Red spruce - heath - cinquefoil rocky ridge  (S3S4)

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Red spruce - heath - cinquefoil rocky ridge is the most common of the four rocky ridge communities in mountainous regions of central and northern New Hampshire. This dry, conifer woodland community occurs between 1,700 and 3,000 feet elevation. It is characterized by red spruce, three-toothed cinquefoil, dense low heath shrubs, a sparse herb layer, and lichens. It lacks most plant species found in the oak - pine zone at lower elevations in southern New Hampshire as well as plants found in alpine and subalpine habitats at higher elevations.

The tree canopy is moderately short (10-30 ft. tall), and ranges from a woodland structure (25-60% cover) with small glade-like openings and sparsely-treed rock outcrops (generally 25-50% rock cover) to larger open barrens of several acres or more with extensive outcrops. In the absence of fire, soils accumulate and this community can succeed to forests over time. It transitions to oak - pine rocky ridge woodlands at lower elevations and heath - krummholz communities at higher elevations. Jack pine rocky ridges are a floristically similar community characterized by an abundance of jack pine.

The dominant tree in this community, red spruce, is restricted to the northern Appalachian region, in contrast to the more boreal distributions of both jack and red pine. It is not tolerant of fire, but readily colonizes the thin soils of rocky ridges. Red spruce mixes and competes with red oak at elevations below 2,000 feet, and with red pine up to about 2,700 feet.

Soils are thin, dry, and acidic with a shallow O horizon over coarse gravelly or sandy A and B horizons or bedrock. Most examples occur on bedrock that yields acidic soil conditions. 

Characteristic vegetation: The tree canopy is dominated by red spruce (Picea rubens). Balsam fir (Abies balsamea) is occasional and sometimes co-dominant while red pine (Pinus resinosa) is frequent but not dominant. Other tree species that may be present include paper birch (Betula papyrifera), heartleaf birch (B. papyrifera var. cordifolia), white pine (Pinus strobus), and mountain ashes (Sorbus spp.). Red oak (Quercus rubra) is occasional only at lower elevation transitions to other communities.

A prominent low heath shrub layer is dominated by lowbush blueberry (Vaccinium angustifolium), with variable amounts of velvet-leaf blueberry (V. myrtilloides) and sheep laurel (Kalmia angustifolia). Rhodora (Rhododendron canadense) is also occasional, particularly in moister microhabitats. Tall shrubs are generally sparse but may include Bartram’s serviceberry (Amelanchier bartramiana) and witherod (Viburnum nudum) in more protected areas. 

Herbs are relatively sparse, though they can be locally abundant, and may include common hair-grass (Deschampsia flexuosa), Rand’s goldenrod (Solidago randii), three-toothed cinquefoil (Sibbaldiopsis tridentata), bristly sarsaparilla (Aralia hispida), poverty oatgrass (Danthonia spicata), and Canada mayflower (Maianthemum canadense). The herb layer includes various species that grow well in crevices. The rare plant silverling (Paronychia argyrocoma) is sometimes present. Lichens and mosses are common, including an abundance of reindeer lichen (Cladonia rangiferina) and haircap mosses (Polytrichum spp.), but are poorly documented.


Good examples of this community can be found on Mt. Monadnock (Jaffrey), Mt. Cardigan (Alexandria), Black Mountain (Benton), South Baldface Mtn. (Chatham), and Percy Peaks (Stark).

Red spruce - heath - cinquefoil rocky ridge often occurs as part of larger montane rocky ridge systems, and sometimes as part of higher subalpine heath - krummholz/rocky bald systems.