Northern hardwood - spruce - fir forest (S4)
Northern hardwood - spruce - fir forest is typically found at intermediate elevations in cool, mesic settings on shallow, rocky, nutrient-poor till or boulder substrates in mountains of central and northern New Hampshire. This mixed forest is a transitional community type, occuring between sugar maple - beech - yellow birch forests and either high-elevation or lowland spruce - fir forests.
Characteristic Vegetation: Sugar maple (Acer saccharum) and beech (Fagus grandifolia) are generally dominant, with abundant yellow birch (Betula alleghaniensis) and modest amounts of red spruce (Picea rubens) and/or balsam fir (Abies balsamea). Spruce and fir trees are generally in lower abundance than hardwoods, but they become dominant with increased elevation, where yellow birch or sometimes paper birch (Betula papyrifera) become the primary hardwoods. Sugar maple and beech disappear above 2,500 feet elevation, leaving only the birches, spruce, and fir. American mountain ash (Sorbus americana), Canadian honeysuckle (Lonicera canadensis), mountain maple (Acer spicatum), and hobblebush (Viburnum lantanoides) often occur in the shrub layer. Understory plants are similar to those in sugar maple - beech - yellow birch forest, but they may achieve higher average cover in this community, particularly intermediate wood fern (Dryopteris intermedia) and mountain wood fern (D. campyloptera). Common characteristic herbaceous species include northern wood sorrel (Oxalis
Variants: Two variants are described:
1. Typic variant
(as described above)
2. Yellow birch variant
This yellow birch (Betula alleghaniensis) dominated variant occurs along high-gradient stream drainages, in ravines, or associated with large boulders or talus. It occupies a narrow elevation zone between hardwood forests below and spruce - fir forests above. Boulders in this variant are festooned with bryophytes and herbs including rock polypody (Polypodium virginianum), whorled aster (Oclemena acuminata), northern wood sorrel (Oxalis montana), mountain wood fern (Dryopteris campyloptera), intermediate wood fern (Dryopteris intermedia), feather moss (Hylocomium splendens), and liverwort (Bazzania trilobata). Yellow birch is well adapted to establishing itself on large boulders, and can persist at some of these sites for relatively long time frames.
Good examples of this community can be found at Lafayette Brook Scenic Area (Franconia), Greeley Ponds Scenic Area (
Northern hardwood - spruce - fir forests often occur as part of larger northern hardwood - conifer forest systems, and sometimes as part of high-elevation spruce - fir forest systems.
Northern hardwood - spruce - fir forest at Mt. Moosilauke (photo by Ben Kimball)
1. Northern hardwood spruce - fir forest in the Rattle River valley
2. Northern hardwood spruce - fir forest in Franconia Notch
(photos by Dan Sperduto)
Northern hardwood - spruce - fir forest in Shelburne (photo by Ben Kimball)
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