Black spruce [Picea mariana] in forest outliers, has a slower growth rate, higher frequency variation and less persistence than at the forest limit. [other forest species consist of Betula glandulosa, Salix spp. and members of Ericaceae, Gramineae, Compositae and Cyperaceae.] Climate variation accounts for more variance in ring widths at the forest limit than within outliers, which occupy protective sites that mitigate stress. Growth behavior at the forest limit can be interpreted in terms of Arctic Front positions. A 2-century long chronology of tree growth is presented.