Modeling compatible taper and stem volume of pure Scots pine stands in Northeastern Turkey

Compatible taper and volume equations for pure and natural Scots pine stands in the northeastern part of Turkey (Ardahan Province) were developed using a nonlinear mixed-effects modeling approach. Experimental data were obtained from 137 felled sample trees in different diameter and height classes....

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Bibliographic Details
Published inIForest (Viterbo) Vol. 16; no. 1; pp. 38 - 46
Main Authors Saygili, B, Kahriman, A
Format Journal Article
LanguageEnglish
Published Potenza The Italian Society of Silviculture and Forest Ecology (SISEF) 01.01.2023
Italian Society of Silviculture and Forest Ecology (SISEF)
Subjects
Autocorrelation
Autoregressive processes
Calibration
Case studies
Diameters
Estimates
Forest management
Forestry
Mathematical functions
Mathematical models
Modelling
Nonlinear Mixed-effects Model
Parameters
Pine
Pine trees
Pinus sylvestris
Random Parameters
Segmented Polynomial Taper Models
Stem Volume
Stems
Tapering
Trees
Variance
Wood
Turkey
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Summary:Compatible taper and volume equations for pure and natural Scots pine stands in the northeastern part of Turkey (Ardahan Province) were developed using a nonlinear mixed-effects modeling approach. Experimental data were obtained from 137 felled sample trees in different diameter and height classes. The most successful model (Jiang et al. 2005) explained 98.3% of the variance in stem diameter estimation and the RMSE, ME, MAE, AIC and BIC value obtained using this model were 1.955 cm, 0.043 cm, 1.300 cm, 9783.8 and 9812.6, respectively. Considering the criterion values of AIC, BIC and -2LnL, the model with random-effects in two parameters (b1 and b3) was the most successful for Scots pine. While the mixed model including random parameters did not completely solved the problem of the autocorrelation of errors in this study, the use of the autoregressive error structure AR(1) eliminated the autocorrelation in the residuals. In addition, the best estimation results among 20 different calibration options were obtained using the option of measuring two tree diameters at d1.30 and d5.30 with validation data. The most successful model explained 99.18% of the total variance in stem volume estimation in Scots pine.
ISSN:1971-7458
1971-7458
DOI:10.3832/ifor4099-015