Predicting External Branch Characteristics of Planted Silver Birch (Betula pendula Roth.) on the Basis of Routine Stand and Tree Measurements

Abstract The aim of this study was to develop simultaneous models for external branch characteristics along the stem that could be applied as a part of a growth simulation system. Data were collected from planted pure stands of silver birch (Betula pendula Roth.) growing on abandoned agricultural land and forest sites of different fertility, with different stand density and age. The data were used to develop generalized linear variance component models for (1) crown ratio, (2) self-pruning ratio, i.e., height of the lowest dead branch divided by the height of the crown base, (3) number of living branches along the stem, (4) total number of branches, (5) diameter of the thickest branch, (6) diameters of smaller branches, and (7) branch angle. The independent variables of the models were restricted to those measured in forest inventories and used for forest management planning purposes. Even though there was bias in predicting some of the branch characteristics in the independent evaluation data set of silver birch, the behavior of the models was logical. No major additional bias was found when the models were applied to downy birch (Betula pubescens Ehrh.). The models provide a framework for predicting the development of wood quality and the possibilities of using silvicultural treatments to control branch characteristics. FOR. SCI. 49(2):301–317.