Predicting branch characteristics of Norway spruce (Picea abies (L.) Karst.) from simple stand and tree measurements

• Published in: Forestry
• Main Authors: Mäkinen, Harri, Ojansuu, Risto, Sairanen, Pentti, Yli-Kojola, Hannu
• Format: Text
• Language: English
• Published: Oxford University Press 2003
• Subjects: Articles; Norway; Northern Sweden
• Online Access: http://forestry.oxfordjournals.org/cgi/content/short/76/5/525; https://doi.org/10.1093/forestry/76.5.525

The aim of the study was to develop models for external branch characteristics along the stem that could be applied as a part of a growth simulation system. The models provide a framework for predicting branch characteristics on the basis of routine stand and tree measurements. Data were collected from 677 Norway spruce ( Picea abies (L.) Karst.) trees of different age and canopy position growing on mineral soils and peatlands of different fertility in southern and central Finland, and also in northern Sweden. The material was used to construct models to predict (1) the crown ratio, (2) the self‐pruning ratio, i.e. height of the lowest dead whorl divided by the height of the crown base, (3) number of living branches in a whorl, (4) total number of branches in a whorl, (5) diameter of the thickest living branch of a whorl, (6) diameters of smaller living branches of a whorl, and (7) branch angle. Generalized variance component models were used to separate the region, stand, tree, whorl and branch level variation, and to take the statistical properties of the variables into account. Adding stand level variables as regressors to the models slightly improved the model performance. However, stem properties were often sufficient to reliably predict branch characteristics. Even though there was bias in predicting some of the branch characteristics, the models gave a relatively accurate and logical prediction of branch characteristics.