Palustrine Shrublands BROADLEAF PALUSTRINE SHRUBLANDS the base of slopes. The substrate is generally mineral Buttonbush wetland soil with a thin organic layer, although it may occasionally occur on shallow peat. In Pennsylvania, These wetlands are characterized by prolonged or many of these are beaver influenced or otherwise semipermanent flooding. The substrate may be organic impounded systems. Grazing (past or present) may or mineral soil. This community type may occur in also be a factor. The species composition is variable, shallow water along lake or pond shores, associated and dominance may be shared by any of the associate with river systems in oxbows, in wet swales or along shrubs, which may include Salix spp. (willows), floodplains, or in upland depressions. In some cases, Sambucus canadensis (American elder), Cornus this community represents a zone of vegetation amomum (red-willow), Rhododendron viscosum (swamp between forest on the upland side and herbaceous azalea), Decodon verticillatus (water-willow), vegetation downslope. Other shrubs, such as Decodon Cephalanthus occidentalis (buttonbush), Ilex verticillata verticillatus (water-willow), Rhododendron viscosum (winterberry), and seedling/sapling size Acer rubrum (swamp azalea), Corpus amomum (red-willow), C. (red maple). Herbaceous species include Osmunda sericea (red-osier dogwood), Salix sericea (silky regalis (royal fern), Thelypteris palustris (marsh fern), willow), S. eriocephala (heart-leaved willow), Sambucus Typha latifolia (common cat-tail), Peltandra uirginica canadensis (American elder), Vaccinium corymbosum (arrow-arum), Carex stricta (tussock sedge), and (highbush blueberry), and Acer rubrum (red maple) Galium spp. seedlings and saplings may occur, but Cephalanthus occidentalis (buttonbush) is usually a clear dominant. Characteristic herbs include Dulichium arundinaceum Related types: The "Buttonbush wetland" type above (three-way sedge), Triadenum virginicum (marsh St.- may contain alder, but is dominated by Cephalanthus John's-wort), Lycopus uniflorus (bugleweed), Nuphar occidentalis. This type is broadly circumneutral, while lutea (spatterdock), Polygonum hydropiperoides (mild the "Alder - sphagnum wetland" type is more acidic. water-pepper), P. punctatum (dotted smartweed), P. amphibium (water smartweed), Proserpinaca Range: Glaciated NW, Pittsburgh Plateau, Ridge palustris var. crebra (mermaid-weed), Carex lurida (a and Valley. sedge), C. uesicaria (a sedge), Scirpus cyperinus (wool- grass), Woodwardia virginica (Virginia chain fern), and Selected references: Jennings 1927, Metzler and Thelypteris palustris (marsh fern). Tiner 1992, PNDI field surveys, Sneddon, Anderson and Metzler 1996. Related types: The "Alder - ninebark wetland" type below may also contain Cephalanthus. The two [Crosswalk: Smith's "Circumneutral Shrub Swamp" communities are distinguished by a clear dominance (in part), TNC's Alnus (serrulata, incana) Shrubland of buttonbush in the case of the former. The "Alder - Alliance, Alnus serrulata - Physocarpus Community.] ninebark wetland" type is typically more mixed, with either Alnus spp. (alder) and or Physocarpus opulifolius (ninebark) dominant or codominant. Alder - sphagnum wetland These are wetlands dominated by Alnus Range: Entire state. serrulata (smooth alder) and/or A. incana (speckled alder), and having a sphagnum layer. The substrate Selected references: Jennings 1927, Metzler and may be peat or mineral soil with a substantial Tiner 1992, PNDI field surveys. accumulation of organic matter. This community type typically occurs in upland depressions, along slow- [Crosswalk: Smith's "Circumneutral Shrub Swamp" moving streams, or associated with large wetland (in part), TNC's Cephalanthus occidentalis Shrubland complexes, frequently influenced by beaver action or Alliance.] other impoundment. Shrub associates include Vaccinium corymbosum (highbush blueberry), Lyonia ligustrina (maleberry), Ilex Alder - ninebark wetland verticillata (winterberry), Cornus racemosa (swamp dogwood), and seedling and sapling size Acer rubrum These are shrub swamps dominated by Alnus serrulata (red maple). The most characteristic herbaceous (smooth alder) or A. incana (speckled alder) and /or species is Osmunda cinnamomea (cinnamon fern), Physocarpus opulifolius (ninebark). The pH of these although a variety of species, mostly ferns and systems is broadly circumneutral to somewhat sedges, may also occur. calcareous, and calciphiles may be present. These communities may occur at the upland edge of marshes, at the wetter edge of red maple wetlands, Related types: This community type may be in small upland depressions, or at differentiated from the "Alder - ninebark" type described above, in that this type occupies the lower end of the pH spectrum for alder-dominated