Regional stem taper equations for eleven conifer species in the Acadian Region of North America: development and assessment.

Taper models to predict upper stem diameters, as well as total tree volume, are presented for 11 major conifer species in the Acadian Forest Region of North America. The Kozak (2004. My last words on taper equations. For. Chron. 80:507–514) Model 02 taper equation was used as the base model form. A nonlinear mixed-effects modeling approach was used to account for autocorrelation present among multiple stem analysis observations collected from the same tree. Results show that fitted taper equations can accurately predict both stem form and volume across a range of conditions. The taper models generally had slightly lower bias and root mean square error than the commonly used regional Honer refitted volume equations (1965. A new total cubic foot volume function. For. Chron. 41:476 – 493). The mean absolute bias was reduced up to 28% for certain species using the fitted taper equations compared with the refitted Honer (1965) equations, although the refitted Honer’s models are also quite accurate where total stemwood volumes are needed. Independent validation data sets were used to further confirm reliability and accuracy of fitted taper models in predicting tree volume. These data sets indicated that the equations performed well, in general, but were slightly biased in certain thinned stands and in some New Brunswick ecoregions. Additional data are needed to confirm this and potentially improve model behavior. Overall, the models will be useful for predicting both stem form and merchantable and total volume.

[1]  D. Gilmore,et al.  Alternative measures of stem growth efficiency applied to Abies balsamea from four canopy positions in central Maine, USA , 1996 .

[2]  D. Bates,et al.  Mixed-Effects Models in S and S-PLUS , 2001 .

[3]  X. Guo,et al.  A simple stem taper model with mixed effects for boreal black spruce , 2009, European Journal of Forest Research.

[4]  Robert L. Bailey,et al.  Nonlinear Mixed Effects Modeling for Slash Pine Dominant Height Growth Following Intensive Silvicultural Treatments , 2001 .

[5]  Robert L. Bailey,et al.  Modeling and Prediction of Forest Growth Variables Based on Multilevel Nonlinear Mixed Models , 2001 .

[6]  Michael Clutter,et al.  Multivariate Multilevel Nonlinear Mixed Effects Models for Timber Yield Predictions , 2004, Biometrics.

[7]  T. Gregoire,et al.  A switching model of bole taper , 2001 .

[8]  A. Weiskittel,et al.  Long-term effects of precommercial thinning on stem form, volume, and branch characteristics of red spruce and balsam fir crop trees , 2009 .

[9]  A. Goodwin.  A cubic tree taper model , 2009 .

[10]  H. Burkhart,et al.  An application of mixed effects analysis to modeling thinning effects on stem profile of loblolly pine , 1998 .

[11]  R. Seymour,et al.  Influence of Soil Site Class on Growth and Decay of Northern White-Cedar and Two Associates in Maine , 2009, Northern Journal of Applied Forestry.

[12]  Shongming Huang,et al.  Using Nonlinear Mixed Model Technique to Determine the Optimal Tree Height Prediction Model for Black Spruce , 2009 .

[13]  A. Kozak,et al.  A variable-exponent taper equation , 1988 .

[14]  Timothy G. Gregoire,et al.  A non-linear mixed-effects model to predict cumulative bole volume of standing trees , 1996 .

[15]  D. Pitt,et al.  Long-term outcome of precommercial thinning in northwestern New Brunswick: growth and yield of balsam fir and red spruce , 2008 .

[16]  Harold E. Burkhart,et al.  Segmented Polynomial Regression Applied to Taper Equations , 1976 .

[17]  S. Huang,et al.  Development of a tree-specific stem profile model for white spruce: a nonlinear mixed model approach with a generalized covariance structure , 2009 .

[18]  Douglas A. Maguire,et al.  Modeling stem taper of three central Oregon species using nonlinear mixed effects models and autoregressive error structures , 2003 .

[19]  V. Lemay,et al.  Effects of adding tree, stand, and site variables to Kozak's variable-exponent taper equation , 1994 .

[20]  R. Seymour,et al.  Leaf area prediction models for Tsuga canadensis in Maine , 1999, Canadian Journal of Forest Research.

[21]  K. von Gadow,et al.  Stem taper functions for maritime pine (Pinus pinaster Ait.) in Galicia (Northwestern Spain) , 2005, European Journal of Forest Research.

[22]  Aaron R. Weiskittel,et al.  Comparison of model forms for estimating stem taper and volume in the primary conifer species of the North American Acadian Region , 2010, Annals of Forest Science.

[23]  L. Gu,et al.  Crown structure and growth efficiency of red spruce in uneven-aged, mixed-species stands in Maine , 1998 .

[24]  T. Honer.  A NEW TOTAL CUBIC FOOT VOLUME FUNCTION , 1965 .

[25]  Guillermo Trincado,et al.  Nonlinear mixed-effects modeling of variable-exponent taper equations for lodgepole pine in Alberta, Canada , 2009, European Journal of Forest Research.

[26]  R. Bailey,et al.  Compatible Volume-Taper Models for Loblolly and Slash Pine Based on a System with Segmented-Stem Form Factors , 2000, Forest Science.

[27]  V. M. Conway,et al.  Deciduous Forests of Eastern North America. , 1951 .

[28]  C. Scott,et al.  Taper models for commercial tree species in the northeastern United States. , 2010 .

[29]  A. Kozak,et al.  My last words on taper equations , 2004 .

[30]  Timothy G. Gregoire,et al.  Linear modelling of irregularly spaced, unbalanced, longitudinal data from permanent-plot measurements , 1995 .

[31]  Huiquan Bi,et al.  Trigonometric Variable-Form Taper Equations for Australian Eucalypts , 2000, Forest Science.

[32]  Leah M. Phillips.  Crop Tree Growth and Quality Twenty-five Years after Precommercial Thinning in a Northern Conifer Stand , 2002 .

[33]  S. Zhang,et al.  Variable-exponent taper equations for jack pine, black spruce, and balsam fir in eastern Canada , 2004 .

[34]  W. Zakrzewski.  A Mathematically Tractable Stem Profile Model for Jack Pine in Ontario , 1999 .