A Numerical Rating System for Crown Classes of Southern Hardwoods

Abstract

Abstract A numerical rating system to delineate crown classes of southern hardwoods is described. The system is based on four criteria: (1) amount of direct sunlight from above, (2) amount of direct sunlight from the sides, (3) crown balance, and (4) relative crown size. The total point value assigned places the tree within one of the four crown classes. The rating system can be used to train inexperienced hardwood foresters and should give experienced foresters a better grasp of those factors important in hardwood crown classification. Time required to evaluate a tree varies by tree, by stand conditions, and by observer, but experienced users of the system can easily rate most trees in 30–45 seconds. The rating system is particularly useful in situations where an individual tree appears to be borderline between two crown classes. For researchers, the system provides: (1) an expression of individual-tree crown characteristics, and (2) documentation of changes in crown position and condition. In two tests comparing the numerical rating system with the conventional crown classification system, use of the rating system consistently improved the ability of participants to correctly identify crown classes. Dominant and suppressed trees were the easiest to assess with the numerical rating system, whereas codominant and intermediate trees were the most difficult. Agreement between participants and experts in identification of crown classes increased with the level of the participants' forestry knowledge and experience. In one test, a group of participants attending a continuing-education hardwood shortcourse, but with little to moderate hardwood experience, correctly identified the crown class of 78% of the trees after only 1 hr of training. South. J. Appl. For. 25(4):154–158.