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Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Modelling juvenile-mature wood transition in Scots pine (Pinus sylvestris L.) using nonlinear mixed-effects models. | Ann. For. Sci. 61 2004 831-841 INRA EDP Sciences 2005 DOI 10.1051 forest 2004084 831 Original article Modelling juvenile-mature wood transition in Scots pine Pinus sylvestris L. using nonlinear mixed-effects models Rudiger MUTZa Edith GuiLLEYb Udo H. SAUTERc Gérard NEPVEUb a Eidgenossische Technische Hochschule Zahringerstrasse 24 8092 Zurich Switzerland b Équipe de Recherches sur la Qualité des Bois LERFOB-Laboratoire d Etude des Ressources Forêt-Bois UMR INRA-ENGREF 1092 Centre de Recherches de Nancy INRA 54280 Champenoux France c Institut fur Forstbenutzung und Forstliche Arbeitswissenschaft Universitat Freiburg Werderring 6 79085 Freiburg i. Br. Germany Received 27 March 2003 accepted 15 September 2004 Abstract - Nonlinear mixed-effects-models are applied successfully to estimate the cambial age of juvenile-mature wood transition in Scots pine sample trees from slow-grown stands. Till now segmented regression models are applied separately for each pith-to-bark-profile of wood density. The nonlinear mixed-effects-model overcomes this limitation while consistently and efficiently estimating the transition point for the whole sample. Furthermore standard errors can be calculated and impacts of stand and tree variables on the shape of pith-to-bark-curves can be tested. Mean ring density earlywood and latewood density profiles from 99 trees were determined by X-ray densitometric analysis of disks taken at 4-m stem height. The cambial age of transition from juvenile to mature wood is described according to nonlinear mixed-effects-models based on latewood density profiles. The time-series nature of the data are taken into account. The segmented quadratic-linear model shows the transition at cambial age of 21.77 which vary with the probability of 0.95 within the interval of 18.31 26.85 . Impacts of tree variables or stands on the location of the transition point were not found but impacts of stands on the shape of pith-to-bark-curves. Pinus silvestris microdensitometry
