Maritime rocky barren (S2)
Maritime rocky barrens are exposed, sparsely-vegetated outcrops with few herbs and even fewer shrubs. Plant cover is affected by concentrations of seabird guano, lack of soil, and exposure to heavy surf, wind, and salt spray. The substrate is dominated by exposed bedrock. This community lies above intertidal rocky shores. Small depressions within these rocky barrens hold brackish water pools. At slightly higher elevations, this community may grade into maritime meadow or maritime shrub thicket communities.
Soil is primarily restricted to protected crevices in the bedrock. This community is restricted to the Isles of Shoals where it occurs on all nine islands, and to occasional exposed coastal shorelines on the mainland. All examples occur within the Coastal Lowland subsection.
Characteristic vegetation: The most frequent species are yarrow (Achillea millefolium), quack grass (Elymus repens), red fescue (Festuca rubra), narrow-leaved peppergrass (Lepidium ruderale), poor-man's pepper (L. virginicum), birds' knotweed (Polygonum aviculare), common purslane (Portulaca oleracea), nightshade (Solanum dulcamara), seaside goldenrod (Solidago sempervirens), red sand spurrey (Spergularia rubra), and New York aster (Symphyotrichum novi-belgii). Several other associated species occur with an even sparser cover.
Good examples of these communities can be found on the Isles of Shoals.
Maritime rocky barrens sometimes occur as part of a larger maritime rocky shore system.
Maritime rocky barren at the Isles of Shoals (photo by Bill Nichols)