Semi-empirical estimation of log taper using stem profile equations

Bilous A., Myroniuk V., Svynchuk V., Soshenskyi O., Lesnik O., Kovbasa Ya. (2021): Semi-empirical estimation of log taper using stem profile equations. J. For. Sci., 67: 318–327.

supplementary materialdownload PDF

In January 2019 the forest industry in Ukraine adopted European standards for measuring and grading of round wood based on mid-point diameters, which caused major discrepancies from traditionally used estimates of timber volume using top diameters. To compare methods of merchantable wood volume estimation, we investigated the stem form inside bark for two dominant tree species in Ukraine, i.e. Scots pine (Pinus sylvestris L.) and common oak (Quercus robur L.). We used tree stem measurements to fit stem profile equations, whereas simulation was applied to derive log taper. We found that Newnham's (1992) variable-exponent taper equation performed well for predicting stem taper for both tree species. Then, we simulated the structure of harvested wood, so that it replicated annual distribution of logs by their length and diameters. As a result, the average log taper was estimated at 0.836 ÷ 0.855 cm·m–1 and 1.180 ÷ 0.121 cm·m–1 for pine and oak, respectively. The study also indicated that log taper varied along stems. The higher rates of diameter decrease were found for butt logs, for which the taper was 2.5–3.5 times higher than its average for the whole stem. The results of our study ensure the stacked round wood volume conversion between estimates obtained using top and mid-point diameters.

