Ground char [Depth of burn]
n. Visual estimate of burn severity that serves as an indicator of potential root damage or soil heating.
Ground char, also referred to as “depth of burn,” is a surrogate measure for the downward heat pulse into the soil and is used to determine burn severity and potential root damage (Ryan 1982). Ground char is usually measured in ground char classes (see table 1 below). These classes, developed by Ryan (1982), describe the burn severity around the base of an individual tree as evidenced by post-fire soil and vegetation characteristics (see table 1 below). The classes described in the National Park Service’s Fire Monitoring Handbook (USDI National Park Service 2001) can be assessed at the individual-tree level or plot level (see table 2 below).
Table 1. Ground char classes developed by Ryan (1982).
Table 2. Ground char classes in Fire Monitoring Handbook (USDI National Park Service 2001).