The eastern boreal old-growth balsam fir forest: a distinct ecosystem

The objective of this project was to assess the importance of pristine forests in maintaining the botanical biodiversity of the humid boreal balsam fir forest of eastern Canada. The study was based on a comparative analysis of silviculturally mature second-growth stands and pristine forest stands at two stages of development (senescent and old growth) in the Gaspe Peninsula. The structure and composition of the stands was described, and the abundance of structural attributes evaluated. The communities of nonvascular plant species (mosses, liverworts), lichens, and saprophytic fungi were compared. The study demonstrated that the pristine forest landscape studied was composed largely of old-growth and senescent stands. Old-growth forests are differentiated by their irregular structure. The results regarding nonvascular plant species, lichens, and saprophytic fungi show higher species diversity in old-growth forests, corresponding to higher habitat diversity. Species assemblages were comparable between the pristine forests, but differ- ent from those of second-growth stands. Rare species are found more frequently in the old-growth forests. The results indicate that the old-growth balsam fir stands of the Gaspe Peninsula constitute critical habitats for maintaining a large number of species threatened by the gradual disappearance of primeval stands.