Think of the types of plants that you would expect to see in a Hawaiian rainforest and an Arctic tundra. These plant communities look very different, however, if you examine the types of microorganisms that live in the soil in these two ecosystems, they are surprisingly similar. The fundamental reason for this difference is hypothesized to be that plants are limited by dispersal (that is, plant seeds cannot be transported to every location on Earth), but that this is not true for microbes. The atmosphere is the most likely conduit for transporting these microbial cells to their final global destinations.  However, very little is known about what types of microbes can survive harsh atmospheric conditions, whether the underlying terrestrial ecosystems influence the types of microbes in the atmosphere, and whether microbes are actually active while they are tranpsorted. If microbes are active in the atmosphere, then they may comprise a vast, uncharacterized source of biodiversity and sink for global carbon.  We are collaborating with Dr. Kristina Lemmer's group in WMU's Department of Mechanical and Aerospace Engineering to collect high-altitude samples using balloon-borne samplers. We are specifically focused on examining how land use (rural vs. urban), ecosystem type and altitude influence the composition and activity of airborne microbial communities.