This project will study factors controlling carbon flux from two tundra types that are largely differentiated on the basis of the underlying soil type: acidic vs. non-acidic. The factors leading to flux of carbon from each tundra type will be determined in order to examine the role of climate on landscape vegetation and subsequent carbon release or sequestration. A combination of field, laboratory, and modeling studies will be preformed to examine the factors controlling carbon flux in each tundra soil type. A model will be developed to look at possible future scenarios for warmer climates so that the role global warming in the Arctic may be assessed. The study is critical for understanding climate impacts on tundra composition and concomitant carbon flux on a regional scale. Current understanding of tundra soil effects on carbon flux are limited to only one soil type in spite of the prevalence of the other type as well.