Natural Communities of NH -- Photo Guide

Northern hardwood seepage forest  (S3)

Northern hardwood seepage forests
are common in the northern part of the state. These swampy, semi-rich northern hardwood forests occur on lower mountain slopes that have frequent seep openings and seepage runs. Because of the frequency of wet areas, this forest is characterized by a mosaic of both upland and wetland plant species. In some examples, the seepage zones occupy extensive areas, with lush glade openings that can reach a half-acre in size. The tree canopy is typically dominated by northern hardwoods, or sometimes by a hardwood - conifer mix. This community differs from red maple - black ash swamps by having higher angle slopes and by the co-dominance of sugar maple, yellow birch, and occasionally balsam fir or red spruce. This community is most frequent in the Connecticut Lakes subsection of the North Country, where the combination of a cold northern climate and sloping silt soils with a densipan and impeded drainage are more common than further south in New Hampshire.

Soils are usually poorly to very poorly drained silt loams with 3-10 (-20) degree slopes. In drier portions of seepage forests, soils consist of shallow mucky silt loams over silt loam with some mottling apparent near the surface (ca. 15-20 cm down). In wetter portions, soils have a deeper mucky silt loam at the surface. This community is found on Monarda (Cabot) and Peacham soil series in Coos County.

Characteristic Vegetation: Common trees include sugar maple (Acer saccharum), yellow birch (Betula alleghaniensis), and occasionally black ash (Fraxinus nigra). Other trees that may be present include white spruce (Picea glauca), red spruce (Picea rubens), balsam fir (Abies balsamea), and heartleaf birch (Betula cordifolia). Black ash (Fraxinus nigra) may be present, but is generally restricted to drainages and other wetter portions of the forest.

The herb layer is lush and diverse, and often contains northeastern manna-grass (Glyceria melicaria), spotted touch-me-not (Impatiens capensis), purple-stemmed aster (Aster puniceus), foamflower (Tiarella cordifolia), great willow-herb (Epilobium angustifolium), northern lady fern (Athyrium filix-femina), and dwarf raspberry (Rubus pubescens).

Other herbs include perfect-awned sedge (Carex gynandra), ciliated willowherb (Epilobium ciliatum), mountain wood fern (Dryopteris campyloptera), sweet-scented bedstraw (Galium triflorum), tall meadow-rue (Thalictrum pubescens), Braun's holly fern (Polystichum braunii), sensitive fern (Onoclea sensibilis), white snakeroot (Ageratina altissima), bluebead lily (Clintonia borealis), zigzag goldenrod (Solidago flexicaulis), red baneberry (Actaea rubra), white baneberry (Actaea pachypoda), long beech fern (Phegopteris connectilis), intermediate wood fern (Dryopteris intermedia), northeastern spotted Joe-pye-weed (Eupatorium maculatum var. foliosum), grassleaf goldenrod (Euthamia graminifolia), bluejoint (Calamagrostis canadensis), and white turtlehead (Chelone glabra).

Shrubs include red raspberry (Rubus idaeus), red elderberry (Sambucus racemosa), hobblebush (Viburnum lantanoides), striped maple (Acer pensylvanicum), and speckled alder (Alnus incana).

Rare or uncommon plants that may be found in this community include large yellow lady's slipper (Cypripedium parviflorum var. pubescens), northern wild licorice (Galium kamtschaticum), and millet grass (Milium effusum).

Good examples
of this community occur in the Connecticut Lakes Headwaters Natural Area (Pittsburg) and Franconia Notch (Lincoln).

Northern hardwood seepage forests often occur as a diagnostic community of forest seep/seepage forest systems, and sometimes as an interwoven wetland community within northern hardwood - conifer forest systems.

northern hardwood seepage forest (photo by Dan Sperduto for the NH Natural Heritage Bureau)
northern hardwood seepage forest (photo by Dan Sperduto)

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