Crown scorch and bud kill
Vilà-Vilardell, L.1
1Forest Science and Technology Centre of Catalonia (CTFC)
Last updated: 28/09/2026
Recommended citation:
Vilà-Vilardell, L. 2026. Crown scorch and bud kill. In: Pere Casals, Davide Ascoli, Lena Vilà-Vilardell, Imma Oliveras, Madoka Krick (eds.) 2026. Methods handbook for characterizing fire use behavior, assessing fire effects, and monitoring soil and vegetation responses at the stand level. FIRE-ADAPT project (number 101086416), deliverable D1.1
Indicator
Fire severity: Severity on vegetation
Brief introduction
Crown scorch is the portion of the tree’s foliage killed during a fire, usually expressed as a percentage of either the pre-fire crown volume or the pre-fire crown length. The foliage turns brown-red within a few days after the fire and is shed as litter within weeks or months, depending on the species, the season, and the weather conditions. Bud kill (or crown kill) is the portion of the tree’s buds killed during the fire. Bud kill can be easily estimated during the growing season following fire.
Crown scorch does not necessarily imply bud kill as there are some species with large buds that can survive even when needles are scorched. Thus, it is interesting to record both parameters.
Both parameters are used as an indicator of crown injury and are the main predictors of tree mortality post-fire.
Method specifications
Method type
Soft
Hard
Method timing
Before
fire
During
fire
After fire
(short-term)
After fire
(mid-term)
After fire
(long-term)
Field skills
Low
Medium
Hard
Lab skills
Low
Medium
Hard
Material cost
Low
Medium
Hard
Time cost
Low
Medium
Hard
Calculation expertise
Low
Medium
Hard
Equipment
Diameter tape (0.1 mm accuracy)
Spray paint
Experimental design
Measure crown scorch one week after the prescribed burn and bud kill at the beginning of the first growing season following the burn.
The number of trees to measure depends on the objective of the study. As a rule of thumb, when the objective is to assess tree mortality or recovery following the fire, select several levels of crown scorch and bud kill, and measure at least 10 individuals of each species for each crown scorch level. If relevant, this sampling can be further stratified by crown class (dominant, co-dominant, intermediate, and suppressed) within the study site.
Methodology
- Select the trees to be measured and marking them using spray paint at DBH.
- Visually estimate the percent crown scorch and bud kill. Percent crown scorch is best assessed within the first few weeks following the fire and is visually estimated as the percentage of crown foliage that has turned brown or red. Bud kill is best assessed at the beginning of the first growing season and is visually estimated as the percentage of buds that fail to flush at the onset of the growing season.
- Measure the DBH using a diameter tape and recording the tree species and, if relevant, their crown class.
Calculations
Calculate the average crown scorch and bud kill for each species.
\mathrm{CS}(\%) = \frac{\sum_{i=1}^{n} CS_i}{n}
Relation with other methods
Crown scorch and bud kill are usually assessed in combination with other fire behaviour or fire severity indicators such as Stem char height, Cambium injury, Tree mortality, and Surface fireline intensity.
Illustrations
Data templates
NA
Further information
Varner, J. M., Hood, S. M., Aubrey, D. P., Yedinak, K., Hiers, J. K., Jolly, W. M., … & Rowell, E. M. (2021). Tree crown injury from wildland fires: causes, measurement and ecological and physiological consequences. New Phytologist, 231(5), 1676-1685.