Stand-level growth models for young Scots pine stands in Finland

Abstract

This study predicts the stand-level growth variables of young, even-aged Scots pine ( Pinus sylvestris L.) stands in Finland using repeatedly measured sample plots. The extensive inventory data of young coniferous stands represented all the appropriate site types for Scots pine and all the wood production areas in Finland. Non-linear mixed-effect models were constructed for the survival and dominant height and diameter of crop-tree pines. Models for stand basal area and volume, as well as for the difference between the dominant and mean stand variables (height and diameter), were constructed using linear mixed-effect modelling. The survival model was a projection model that predicts the future number of trees as a function of the current number of trees. In the other models, the response was predicted directly as a function of regeneration method, site and other stand characteristics. This system of biologically based models serves as an unbiased predictor of the stand-level variables of young Scots pine stands in Finland. The random parameters of the models enable calibration of the models using field measurements. The estimated models could be connected to a stand simulator for generating, together with size distribution models, predictions of juvenile stand growth up until a dominant height of 10–15 m or a stand age of 30–40 years, depending on the site fertility. The stand variables modelled in this study can be used to predict the height and diameter distributions.