Permafrost (USDA Soil Taxonomy, 13th edition)
Source:R/diagnostics-conditions-usda.R
permafrost_within_usda.Rd"Permafrost is defined as a thermal condition in which a material (including soil material) remains below 0 C for 2 or more years in succession." – KST 13ed, Ch 3, p 47.
Arguments
- pedon
A
PedonRecord.- max_top_cm
Maximum depth where permafrost must occur (default 100 cm – Gelisols criterion at Order level).
Details
Permafrost is the defining characteristic of the Gelisols order (within 100 cm of the soil surface) and qualifies many subgroups across Histosols (Histels), Inceptisols, and others.
Implementation: Uses permafrost_temp_C from schema. A
layer qualifies as permafrost when its permafrost_temp_C
is <= 0 C. The function checks whether any qualifying layer
occurs within max_top_cm of the surface.