Monitoring & Post-Fire Evaluation Flashcards

How is the differenced Normalized Burn Ratio (dNBR) calculated?

Answer: Pre-fire NBR minus post-fire NBR

dNBR = prefire NBR − postfire NBR, so higher values mean greater burn severity.

Which two spectral bands are used to compute the Normalized Burn Ratio?

Answer: Near-infrared and shortwave infrared

NBR = (NIR − SWIR)/(NIR + SWIR), because burning lowers NIR reflectance and raises SWIR reflectance.

The Composite Burn Index (CBI) field plot is usually what size and shape?

Answer: A 30 m diameter circular plot

CBI uses roughly 30 m diameter plots, which approximately match one Landsat pixel.

With Brown's planar intersect method, how are 1000-hour (≥3 in.) woody fuels recorded?

Answer: Recorded individually by diameter and decay class along the full transect

Each large (1000-hr) piece is measured for diameter and rated sound or rotten along the full transect length.

Duff pins placed before a burn are mainly used to measure what?

Answer: Duff and litter depth reduction (consumption)

Measuring from the pin top to the duff surface before and after the burn gives depth consumed.

Why are delayed tree mortality assessments usually repeated 1 to 3 years after a burn?

Answer: Bark beetle attacks and root or cambium damage can kill trees after the first season

Many fire-injured trees die later from cambial or root damage and secondary insect attack.

What is the difference between scorch height and char height?

Answer: Scorch height is where foliage was killed by heat; char height is the blackened bark on the bole

Scorch height reflects lethal heating of foliage, while char height is direct blackening of the bark.