Diapensia shrubland (S1)
Diapensia shrublands occur in exposed alpine environments where winds are severe enough to keep snow cover light in winter. Diapensia (Diapensia lapponica) and other dwarf shrubs are the dominant plants. The dwarf shrubs form low, compact mats and domes that reduce exposure to desiccating winds. Overall, dwarf shrubs are more abundant than graminoids, and forbs are in very low abundance. Soils are well drained gravel or gravel and stone mixes, soils freeze deeply, and active frost heaving of the soil is common.
Characteristic vegetation: This community is indicated by the dominance of diapensia (usually >5% cover) along with mixtures of alpine bilberry (Vaccinium uliginosum), highland rush (Juncus trifidus), mountain cranberry (Vaccinium vitis-idaea ssp. minus), three-toothed cinquefoil (Sibbaldiopsis tridentata), mountain sandwort (Minuartia groenlandica), Bigelow's sedge (Carex bigelowii), and boreal bentgrass (Agrostis mertensii). On higher peaks,
In contrast to sedge - rush - heath meadows, diapensia is usually more abundant than Bigelow’s sedge, and
Variants: Two variants are described.
1. Lapland rosebay variant:
This variant occurs from 4,500 - 5,500 ft., primarily in the Presidential Range, and contains a characteristic mix of diapensia (Diapensia lapponica), alpine azalea (Kalmia procumbens), and Lapland rosebay (Rhododendron lapponicum). Bearberry willow (Salix uva-ursi), Cutler's goldenrod (Solidago cutleri), and Bigelow's sedge (Carex bigelowii) are frequent.
2. Alpine bilberry variant:
This uncommon variant is less diverse expression of the community, and is found on lower alpine/subalpine peaks from 4,000 - 4,500 ft. Diapensia is still the dominant species, but alpine bilberry is more common. Bearberry willow, Cutler’s goldenrod, and Bigelow’s sedge are less frequent, and alpine azalea and
Good examples of this community occur throughout the alpine zone of the Presidential Range, on Franconia Ridge, and on Bondcliff. A particularly large example occurs on the summit of Mt. Eisenhower.
Diapensia shrublands frequently occurs along with other alpine communities as part of a larger alpine tundra system.
Diapensia shrubland on the summit of Mt. Eisenhower (photo by Ben Kimball)
Diapensia flowers close-up in the Alpine Garden on Mt. Washington (photo by Ben Kimball)
Diapensia shrubland in the Alpine Garden on Mt. Washington (photo by Ben Kimball)
Diapensia shrubland (foreground) on Mt. Guyot (photo by Ben Kimball)
Diapensia shrubland on Franconia Ridge (photo by Ben Kimball)