Lowland spruce - fir forest (S3)
Lowland spruce - fir forests occupy cold valley bottoms below northern hardwood forests in northern New Hampshire. They form along stream drainages, adjacent to swamps and peatlands, and in former lake basins. Red spruce (Picea rubens), balsam fir (Abies balsamea), mosses, and lichens are abundant, and a variety of herbs and shrubs may be present. The community is floristically similar to high-elevation spruce - fir forest, but differs in landscape setting, soil drainage, and wind-stress characteristics. Tree species present in lowland forests, but absent in their high-elevation counterpart, include Picea glauca (white spruce), Picea mariana (black spruce), and Pinus strobus (white pine). The composition of these forests often varies in a complex way in response to drainage class, which ranges from somewhat poorly to well drained conditions. Wetland plants are frequent at the wetter end of this gradient, but are not as abundant as in spruce swamps. Lowland spruce - fir forests are often associated with spruce swamps and open peatlands.
Spruce budworm infestations are a major disturbance factor in this community in extreme northern New Hampshire, occurring on 40–70 year cycles. Windthrow is also common, though the frequency and intensity of windthrow is less than in the high-elevation spruce - fir forest community.
Nutrient-poor soils derive from various parent materials including compact and loose glacial tills, and water-deposited lake-bottom, river, and kame terrace sediments. Silty, compact basal tills with impeded drainage are frequent north of the White Mountains, often associated with low-grade pelite bedrock. Coarse, well drained ice-contact deposits include outwash, eskers, and kames. In the White Mountains region this community occurs mostly on till derived from siliceous igneous or metamorphic bedrock (e.g., granite or schist). Sites north of the White Mountains generally have a higher base saturation and, in combination with the more northern latitude and boreal climate, tend to support Picea glauca (white spruce).
Characteristic vegetation: Red spruce and balsam fir dominate in various combinations, with paper birch (Betula papyrifera) and yellow birch (B. alleghaniensis) being common associates. Heartleaf birch (Betula cordifolia) is occasional, and hemlock (Tsuga canadensis) and white pine (Pinus strobus) are infrequent or absent (see hemlock - spruce - northern hardwood forest). White spruce is characteristic north of the main core of the White Mountains, where it replaces white pine as an old-field species. Quaking aspen (Populus tremuloides) and larch (Larix laricina) are occasional.
Species absent or uncommon in high-elevation spruce - fir forests that are occasional in this community include wild sarsaparilla (Aralia nudicaulis), striped maple (Acer pensylvanicum), wakerobin (Trillium erectum), and foamflower (Tiarella cordifolia). Characteristic species also found in high-elevation spruce - fir forest include mountain wood fern (Dryopteris campyloptera), intermediate wood fern (D. intermedia), bunchberry (Cornus canadensis), twinflower (Linnaea borealis), Bartram’s serviceberry (Amelanchier bartramiana), goldthread (Coptis trifolia), mountain ashes (Sorbus decora and S. americana), black spruce (Picea mariana), mountain holly (Nemopanthus mucronatus), velvet-leaf blueberry (Vaccinium myrtilloides), and creeping snowberry (Gaultheria hispidula). The woody understoryis usually sparse.
Mosses and liverworts can be abundant and include Bazzania trilobata, Dicranum scoparium, Hypnum curvifolium, Pleurozium schreberi, Ptilium crista-castrensis, Brotherella recurvans, Bazzania denudata, Scapania nemoria, Drepanocladus uncinatus, Pohlia nutans, Sphagnum russowii, S. girgenshonii, and others. Potential rare plants include heart-leaved twayblade (Listera cordata) and/or lily-leaved twayblade (L. convallarioides) in moist or seepy mossy areas.
Good examples of lowland spruce - fir forest communities can be seen at Norton Pool (
These forests often occur as part of a larger lowland spruce - fir forest/swamp system.
Trail through lowland spruce - fir forest at Pondicherry (photo by Ben Kimball)
Mossy ground in a lowland spruce - fir forest at Pondicherry (photo by Ben Kimball)
lowland spruce - fir forest at the edge of a peatland in the North Country
(photo by Ben Kimball)