Alpine/subalpine bog (S1)
(formerly wet alpine/subalpine bog)
Alpine/subalpine bogs are a peat moss (Sphagnum spp.) dominated peatland community that occurs on mostly level to sloping terrain, generally above 3,500 feet elevation. They form in poorly-drained depressions on summit ridges, where deep, late-melting snowbanks facilitate the development of peat soils. Species composition and abundance patterns indicate more permanently saturated conditions than are found in wooded subalpine bog/heath snowbank communities. Sedges are common, and trees are absent or sparse. The shrub layer is dwarfed and typically less than 20 cm high. Peat moss is abundant. Peat soils are moderately deep, ranging from 45-75 cm, and are poorly decomposed near the surface. Slopes are mostly 0-8 degrees, but occasionally as steep as 35 degrees.
Characteristic vegetation: This community is distinguished from lowland peatlands by the presence of subalpine plants including black crowberry (Empetrum nigrum), alpine bilberry (Vaccinium uliginosum), tussock bulrush (Scirpus cespitosus), and baked apple berry (Rubus chamaemorus). Saturated conditions are indicated by the presence of small cranberry (Vaccinium oxycoccos), hare's-tail cottongrass (Eriophorum vaginatum), and an abundance and high constancy of peat mosses (Sphagnum spp.). Sphagnum fuscum and S. capillifolium are the most common species; Sphagnum rubellum, S. russowii, and S. lescurii may also be present.
Variants: Two variants are recognized:
1. Baked apple berry - bilberry variant:
This variant contains a greater abundance of baked apple berry (a.k.a. cloudberry), alpine bilberry, and tussock bulrush (Trichophorum cespitosum). Mountain cranberry (Vaccinium vitis-idaea) is occasional. Rhodora is notably absent. The highest occurrence of this variant is at 4,900 ft.
2. Rhodora - shrub heath variant:
This variant has a denser overall cover of shrubs than the other variant. It also tends to lack tussock bulrush and baked apple berry, and has less alpine bilberry. There is a denser cover of dwarf shrubs than in the other variant. Black crowberry (Empetrum nigrum) is occasional, while rhodora (Rhododendron canadense) is frequent. Black spruce (Picea mariana) is also more frequent. The highest occurrence of this variant is at 3,700 ft., and it is transitional to the wooded subalpine bog/heath snowbank community at some sites.
Good examples of this community occur on Mt. Success, Shelburne-Moriah Mtn., Mt. Jackson, Mt. Eisenhower, Mt. Adams, and Bald Cap Mtn.
Alpine/subalpine bogs are often associated with the following natural community systems: alpine/subalpine bog system, alpine tundra system, and subalpine heath - krummholz/rocky bald system.
Alpine/subalpine bog at Star Lake in the Presidential Range (photo by Ben Kimball)
Alpine/subalpine bog on Shelburne-Moriah Mtn. (photo by Ben Kimball)
(Sloping) alpine/subalpine bog in the Mahoosuc Range (photo by Dan Sperduto)
Alpine/subalpine bog (cloudberry - bilberry variant) at the top of Mt. Success
(photo by Ben Kimball)
Alpine/subalpine bog on Mt. Eisenhower (photo by Dan Sperduto)