click on magnifying glass below

Click on a magnifying glass below to find out more about humus forms

Generally, mor humus forms are associated with coniferous forests at relatively nutrient poor sites. Mull humus forms are more likely to occur where deciduous forests grow atop faunally and bacterially active soils. Moder humus forms are found at sites where conditions are not favorable to the development of a mor or mull, but somewhere in-between.
explore the forest floor


  • To introduce students to the properties of forest floors, the processes that occur in forest floors, and the description of forest floor
  • To introduce students to organic horizons under well drained and poorly drained conditions.
  • To introduce students to the main types of humus forms, and provide students with the tools to undertake a basic humus form classification
  • To identify the forest floor as an integral component of soils and forest ecosystems

The forest floor influences, and is influenced by, the vegetation growing at any given location. Material shown on this website follows the taxonomic classification of humus forms derived by Green et al. (1993) and soil horizon description as presented by the Soil Classification Working Group (1998). As such, this information is most relevant for forests of coastal British Columbia, Canada.