The McMurdo Dry Valleys have no rainfall and most snowfall sublimates before wetting the soils significantly. Glacial melt streams are also seasonal, flowing for only 4 to 6 weeks per year. Consequently, hydrology does not provide significant connections among ecosystem components. Conversely, wind is a persistent daily feature of the McMurdo Dry Valleys environment throughout the year. In summer, cool air from the ice-covered oceans flows into the relatively warm valleys creating a strong thermal gradient in the valleys.

Nematodes are the dominant and perhaps best studied soil animals of the Antarctic Dry Valleys, yet the genetic mechanisms by which these nematodes can survive multiple environmental stresses, such as freezing and desiccation, are poorly known. To reveal the molecular genetic mechanisms of anhydrobiotic survival, we investigated gene expression in a desiccation and freeze tolerant Antarctic nematode, Plectus murrayi.

Soil microbes are key drivers of ecosystem processes, yet their role in regulating landscape-scale vegetation change is not known. Comprehensive studies of treeline position have noted that ectomycorrhizal fungi may be an important factor delineating the boundary between forest and tundra. Yet, these critical plant-fungal symbioses are sensitive to wildfires. Fire is the primary landscape-scale disturbance in the boreal forest and increasingly important in tundra.

Stream microbial mats are dynamic communities of phototrophic and heterotrophic organisms that develop over intra-seasonal and inter-seasonal time scales. Diatom community composition is influenced by successional processes and physical and chemical gradients that together act to shape stream benthic habitats. In ephemeral streams of the McMurdo Dry Valleys (Antarctica, MCM LTER), previous work has demonstrated that in streams across the Fryxell Lake Basin, the diatom composition in microbial mat communities is determined largely by the annual and historical flow regime.

 Tropical reef ecosystems lie at the interface of productive, populated terrestrial coastlines and unproductive, oligotrophic oceanic waters. Corals and other dominant reef organisms maintain complex symbiotic interactions with both surficial and planktonic aquatic microbial communities, but the processes defining the composition and life history of these communities are poorly understood.

The MIRADA LTERs project (see working group materials) is an  NSF-funded Microbial Biodiversity Survey and Inventory across all 13 of the major aquatic (marine and freshwater) Long Term Ecological Research (LTER) sites. The long-term objective of our study is to document and describe baseline diversity and relative abundance data for both common and rare members of microbial communities located in aquatic LTER sites and to relate this diversity to the underlying physical and chemical environment.

The distinct rhizomorphic mats formed by Piloderma fungi are significant features of the organic soil horizons of coniferous forests throughout the Pacific Northwest. These ectomycorrhizal (EcM) fungal mats have been found to cover over 40% of the forest floor in some Douglas-fir stands and are associated with a variety of physical and biochemical properties that distinguish them from the surrounding non-mat soils. As part of an NSF-funded Microbial Observatory at the H.J.

Within the last few years the topic of microbial diversity and its relationship to system function has exploded on the scene of ecology, and many new ideas and advances have come about. We held a session at the last (2007) LTER All-Scientists’ Meeting to address and compare bacteria diversity and dynamics in a range of aquatic and terrestrial soil systems exemplified by LTER Sites. We also formed a Microbial Ecology Working Group A follow-up workshop on cross-site comparisons and integrating LTER studies performed in this area was funded by the LNO and held at MSU on this topic.