Tree Risk Assessment Qualification (TRAQ) Practice Exam

The live crown ratio expresses the portion of a tree’s total height that is occupied by the live, foliage-bearing crown. It is calculated by dividing crown length by the total tree height, so you’re directly comparing how much of the tree’s height is still contributing leaves and photosynthesis to overall growth. This is the best definition because it captures the vertical occupancy of the crown relative to the tree’s full height, which is a key indicator of vigor and canopy dominance. For example, a crown length of 60 ft on a 100 ft tree yields an LCR of 0.60 (60%), signaling substantial foliage up the height of the tree. The other formulations don’t reflect this vertical proportion: pairing crown length with trunk height uses a different, ambiguous measurement of height; using SAMPLEcrown width with trunk diameter mixes horizontal spread with girth; and inverting the ratio (total height divided by crown length) does not describe how much of the tree’s height is still live crown.