A framework for modeling the dynamics of first-order branches and spatial distribution of knots in loblolly pine trees

Abstract

A stochastic model to simulate the processes of initiation, diameter growth, death, and self-pruning of branches in loblolly pine ( Pinus taeda L.) trees is presented. Information on whorl formation and branch growth was obtained from destructive sampling of whorl sections from 34 trees growing under 10 different initial spacings. Three different components were modeled and hierarchically connected: whorl, branches, and knots. For each new growing season, whorls and branches are assigned stochastically along and around the stem. Thereafter, branch diameter growth is predicted as a function of relative location within the live crown and stem growth. The branch model was linked to an individual-tree growth model, PTAEDA3.1, to simulate the dynamics of first-order branches arising from the main stem. Information on (i) vertical trend of branch diameter along and around the stem, (ii) volume of knots (live and dead portions), and (iii) spatial location, size, and type (live and dead) of knots can be obtained. In its current stage, the framework allows evaluation of the quality of trees and sawlogs produced, inclusion of additional wood properties, and linkage with industrial conversion processes (e.g., sawing simulation). However, further research is needed to obtain data on branch dynamics to validate the overall performance of the model and improve developed submodels.