| Summary: | This paper presents an analysis of the relation between shrub mat development and the expansion of conifer forest margins over a rapidly emerging coast (average rates ranging between 1.1 and 1.5 cm/year) in response to postglacial isostatic adjustment. Shore emergence stimulates the downward expansion of shrub communities on shore (mostly willows) that form dense mats acting as snow traps protecting conifer seedlings on shores. Conifer population structures and tree rings indicate three phases in the forest margin expansion process: (1) an initial period of slow growth and juvenile sparse stands controlled by shrub mat distribution and densities. (2) a phase characterized by denser conifer mats, and growth release of above shrub tree stems and (3) a final phase of maturation dominated by a vegetative regeneration process (clones) and regressive growth forms, highly controlled by the shore climatic conditions.
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