Compatible crown ratio and crown height models

Abstract

Several published crown ratio and crown height models were fitted to plantation loblolly pine tree data, but none were considered entirely adequate. A nonlinear model form that yields logical estimates is presented. Required inputs are stand age, tree diameter, and tree height. Both ordinary least squares and seemingly unrelated regression (SUR) were used to estimate model parameters. Cross equation constraints with the SUR procedure result in compatible estimates of crown ratio and crown height for a tree of given height.