What is the probability that a given Douglas-fir tree will die in the next 2 years? This question is particularly relevant when marking trees for take or leave in a thinning. Three factors are used to assess the likelihood of individual tree mortality (Table A1): beetle pressure, severity of crown decline, and abundance of pitch droplets within bark crevices. Beetle pressure refers to the abundance of beetles in the local area, as evidenced by the amount of recent mortality in the vicinity of the tree that is being assessed. This represents a contagion effect, the dispersal of beetle from infested trees to nearby un-infested trees. Infestation can be verified by the presence of trees with woodpecker shaved or flaked bark and/or the presence of flatheaded fir borer larvae, adults, and galleries under the bark of symptomatic trees (chop bark away and examine bark/wood surface area). Judging the severity of crown decline is subjective but in general trees with more severe decline will have more of the symptoms described above and/or symptoms will be more advanced.
As we gather additional monitoring data, this rating system will be refined.
Table A1. Proposed drought/FFB mortality risk rating for individual Douglas-fir trees
| Points | Risk Factor | Score |
| Beetle pressure | ||
| 4 | DF mortality from FFB is found within 1-acre plot (120’ radius) | |
| 0 | DF mortality from FFB not found within 1-acre plot | |
| Beetle pressure points = | ________ | |
| Crown decline | ||
| 3 | Severe crown decline | |
| 2 | Moderate crown decline | |
| 1 | Light crown decline | |
| 0 | No recent crown decline | |
| Crown decline points = | ________ | |
| Abundance of pitch jewels | ||
| 3 | Abundant pitch jewels | |
| 1 | Light pitch jewels | |
| 0 | Pitch jewels absent | |
| Pitch jewels = | ________ |
| Total Points | Relative Risk Category |
| ≥6 | 2-year mortality probability high |
| 3-5 | 2-year mortality probability moderate |
| 0-2 | 2-year mortality probability low |
