Models of internodal growth for the black spruce, the jack pine and the balsam fir in Quebec

The objective of this study was to develop variable growth intercept models for coniferous Species of major importance in Quebec using Nigh's (1997a) modelling technique. Eighty-three, 68 and 70 stem analysis plots of black spruce (Picea rnariana [Mill.] BSP), jack pine (Pinus banksiana Lamb.) and balsam fir (Abies balsamea (L.) Mill) were used, respectively. The growth intercept models for black spruce were the most precise, followed by those for jack pine and finally by those for balsam fir, based on the root mean square errors. Results indicated that the accuracy of the models was good, relative to those previously published for other species in Canada. Interim testing of the models revealed a low mean error for all three species that may not be of practical significance for site index determination, although more data should be obtained to further test the models.