Humusica 2, article 12: Aqueous humipedons – Tidal and subtidal humus systems and forms

Soils formed in tidal and subtidal environments often do not show sufficient accumulation of undecomposed plant tissues to be classified as Histosols. In this article we present a first attempt of morpho-functional classification of aquatic humus, a revision of the terminology and of the diagnostic features employed by pedologists in the description of aqueous and submerged soils, and we finally suggest some criteria to be used during field investigations. According to the proposed criteria, Redoxi, Reductitidal, and Subtidal humus forms can be distinguished in aquatic systems, avoiding any possible confusion with Histic, Epihisto, Hydro and Para Anaero/Archaeo or Crusto humus forms. The article concludes with some examples of classification, including prefixes for detailing particular intergrades with the other groups of humipedons and with the discussion of the contribution of algae and seagrasses to the formation of Crusto forms.