Dynamics of the boreal forest south of James Bay

Abstract

Ordination models of approximate environmental and dynamic relationship between 7 boreal tree spp. [Picea mariana, P. rubens, Abies balsamea, P. glauca, Pinus banksiana, Larix laricina, Populus balsamifera] were constructed based upon principal components analysis and Krusakal''s nonmetric multidimensional scaling. The assumptions inherent in these models are stated and discussed. The data consisted of 152 forest stands [Other species discussed include Populus tremuloides, Betula papyrifera, Thuja occidentalis, Prunus pensylvanica, Fraxinus nigra, Acer rubrum, Prunus virginiana, Acer saccharum, A. spicatum, Alnus rugosa, Pyrus americana and P. decora] from the closed-crown boreal forest zone of Ontario and Quebec south of James Bay. Sequential forest succession, as demonstrated by similar techniques for a section of the Wisconsin [USA] evergreen-hardwood forest, is not common in the region of boreal forest studied. However, for those species in common between this and the Wisconsin study, similar dynamic pathways are indicated despite difference in samples size and field technique. Tree species developmental pathways, as indicated by succession vectors'' on the ordination models are, for the most part, short and circular with the exception of A. balsamea (balsam fir). This reflects the reestablishment of similar, relatively monospecific forest stands following catastrophic forest destruction by fire and (or) other agencies. Where catastrophe does not intervene deciduous primary forest species may be succeeded by an understory of A. balsamea or by P. mariana (black spruce). Equally, some forest stands of primary establishment may become decadent with little or no subsequent tree growth. These observations are discussed with respect to the general notion of forest succession.