Stem taper functions for maritime pine (<Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait.) in Galicia (Northwestern Spain) |
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Authors: | Email author" target="_blank">A?RojoEmail author X?Perales F?Sánchez-Rodríguez J?G?álvarez-González K?von?Gadow |
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Institution: | 1.Department of Ingeniería Agroforestal, Escuela Politécnica Superior,Universidad de Santiago de Compostela,Lugo,Spain;2.Department of Producción Vegetal, Escuela Politécnica Superior,Universidad de Santiago de Compostela,Lugo,Spain;3.Institut für Waldinventur und Waldwachstum,Georg-August-Universit?t G?ttingen,Gottingen,Germany |
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Abstract: | A total of 31 taper functions from 3 different groups of models (single, segmented and variable-form taper functions) were
fitted to diameter-height data from 203 Pinus pinaster trees sampled across even-aged stands in Galicia (northwestern Spain). Most of the taper functions analyzed showed problems
of multicollinearity as indicated by the condition number. A second-order autoregressive CAR(2) error process was incorporated
into the models to minimize the effect of autocorrelation inherent in the longitudinal data used, and to provide valid tests
of significance for model parameter estimates. In general, variable-form taper functions provided the most accurate predictions.
The flexibility and predictive performance of the variable-form model developed by Kozak (For Chron 80(4):507–515, 2004) indicated
its usefulness for estimating diameter at a specific height, merchantable volume, and total volume of Maritime pine in the
study area. |
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Keywords: | Taper functions Autocorrelation Multicollinearity |
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