Modeling of stem taper model with mixed effects approach for oriental spruce
Oriental spruce (Picea orientalis L.) is one of the most important tree species in Turkey. Therefore, the information is necessary about growth and yield of the species for developing future management and planning strategies. The one of the essential building blocks in forest growth and yield predi...
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| Format: | Article |
| Language: | English |
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Isparta University of Applied Sciences Faculty of Forestry
2017-07-01
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| Series: | Turkish Journal of Forestry |
| Subjects: | |
| Online Access: | https://dergipark.org.tr/tr/pub/tjf/issue/30743/302073?publisher=iubu |
| _version_ | 1828025959395098624 |
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| author | Ramazan Özçelik Ahmet Sarıtaş Manuel Arias-Rodil |
| author_facet | Ramazan Özçelik Ahmet Sarıtaş Manuel Arias-Rodil |
| author_sort | Ramazan Özçelik |
| collection | DOAJ |
| description | Oriental spruce (Picea orientalis
L.) is one of the most important tree species in Turkey. Therefore, the
information is necessary about growth and yield of the species for developing
future management and planning strategies. The one of the essential building
blocks in forest growth and yield prediction models is the equations for
estimating individual tree volume. One of the most accurate and reliable
approaches for estimating stem total volume and merchantable volume is the use
of taper models. In this study, a taper model was developed by using nonlinear
mixed effects modeling approach (NLME) using data from 170 trees felled in
oriental spruce stands from Ardahan-Posof Region. An NLME approach accounted
for within-and between tree variations in stem form. In the first stage, all
possible combinations of expansion with random effects in one and two model
parameters were tested, selecting then the best one. The inclusion of random
effects was not enough to account for the existing autocorrelation between the
residuals and then the variance-covariance matrix of the error term was
modelled through a first order autocorrelation structure AR (1). In a second
step, we evaluated the response obtained by calibration (which implies
estimation of random effects for a new tree) based on upper-stem diameter
measurements at different points. The selected mixed-effects model produced the
best results both in fitting and calibration process. It was found that an
upper-stem diameter measurement at 40-80% of total height was best suited for
calibrating tree-specific predictions. As a result, model calibration should be
considered an essential criterion in mixed model selection. |
| first_indexed | 2024-04-10T13:10:23Z |
| format | Article |
| id | doaj.art-5ced7bacbf94446199f313c975b5f1c8 |
| institution | Directory Open Access Journal |
| issn | 2149-3898 |
| language | English |
| last_indexed | 2024-04-10T13:10:23Z |
| publishDate | 2017-07-01 |
| publisher | Isparta University of Applied Sciences Faculty of Forestry |
| record_format | Article |
| series | Turkish Journal of Forestry |
| spelling | doaj.art-5ced7bacbf94446199f313c975b5f1c82023-02-15T16:12:39ZengIsparta University of Applied Sciences Faculty of ForestryTurkish Journal of Forestry2149-38982017-07-0118211011810.18182/tjf.3020731656Modeling of stem taper model with mixed effects approach for oriental spruceRamazan Özçelik0Ahmet Sarıtaş1Manuel Arias-Rodil2SÜLEYMAN DEMİREL ÜNİVERSİTESİ, ORMAN FAKÜLTESİSÜLEYMAN DEMİREL ÜNİVERSİTESİ, FEN BİLİMLERİ ENSTİTÜSÜ, ORMAN MÜHENDİSLİĞİ (DR)Unidad de Gestión Forestal Sostenible, Departamento de Ingeniería Agroforestal, Universidade de Santiago de CompostelaOriental spruce (Picea orientalis L.) is one of the most important tree species in Turkey. Therefore, the information is necessary about growth and yield of the species for developing future management and planning strategies. The one of the essential building blocks in forest growth and yield prediction models is the equations for estimating individual tree volume. One of the most accurate and reliable approaches for estimating stem total volume and merchantable volume is the use of taper models. In this study, a taper model was developed by using nonlinear mixed effects modeling approach (NLME) using data from 170 trees felled in oriental spruce stands from Ardahan-Posof Region. An NLME approach accounted for within-and between tree variations in stem form. In the first stage, all possible combinations of expansion with random effects in one and two model parameters were tested, selecting then the best one. The inclusion of random effects was not enough to account for the existing autocorrelation between the residuals and then the variance-covariance matrix of the error term was modelled through a first order autocorrelation structure AR (1). In a second step, we evaluated the response obtained by calibration (which implies estimation of random effects for a new tree) based on upper-stem diameter measurements at different points. The selected mixed-effects model produced the best results both in fitting and calibration process. It was found that an upper-stem diameter measurement at 40-80% of total height was best suited for calibrating tree-specific predictions. As a result, model calibration should be considered an essential criterion in mixed model selection.https://dergipark.org.tr/tr/pub/tjf/issue/30743/302073?publisher=iubupicea orientalisgövde çapı modeliotokorelasyonkalibrasyonardahan-posofpicea orientalistaper modelautocorrelationcalibrationardahan-posof |
| spellingShingle | Ramazan Özçelik Ahmet Sarıtaş Manuel Arias-Rodil Modeling of stem taper model with mixed effects approach for oriental spruce Turkish Journal of Forestry picea orientalis gövde çapı modeli otokorelasyon kalibrasyon ardahan-posof picea orientalis taper model autocorrelation calibration ardahan-posof |
| title | Modeling of stem taper model with mixed effects approach for oriental spruce |
| title_full | Modeling of stem taper model with mixed effects approach for oriental spruce |
| title_fullStr | Modeling of stem taper model with mixed effects approach for oriental spruce |
| title_full_unstemmed | Modeling of stem taper model with mixed effects approach for oriental spruce |
| title_short | Modeling of stem taper model with mixed effects approach for oriental spruce |
| title_sort | modeling of stem taper model with mixed effects approach for oriental spruce |
| topic | picea orientalis gövde çapı modeli otokorelasyon kalibrasyon ardahan-posof picea orientalis taper model autocorrelation calibration ardahan-posof |
| url | https://dergipark.org.tr/tr/pub/tjf/issue/30743/302073?publisher=iubu |
| work_keys_str_mv | AT ramazanozcelik modelingofstemtapermodelwithmixedeffectsapproachfororientalspruce AT ahmetsarıtas modelingofstemtapermodelwithmixedeffectsapproachfororientalspruce AT manuelariasrodil modelingofstemtapermodelwithmixedeffectsapproachfororientalspruce |