tailieunhanh - Báo cáo khoa học: "Increasing N and P resorption efficiency and proficiency in northern deciduous hardwoods with decreasing foliar N and P concentrations"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Increasing N and P resorption efficiency and proficiency in northern deciduous hardwoods with decreasing foliar N and P concentrations. | 275 Ann. For. Sci. 59 2002 275-281 INRA EDP Sciences 2002 DOI forest 2002023 Original article Increasing N and P resorption efficiency and proficiency in northern deciduous hardwoods with decreasing foliar N and P concentrations Benoit Côté James W. Fyles and Hamid Djalilvand Department of Natural Resource Sciences Macdonald Campus of McGill University 21 111 Lakeshore Ste-Anne-de-Bellevue QC h9x 3V9 Canada Received 7 May 2001 accepted 27 November 2001 Abstract - The objective of this study was to assess the relationships between pre-senescence leaf N and P concentrations and resorption efficiency and proficiency of eight deciduous hardwood tree species. Trees were sampled on two sites of contrasting fertility pro-ductivity in southern Quebec. Measured resorption efficiencies ranged from 56 to 71 for N and from 30 to 78 for P. Linear and exponential models between leaf N and litter N and between leaf P and litter P were significant. Intercepts of linear models were significantly different from zero. Resorption efficiency and proficiency increased with a decrease in leaf N and P and the rate of change of resorption efficiency increased with leaf nutrient concentration. Concentrations corresponding to ultimate potential resorption were calculated to be mg N g-1 and mg P g-1. Maximum resorption efficiencies were estimated at 70 for N and 80 for P. The concept of ultimate potential resorption in hardwoods is discussed. hardwoods litter nutrient resorption senescence Résumé - Augmentation de l efficacite et de la competence en résorption du N et P foliaire de feuillus nobles nordiques avec la diminution des concentrations foliaires en N et P. L objectif de cette étude était d évaluer les relations entre les concentrations foliai-res enN et P et l efficacité et la compétence de la résorption de huit espèces de feuillus nobles. Les arbres ont été échantillonnés à deux stations de fertilité productivité contrastante. L efficacitéderésorptiona varié de 56 à

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