Coupling of Soils and Vegetation in Peatland Succession

Evidence for coupling between vegetation and soils is examined along a successional sequence from forest to bog in southeast Alaska. Soil morphology and taxonomy were determined at 19 sites along an 8-km transect extending from the coast to treeline on Kruzof Island. Patterns in soil development appear to be closely related with successional status of the vegetation at each site. During the succession from forest to bog, soils exhibit increased acidification, podzolization, placic horizon formation, and histosol development. Soil chemistry data from Kruzof Island suggest that bryophytes, especially Sphagnum mosses, play a critical role in acidification and podzolization of soils. Feedback effects of these soil processes should favor the development and spread of bog vegetation. The findings support the hypothesis that, due to the coupling of iron-bearing soils and vegetation, changes in soil morphology and chemistry along vegetation succession in upland northern forests favor the establishment and spread of climax bog communities.