Marshy moat (S4)
Marshy moats (also known as laggs) are wet zones that occur between interior peatland communities and adjacent upland habitats, or sometimes between different peatland community types. Moat development is likely related to increased peat decomposition along the edges of these communities. Vegetation is sparse and open water patches are common, but emergent marsh and aquatic bed species are prominent, reflecting both relatively higher nutrient availability and pH. A number of minerotrophic indicator species may be present. These moats are typically found in southern and central parts of NH.
Characteristic vegetation: Temporarily to seasonally flooded moat zones support most of the shrub and emergent marsh species present. Emergent or aquatic species generally absent from other peatland types include lesser bur-reed (Sparganium americanum), mannagrass (Glyceria spp.), woolly bulrush (Scirpus cyperinus), Small’s spike-rush (Eleocharis smallii), bluejoint (Calamagrostis canadensis), Canada rush (Juncus canadensis), and soft rush (Juncus effusus ).
In semi-permanently flooded moat zones, several aquatic species may be present, including pondweeds (Potamogeton spp.), water shield (Brasenia schreberi), common bladderwort (Utricularia vulgaris), variegated yellow pond-lily (Nuphar variegata), and white water-lily (Nymphaea odorata). Other characteristic emergent and other species also occasional in other peatland communities include arrow-arum (Peltandra virginica), three-way sedge (Dulichium arundinaceum), marsh St. John’s-wort (Triadenum virginicum), silvery sedge (Carex canescens), wire sedge (C. lasiocarpa), common water horehound (Lycopus uniflorus), and swamp candles (Lysimachia terrestris). Shrubs may include buttonbush (Cephalanthus occidentalis), highbush blueberry (Vaccinium corymbosum), winterberry (Ilex verticillata), water willow (Decodon verticillatus), leatherleaf (Chamaedaphne calyculata), meadowsweet (Spiraea alba), black chokeberry (Aronia melanocarpa), and sweet gale (Myrica gale).
Sphagnum species may be absent or, when present, unconsolidated and often characterized by S. cuspidatum and other Sphagna found in “soupy” conditions. Moss species that may be found on woody stem bases and elsewhere in the moat include Callicladium haldanianum, Hypnum pallescens, and Aulocomnium palustre.
Good examples of this community occur at
Marshy moats often occur as part of larger kettle hole bog systems, and sometimes as part of poor level fen/bog systems and medium level fen systems.
Marshy moat (in foreground) at Dead Pond in Pawtuckaway State Park (photo by Dan Sperduto)
Marshy moat (in foreground) at Lee Town Hall Bog (photos by Ben Kimball)