Natural Communities of NH -- Photo Guide

Red maple - black ash swamp  (S3)


(formerly red maple - black ash - swamp saxifrage swamp)

Red maple - black ash swamps occur in central and southern New Hampshire and contain plants indicative of seepage and/or enriched conditions. They most often occur in one of three types of settings: 1.) in gently sloping, spring-fed headwater basin wetlands where groundwater discharge and/or subsurface upland runoff influence the rooting zone of the swamp, 2.) where groundwater discharge in flat basins is pronounced or influenced by intermediate/basic bedrock or soils, or 3.) along the upland borders of larger swamp systems. Red maple (Acer rubrum) dominates the tree canopy, and black ash is present in low abundance. A diverse assemblage of shrubs, herbs, and bryophytes indicative of nutrient-rich seepage conditions distinguish this community from most other types of rich swamps. 

Soils in these seepage swamps are usually poorly to very poorly drained mineral histic or histic epipedons (shallow muck or peat over grayish or gleyed subsoil). In the seacoast region, these swamps often occur on silt loam and silt soils of marine origin (e.g., Buxton or Scitico silt loams), or other soils with high base-cation status.

Characteristic vegetation:
The tree canopy is dominated by red maple with lesser quantities of black ash (Fraxinus nigra), white ash (Fraxinus americana), yellow birch (Betula alleghaniensis), and occasionally basswood (Tilia americana). A diverse assemblage of moss species is present (e.g., Mnium spp.); peat mosses (Sphagnum spp.) are sparse or absent but when present include species restricted to mineral-rich conditions.

Seepage indicators are often present, such as swamp saxifrage (Saxifraga pensylvanica), golden saxifrage (Chrysosplenium americanum), purple avens (Geum rivale), marsh marigold (Caltha palustris), water pennywort (Hydrocotyle americana), northern spicebush (Lindera benzoin), and Robbins’ ragwort (Senecio robbinsii). Other herbs and shrubs that are likely to be abundant include sensitive fern (Onoclea sensibilis), poison ivy (Toxicodendron radicans), violets (Viola spp.), spotted touch-me-not (Impatiens capensis), Alnus incana (speckled alder), Pennsylvania bitter cress (Cardamine pensylvanica), small enchanter's nightshade (Circaea alpina), and red osier dogwood (Cornus sericea). Peat mosses (Sphagnum spp.) are infrequent, but when they do occur, they are often species indicative of seepage conditions (e.g., Sphagnum squarrosum). 

Variants: Three variants are described.

1.  Typic variant: This is the typic variant as described above.

2.  Circumneutral variant: This rare type has many of the same species found in the typic variant but is influenced to a greater degree by base-rich groundwater and contains more species indicative of richer conditions. These indicator species include bulbous bitter-cress (Cardamine bulbosa), Loesel’s twayblade (Liparis loeselii), American alder-buckthorn (Rhamnus alnifolia), Bebb’s sedge (Carex bebbii), and tufted loosestrife (Lysimachia thyrsiflora).

3.  Skunk cabbage variant: This variant has fewer seepage indicators and is less species rich than the other two variants. Skunk cabbage (Symplocarpus foetidus) cover is moderate to high. Peat moss (Sphagnum spp.) is most frequent in this variant but even here does not form extensive carpets.


Good examples of this community occur at College Woods (Durham), Pawtuckaway State Park (Nottingham), and Canterbury Shaker Village (Canterbury).

Red maple - black ash swamps often occur as part of temperate minerotrophic swamp systems.

Red maple - black ash swamp in Hampstead (photo by Ben Kimball for the NH Natural Heritage Bureau)
Red maple - black ash swamp in Hampstead (photo by Ben Kimball)

RM - black ash - swamp saxifrage swamp in Hampstead (photo by Ben Kimball for the NH Natural Heritage Bureau)
red maple - black ash swamp in Hampstead (photo by Ben Kimball)

red maple - black ash swamp in the Seacoast region (photo by Ben Kimball)
red maple - black ash swamp in the Seacoast region (photo by Ben Kimball)


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