Natural Communities of NH -- Photo Guide

Larch - mixed conifer swamp  (S3)

(formerly black spruce - larch swamp, which was split into this community and black spruce swamp

Larch - mixed conifer swamp is a saturated, mixed conifer swamp of basins in northern New Hampshire, primarily north of the White Mountains. It is intermediate in mineral enrichment between the nutrient-poor black spruce swamp and the northern white cedar - balsam fir swamp. Larch and balsam fir are typically dominant, but other conifer and hardwood species are frequently present. Herbs commonly include cinnamon fern, northern wood sorrel, dwarf raspberry, and three-seeded sedge. Soils are saturated, deep to moderately-deep peats, which generally receive at least some groundwater inputs, providing the elevated levels of mineral nutrients.

Characteristic vegetation: The canopy is dominated by a mix of eastern larch (Larix laricina) and balsam fir (Abies balsamea). Other trees that may be present include black spruce (Picea mariana), red spruce (P. rubens), white spruce (P. glauca), northern white cedar (Thuja occidentalis), red maple (Acer rubrum), and black ash (Fraxinus nigra). Mountain holly (Nemopanthus mucronatus) is common in the understory, and may be joined by winterberry (Ilex verticillata) and alders (Alnus spp.). The herbaceous layer is variable in cover, but usually includes three-seeded sedge (Carex trisperma), cinnamon fern Osmunda cinnamomea), northern wood sorrel (Oxalis montana), dwarf raspberry (Rubus pubescens), and bunchberry (Cornus canadensis).

A good example of this community occurs at Cape Horn State Forest (Northumberland).

Larch - mixed conifer swamps often occur as part of black spruce peat swamp systems, and sometimes as part of near-boreal minerotrophic peat swamp systems.

Larch - mixed conifer swamp at Bradford Bog (photo by Ben Kimball for the NH Natural Heritage Bureau)
Larch - mixed conifer swamp at Bradford Bog (photo by Ben Kimball)

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