Development of Douglas fir merchantable stem volume model in the conditions of the Czech Republic

Radoslav Hlavica and Zdeněk Adamec
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Radoslav Hlavica: Department of Forest Management and Applied Geoinformatics, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic
Zdeněk Adamec: Department of Forest Management and Applied Geoinformatics, Faculty of Forestry and Wood Technology, Mendel University in Brno, Brno, Czech Republic

Journal of Forest Science, 2023, vol. 69, issue 12, 515-524

Abstract: A precise merchantable stem volume model of Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] is missing in the Czech Republic. The aim of this study was to fit a new model through the reparametrization of volume equations (used in the Czech Republic or in other countries). We tested four volume equations (two from the Czech Republic, one from France and one from British Columbia) in the form of a nonlinear least squares model (NLS), weighted least squares model (WLS), and nonlinear mixed effects model (NLME). In all the tested models, the diameter at breast height of a tree and the total height of a tree were used as independent variables. Models were fitted on a dataset of 185 felled sample trees from eleven research areas with ages between 19-113 years. We have found that the model according to Omule et al. (1987) fits the merchantable stem volume as the best in the version of WLS model. Median value of the relative error of the final model was only -0.53%, which is less than the errors of models which are still used in the Czech Republic today.

Keywords: Pseudotsuga menziesii; relative volume error; Smalian equation; stem profiles; stem shape; volume equation (search for similar items in EconPapers)
Date: 2023
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Persistent link: https://EconPapers.repec.org/RePEc:caa:jnljfs:v:69:y:2023:i:12:id:92-2023-jfs

DOI: 10.17221/92/2023-JFS

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