MODELING THE BASAL AREA-SIZE DISTRIBUTION OF FOREST STANDS - A COMPATIBLE APPROACH

This paper presents a methodology that allows diameter distributions t o be conformably modeled by letting the probability density represent either tree frequency as in the classic case, or basal area. The key t o relating the two forms of the probability density is shown to lie in weighted distribution theory, The motivation for the relationship lie s in the quadratic relationship between diameter at breast height and basal area. The weighted distribution approach is shown to be compatib le with current methods of calculating quantities such as basal area b y diameter class, but in addition, affords the development of new equa tions useful in parameter recovery or similar modeling strategies. Rel ationships are developed for ail of the major distributions found to h ave been useful in forestry for fitting diameter distribution models. Several stands to which the two-and three-parameter Weibull distributi ons have been fitted are also presented.