Coastal Plateau Bogs and Shrub Slope Peatlands 



Coastal plateau bogs, or plateau peatlands, are a type of raised bog found 

 primarily in eastern coastal Maine, usually within 6 miles (10 km) of open 

 ocean. They differ from inland domed bogs, the more common type of raised bog 

 found in coastal Maine, in surface topography and plant species composition. 

 Plateau bogs have a pronounced slope which rises from a well-developed bog 

 moat, or lagg, to an almost flat central bog plain (figure 20-1; Damman 1977). 

 Inland domed bogs, such as the Great Heath in Cherryfield (region 5), are 

 clearly domed with a gentle or gradual slope in all directions from the 

 center, and the moat or lagg is usually lacking (figure 20-1). Plateau bogs 

 and domed bogs correspond to Types 3 and 4, respectively, of Cameron's (1975) 

 classification which is discussed and illustrated (figure 8-4) in chapter 8, 

 "The Palustrine System." 



A unique plant community dominated by black crowberry ( Empetrum nigrum ) , 

 Scirpus cespitosus , and baked apple berry ( Rubus chamaemorus ) , is found on the 

 flat central bog plain of plateau bogs. This community is very rare or absent 

 from inland domed bogs but may occur on the tops of higher inland mountains. 

 Several rare plant species occur in association with this plant community 

 including baked apple berry, dragon's mouth (Arethusa bulbosa ) , a sedge ( Carex 

 rariflora) , northern comandra ( Geocaulon lividum ) , and possibly purple 

 crowberry ( Empetrum atropurpureum ) . 



Coastal plateau bogs are found only along the Atlantic coast from eastern 

 Maine to Labrador. These areas are characterized by a maritime climate with 

 frequent summer fogs, cool temperatures (2.5 to 4°C; 4.5 to 7 F; less than 

 nearby inland domed bogs; Damman 1977), high rainfall, high moisture input 

 from fog drip (Davis 1966) , and reduced evapotranspiration which results in a 

 surplus of moisture during the growing season. The larger coastal plateau bogs 

 are plotted on atlas map 4. 



Shrub slope peatlands have been described only recently (Worley 1980b). They 

 generally are associated with plateau peatlands, but are more restricted in 

 distribution, being found only within a few km of open ocean (principally in 

 region 6). Shrub slope peatlands have a dense cover of ericaceous shrubs, 

 such as sheep laurel (Kalmia angustifolia ) and leather leaf ( Chamaedaphne 

 calyculata ) . Black crowberry, baked apple berry, and Sphagnum spp. are also 

 present. The dense vegetation covers a layer of peat some 4 to 16 inches (10 

 to 40 cm) thick that lies over undulating bedrock with slopes of at least 13 

 (figure 20-1; Worley 1980b). Shrub slope peatlands occupy terrain with "the 

 most exposed, rainy, foggy, cool, temperate, maritime climate on the Maine 

 coast" (Worley 1980b:31). The best examples are found on the southern end of 

 Great Wass Island. 



Outer Headlands and Outer Island Communities 



Plant communities occupying exposed outer headlands and outer islands support 

 rare plant species with northern affinities. These communities occupy the 

 area between the exposed shoreline and the coastal spruce-fir stands, and are 

 characterized by a dense shrub and herbaceous ground cover. Plant species 

 that commonly occur in these communities are sheep laurel, ground juniper 

 ( Juniperus horizontalis ) , mountain cranberry ( Vaccinium vitis-idae ) , black 



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10-80 



