is understood about the roles and responses of soil microbes, including Bacteria, Archaea and Fungi, in many of the continental-scale processes that constitute NEON's grand challenges. The NEON Soil Microbe Prototype was designed to measure temporal and spatial variability in microbial community composition within and among four eco-climatic domains over an annual cycle.  The prototype focused on four domains that represent a broad environmental gradient including the Southeast (Florida, Domain 3), Great Basin (Utah, Domain 15), Taiga (Alaska, Domain 19) and Pacific Tropical (Hawai'i Domain 20).  Using these archived samples, we performed phylogenetic-based analyses on DNA extracted from cores collected five times over an annual cycle from each of the domain sites.  Sequences and analyses of 16S and 18S rDNA genes to identify soil Bacterial/Archaeal and Fungal biodiversity and community similarity were generated through Roche 454 pyrosequencing using the Titanium protocol and analyzed using the Quantitative Insights into Microbial Ecology (QIIME) pipeline.

Results/Conclusions

Our data indicates that microbial communities are distincitve to each different domain, but that there is a surprising amount of overlap between geographically distant locations, particularly the Taiga and Pacific Tropical domains.  This suggests that microbial communities are not as limited by dispersal abilities as macroorganisms, but are constrained more by environmental factors.  We suggest that the environmental factors driving microbial community composition at these sites are related to soil pH and soil moisture.  Additionally, our data shows that microbial communities based on DNA-extraction vary more by these environmental factors than by sampling season.  These prototype data provide new insights into continental-scale microbial ecology and will help constrain the extent of spatial and temporal sampling necessary to capture long-term trends in microbial communities.