Predicting diameter at breast height from total height and crown lengthThis article is part of a larger document. View the larger document here.
Tree diameter at breast height (d.b.h.) is often predicted from total height (model 1a) or both total height and number of trees per acre (model 1b). These approaches are useful when Light Detection and Ranging (LiDAR) data are available. LiDAR height data can be employed to predict tree d.b.h., and consequently individual tree volumes and volume/ ha can be obtained for the tract. In this paper, we will examine alternative methods of predicting d.b.h. from total height and crown length (model 2a), or from total height, crown length, and number of trees per acre (model 2b), based on the uniform stress theory. The uniform stress theory hypothesizes that stems behave like tapered cantilever beams to equalize bending stress across their length. The four models were evaluated based on the mean difference between observed and predicted diameters, mean absolute difference, and fit index. Results revealed that the two models based on the uniform stress theory (models 2a and 2b) were more appropriate for predicting d.b.h., which is needed to compute tract volume using LiDAR data.