A CIRCUMNEUTRAL PATTERNED FEN IN NORTHERN NEW HAMPSHIRE

摘要

Patterned fens (also called ribbed or string fens) are a rare type of peatland in New Hampshire. Here, we document a single circum-neutral patterned fen system for the state. Observed initially from aerial photographs and visited by the authors on August 20, 1998, and June 16, 1999, this 6.5-ha, gently sloping peatland is located in Errol, NH, and Upton, ME (44 43'11.7"N, 71°02'06.0"W). Although two other patterned fen systems occur in the state (both in Pittsburg), they are acidic and have weaker surface patterning.The circumneutral patterned fen occurs on an upland peninsula on the east side of Umbagog Lake. It is surrounded by a northern white cedar-balsam fir swamp (Sperduto and Nichols 2011), a forested wetland type associated with minerotrophic conditions. Thewetland complex is bounded by heavily harvested spruce-fir and northern hardwood forests in a low-relief upland landscape. Poorly to moderately well-drained soils derived from compact glacial till occur to the north, and moderately well- to well-drainedsoils derived from a range of loose to compact till occur to the west and southwest. Felsic bedrock (New Hampshire Plutonic Suite, biotite quartz diorite) underlies the entire peninsula, though it is not an obvious source of the base-cation enrichment that presumably affects the fen. A sliver of Ammonoosuc Volcanic bedrock, which yields moderately high calcium levels in other parts of New Hampshire, occurs more than a kilometer to the west and northwest, and is a potential source of glacial till in the vicinity of the fen.