Adamec Z., Adolt R., Drápela K., Závodský J. (2019): Evaluation of different calibration approaches for merchantable volume predictions of Norway spruce using nonlinear mixed effects model. Forests, 10: 1104.
Anonymous (1987): Materials for Forest Estimation of Ukraine and Moldova (1987). Kiev, Urozhay: 560. (in Russian)
Anonymous (2012): Reference book of forest resources of Ukraine: according to state forest records as of 01.01.2011 (2012). Irpin, PA Ukrderzhlisproekt. (in Ukrainian)
Arias-Rodil M., Castedo-Dorado F., Cámara-Obregón A., Diéguez-Aranda U. (2015): Fitting and calibrating a multilevel mixed-effects stem taper model for maritime pine in NW Spain. PLoS One, 10: e0143521.
Beltran H.A., Chauchard L., Iaconis A., Pastur G.M. (2017): Volume and taper equations for commercial stems of Nothofagus obliqua and N. alpina. CERNE, 23: 299–309.
Burkhart H.E., Tomé M. (2012): Modeling Forest Trees and Stands. Dordrecht, Springer Netherlands: 458.
Clark A., Souter R.A., Schlaegel B.E. (1991): Stem Profile Equations for Southern Tree Species. Asheville, U.S. Department of Agriculture, Forest Service, Southeastern Forest Experiment Station: 117.
Clutter J.L. (1980): Development of taper functions from variable-top merchantable volume equations. Forest Science, 26: 117–120.
David H.C., Veiga Miranda R.O., Welker J., Fiorentin L.D., Ebling Â.A., Belavenutti Martins da Silva P.H. (2016): Strategies for stem measurement sampling: A statistical approach of modelling individual tree volume. CERNE, 22: 249–259.
Duan A., Zhang S., Zhang X., Zhang J. (2016): Development of a stem taper equation and modelling the effect of stand density on taper for Chinese fir plantations in Southern China. PeerJ, 4: e1929.
Fonweban J., Gardiner B., Macdonald E., Auty D. (2011): Taper functions for Scots pine (Pinus sylvestris L.) and Sitka spruce (Picea sitchensis (Bong.) Carr.) in Northern Britain. Forestry, 84: 49–60.
Gómez-García E., Crecente-Campo F., Diéguez-Aranda U. (2013): Selection of mixed-effects parameters in a variable–exponent taper equation for birch trees in northwestern Spain. Annals of Forest Science, 70: 707–715.
Kershaw J.A., Ducey M.J., Beers T., Hush B. (2016): Forest Mensuration. 5th Ed. Chichester, Hoboken, Wiley-Blackwell: 630.
Kozak A. (1997): Effects of multicollinearity and autocorrelation on the variable-exponent taper functions. Canadian Journal of Forest Research. 27: 619–629.
Kozak A. (1998): Effects of upper stem measurements on the predictive ability of a variable-exponent taper equation. Canadian Journal of Forest Research, 28: 1078–1083.
Kozak A. (2004): My last words on taper equations. The Forestry Chronicle, 80: 507–515.
Kozak A., Munro D.D., Smith J.H.G. (1969): Taper functions and their application in forest inventory. The Forestry Chronicle, 45: 278–283.
Kozak A., Smith J.H.G. (1993): Standards for evaluating taper estimating systems. The Forestry Chronicle, 69: 438–444.
Larsen D.R. (2017): Simple taper: Taper equations for the field forester. In: Kabrick J.M., Dey D.C., Knapp B.O., Larsen D.R., Shifley S.R., Stelzer H.E. (eds): Proceedings of the 20th Central Hardwood Forest Conference, Columbia, March 28–April 1, 2016: 265–278.
Larson P.R. (1963): Stem form development of forest trees. Forest Science, 9: a0001–42.
Lee W.K, Seo J.H, Son Y.M., Lee K.H., Von Gadow K. (2003): Modeling stem profiles for Pinus densiflora in Korea. Forest Ecology and Management, 172: 69–77.
Leites L.P., Robinson A.P. (2004): Improving taper equations of loblolly pine with crown dimensions in a mixed-effects modeling framework. Forest Science, 50: 204–212.
Li R., Weiskittel A.R. (2010): Comparison of model forms for estimating stem taper and volume in the primary conifer species of the North American Acadian Region. Annals of Forest Science, 67: 302.
Max T.A., Burkhart H.E. (1976): Segmented polynomial regression applied to taper equations. Forest Science, 22: 283–289.
Menendéz-Miguélez M., Canga E., Álvarez-Álvarez P., Majada J. (2014): Stem taper function for sweet chestnut (Castanea sativa Mill.) coppice stands in northwest Spain. Annals of Forest Science, 71: 761–770.
Monness E. (2015): The bivariate power-normal distribution and the bivariate Johnson system bounded distribution in forestry, including height curves. Canadian Journal of Forest Research, 45: 307–313.
Newberry J.D., Burkhart H.E. (1986): Variable form stem profile models for loblolly pine. Canadian Journal of Forest Research, 16: 109–114.
Newnham R.M. (1992): Variable-form taper functions for four Alberta tree species. Canadian Journal of Forest Research, 22: 210–223.
Rojo A., Perales X., Sanchez-Rodriguez F., Alvarez-Gonzalez J.G., Von Gadow K. (2005): Stem taper functions for maritime pine (Pinus pinaster Ait.) in Galicia (Northwestern Spain). European Journal of Forest Research, 124: 177–186.
Sharma M., Oderwald R.G. (2001): Dimensionally compatible volume and taper equations. Canadian Journal of Forest Research, 31: 797–803.
SSSU (State Statistics Service of Ukraine) (2019): Statistical Yearbook of Ukraine for 2018: Kyiv, State Statistics Service of Ukraine: 481. Available at (in Ukrainian).
Svynchuk V., Kashpor S., Myroniuk V. (2014): Model of round wood volumes based on top diameter and length of logs. Scientific Bulletin of the National University of Life and Environmental Sciences of Ukraine, 1: 58–64. (in Ukrainian)
West P.W. (2015): Tree and Forest Measurement. 3rd Ed. Berlin, Springer: 214.
Yang Y., Huang S., Meng S.X. (2009): Development of a tree-specific stem profile model for white spruce: A nonlinear mixed model approach with a generalized covariance structure. Forestry, 82: 541–555.
supplementary materialdownload PDF

© 2021 Czech Academy of Agricultural Sciences | Prohlášení o přístupnosti