Maritime shrub thicket (S1)
Maritime shrub thickets are dominated by shrubs with a low abundance of stunted trees and understory herbs. The substrate consists of relatively thin, dry to dry-mesic, sandy loams. They are are restricted to only a few locations along
Two expressions occur: 1) a short to moderate-height shrub thicket comprising stunted and low-growing shrubs on thin-soiled, exposed ridgelines and areas closer to shorelines near rocky barrens, and 2) a moderate to tall shrub thicket in more protected island interiors in deeper soils.
Characteristic Vegetation: Common shrubs, including Amelanchier canadensis (eastern shadbush), A. stolonifera (dwarf shadbush), Gaylussacia baccata (black huckleberry), Myrica pensylvanica (northern bayberry), Parthenocissus quinquefolia (Virginia creeper), Photinia melanocarpa (black chokeberry), Rosa rugosa (beach rose), R. virginiana (Virginia rose), Rubus allegheniensis (common blackberry), R. idaeus (red raspberry), Toxicodendron radicans (poison ivy), and occasionally, stunted forms of Acer rubrum (red maple) and Prunus serotina (black cherry). Common herbs are Achillea millefolium (yarrow), Agrostis capillaris (Rhode Island bentgrass), Anthoxanthum odoratum (sweet vernal grass), Elymus repens (quack grass), Fallopia scandens (large climbing false buckwheat), Festuca rubra (red fescue), Fragaria virginiana (wild strawberry), Maianthemum stellatum (starry false Solomon's seal), Poa compressa (Canada bluegrass), P. pratensis (Kentucky bluegrass), Sedum spp. (stonecrops), Sibbaldiopsis tridentata (three-toothed cinquefoil), and Symphyotrichum novi-belgii (New York aster).
Variants: Two variants are described:
Good examples of this community can be found on the Isles of Shoals.
1. Typic maritime island variant: Vegetation as described above. This variant covers most of the natural upland habitat landward of maritime rocky barrens on Star Island and on other larger islands in the Isles of Shoals nearby in Maine (i.e., Appledore, Cedar, and Smuttynose). Vegetation structure varies depending on degree of exposure and soil depth. A short to moderate-height shrub thicket comprised of stunted and low-growing shrubs grows on thin-soiled, exposed ridgelines and areas close to shorelines (near rocky barrens). Moderate-height to tall shrub thickets grow in more protected island interiors with deeper soils.
2. Mainland variant: The mainland example occurs on a dry sandy, cobble berm and is impacted by high cover of invasive species. Common shrubs are Rhus typhina (staghorn sumac), Toxicodendron radicans (poison ivy), Lonicera morrowii (Morrow's honeysuckle), and Rosa rugosa (beach rose). Stunted, scattered tree species include Prunus serotina (black cherry) and Juniperus virginiana (eastern red cedar). Herbs include several found in the typic variant along with Lathyrus japonicus (beach pea), Oenothera biennis (biennial evening primrose), Artemisia vulgaris (common mugwort), Rumex crispus (curly dock), and others.
Maritime shrub thickets sometimes occur as part of a larger maritime rocky shore system.
Maritime shrub thicket community on Star Island (photo by Bill Nichols)