Évolution de la régénération de peuplements résineux et mélangés au cours des 30 années après coupe à blanc mécanisée

Abstract

This paper presents results from a 30 year monitoring of 15 clearcut areas. Study areas were located before cutting in stands having an abundant advance regeneration. Four study areas were initially dominated by black spruce, four by balsam fir, three by jack pine and the last four comprised a mix of species. Stand inventories and regeneration surveys were conducted before harvesting. Harvesting was done in regular logging operations, without any special care to protect the advance growth. Regeneration surveys were taken again after harvesting, 5 years, 10 years, 20 years and 30 years after harvesting. Black spruce stands regenerated to black spruce dominated stands. Balsam fir, which was sometimes abundant in the advance regeneration, did not invade the stands and the abundance of hardwoods was temporary. In some cases a reduction in yield is to be expected. In balsam fir stands, harwoods were more aggressive. A reduction in softwood yield is predicted for three of the four cutovers. The presence of a tall regeneration seems to lead to higher yields in black spruce and balsam fir stands. The evolution of jack pine and mixed stands is quite variable. In some jack pine stands, hardwoods will constitute a significant component of the new stand. In some mixed stands, softwoods are not very abundant whereas in others they form an important part of the stand at 30 years. This study has shown an urgent need for a better understanding of stand dynamics in young stands. Such an understanding is necessary for an adequate forecast of the yield of second growth stands.