Organic soils of Canada: Part 2. Upland organic soils. (Special Issue: Soils of Canada.)

摘要

Soils from upland moderately well-drained environments with thick accumulations (>10 cm over lithic contact; >40 cm over mineral soil) of folic materials (forest materials, branches, roots, and other non-wetland materials) are classified within the Folisol great group in the Organic Order since the 1987 revision of the Canadian System of Soil Classification. The Folisol great group correlates to Folist in Keys to Soil Taxonomy and Folic Histosol in World Reference Base for Soil Resources (FAO). Two subgroups - Hemic and Humic Folisol - account for most Folisols addressing the state of decomposition of folic materials. The Lignic and Histic Folisol subgroups identify specific kinds of folic accumulations. Folisolic soils can occur throughout Canada, in forest, heath, and alpine ecosytems with cool, moist, humid environments, but are most prominent within the Pacific Maritime Ecozone; areal extent in Canada is ~12 505 km2. The main genetic process is the accumulation and decomposition of the folic materials that lead to distinct F and H horizons. Recommendations for research needs are presented to address outstanding taxonomic questions for: 1. Classification of Folisols as a separate soil order; and 2. Taxonomic protocols for lowercase suffixes for the L, F and H horizons and the need for enhanced humus form classifications. Some of the historical proposals to address these issues are discussed. Folisols should be considered extremely sensitive environmentally because of their markedly different genetic development being dependent on thick accumulations of folic materials, their limited and unique distribution in Canada, and their importance for forest sustainability.