EFFECTS OF CLEAR-CUTTING AND STRIP CUTTIN G ON 5-YEAR REGENERATION OFBLACK SPRUCE FORESTS IN QUEBEC

An experiment was conducted to compare the effects of traditional clea r-cutting with those of strip cutting on regeneration of black spruce, Picea mariana (Mill.) B.S.P., stands on scarified and unscarified upl ands and on lowlands. To that effect, regeneration surveys were done b efore cutting, in the following year, and 3 and 5 years after cutting. Five years after harvesting, strip cutting led to higher coniferous s tocking than clear-cutting on scarified uplands and on lowlands. On un scarified uplands, the gain attributable to strip cutting was not sign ificant. The coniferous stocking of strip cuts on scarified uplands wa s not greater than on unscarified uplands. So the efficiency of scarif ication could not be proved in that study. Stocking obtained after 5 y ears remained closely related to the one observed immediately after ha rvesting in the strip cuts as in the clear-cuttings. This is particula rly true for balsam fir, Abies balsamea (L.) Mill. In the strip cuts, the balsam fir stocking was constant while the one of black spruce inc reased. This could have an impact on the evolution of the composition of the new stands and, consequently, on their vulnerability to spruce budworm, Choristoneura fumiferana (Clem.). The majority of the clear-c uttings were well regenerated 5 years after harvesting. Their average coniferous stocking was slightly above 60%. However, 48% of the clear- cuttings did not reach this level when only unscarified plots on uplan ds were considered. Advance growth was abundant in those plots but suf fered high losses during harvesting. Consequently, reducing the losses during harvesting would result in a lower proportion of clear-cutting s with insufficient coniferous stocking 5 years after cutting. On the other hand, almost all the strip cuts with insufficient regeneration a fter harvesting were well regenerated 5 years later. Thus, strip cutti ng could be an interesting option on sites with insufficient advance g rowth and on sites well regenerated before cutting but where important losses during harvesting are anticipated.