Natural Communities of NH -- Photo Guide

Bog rosemary - sedge fen  (S3)

(formerly bog rosemary - sweet gale - sedge fen)

Bog rosemary - sedge fen is a weakly minerotrophic fen community dominated by a mixture of dwarf shrubs, Carex sedge species, and several peat mosses. It occurs throughout the state (primarily in central and southern parts) on grounded or thick floating mats. Most examples are extremely acidic. The abundance of shrubs and sedges varies between examples. Trees and tall shrubs are sparse or absent. Shrub stature is somewhat low with an average height of 0.49 m. Average pH is 4.1. Hummocks are weakly developed (average height 0.16 m and usually <0.20 m) and peat is poorly decomposed in the upper 0.5 m. Some occurrences approach a dwarf heath shrub structure, but the relatively flat surface and the presence of poor fen sedges align the community with the moss - sedge carpet types.

Characteristic vegetation: Various peat mosses dominate the mat, and leatherleaf (Chamaedaphne calyculata), bog rosemary (Andromeda polifolia), bog laurel (Kalmia polifolia), few seeded sedge (Carex oligosperma), bottle-shaped sedge (Carex utriculata), small cranberry (Vaccinium oxycoccus), and three-leaved false Solomon’s seal (Smilacena trifolia) are common. Sweet gale (Myrica gale) is sometimes present.

These fens differ from other fens that contain sweet gale and bottle-shaped sedge by having an abundance of Sphagnum fallax, S. angustifolium, and S. magellanicum, and some combination of bog rosemary, bog laurel, small cranberry, and three-leaved false Solomon’s seal. 

A good example of this community occurs in the Ossipee Lake Natural Area between Ossipee Lake and Rte. 25 (Ossipee). Other examples occur at the delta of the Bearcamp River (Ossipee) and in the Broad/Leavitt Bay kettles (Ossipee).

Bog rosemary - sedge fen
sometimes occur as part of larger medium level fen systems.

Bog rosemary - sedge fen in Errol (photo by Ben Kimball for the NH Natural Heritage Bureau)
Bog rosemary - sedge fen in Errol (photo by Ben Kimball)

Bog rosemary - sedge fen in Ossipee (photo by Dan Sperduto)
Bog rosemary - sedge fen in Ossipee (photo by Dan Sperduto)

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