tailieunhanh - Báo cáo khoa học: "Evaluation of annual ring width and ring density development following fertilisation and thinning of Scots pine"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: Evaluation of annual ring width and ring density development following fertilisation and thinning of Scots pine. | Ann. For. Sci. 59 2002 29-40 INRA EDP Sciences 2002 DOI forest 2001003 29 Original article Evaluation of annual ring width and ring density development following fertilisation and thinning of Scots pine Tommy Morling Department of Silviculture University of Agricultural Sciences 901 83 Umeả Sweden Received 24 November 2000 accepted 6 July 2001 Abstract - Effects of nitrogen fertilisation and thinning 40 basal area removal on annual ring width and ring density were studied in a 2 X 2 factorial field experiment in northern Sweden in an even aged 56-year-old Scots pine stand twelve years after treatment. Each treatment was replicated six times. From four stem heights wood specimens were measured using direct scanning X-ray microdensitometry. For the whole period mean ring width increased by 14 following fertilisation and by 40 after thinning. Neither fertilisation 1 nor thinning -4 significantly p changed ring density during the twelve-year period. Based on four-year mean values at m ring width increased in all cases except for fertilisation in the last four-year period. The only significant effect on wood density was a 5 decrease following thinning during the second four-year period. Linear regression showed negative correlation between ring density and ring width and no additional effects of treatments per se. growth Pinus sylvestris wood density X-ray densitometry Résumé - Evaluation de la largeur et de la densité des cernes après fertilisation et éclaircie dans un peuplement de pin sylvestre. Les effets de la fertilisation et de l eclaircie sur la largeur et sur la densité des cernes ont été étudiés dans un peuplement experimental du nord de la Suède 12 ans après traitement dans un peuplement équienne de pins sylvestres âgé de 56 ans. Chaque traitement était répété six fois. Des échantillons de bois représentant deux rayons opposés ont été prélevés à quatre hauteurs et analysés par microdensitométrie scanning direct. Au cours des douze années .