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Báo cáo khao học: "Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry. | Ann. For. Sci. 59 2002 511-518 INRA EDP Sciences 2002 DOI 10.1051 forest 2002035 511 Original article Defining the transition from earlywood to latewood in black spruce based on intra-ring wood density profiles from X-ray densitometry Ahmed Koubaaa S.Y. Tony Zhangb and Sami Maknic Service de recherche et d expertise en transformation des produits forestiers 25 rue du Motel-Industriel porte 5 Amqui Québec G5J 1K Canada bForintek Canada Corp. 319 rue Franquet Sainte-Foy Québec G1P 4R4 Canada c COREM 1180 rue de la Minéralogie Québec City Québec G1N 1X7 Canada Received 16 August 2001 accepted 12 February 2002 Abstract - Defining the transition from earlywood to latewood in annual rings is an important task since the accuracy of measuring wood density and ring width components depends on the definition. Mork s index has long been used as an anatomical definition of the transition from earlywood to latewood. This definition is arbitrary and extremely difficult to apply to X-ray densitometry. For X-ray densitometry a threshold density of between 0.40 to 0.55 g cm-3 depending on species has been chosen to differentiate between earlywood and latewood density but this method has shortfall. Therefore new methods need to be developed and integrated into the computational programs used to generate X-ray densitometry data. In this study we presented a mathematical method. We modelled the intra-ring wood density profiles in 100 plantation-grown black spruce Picea mariana Mill. B.S.P. trees using high order polynomials. The correlation between the predicted and the measured densities is very high and highly significant. Based on this model we define the transition from earlywood to latewood as the inflexion point. Results indicate that wood density at the earlywood-latewood transition point varies from juvenile to mature wood. This method could be easily integrated into any X-ray densitometry program and allows to compare individual rings in a consistent manner. transition .