Relationships among indices of fire severity in riparian zones

There is no standard quantitative measure of fire severity. Although different measures of fire severity are often assumed to be closely related, information on the relationships between these measures of fire severity is limited. Information on the relationship between various fire severity indices is particularly lacking for riparian zones, critical areas of the landscape for both habitat and water quality. The present study explores relationships among several ground-based and remotely sensed indices of fire severity in riparian areas of recent fires in Oregon, including ground-based indices of overstorey fire severity (crown scorch and basal area mortality) and understorey fire severity (height of bole char and exposed mineral soil). There were relatively strong associations between the two overstorey indices of fire severity and also between the two understorey indices of fire severity. However, there were weaker associations between understorey and overstorey fire severity indices, suggesting they are at least partially independent. Results also suggested weak associations between ground-based fire severity indices and remotely sensed fire severity assessments in riparian areas. Overall, we show there are limitations to the interpretation and use of these commonly used fire severity assessments in riparian areas.