Black spruce may produce a few cones as early as 10 years of age, but maximum production occurs between 100 and 200 years. Heavy seed years occur at intervals of 2-6 years and peak crops every 4 years over most of the range. Fires open the cones and accelerate seed release for periods of 60 days to 2-3 years, depending on fire intensity. Viable seed may be dispersed from a cone for up to 25 years, providing a seed supply after fires occur.
Sphagnum mosses can provide a continuously moist seedbed for black spruce, but growth of seedling growth may be slow here because of inadequate nutrients. Feathermosses may provide a suitable seedbed during wet years but may dry out before penetration by the seedling root. Moist mineral soils usually provide good seedbeds, but exposed mineral soil may be too waterlogged or subject to frost heaving in some low-lying areas. Fires that completely remove the surface organic layer usually provide good seedbeds. Seedling mortality seems to be highest on burned duff and lowest on moss and mineral soil surfaces with adequate moisture. Seedlings develop in as little as 10% of full light intensity, but survival and growth are much better in the open.
Layering is an important means of reproduction in black spruce on some sites, especially where rapidly growing mosses cover lower branches. Such layering develops most abundantly in the more open-grown stands and less frequently in dense stands with higher wood volume. It also is common at tree line, probably as a result of depression of the lower branches by snow, and accounts for the presence of "candelabrum" spruce, a circular clump originating from one individual with the tallest tree in the center.
The average maximum age for black spruce is about 200 years, but ages up to 300 years have been reported.
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