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A3400 Chamaecyparis thyoides Northern Peat Swamp Forest Alliance

Type Concept Sentence: This alliance is characterized by peatlands dominated or codominated by Chamaecyparis thyoides occurring in saturated basins and, less commonly, along streamsides and seasonally flooded pondshores, from northern New Jersey north to southern Maine.


Common (Translated Scientific) Name: Atlantic White-cedar Northern Peat Swamp Forest Alliance

Colloquial Name: Northern Atlantic White-cedar Peat Swamp Forest

Hierarchy Level:  Alliance

Type Concept: This alliance is characterized by peatlands dominated or codominated by Chamaecyparis thyoides occurring in saturated basins and, less commonly, along streamsides and seasonally flooded pondshores, from New Jersey north to southern Maine. Associates usually include Acer rubrum, Clethra alnifolia, and Vaccinium corymbosum. In the northern portion of the range, Betula alleghaniensis, Larix laricina, Ledum groenlandicum, Nemopanthus mucronatus, and Picea rubens may occur. In the south, Rhododendron maximum, Ilex glabra, and others are common associates. Gap succession is more important in this community than post-fire regeneration and accounts for the mixed, uneven-aged stands. Lightning strikes are the main cause of mortality in mature white-cedar trees within the range of this alliance. Atlantic white-cedar communities are early-successional but Chamaecyparis thyoides is a long-lived species (250+ years); gap regeneration is hypothesized to be the primary means of reproduction. The community often succeeds to itself following fire or other disturbance. In the absence of fire and adequate gap regeneration, Atlantic white-cedar forests may be replaced by bay forest. Known examples are generally neither flood-prone, nor exposed to frequent fire. One association is thought to become established following fire, with a return time of 25-100+ years.

Diagnostic Characteristics: Dominated or codominated by Chamaecyparis thyoides, in saturated peatlands, streamsides, or seasonally flooded pondshores, from northern New Jersey north to southern Maine.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: No Data Available

Similar NVC Types: No Data Available
note: No Data Available

Physiognomy and Structure: The canopy ranges from dense to open, and from strongly coniferous to mixed coniferous and deciduous. Where canopy closure is complete and little light reaches the understory, the shrub and herbaceous layers are poorly developed. In bogs, the canopy may be stunted and trees widely spaced.

Floristics: The canopy of forests in this alliance may be heavily dominated by Chamaecyparis thyoides, or they may contain hardwoods (for instance Acer rubrum, Betula alleghaniensis, Nyssa sylvatica), or conifers (Tsuga canadensis and Pinus strobus). At the northern range limit, Picea rubens is an associate. The shrub stratum ranges from open to dense and may contain Clethra alnifolia, Gaylussacia baccata, Ilex glabra, Ilex glabra, Ilex laevigata, Ilex verticillata, Kalmia angustifolia, Ledum groenlandicum, Nemopanthus mucronatus, Rhododendron viscosum, and Vaccinium corymbosum. In some examples, Rhododendron maximum forms a nearly impenetrable shrub thicket. The herbaceous stratum is sparse to well-developed and may contain Carex atlantica, Carex collinsii, Carex striata, Carex trisperma, Drosera spp., Gaultheria procumbens, Mitchella repens, Osmunda cinnamomea, Osmunda regalis var. spectabilis, Pogonia ophioglossoides, Sarracenia purpurea, Thelypteris palustris, Thelypteris simulata, Woodwardia areolata, and Woodwardia virginica. Sphagnum spp., other nonvascular plants, and lichens may be common on exposed peat and rotting wood. In New England Atlantic white-cedar bogs, there is a sparse, stunted canopy of Chamaecyparis thyoides over a dense dwarf-shrub heath dominated by Chamaedaphne calyculata.

Dynamics:  Gap succession is more important in this community than post-fire regeneration and accounts for the mixed, uneven-aged stands. Lightning strikes are the main cause of mortality in mature white-cedar trees within the range of this association. Atlantic white-cedar communities are early-successional but Chamaecyparis thyoides is a long-lived species (250+ years); gap regeneration is hypothesized to be the primary means of reproduction. The community often succeeds to itself following fire or other disturbance. In the absence of fire and adequate gap regeneration, Atlantic White-cedar forests may be replaced by bay forest. Known examples are generally neither flood-prone, nor exposed to frequent fire. One association is thought to become established following fire, with a return time of 25-100+ years.

Environmental Description:  Examples of this alliance may be found in poorly drained basins.

Geographic Range: This alliance ranges from New Jersey through southern New England and New York to southern Maine.

Nations: US

States/Provinces:  CT, DE, MA, ME, NH, NJ, NY, RI




Confidence Level: Moderate

Confidence Level Comments: No Data Available

Grank: GNR

Greasons: No Data Available


Concept Lineage: No Data Available

Predecessors: No Data Available

Obsolete Names: No Data Available

Obsolete Parents: No Data Available

Synonomy: ? Atlantic White Cedar Alliance (Windisch 2014a)
>< Atlantic White-Cedar: 97 (Eyre 1980)
< Atlantic white cedar - hemlock - yellow birch type (Enser and Lundgren 2006)
< Atlantic white cedar - swamp azalea type (Enser and Lundgren 2006)
< Atlantic white cedar / Rhododendron swamp (Enser and Lundgren 2006)
< Coastal Atlantic white cedar type (Motzkin 1991)
< Mixed hemlock-AWC-red maple-yellow birch type (Motzkin 1991)
< Spruce-hemlock-AWC type (Motzkin 1991)

Concept Author(s): L. Sneddon, in Faber-Langendoen et al. (2013)

Author of Description: L. Sneddon

Acknowledgements: No Data Available

Version Date: 01-08-14

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  • Enser, R. W., and J. A. Lundgren. 2006. Natural communities of Rhode Island. A joint project of the Rhode Island Department of Environmental Management Natural Heritage Program and The Nature Conservancy of Rhode Island. Rhode Island Natural History Survey, Kingston. 40 pp. [www.rinhs.org]
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  • Sperduto, D. A., and K. F. Crowley. 2002b. Atlantic white cedar in New England: Analysis and proposed classification. New Hampshire Natural Heritage Inventory. DRED Division of Forests & Lands and The Nature Conservancy, Concord, NH.
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