A fast and reliable method for the delineation of tree crown outlines for the computation of crown openness values and other crown parameters

Boivin, Frédéric; Paquette, Alain; Racine, Pierre et Messier, Christian (2011). « A fast and reliable method for the delineation of tree crown outlines for the computation of crown openness values and other crown parameters ». Canadian Journal of Forest Research, 41, pp. 1827-1835.

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Résumé

Numerous crown parameters (e.g., leaf area index, diameter, height, volume) can be obtained via the analysis of tree crown photographs. In all cases, parameter values are functions of the position of the crown outline. However, no standardized method to delineate crowns exists. To explore the effect of different outlines on tree crown descriptors, in this case crown openness (CO), and facilitate the adoption of a standard method free of user bias, we developed the program Crown Delineator that automatically delineates any outline around tree crowns following predetermined sensibility settings. We used different outlines to analyze tree CO in contrasting settings: using saplings from four species in young boreal mixedwood forests and medium-sized hybrid poplar trees from a low-density plantation. In both cases, the estimated CO increases when calculated from a looser outline, which had a strong influence on understory available light simulations using a forest simulator. These results demonstrate that the method used to trace crown outlines is an important step in the determination of CO values. We provide a much-needed computer-assisted solution to help standardize this procedure, which can also be used in many other situations in which the delineation of tree crowns is needed (e.g., competition and crown shyness).

Type:	Article de revue scientifique
Mots-clés ou Sujets:	Delineation of tree crown, Crown shyness, Crown openness, Crown parameters
Unité d'appartenance:	Centres institutionnels > Centre d'étude de la forêt (CEF) Faculté des sciences > Département des sciences biologiques
Déposé par:	Christian Messier
Date de dépôt:	29 nov. 2011 14:06
Dernière modification:	01 nov. 2014 02:20
Adresse URL :	http://archipel.uqam.ca/id/eprint/4273

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