distribution of palustrine wetlands in coastal Maine and describes their com- 

 ponents and functions. The specific locations of palustrine wetlands in 

 coastal Maine are detailed in atlas map 1. Common names of species are used 

 except where accepted common names do not exist. Taxonomic names of all spe- 

 cies mentioned are given in the appendix to chapter 1. 



SOURCES OF AND COMPILATION OF DATA 



The data sources used for characterizing the palustrine system include perti- 

 nent scientific literature, unpublished theses and reports, personal 

 communications, and preliminary results of the NWl of the U.S. Fish and 

 Wildlife Service (FWS). Information on the location and extent of wetlands 

 mapped by the NWI project has been incorporated. NWI has mapped wetland units 

 at a minimum resolution of about 3 to 5 acres (1 to 2 ha; personal communica- 

 tion from R. W. Tiner, Jr., U.S. Fish and Wildlife Service, Newton Corner, MA, 

 September, 1978). Thus, palustrine areas smaller than 3 acres (1 ha) gen- 

 erally were not mapped. A particular palustrine wetland may contain more than 

 one palustrine class and a particular palustrine class may contain areas <3 

 acres (1 ha) of other palustrine classes. For example, an area mapped as a 5 

 acre (2 ha) scrub/shrub wetland may consist of an area of open water sur- 

 rounded by a floating mat of emergent vegetation mixed with hummocks of 

 moss/lichen vegetation, with the general scrub/shrub cover intergrading occa- 

 sionally into forested wetlands. If each of these habitat types (scrub/shrub, 

 open water, emergent, forested) were 3 to 5 acres (1 to 2 ha) or larger, they 

 would be mapped as distinct units. This complexity exists primarily because 

 of small-scale variations in abiotic factors affecting palustrine areas. In 

 combination with phenomena of plant ecology such as competition and 

 succession, these small-scale variations in abiotic factors often result in 

 several palustrine classes comprising the same wetland (figure 8-2) . These 

 classes may intergrade into one another, also, adding to the difficulty of 

 precise classification. The NWI provides the user with the most detailed data 

 to date on the distribution of wetlands in the Maine coastal zone. These data 

 provide a baseline to which the future status of palustrine wetland habitats 

 can be compared. 



Twelve palustrine classes (and mixed classes) were identified by NWI (figure 

 8-1 and atlas map 1): aquatic bed, unconsolidated bottom, forested wetland, 

 forested scrub/shrub wetland, forested emergent wetland, forested/open water 

 wetland, scrub/shrub wetland, scrub/shrub emergent wetland, scrub/shrub/open 

 water wetland, emergent wetland, emergent/open water wetland, and open water 

 wetland. Mixing of wetland classes occurred when 307o of the area was covered 

 by the upper canopy of the dominant vegetation. Palustrine flats and 

 moss/lichen wetlands occur in the coastal zone but these areas are oversha- 

 dowed by higher canopy vegetation or are below the size resolution for 

 mapping. Palustrine classes of rock bottom, unconsolidated bottom, and 

 aquatic bed have been mapped mostly as open water (atlas map 1), although a 

 few areas have been designated as unconsolidated bottom and aquatic bed. 



Most bogs are classified as forested and scrub/shrub wetland. Relatively few 

 scientific studies have been made on the ecology of palustrine areas in 

 coastal Maine. The shortage of useful data is sufficient to require a review 

 of research needs. 



8-2 



