Natural Communities of NH -- Photo Guide

Northern white cedar seepage forest  (S2)



Northern white cedar seepage forests
occur on sloping mineral soils between uplands and swamps on organic soil. The ground is seasonally saturated. This is a forested wetland community, often located along a seasonally saturated, sloping transition zone between uplands and flat swamps, or along drainages. It has less developed micro-topography than swamp communities, and moderately to poorly drained soils. While this is not a swamp community, species composition is similar to northern white cedar - balsam fir swamp. It is characterized by moderately low moss cover, a sparse shrub layer, and a greater abundance of upland herbs, including rich-site species.

Shallow, well-decomposed muck (generally <50 cm) often overlays gleyed silty loam. Two pH measurements taken in associated “seepage runs” were 7.0 and 7.8. 

Characteristic Vegetation:
Northern white cedar (Thuja occidentalis) is the dominant tree. The shrub layer is sparse and moss cover is low. Plants of both rich woods and seepage wetlands are present. Diagnostic upland and rich-site species infrequent or absent in other northern white cedar swamps include foamflower (Tiarella cordifolia), zigzag goldenrod (Solidago flexicaulis), Jack-in-the-pulpit (Arisaema triphyllum), bluebead lily (Clintonia borealis), contracted drooping wood sedge (Carex arctata), Indian cucumber-root (Medeola virginiana), shining clubmoss (Huperzia lucidula), and sugar maple (Acer saccharum). Other species include northeastern mannagrass (Glyceria melicaria), three-seeded sedge (Carex trisperma var. trisperma), long-stalked sedge (Carex pedunculata), hooked sedge (Carex retrorsa), naked miterwort (Mitella nuda), oak fern (Gymnocarpium dryopteris), and Robbins' ragwort (Packera schweinitziana). 
 

A good example of this community occurs in the vicinity of Mud Pond (Pittsburg). 

Northern white cedar seepage forests often occur as part of near-boreal minerotrophic peat swamp systems.


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