High-elevation spruce - fir forest (S4)
High-elevation spruce - fir forests occur on upper mountain slopes and ridges in New Hampshire. The composition of these forests is significantly influenced by disturbance history, and to a lesser extent by variations in soil and elevation. Species composition also varies along a moisture gradient. In drier conditions, the community has more heath shrubs and other dry-site species, and can be transitional on shallow-to-bedrock sites to the red spruce - heath - cinquefoil rocky ridge community. In moister conditions, it has greater bryophyte cover. Red spruce and balsam fir are typical canopy dominants. The importance of heartleaf birch and paper birch may increase after disturbance. Some post-disturbance patches may be strongly birch-dominated, and in some examples these “birch glades” persist for decades after disturbance. This community is generally found in the mountains, from 2,500–4,000 ft. in elevation, but it also occurs locally on on shallow, rocky soils of lower ridges and other infertile sites (e.g. talus slopes), and higher on relatively protected sites (e.g., ravines).
Soils are generally very nutrient-poor, acidic Inceptisols or Spodosols with a deep, slowly-decomposing humus layer and the variable presence of a grey, leached E (elluviated) horizon. Drainage varies from well to moderately-well drained (somewhat poorly to poorly drained soils are more typical of lowland spruce - fir forest and spruce swamps). The needle litter of conifers is low in nutrients, and due to its acidity it decomposes slowly and contributes to organic matter accumulation. Condensation from cloud-intercept contributes a significant amount of moisture to this forest community. Colder temperatures and deep, late-melting snowpacks at high elevations also contribute to high moisture levels, low soil temperatures, a shortened growing season, and accumulation of soil humus.
Characteristic vegetation: The canopy consists of various combinations of Red spruce (Picea rubens), balsam fir (Abies balsamea), and heartleaf birch (Betula cordifolia), paper birch (Betula papyrifera), and yellow birch (Betula alleghaniensis). Common understory plants that are more restricted to or more abundant in this community than lower elevation forests include 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).
Understory plants shared with northern hardwood forests include intermediate wood fern (Dryopteris intermedia), spinulose wood fern (D. campyloptera), northern wood sorrel (Oxalis acetosella), shining clubmoss (Huperzia lucidula), starflower (Trientalis borealis), Canada mayflower (Maianthemum canadense), bluebead lily (Clintonia borealis), and long beech fern (Phegopteris connectilis). The woody understory is usually sparse. Mosses and liverworts are often abundant and commonly include Bazzania trilobata, Dicranum scoparium, Hypnum curvifolium, Pleurozium schreberi, and Ptilium crista-castrensis. Others bryophytes include Brotherella recurvans, Bazzania denudata, Scapania nemoria, Drepanocladus uncinatus, Pohlia nutans, Sphagnum russowii, S. girgenshonii, and others. Lichens often cover trees and boulders.
A very similar, related community is the high-elevation balsam fir forest.
Good examples of high-elevation spruce - fir forest communities can be seen at Nancy Brook RNA, The Bowl RNA, and on the upper slopes of nearly any peak in the state that rises above 3,000 ft. elevation.
These forests often occur as part of a larger high-elevation spruce - fir forest system.
Old-growth high-elevation spruce - fir forest at Nancy Brook (photos by Ben Kimball)
High-elevation spruce - fir forest (foreground) on Ridge of the Caps (photo by Ben Kimball)
Coarse woody debris in a high-elevation spruce - fir forest
in the White Mountains (photo by Ben Kimball)
High-elevation spruce-fir forest on Cannon Mtn. (photo by Ben Kimball)
High-elevation spruce-fir forest on Franconia Ridge in the White Mountains.
View of Mt. Flume and Mt. Liberty from Little Haystack (photo by Ben Kimball)
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