Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: A comparison of fitting techniques for ponderosa pine height-age models in British Columbia. | Ann. For. Sci. 61 2004 609-615 INRA EDP Sciences 2004 DOI forest 2004064 609 Original article A comparison of fitting techniques for ponderosa pine height-age models in British Columbia Gordon Nigh Research Branch BC Ministry of Forests PO Box 9519 Stn. Prov. Govt. Victoria BC Canada V8W 9C2 Received 28 April 2003 accepted 26 August 2003 Abstract - The ponderosa pine height models currently in use in British Columbia Canada were calibrated for southwest Oregon USA. Height growth patterns in British Columbia may be different from those in Oregon. Furthermore they may be different between biogeoclimatic zones within British Columbia. To check this 80 stem analysis plots were established to develop a new ponderosa pine height model. One tree in each ha plot was intensively sampled to obtain annual heights from the pith nodes. A conditioned log-logistic function was used as the base height model. Various model fitting procedures were employed to meet assumptions about the data and the regressions. These procedures included using an autoregressive model to account for serial correlation and using nonlinear mixed modelling so that site index could be treated as having a random component. The final version of the model tested for differences in height growth patterns across the four biogeoclimatic zones where ponderosa pine most often grows. Although growth differences between the zones were detected the results may be uncertain due to small differences in height growth trajectories and small sample sizes for some zones. A new height model for ponderosa pine is now available for British Columbia. This model gives only slightly different height estimates from the current models so the use of the previous model in the past has not led to poor forest management decisions. height model mixed effects model nonlinear regression site index yellow pine Résumé - Modèle de croissance en hauteur pour le pin ponderosa en Colombie-Britannique. Les modèles de croissance en
