The basal zone of Part 2 usually contains <25% ash, unless a period of oxida- 

 tion and decay has interrupted plant growth, and consists of a variety of 

 plant communities such as marshes, mosses, heaths, and perhaps forest growth. 

 Because moss becomes the dominant plant type as the dome increases in height, 

 ash content decreases to <27o, the percent of fibers that are 0.15 mm (0.016 

 inches) long increases to >67%, and water-holding capacity increases to sev- 

 eral thousand percent. However, as soon as oxidation begins to destroy peat, 

 a layer of humus develops at the surface, especially near the margin of the 

 dome where oxygenated water moves most freely. As humus develops, ash content 

 increases, fibers become shorter, water-holding capacity decreases, and forest 

 invades the heath from the margin and migrates toward the center of the dome. 



Chemical Characteristics 



No specific comparative data base exists on the chemical parameters of palus- 

 trine wetlands in the characterization area. Specific conductance, 

 alkalinity, and ion concentration in Maine wetlands are much lower than those 

 in prairie potholes (Swanson et al. 1974, cited in Reinecke 1977) and are pro- 

 bably much lower than those in other temperate wetlands. Relatively nutrient 

 poor, acidic waters are characteristic of bog wetlands. In areas of nutrient- 

 rich soils (agricultural areas) and/or water, or in areas where nutrient-rich 

 water flushes palustrine wetlands, nutrient levels are higher and vegetation 

 is characteristic of marshes. This flushing occurs on a regular basis by 

 riverine waters and irregularly by marine and estuarine waters (once or twice 

 a year during storms). 



ABIOTIC FACTORS AFFECTING PALUSTRINE SYSTEMS 



The composition of any palustrine system depends upon a combination of abiotic 

 conditions prevailing at its site. In general, Maine palustrine systems are 

 relatively infertile compared to most temperate zone palustrine wetlands. Due 

 to different abiotic conditions, certain palustrine systems have developed 

 into marshes and others into bogs. Climatic, hydrologic, and geologic factors 

 that affect palustrine wetlands are considered here. These factors work in 

 combination and their combined effects usually cannot be separated. As palus- 

 trine and lacustrine systems are closely related, a review of the abiotic fac- 

 tors in the lacustrine system provides additional information (see chapter 7, 

 "The Lacustrine System"). 



Climate 



The climate of the characterization area and its gradients are discussed in 

 chapter 2. The effects of climate on the palustrine system generally are sim- 

 ilar to those on the lacustrine system (see chapter 7, "The Lacustrine 

 System"). The relatively cold waters of the Maine coastal zone contribute to 

 the formation of bogs. In combination with other abiotic factors cold waters 

 restrict the activity and numbers of decomposer organisms. Thus, much of the 

 organic matter formed in palustrine wetlands is not broken down for use by 

 other organisms but is stored as peat. 



Ice and frost action affect the palustrine system by breaking up peat mats and 

 the accompanying flora. Climate also affects the growing season and floral 

 composition of palustrine systems. 



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10-80 



