Much of the previous research on arctic soil biogeochemistry has focused largely on the effects of climate, organisms, and relief rather than on geologic factors. However, a few studies of limited scope suggest that biogeochemical cycling in tundra soils may be significantly affected by variation in glacial history. To determine if variation in landscape age-related differences in geochemistry influence rates of organic matter decomposition in tundra soils, we conducted soil analyses and a 5-mo soil incubation study across a chronosequence of landscape ages in northern Alaska. Our results indicate that there were landscape-age related controls on microbial activity, with higher microbial biomass, rates of respiration, and production of dissolved organic C (DOC) and N (DON) in soils from the older landscape ages than in soils from younger, less weathered landscapes. This biological boundary corresponded to a chemical boundary, as older soils had lower pH (4.5-5 vs. 6.5) and exchangeablecation concentrations than the youngest soils. There were no differences among landscape ages in total C stocks in organic soils; however, total N stocks in the organic soil decreased with increasing landscape age. Differences among landscape ages in microbial activity due to geochemical variation may have important consequences for tundra C budgets because differences in soil pH and cation content exist throughout the circumpolar region.