Approach to the estimation of red heart occurrence in Fagus sylvatica based on geometric relationships between branch scar development and knot dimensions

Abstract

The effect of branch scars on the initiation and occurrence of red heart in beech (Fagus sylvatica L.) was studied on 17 trees with red heartwood and 14 trees with no discoloured heartwood, all of which were selected from a 120-year-old high-forest stand in Germany. Logistic regression was used to predict the probability of red heart occurrence for a given tree. The model was based on individual probabilities derived from geometric relationships between scar and knot morphologies, and integrated the diameter at breast height. Using this model, 27 of 31 trees were correctly classified, and the two groups of trees were clearly distinguished by probabilities below 0.25 and above 0.85 (with one exception). Given the constitution of the model, only 17 of 616 scars were found to initiate red heart formation, and the parameters of mechanistic variables were strongly correlated. The results suggest specifying the relationship between scars, knots and red heart, and extending the scope of the model.

Keywords:

• Beech
• mechanism
• model
• probability
• red heart initiation
• standing tree

Thanks are extended to H.-O. Denstorf and K. H. Spissinger (Waldgesellschaft der Riedesel Freiherren zu Eisenbach GbR, Germany) for their organization of the fieldwork. The authors also wish to thank E. Cornu, C. Houssement, A. Mercanti and D. Rittié (LERFoB), as well as E. Hummel, H. Lechner and R. Robert (University of Freiburg) for carrying out field and laboratory measurements. This work was funded by a grant according to the Landesgraduiertenförderungsgesetz (LGFG) of Baden-Württemberg, Germany [project “Ansätze zur Modellierung der stammaxialen und stammradialen Ausdehnung sowie der jahrringgenauen Lage des Rotkerns in Buche (Fagus sylvatica L.) unter Berücksichtigung der Variabilität zwischen den Bäumen”] and the Office National des Forêts, France (project “Modélisation intra- et interarbre de l'extension du coeur rouge chez le hêtre. Recherche de descripteurs externes de l'arbre susceptibles d'indiquer l'occurrence et l'extension du défaut”).