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The Ecology and Management of
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Sharon Great Cedar Swamp (GCS) is a >250acre wetland surrounded by a small New England town. Our team was called in to discover the cause(s) of the death of the thriving Atlantic White Cedars (AWC)(Chamaecyparis thyoides) that formerly dominated the area, and to restore the AWC forest. This report summarizes 5 yrs of observations and measurements documenting severe degradation of the hydrology, geomorphology and vegetation. Monitoring of 46 wells and an engineering survey of surface elevations revealed that in ~1/3 of the area, groundwater levels have dropped 2-4 ft below the surface. Soil subsidence of up to 3ft and large expanses of exposed roots arched high above the lowered forest floor reflect extensive oxidation and decomposition of the peat substrate. The AWC swamp’s characteristic tree, shrub and groundcover vegetation is greatly altered and is now documented to be a facultative wetland assemblage, with areas in transition to a dryland community. Thousands of snags and criss-crossed fallen dead AWC are remnants of the former cedar dominants, with no AWC regeneration in >1/2 of the GCS. Ancillary damage: 1) The large accumulation of dry woody debris and drained dry peat poses a severe fire hazard. 2) Deterioration of town water well quality and quantity are important consequences of the GCS dehydration. We conclude that the major cause of the cedar deaths is a ~1.25 mile-long drainage ditch dug to protect a residential subdivision over ˝ century ago, now extending up to 10ft deep and 30 ft wide. Additional contributing factors are 1) 6 municipal wells with GCS as the major water source, and 2) the AMTRAK railroad bed which cuts across the wetland and restricts groundwater flow.
Atlantic White Cedar, Chamaecyparis thyoides, forested wetland, swamp hydrology, vegetation, soils, wetland drying, wetland deterioration, wetland restoration, Sharon Massachusetts, wetlands USA