Impact à court terme d'une coupe avec protection de la régénération sur la gélinotte huppée (Bonasaumbellus) en forêt boréale

Abstract

We studied the short-term impact of cutting with the protection of regeneration (CPR) on ruffed grouse (Bonasa umbellus) and its habitat. Drumming males were surveyed in the boreal forest of western Quebec between 1990 and 1994 in 5 control stands and 10 stands that were cut in 1992. Cutting caused a 50% decline in total density and basal area of trees. In harvested stands, shrubs were less abundant than in control stands. Lateral cover between 1 and 2 m and canopy closure were also lower in cut stands. In the harvested stands, the density varied between 14.1 and 22.6 drummers/km2between 1990 and 1992 before the CPR. In 1993, density declined to 10.1 but was reestablished at 21.5 in 1994. Densities did not differ significantly before or after the CPR nor between cut and uncut stands (p > 0.05). After the CPR, the grouse generally established their drumming sites in the periphery of cut areas. There they found lateral cover and canopy closure similar to those measured in control stands by choosing sites where deciduous shrubs were more abundant than in the remainder of the stand. However, the characteristics of the tree stratum were not optimal; their overall density, that of Betulaceae, and that of Salicaceae were higher near drumming sites located in control stands than those in harvested stands. In harvested stands, drumming sites had a lower total basal area of trees, and namely that of deciduous trees, than in control sites. To maintain ruffed grouse populations immediately after cutting in mixed and deciduous stands of public lands, we suggest that CPRs be in 15-ha blocks while maintaining a basal area of at least 7.5 m2/ha, half of which should be in trembling aspen (Populus tremuloides Michx.) and paper birch (Betula papyrifera Marsh.).