Variations in organic matter, mineral fractions, and waterlogging (saturation 

 of sediments) determine palustrine soil types, which in turn determine plant 

 species. At present there are no data available detailing soil types in 

 palustrine wetlands in coastal Maine. 



BIOGEOCHEMICAL CYCLES AND BUDGETS 



Biogeochemicals (e.g., nitrogen, phophorus, potassium) are those substances 

 derived from the earth's crust, hydrosphere, and atmosphere that are essential 

 to life processes. Because the supply of biogeochemicals is limited 

 sometimes, the availability of these substances to organisms is dependent upon 

 continuous cycling. Low availability of biogeochemicals (nutrient limitation) 

 usually results in low populations of organisms and low biological 

 productivity. 



Peat, which is formed in many coastal Maine palustrine wetlands, has an excep- 

 tionally high water absorption and ion exchange capacity (Moore and Bellamy 

 1974). Biogeochemical ions from palustrine waters are bound to the peat and 

 held strongly by physiochemical forces. These ions, once bound, are not eas- 

 ily leached. As peat formation progresses the bound ions may be buried below 

 the reach of plant roots and become fossilized. 



Respiration 



Microorganisms 



Oxidation of Peat 

 (e.g. by Combustion) 



C-Compounds 

 in Peat 



Figure 8-6. Cycling of carbon in a palustrine wetland (Moore and 

 Bellamy 1974). 



3-18 



