Black spruce - balsam fir krummholz (S2S3)
Krummholz is a German word meaning “crooked wood.” Krummholz trees are usually short, attaining no more than 6 feet in height. The adoption of a twisted, stunted life form allows the spruce and fir trees to persist at higher elevations where wind and blowing snow prune branches so severely that an upright tree would not be able to gather sufficient mineral nutrients to offset losses.
The black spruce - balsam fir krummholz community is characterized by pure or nearly pure krummholz (>60% cover) areas that form either extensive patches or long, more or less continuous zones at treeline. It is distinguished here from heath - krummholz communities in which krummholz occurs as small patches within a fine-scaled mosaic along with heath shrubs. It typically forms a narrow transition zone to alpine tundra on steep slopes or a wider transition on relatively shallow slopes. Snow swept off more exposed alpine/subalpine areas tends to accumulate in and around this community, affording protection to leaves and branches from wind, snow, and ice-blasting. As exposure increases, snow accumulation is reduced, and tree growth cannot keep up with physical losses. Stunted black spruce - balsam fir krummholz can reach at least 130–140 years of age. Climatic treeline occurs at 4,900 ft., although this community can occur as low as 3,500 feet, and examples with more red spruce as low as 3,000 feet.
Characteristic vegetation: Black spruce (Picea mariana) and balsam fir (Abies balsamia) are the dominant conifers, but red spruce (Picea rubens) may also be a component of this community, especially in lower elevation examples. The spruce and fir are often joined by lesser amounts of heartleaf birch (Betula cordifolia) and heath shrubs. Other plants that may be present include mountain cranberry (Vaccinium vitis-idaea), bunchberry (Cornus canadensis), bluebead lily (Clintonia borealis), starflower (Trientalis borealis), creeping snowberry (Gaultheria hispidula), large-leaved goldenrod (Solidago macrophylla), and various mosses.
Below this community, a black spruce drops out, the trees grow taller, and a dense canopy of balsam fir dominates New Hampshire’s highest elevation forests, the high-elevation balsam fir forest community.
Good examples of this community occur throughout the Presidential Range and on Mt. Guyot.
Black spruce - balsam fir krummholz may transition at lower elevations to Labrador tea heath - krummholz, and often occurs as part of the following natural community systems: alpine tundra system, alpine ravine/snowbank system, alpine/subalpine bog system, and subalpine heath - krummholz/rocky bald system.
Black spruce - balsam fir krummholz on Mt. Guyot (photo by Dan Sperduto)
Black spruce - balsam fir krummholz near treeline in the Presidential Range
of New Hampshire's White Mountains (photo by Ben Kimball)
Hiking through a black spruce - balsam fir krummholz community along the
Davis Path on the south side of Mt. Washington (photo by Ben Kimball)
black spruce - balsam fir krummholz
along the Jewel Trail on the west side of
Mt. Washington (photo by Ben Kimball)