Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp quốc tế đề tài: "Analysis of growth and light interception of balsam fir and white birch saplings following precommercial thinning D Pothier A. | Ann Sci For 1991 48 123-132 Elsevier INRA 123 Original article Analysis of growth and light interception of balsam fir and white birch saplings following precommercial thinning D Pothier A Margolis Centre de Recherche en Biologie Forestière Facultd de Foresterie et de Géomatique Université Laval Ste-Foy Québec Canada G1K 7P4 418 656-7120 Received 14 May 1990 accepted 15 January 1990 Summary A precommercial thinning was conducted on young balsam fir Abies balsamea L Mill and white birch Betula papyrifera Marsh trees. Changes in light environment and growth response of the trees were followed during the next 2 growing seasons. The relative growth rate RGR of thinned balsam firs increased during both the first and the second growing season. This increase in growth was attributed to a greater net assimilation rate NAR which was associated with a higher level of light availability. Thinning tended to positively affect the RGR of white birch during the first summer following treatment but not during the second growing season. Similar fluctuations were noted for NAR even though light levels remained high for thinned white birch trees during both the first and the second growing season. Balsam fir produced more sapwood per unit of additional leaf area than controls during the first summer following treatment but no differences were observed during the second. The sapwood area growth to leaf area growth ratios of thinned and control white birches were similar during both the first and the second summer following thinning. Thus the sapwood area-leaf area relationship appears to be more stable following abrupt changes in environmental conditions for the indeterminate growth species white birch than for the determinate growth species balsam fir. growth analysis I thinning I net assimilation rate light use efficiency I sapwood area-leaf area ratio Résumé Analyse de la croissance et de I interception de la lumière du sapin baumier et du bouleau à papier à la suite d une .
