Past Tree Spacing Levels Estimated by Current Stand Conditions and Past Radial Growth Rates

Given current stand conditions and past radial growth rates the initial point density (in stems per hectare at age 10) of ponderosa pine ( Pinus ponderosa Laws.) stands in western Montana was estimated. A modified tree polygon method was utilized to compute a measure of the current "growing space" occupied by a "target" tree and then the point density represented by that growing space. A logistic function was developed to determine the annual probability of a tree dying due to intertree competition with site index, dbh, and mean annual diameter growth rate as independent variables. Using a double convergence algorithm, actual current point density was compared with an estimated current point density which was computed by "growing" a tree from an arbitrarily selected initial density. Then this initial point density was adjusted until the estimated and actual current point density converged. The initial point density was further adjusted to allow no competition-based mortality until the age of canopy closure. Forest Sci. 30:209-218.