Ferréol Berendt, Felix Wolfgramm, Tobias Cremer. (2021). Reliability of photo-optical measurements of log stack gross volume. Silva Fennica vol. 55 no. 3 article id 10555. https://doi.org/10.14214/sf.10555

Keywords: photogrammetry; timber trade; logistic; volume estimation; wood pile

Highlights: Gross volume estimations of larger log stacks showed a smaller deviation compared to those of piles with smaller volumes; Log stack quality affects estimation accuracy; The deviations between the manual section-wise estimations were of similar amplitude as those for the photo-optical estimations.

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In terms of assessing economic impact, one of the most important elements in the wood supply chain is the measurement of round wood. Besides the one-by-one measurement of logs, logs are often measured when stacked at the forest road. The gross stacked volume includes the volume of the wood, bark and airspace and is widely used for industrial wood assortments. The increasing international attention given to photo-optical measurement systems for portable devices is due to their simplicity of use and efficiency. The aim of this study was to compare the gross volumes of hardwood log stacks measured using one widespread photo-optical app with two manual section-wise volume estimations of log stacks based on the German framework agreement for timber trade (RVR). The manual volume estimations were done starting from the left (RVR_left) and right (RVR_right) sides of the log stacks. The results showed an average deviation of the photo-optical gross volume estimation in comparison to the manual estimation of –2.09% (RVR_left) and –3.66% (RVR_right) while the deviation between RVR_left and RVR_right was +2.54%. However, the log stack gross volume had a highly significant effect on the deviation and better accuracy with smaller deviation were reached for larger log stacks. Moreover, results indicated that the gross volume estimations of higher quality log stacks were closer for the three analyzed methods compared to estimations of poor-quality log stacks.

Berendt, Department of Forest Utilization and Timber Markets, Eberswalde University for Sustainable Development, 16225 Eberswalde, Germany https://orcid.org/0000-0002-6285-7590 E-mail: ferreol.berendt@hnee.de
Wolfgramm, Landesforst MV Anstalt des öffentlichen Rechts, Forstamt Billenhagen, 18182 Blankenhagen, Germany E-mail: felixwolfgramm@yahoo.de
Cremer, Department of Forest Utilization and Timber Markets, Eberswalde University for Sustainable Development, 16225 Eberswalde, Germany E-mail: tobias.cremer@hnee.de

Category : Review article

article id 22018, category Review article

Felipe de Miguel-Díez, Thomas Purfürst, Mauricio Acuna, Eduardo Tolosana-Esteban, Tobias Cremer. (2023). Estimation of conversion factors for wood stacks in landings and their influencing parameters: a comprehensive literature review for America and Europe. Silva Fennica vol. 57 no. 1 article id 22018. https://doi.org/10.14214/sf.22018

Keywords: log properties; roundwood measurement; roundwood purchase; stack properties; wood supply chain

Highlights: Midpoint diameter, stacking quality, crookedness, log length, delimbing quality and bark thickness strongly influence the conversion factors; In Europe and America, a total of 48 methods were developed to estimate the conversion factors of wood stacks; The conversion factors should be estimated for each wood assortment and tree species.

Abstract | Full text in HTML | Full text in PDF | Author Info

In commercial transaction of stacked roundwood, the estimation of the stack net volume plays a key role. One generalized method to determine the net volume is using conversion factors that relate the gross and net volumes. In this literature review the developed methods to estimate the conversion factors as well as their influencing parameters were analyzed based on 153 references from America and Europe. According to the results, 48 different methods (including their variants) for estimating the conversion factors were developed. The newest methods enabled their accurate determination inexpensively, e.g., photo-optical methods or 3D simulation models. The analyzed references revealed that 30 parameters influence the conversion factors. Based on this comprehensive review, each stakeholder involved in the roundwood supply chain can know which method is used for estimating the conversion factors in the analyzed territories and which influencing parameters should be considered when purchasing roundwood in order to accurately assess the solid wood content in the stacks.

de Miguel-Díez, Eberswalde University for Sustainable Development, Department of Forest Utilization and Timber Markets, Eberswalde, Germany; University of Freiburg, Chair of Forest Operations, Freiburg, Germany https://orcid.org/0000-0002-3800-7449 E-mail: felipe.diez@hnee.de
Purfürst, University of Freiburg, Chair of Forest Operations, Freiburg, Germany https://orcid.org/0000-0001-9661-0193 E-mail: thomas.purfuerst@foresteng.uni-freiburg.de
Acuna, University of the Sunshine Coast, Forest Research Institute, Sunshine Coast, Queensland, Australia E-mail: macuna@usc.edu.au
Tolosana-Esteban, Universidad Politécnica de Madrid, E.T.S.I. Montes, Forestal y del Medio Natural, Madrid, Spain https://orcid.org/0000-0003-2561-0342 E-mail: eduardo.tolosana@upm.es
Cremer, Eberswalde University for Sustainable Development, Department of Forest Utilization and Timber Markets, Eberswalde, Germany https://orcid.org/0000-0001-7866-944X E-mail: Tobias.Cremer@hnee.de

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