Polar desert ecosystems in the high arctic have not been studied in terms of their development and function. To provide an understanding of the critical components controlling development of polar desert ecosystems, Dr. Bliss proposes to study the microclimate of soils, algal crusts, soil invertebrates and vascular plants within these systems. It is hypothesized that algal crusts, especially cyanobacteria, play a central role in soil development and to a greater extent species diversity and biomass of vascular plants. The overall influence of biota on soil development will be estimated from carbon dioxide and carbonate analysis in the soil atmosphere and in solution. To evaluate the hypothesis that the distribution of vascular plants relates primarily to water availability throughout the summer, winter snow fall and summer snow melt will be determined along moisture gradients. It is further believed that the algal crusts play a central role in maintenance of higher levels of soil moisture. Because polar deserts are one of the least understood ecosystems in the arctic, it is critical, in terms of predicted global warming to understand important components controlling development of polar deserts. Additionally, knowing how modern systems develop may provide an analog to development of systems following continental ice retreat.