Root pruning negatively affects tree value: A comparison of tree appraisal methods

Abstract Tree value is sometimes appraised to account for losses linked to insurance claims or legal disputes. In many of the appraisal methods used, tree value is influenced by vitality, size, and lifespan. These three factors can all be negatively impacted by nearby construction activities – ultimately impacting the monetary value of urban trees and the greater urban forest. The objectives of this study were to determine whether tree value was affected by root pruning, and to compare the effectiveness of four common, parametric tree appraisal methods for this purpose. Data from three individual root pruning studies (with varying levels of root pruning) were used. Four different tree valuation methods (CTLA Trunk Formula Method 9 th Edition (CTLA), the Revised Burnley Method (Burnley), the Helliwell Method (Helliwell), and the Standard Tree Evaluation Method (STEM)) were used to assess the value of trees prior to and one growing season after root removal, as well as the average of all four methods. By examining the effects of root removal (reduced growth and vitality) over the course of a growing season, the results show that appraised tree value was negatively affected (Δ value (%)) by root pruning. A general trend towards greater loss in value with increasing root removal intensity was observed for all methods for one or more treatment type (p  Ar (GL) ) defined as the total cross-sectional area of severed roots as a proportion of trunk diameter at ground level) revealed that % tree protection zone removal was the best performing tool for predicting percentage loss in value following root removal. Our results may be useful to those seeking compensation when tree damage has occurred due to construction-related activities.