Natural Community Systems -- Photo Guide

High-elevation spruce - fir forest system

High-elevation spruce-fir forest system covers the upper slopes of many mountains in northern New Hampshire (photo by Ben Kimball for the NH Natural Heritage Bureau)
High-elevation spruce - fir forest system covers the upper slopes of many mountains in
northern New Hampshire. In this aerial image, the north end of Franconia Ridge is in the foreground,
Mt. Garfield and the Twin Range are in the middle (note the conspicuous fir-waves on North Twin Mtn.),
and Mt. Washington and the Presidential Range are on the horizon at the top. (photo by Ben Kimball)

High-elevation spruce - fir forest system on Mt. Bond (photo by Ben Kimball for the NH Natural Heritage Bureau)
High-elevation spruce - fir forest system on Mt. Bond (photo by Ben Kimball)

 

Description:  This system corresponds to the Picea rubens (red spruce) and Abies balsamea (balsam fir) dominated forests of higher elevation mountains in New Hampshire, generally occurring between 2,500 and 4,500 ft. (locally lower and higher).  There are two dominant communities in this system: high-elevation spruce - fir forest that occurs mostly between 2,500–3,500 ft., and high-elevation balsam fir forest that occurs from about 3,5004,500 ft.  This system occurs locally lower on ridges and other rocky or infertile sites, and locally higher on relatively protected sites (e.g., ravines up to ca. 5,200 ft.).

High-elevation balsam fir forest occurs below the krummholz zone and is dominated by balsam fir with little or no red spruce and less Betula cordifolia (heartleaf birch) than at lower elevations.  The canopy height here is typically in the 210 m range, reduced from the taller stature trees at lower elevations (which grow to 2025 m height).  These short trees ultimately diminish to krummholz stature (<2 m) at treeline.  Pease’s (1964) concept of balsam fir “scrub” probably includes both krummholz and the upper portion of balsam fir forest zone where the fir trees are scrubby in nature and of low stature (25 m) from about 4,2004,500+ ft. in elevation.  Here the lower branches of balsam fir trees can form dense thickets, punctuated by a partial woodland canopy of narrow fir spires.  High-elevation fir forests can form patches of wind-induced mortality known as “fir-waves.”  Fir waves are linear patches of blow-down or standing dead trees oriented perpendicular to the prevailing wind, and arranged in a progression of waves of different ages of resulting regeneration adjacent to one another.  A common theory suggests that the trees primarily die from the death of needles and roots due to chronic wind stress.

The high-elevation spruce - fir forest occurs at lower elevations and typically contains red spruce, balsam fir, and heartleaf birch.  The specific composition of these forests is much influenced by the disturbance history, and to a lesser extent by soils and elevations within the zone.  Variation in species composition is noticeable along a moisture gradient: in drier conditions the heaths and other dry-site species dominate (transitional to the red spruce - heath - cinquefoil rocky ridge community on shallow-to-bedrock sites); in moister conditions there is greater bryophyte cover.  Characteristic birds include arctic three-toed woodpecker, black-backed woodpecker, spruce grouse, Bicknell’s thrush, black poll warbler, yellow-rumped warbler, boreal chickadee, and others.

The transition from the high-elevation spruce - fir forest system to northern hardwood - conifer forest systems is often marked by the northern hardwood - spruce - fir forest community.  This community is characterized by spruce, fir, and northern hardwoods (yellow birch, beech, sugar maple).  It forms a narrow to broad zone between the two systems, and it is arguable whether this community is more indicative of one or the other.  Depending on disturbance and cutting history, some examples of current hardwood or mixed forests will eventually succeed to conifer dominance (e.g., high-elevation spruce - fir forest).  However, examples of northern hardwood - spruce - fir forests that are likely to stay more mixed over the long term are probably most closely aligned with sugar maple - beech - yellow birch forests because the northern hardwoods have not been excluded by the climatic and poorer soil conditions closely associated with their disappearance at higher elevations in the high-elevation spruce – fir forest.

Soils in this system are generally very nutrient-poor. They are acidic Inceptisols or Spodosols with a deep, slowly-decomposing humus layer, with the variable presence of a grey, leached (eluviated) E 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 - fir swamps).  Litter of conifers has low nutrient quality and contributes to organic matter accumulation.  Cloud-intercept contributes a significant amount of moisture to this system, particularly in the balsam fir zone.  Colder temperatures and deep, late-melting snowpacks at high elevations also contribute to higher moisture levels, lower soil temperatures, a shortened growing season, and accumulation of humus compared to lower elevation northern hardwood forests.


Diagnostic natural communities:

      • High-elevation spruce - fir forest (S4)

      • High-elevation balsam fir forest (S3S4)


Peripheral or occasional natural communities:

      • Northern hardwood - spruce - fir forest (S4)

      • Montane landslide barren and thicket (S3S4)


Landscape settings: mountain side-slopes

Soils: mostly loose and firm cryic tills; also on stabilized talus

Spatial pattern: large patch to matrix (<10–1,000+ acres); irregular shapes along mountain tops and ridges

Physiognomy: forest

Distribution: generally from 2,5004,500 ft.; lower on side slopes with poor, rocky soils


Characteristic species:
Trees and tall shrubs
   Abundant species
      Picea rubens (red spruce)
      Abies balsamea (balsam fir) 
      Betula papyrifera (paper birch) 
      Betula alleghaniensis (yellow birch) 
      Betula cordifolia (heartleaf birch)

   Occasional species:
      Picea mariana (black spruce) -- higher elevations
      Sorbus decora (showy mountain ash)
      Sorbus americana (American mountain ash) 
      Nemopanthus mucronatus (mountain holly)

Dwarf shrubs
      Cornus canadensis (bunchberry)
      Linnaea borealis (twinflower)
      Amelanchier bartramiana (Bartram’s serviceberry)
      Coptis trifolia (goldthread)
      Vaccinium myrtilloides (velvet-leaf blueberry)
      Gaultheria hispidula (creeping snowberry)

Herbs 
      Dryopteris campyloptera (mountain wood fern)
      Dryopteris intermedia (intermediate wood fern)
      Huperzia lucidula (shining clubmoss)
      Oxalis montana (northern wood sorrel)
      Clintonia borealis (bluebead lily)
      Listera cordata (heart-leaved twayblade) -- moist or seepy areas
      Listera convallarioides (lily-leaved twayblade) -- moist or seepy areas

Bryophytes
      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)


Associated natural community systems
This system transitions to alpine tundra, alpine ravine/snowbank, subalpine heath – krummholz/rocky bald or montane rocky ridge systems at higher elevations, or northern hardwood - conifer forest systems at lower elevations.


balsam fir forest community in a high-elevation spruce - fir forest system on North Twin Mtn. (photo by Ben Kimball)
balsam fir forest community in a high-elevation spruce - fir forest system on North Twin Mtn.
(photo by Ben Kimball)

high-elevation spruce - fir forest on Mt. Chocorua (photo by Ben Kimball)
high-elevation spruce - fir forest on Mt. Chocorua (photo by Ben Kimball)


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