wetlands, while the former is 39 Palustrine Shrublands continued… circumneutral to slightly calcareous. The associate and Tiner 1991. species reflect this shift, with shrubs like Physocarpus opulifolius (ninebark), and Corn us amomum [Crosswalk: Smith's "Acidic Shrub Swamp" (in (red-willow) occurring in circumneutral situation, part), TNC's Vaccinium corymbosum Shrubland while acid-loving heaths like Vaccinium corymbosum Alliance.] (highbush blueberry) and Lyonia ligustrina (maleberry) are more typical under lower pH conditions. The presence of a substantial sphagnum layer generally Highbush blueberry - sphagnum wetland distinguishes the two. This community type is also This community type generally occurs in shallow related to the "Highbush blueberry - sphagnum upland depressions or along the banks of slow moving wetland" type. When Vaccinium corymbosum (highbush acidic streams, or often as an intermediate zone blueberry) and Alnus spp. occur together underlain by between a low shrub type and a woodland or forest sphagnum, the types may be distinguished by type within a structurally diverse wetland complex. It dominance. may also represent a successional phase, especially in beaver-influenced or otherwise impounded systems. Range: Entire state except Coastal Plain. These communities are heath-dominated with a Selected references: Sneddon, Anderson and sphagnum layer beneath. The substrate may be peat Metzler 1996. or mineral soil with a substantial accumulation of organic matter. Aside from Vaccinium corymbosum (highbush blueberry), shrubs commonly present [Crosswalk: Smith's "Acidic Shrub Swamp" (in part), include Rhododendron viscosum (swamp azalea), TNC's Alnus (incana, serrulata) Shrubland Alliance, Nemopanthus mucronatus (mountain holly), Alnus (incana, serrulata) - Osmunda cinnamomea - Chamaedaphne calyculata (leatherleaf), Viburnum Sphagnum spp. Community.] cassinoides (withe-rod), and Lyonia ligustrina (maleberry). Seedling or sapling-size Acer rubrum (red maple), Betula populifolia (gray birch), or Highbush blueberry - meadow-sweet other tree species may also be present. This wetland community type may occur as part of the "Acidic glacial peatland complex." Vaccinium corymbosum (highbush blueberry) and either Spiraea latifolia (meadow-sweet) or S. alba (meadow-sweet) are usually both present. Related types: The "Highbush blueberry - meadow- Additional woody species include Amelanchier spp. sweet wetland" type described above is typically found (serviceberry), Alnus incana (speckled alder), in less acidic to circumneutral situations. The Viburnum recognitum (arrow-wood), S. tomentosa "Highbush blueberry-sphagnum" type here is more (steeple-bush), Rubus hispidus (swamp dewberry), Ilex characteristic of glaciated regions, is dominated by verticillata (winterberry), Sambucus canadensis heaths, and is often associated with larger peatland (American elder), and seedling and sapling-size Acer complexes, while the winterberry type is more often rubrum (red maple). These wetlands generally lack a found in upland depressions or areas of past thick organic layer. In Pennsylvania, many of these impoundment. systems are beaver-influenced or otherwise impounded, although some occur in upland Range: Glaciated NE, Glaciated NW, Piedmont depressions. The herbaceous layer is generally (?), Pocono Plateau, Ridge and Valley, South dominated by graminoids such as Carex stricter Mountain. (tussock sedge), Juncus spp. (rushes), and Eleocharis spp. (spike-rushes), and by ferns, Selected references: Crum 1988, Johnson 1985, especially Osmunda cinnamomea (cinnamon fern), 0. PNDI field surveys, Sneddon, Anderson and Metzler regalis (royal fern), Onoclea sensibilis (sensitive fern), 1996. and Thelypteris palustris (marsh fern). Forbs like Triadenum virginicum (marsh St.-John's -wort), [Crosswalk: Smith's "Nonglacial Bog" (in part), "Acidic Symplocarpus foetidus (skunk-cabbage), and Shrub Swamp" (in part), TNC's Vaccinium corymbosum Impatiens spp. (jewelweed) may also occur. Shrubland Alliance, Vaccinium corymbosum / Sphagnum either forms a continuous layer or occurs Sphagnum spp. Shrubland Community.] on hummocks. Related types: The "Highbush blueberry - Leatherleaf - sedge wetland sphagnum" type below is found in more acidic This community type usually occurs either in upland situations, more often glacial in origin, with a depressions or in areas of past (often beaver) stronger heath component. impoundment. Substrate may be organic soil or mineral soil with a substantial accumulation of Range: Entire state. organic matter. This community may occupy an extensive area or occur as a relatively narrow band Selected references: PNDI field surveys, Metzler between herbaceous vegetation and 40 Palustrine
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