Primary criteria for group tree risk assessment at MacKerricher State Park, Mendocino County, California. Trees with one or more high risk of failure characteristics which are likely to produce a negative contribution to forest stability within the next 5 year inspection interval and are removed or pruned.
| Criteria | Low risk of failure | High risk of failure |
|---|---|---|
| Phellinus pini | < = 1 conk cluster along trunk | > 1 conk cluster along trunk |
| Peridermium harknessii | < 25% trunk circumference | > 25% of trunk circumference |
| Phaeolus schweinitzii | absence | presence |
| Ganoderma applanatum | absence | presence |
| heartrot in hardwoods | < 33% strength loss | > 33% strength loss |
| Bark beetles in pines | absence | presence |
| Physical deformities | absence | presence |
| Lean | absent | > 10 degrees |
| Size | increasing size raises risk | > 25 “ dbh suspect |
| Health | high vigor | low vigor or death |
| Species | native | non-native |
| pines | all tiers | dominant (other pines present) |
| associates | understory (pines present) other tiers (pines absent) | dominant, co-dominant, or intermediate with pines present |
| Tree density (sq ft/ac) | BA = 50 to 200a | BA > 200 or BA < 50 if recently isolated trees |
↵a BA: Basal area per acre equals cross sectional area of wood at breast height (4.5 ft above ground) of all trees on an acre of land.