Cobble - sand river channel (S3S4)
Cobble - sand river channels are fairly common in New Hampshire. They are characterized by sparse vegetation on pointbars and low islands in high-energy rivers. Species richness is occasionally quite high, with some examples supporting a wide variety of scattered graminoids and forbs. The rare cobblestone tiger beetle (Cicindela marginipennis) occurs in this community along the Connecticut River.
Characteristic Vegetation: Characteristic species include blue-grasses (Poa spp.), bent grasses (Agrostis spp.), panic grasses (Panicum spp.), asters (Aster spp.), goldenrods (Solidago spp.), smartweeds (Polygonum spp.), Joe-pye-weeds (Eupatorium spp.), hawkweeds (Hieracium spp.), violets (Viola spp.), bluejoint (Calamagrostis canadensis var. canadensis), little bluestem (Schizachyrium scoparium), big bluestem (Andropogon gerardii), twisted sedge (Carex torta), field horsetail (Equisetum arvense), and several weedy plants, both native and non-native. Shrubs and trees are sparse, but may include silky willow (Salix sericea), stiff willow (Salix eriocephala), shining willow (Salix lucida), poison ivy (Toxicodendron radicans), and various maple, alder, and willow seedlings.
Good examples of this community are documented from the Ashuelot, Saco, Connecticut, Lamprey, and Merrimack Rivers.
Cobble - sand river channels usually occur as part of larger moderate-gradient sandy-cobbly riverbank systems, and sometimes as part of high-gradient rocky riverbank systems and low-gradient silty-sandy riverbank systems.
Cobble - sand river channel community on a point bar in the Baker River (photo by Ben Kimball)
Cobble - sand river channel at the mouth of Bloods Brook on the CT River (photo by Ben Kimball)
Gravel bar along Blow-Me-Down Brook in Cornish (photo by Ben Kimball)
Cobble - sand river channel community on a point bar along the Saco River in Conway, NH,
near the border with Maine (photo by Ben Kimball for the NH Natural Heritage Bureau)
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