Lowland spruce - fir forest/swamp system
lowland spruce - fir forest/swamp system system at Pondicherry (photo by Ben Kimball)
Description: This system is a mosaic of lowland spruce - fir forest and red spruce swamp communities that occur on mineral soils. In northern New Hampshire, these communities intergrade in complex ways on the ground, with various expressions ranging mostly from well or moderately well drained upland forests to poorly or very poorly drained swamps. Somewhat poorly drained soils are intermediate and very common. The average condition for red spruce swamps is acidic and poorly drained, with shallow, well-decomposed organic soils (10–40 cm) over sandy to silty mineral soil. At the very poorly drained end of the spectrum, these systems often grade to black spruce peat swamps. In some moderate-elevation mineral swamp settings, red spruce swamp can be the primary community in the system, with either an abrupt transition to a narrow spruce - fir forest border or direct transition to hardwood forest or high-elevation spruce-fir systems. In general this system is more minerotrophic than black spruce peat swamps, but less so than northern white cedar or near-boreal hardwood-conifer minerotrophic swamp systems.
Lowland spruce - fir forests have a well-developed conifer canopy, a sparse tall shrub understory, sparse to moderate cover of ferns and dwarf shrubs, and moderate to high cover of bryophytes. The transition from lowland spruce - fir forest to red spruce swamp is marked by well developed hummock – hollow topography with wet hollows and higher cover of cinnamon fern and bryophytes.
Diagnostic natural communities:
• Red spruce swamp (S3)
• Lowland spruce - fir forest (S3)
• Montane black spruce - red spruce forest (S1)
Landscape settings: valley bottoms, lowland flats, and lake basins
Soils: mostly on moderately well to poorly drained glacio-fluvial and firm till mineral soils (sand to silt loams, sometimes gravelly), less frequently on loose till; may contain inclusions of well and very poorly drained soils; generally weakly minerotrophic, acidic
Spatial pattern: large patch to extensive (5–500+ acres); linear to broad-linear or irregular; further south, occurs in more isolated small patches; internal zonation of communities typically relates to soil drainage
Physiognomy: forest to woodland
Distribution: well developed and most common north of the White Mountains from 1,000–2,500 ft. (moderate elevations); less frequent in the White Mountains; infrequent in the higher valley bottoms south of the mountains
Lowland spruce - fir forest:
Trees and tall shrubs
Picea rubens (red spruce) -- dom.
Abies balsamea (balsam fir) -- dom.
Betula papyrifera (paper birch) -- com.
Betula alleghaniensis (yellow birch) -- com.
Betula cordifolia (heartleaf birch) -- occ.
Picea glauca (white spruce) -- occ.
Picea mariana (black spruce) -- occ.
Sorbus decora (showy mountain ash)
Sorbus americana (American mountain ash)
Nemopanthus mucronatus (mountain holly)
Cornus canadensis (bunchberry)
Linnaea borealis (twinflower)
Amelanchier bartramiana (Bartram’s serviceberry)
Coptis trifolia (goldthread)
Vaccinium myrtilloides (velvet-leaf blueberry)
Gaultheria hispidula (creeping snowberry)
Dryopteris campyloptera (mountain wood fern)
Dryopteris intermedia (intermediate wood fern)
Listera cordata (heart-leaved twayblade) -- moist or seepy areas
Listera convallarioides (lily-leaved twayblade) -- moist or seepy areas
Bazzania trilobata (liverwort)
Dicranum scoparium (moss)
Hypnum curvifolium (moss)
Pleurozium schreberi (moss)
Ptilium crista-castrensis (moss)
Brotherella recurvans (moss)
Bazzania denudate (liverwort)
Scapania nemoria (liverwort)
Drepanocladus uncinatus (moss)
Pohlia nutans (moss)
Sphagnum russowii (peat moss)
Sphagnum girgenshonii (peat moss)
Occasional species absent or uncommon in the high-elevation spruce – fir:
Aralia nudicaulis (wild sarsaparilla)
Acer pensylvanicum (striped maple)
Trillium erectum (wakerobin)
Tiarella cordifolia (foamflower)
Picea glauca (white spruce)
Osmunda cinnamomea (cinnamon fern)
Associated natural community systems: Black spruce peat swamp systems occur on adjacent very poorly drained peat soils. In more minerotrophic settings this system can be adjacent to and transition into northern white cedar or near-boreal hardwood-conifer minerotrophic swamp systems. Upslope, lowland spruce – fir forest/swamp systems typically transition to northern hardwood – conifer forest systems.
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