Table 9-12. Percentage Contribution of Nutrients from Several Sources 

 in a New Hampshire Deciduous Forest^ 



Nutrient 



Precipitation Gas or aerosol 



Weathering 



Iron 



Calcium 



Potassium 



Magnesium 



Sod ium 



Nitrogen 



Sulfur 



<'! 

 9 

 11 

 15 

 22 

 31 

 65 



^.l 



69' 

 31 



100 

 91 

 89 

 85 

 78 

 <1 

 4 



^Bormann and Likens 

 "nitrogen fixation. 



1979. 



PERTURBATIONS 



More or less permanent and serious disturbances of forests usually are caused 

 by the destruction of forest lands for urban or suburban development and for 

 roads, power lines, and other industrial and commercial developments. 

 Determination of the rate at which forests are destroyed along the coast is a 

 necessity in Maine. The amount of forest land in Maine actually increased 

 slightly (3%) between 1960 and 1970 (Ferguson and Kingsley 1972), because old 

 farmland was abandoned and succeeded to forest at a faster rate than new 

 forest land was cleared. 



Developed areas also affect forests indirectly by the chemical pollutants they 

 release into the water and air. A detailed study of nutrient inputs into a 

 deciduous forest in New Hampshire has revealed a wide array of airborne 

 pollutants entering the ecosystem, even though the area is remote from any 

 large source of pollution. These include sulfuric acid, nitric acid, oxidates 

 (ozone), heavy metals (Pb), and pesticides (DDT; Borman and Likens 1979). 



Acid precipitation is common throughout much of the Northeastern U.S. (Likens 

 and Bormann 1974; and Likens 1976). The effects of these pollutants on forest 

 systems are hard to determine, since the biogeochemical relationships are 

 complex, but some of the direct consequences are the leaching of nutrients 

 from foliage and the soil (Wood and Bormann 1974; and Abrahamsen et. al 1976), 

 erosion of the cuticles of leaves, increased susceptibility of trees to 



9-29 



10-80 



