N-138. Microbial Succession along a Glacial Foreland Chronological Sequence in the High Arctic, Spitsbergen, Norway

U. Schütte1, Z. Abdo1, S. Bent2, C. Williams1, M. Schneider1, B. Solheim3, L. Forney1;
1Univ. of Idaho, Moscow, ID, 2Yale Univ., New Haven, CT, 3Univ. of Tromsø, Tromsø, NORWAY.

The report of the Intergovernmental Panel on Climate Change (IPCC) from 2007 states that average arctic temperatures increased at almost twice the global average rate over the past 100 years. Glacial retreat and physical weathering of rocks and minerals expose new habitats inducing primary succession. While primary succession has been extensively studied in plant communities, little is known about succession in bacterial communities even though microorganisms have key roles in soil development, biogeochemical cycling, and plant succession. In this study we examined primary succession of bacteria along two chronological sequences (chronosequences) in a glacial foreland in the High Arctic. The High Arctic is particularly suitable for studies of primary succession of bacteria because vegetation cover is sparse and chemical weathering following glacial retreat has not occurred to any significant extent. Our aims were to investigate the effect of several factors on the structure of microbial communities structure, including time after glacial retreat, horizontal variation caused by the distance between chronosequences, and vertical variation at two soil depths. To accomplish our aims we sampled extensively along two chronosequences and determined community composition by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes. The data were analyzed using a model-based approach new to the field of microbial ecology. Our results showed that succession occurred in both the surface and mineral soils. We propose that at least three processes may account for the changes in microbial communities of glacial forelands, autogenic succession, changes in plant community composition and diversity, and physical mechanisms that affect both the microhabitat and microclimate. These data show that succession occurs in microbial communities of glacial forefields, and that microorganisms should be considered in studies done to understand the impact of glacial retreat on High Arctic terrestrial ecosystems.