Natural Communities of NH -- Photo Guide

Acidic northern white cedar swamp  (S1)



Acidic northern white cedar swamps develop on sites with more acidic conditions (water pH in the low 5s or less) than other cedar swamps, but they are still more enriched than poor swamps. They are associated with large, very poorly drained peatland basins around fens. The community supports more acid-tolerant species and lacks many of the herbaceous, mineral-rich indicator species found in other cedar swamps. The herb layer is less dense and diverse, but the shrub layer is well developed. Soil conditions are acidic, with pH ranging from 4.1–5.9 (mediacid to subacid). Peat/muck depths range from 125–230 cm.

Characteristic Vegetation: Northern white cedar (Thuja occidentalis) is the dominant species, along with balsam fir (Abies balsamea) and larch (Larix laricena). The vegetation composition of this type is somewhat similar to that of northern white cedar - balsam fir swamps. It differs by having an abundance of peat mosses (Sphagnum spp.), a well developed shrub layer, lower average cover and diversity in the herb layer, a greater abundance or frequency of black spruce (Picea mariana), sheep laurel (Kalmia angustifolia), creeping snowberry (Gaultheria hispidula), mountain holly (Nemopanthus mucronatus), and sometimes speckled alder (Alnus incana), and a sparse cover of herbaceous minerotrophic indicators.

Herbs may include three-seeded sedge (Carex trisperma), northeastern mannagrass (Glyceria melicaria), false violet (Rubus dalibarda), dwarf raspberry (R. pubescens), foamflower (Tiarella cordifolia), northern wood sorrel (Oxalis montana), purple-stemmed aster (Symphyotrichum puniceum), intermediate wood fern (Dryopteris intermedia), northern lady fern (Athyrium filix-femina var. angustum), cinnamon fern (Osmunda cinnamomea), royal fern (Osmunda regalis), and wood horsetail (Equisetum sylvaticum).


Good examples occur in and near Umbagog National Wildlife Refuge (Errol) and along Indian Stream (Pittsburg).

Acidic northern white cedar seepage forests often occur as part of black spruce peat swamp systems, and sometimes as part of near-boreal minerotrophic peat swamp systems.

(no photo available)

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