Achim2004

Référence

Achim, A. (2004) Effets de l'éclaircie sur la résistance au chablis et la qualité du bois en sapinière. Thèse de doctorat, Université Laval.

Résumé

Thinning operations have recently become common practice in balsam fir forests ( Abies balsamea (L.) Mill.) but their effect on windthrow resistance and wood quality are still poorly understood. Tree pulling trials were conducted in balsam fir stands with a minor component of white spruce ( Picea glauca (Moench) Voss.) in order to determine the relationship between the turning moment necessary to uproot a tree and the weight of its stem. No significant effects of the species, the site (mesic or rich mesic) or of the prior application of a precommercial thinning was revealed. The critical wind speeds necessary to cause windthrow in these types of stands were calculated using the GALES method. They neared 20 m s -1 for a mature balsam fir stand on a mesic site. The wind speeds which could cause breakage increased gradually with increased spacing between the stems following a precommercial thinning. The wind speeds which could cause uprooting seemed to reach a maximum at an average spacing of approximately 1.80 m. Regardless of the site or of the prior application of a precommercial thinning, a simulated commercial thinning decreased the critical wind speeds by 4 m s -1 . Wood samples were collected from two stands which had received a precommercial thinning treatment, respectively, 9 and 14 years previously and from two unthinned controls. A decrease in wood relative density was observed following one of the two thinnings. This effect was expressed less importantly on density, longitudinal shrinkage and the moduli of rupture and elasticity measured on small clearwood specimens (150 x 10 x 10 mm). An important effect of cambial age was observed, suggesting that the most harmful effect of precommercial thinning on wood properties may be induced by harvesting the stems at a young age. Overall, the results suggest that thinning could be included in a silvicultural strategy that aims at producing high quality timber whilst maintaining windthrow resistance in a balsam fir forest.

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@PHDTHESIS { Achim2004,
    AUTHOR = { Achim, A. },
    TITLE = { Effets de l'éclaircie sur la résistance au chablis et la qualité du bois en sapinière },
    SCHOOL = { Université Laval },
    YEAR = { 2004 },
    NOTE = { CEFTMS, Ruel, J.-C. and Cloutier, A. and Gardiner, B.A., Alexis Achim. Thèse (de doctorat) Pqdt Thèse (Ph. D.)--Université Laval, 2004. Bibliogr.: f. 105-119. Anglais ou français ; avec des résumés en français et en anglais. Thèse. Foresterie et géodésie Ruel, Jean-Claude, directeur de thèse Cloutier, Alain, directeur de thèse Gardiner, Barry A., directeur de thèse },
    ABSTRACT = { Thinning operations have recently become common practice in balsam fir forests ( Abies balsamea (L.) Mill.) but their effect on windthrow resistance and wood quality are still poorly understood. Tree pulling trials were conducted in balsam fir stands with a minor component of white spruce ( Picea glauca (Moench) Voss.) in order to determine the relationship between the turning moment necessary to uproot a tree and the weight of its stem. No significant effects of the species, the site (mesic or rich mesic) or of the prior application of a precommercial thinning was revealed. The critical wind speeds necessary to cause windthrow in these types of stands were calculated using the GALES method. They neared 20 m s -1 for a mature balsam fir stand on a mesic site. The wind speeds which could cause breakage increased gradually with increased spacing between the stems following a precommercial thinning. The wind speeds which could cause uprooting seemed to reach a maximum at an average spacing of approximately 1.80 m. Regardless of the site or of the prior application of a precommercial thinning, a simulated commercial thinning decreased the critical wind speeds by 4 m s -1 . Wood samples were collected from two stands which had received a precommercial thinning treatment, respectively, 9 and 14 years previously and from two unthinned controls. A decrease in wood relative density was observed following one of the two thinnings. This effect was expressed less importantly on density, longitudinal shrinkage and the moduli of rupture and elasticity measured on small clearwood specimens (150 x 10 x 10 mm). An important effect of cambial age was observed, suggesting that the most harmful effect of precommercial thinning on wood properties may be induced by harvesting the stems at a young age. Overall, the results suggest that thinning could be included in a silvicultural strategy that aims at producing high quality timber whilst maintaining windthrow resistance in a balsam fir forest. },
    KEYWORDS = { Chablis (Sylviculture) Simulation, Méthodes de Éclaircie (Sylviculture) Sapin Bois Qualité },
    OWNER = { brugerolles },
    TIMESTAMP = { 2008.01.17 },
}

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