Vegetation indicators of organic soil properties in Minnesota

Vegetation is the main surface indicator for properties of organic soils. The presence of certain taxa of common vascular plants can be used to classify sites as oligotrophic (surface soil water pH < 4.4), mesotrophic (pH 4.4-5.6), or eutrophic (pH > 5.6) with about 90% accuracy. The significance of trophic status to plants and the ease with which it can be mapped from native vegetation suggest that trophic phases of certain organic soil mapping units should be recognized in soil survey. Vegetation structure (the basal area of coniferous and hardwood trees, and the percent cover of shrubs, herbaceous plants, and mosses) and pH are weakly related to the degree of peat decomposition, the basis for suborders or organic soils in Soil Taxonomy. Extensive field sampling is therefore necessary to taxonomically based units of Histosols.