Black spruce most commonly grows as pure stands on organic soils and as  mixed stands on mineral soil sites. It is a major component of forest  types with white spruce, balsam fir (Abies balsamea), jack pine  (Pinus banksiana), and tamarack and also grows in association with  paper birch (Betula papyrifera), lodgepole pine (P. contorta),  quaking aspen (Populus tremuloides), balsam poplar, northern  white-cedar (Thuja occidentalis), black ash (Fraxinus nigra),  American elm (Ulmus americana), and red maple (Acer  rubrum). In the southern parts of its range, black spruce is commonly  found in mixed stands with several species, especially northern  white-cedar, white spruce, balsam fir, and tamarack. In the main part of  its range, it is commonly associated with white spruce, quaking aspen,  balsam fir, paper birch, and tamarack. Jack pine is a common associate on  dry sites. At the northern and northwestern limits of the range, pure  stands are common, but black spruce is also found associated with paper  birch, quaking aspen, white spruce, and tamarack.

    Because of its broad distribution and varying ecological site  characteristics, the Black Spruce forest cover type (Society of American  Foresters Type 12, eastern, and 204, western) (11) has been divided into  six subtypes: (a) black spruce-feathermoss, most common in the southern  and central boreal forest; (b) black spruce-lichen, most abundant near the  northern limit of the boreal forest; (c) black spruce-dwarf shrub, in the  southern and central portions of the boreal forest; (d) black  spruce-sphagnum, on wet soils; (e) black spruce-speckled alder (Alnus  rugosa), on waterlogged soils with standing or slowly flowing water;  and (f) black spruce-sedge, on peatlands with minerally enriched moving  water. Black spruce is also a major component of cover types Black  Spruce-Tamarack (Type 13); Black Spruce-White Spruce (Type 253); and Black  Spruce-Paper Birch (Type 254).

    One of the most conspicuous aspects of many black spruce stands is a  nearly continuous ground cover of feathermosses (Hylocomium splendens,  Pleurozium schreberi, and Ptilium crista-castrensis) and  sphagnum mosses (Sphagnum spp.). On some sites, the moss layer is  replaced by nearly continuous mats of lichens, primarily species of Cladonia;  this is especially typical of open stands in northern areas where the  open lichen woodland is a common vegetation type.

    The shrubs associated with black spruce change gradually from east to  west. Dominant shrubs in the eastern range include mountain maple (Acer  spicatum), beaked hazel (Corylus cornuta), speckled alder,  red-osier dogwood (Cornus stolonifera), and red raspberry (Rubus  idaeus) on better sites; and low birch (Betula pumila), bog  birch (B. glandulosa), bog-rosemary (Andromeda glaucophylla),  lambkill (Kalmia angustifolia), Labrador-tea (Ledum  groenlandicum), leatherleaf (Chamaedaphne calyculata), and  bog-laurel (Kalmia polifolia) on the less productive peatlands. In  the western part of the range, littletree willow (Salix  arbusculoides), grayleaf willow (S. glauca), Bebb willow  (S. bebbiana), prickly rose (Rosa acicularis), American green  alder (Alnus crispa), Labrador-tea, bog blueberry (Vaccinium  uliginosum), and mountain cranberry (Vaccinium vitis-idaea) are  the most important shrubs. The most important herbs, found over most of  the range, are panicle bluebells (Mertensia paniculata), fireweed  (Epilobium angustifolium), one-sided pyrola (Pyrola secunda),  twinflower (Linnaea borealis), bunchberry (Cornus  canadensis), wild sarsaparilla (Aralia nudicaulis), false  lily-of-the-valley (Maianthemum canadense), starflower (Trientalis  borealis), bluejoint reedgrass (Calamagrostis canadensis), and  sheathed cottonsedge (Eriophorum vaginatum).