Predictability of Individual Tree Growth Using Various Definitions of Competing Basal Area

Methods for evaluating the competition experienced by individual trees in terms of surrounding basal area are reviewed. The properties of an ideal method are outlined. A new model, zone count, is presented, together with an approximation allowing quick fieldwork. The various methods, each for a wide range of plot sizes or basal area factors, are then compared as follows: Each definition (method by size) is used in turn in a regression predicting basal area increment for individual trees of an even-aged stand of Eucalyptus spp., the residual mean square providing a criterion. Other factors bearing on efficiency are discussed.