Terrestrial vegetation is susceptible to acid precipitation. The potential 

 effects of acid precipitation on vegetation include (Tamm and Cowling 1975): 



1. damage to protective surface structures, such as the cuticle , 



2. interference with normal functioning of guard cells, 



3. poisoning of plant cells through diffusion of acidic substances 

 through the stomata or cuticle, 



4. disturbance of normal metabolism or growth processes without necrosis 

 of plant cells, 



5. interference with reproductive processes, 



6. alteration of leaf-acid and root-exudation processes, 



7. synergystic interaction with other environmental stress factors. 



Likens and Bormann (1974) have suggested that the reduction in forest growth 

 in northern New England may be correlated with the concurrent acidification of 

 precipitation. Agricultural crops are impacted also and production may be 

 decreased by about 5% (personal communication from S. Norton, University of 

 Maine, Orono , ME; July, 1979). Numerous reports of sickness and death to 

 wildlife have been attributed to air pollution (Newman 1979). Soils are 

 greatly affected by acid rains (Maimer 1976; Tamm 1976; Norton 1976; and McFee 

 1978). Slow acidification of soils in general decreases plant production 

 (McFee 1978). The effects of acid precipitation in terrestrial habitats 

 include: 



1. lowered soil pH, 



2. accelerated leaching of plant nutrients and other ions, 



3. changes in soil biota, 



4. reduction in organic matter decay rates and associated release of 

 plant nutrients, 



5. reduction in nitrification, 



6. increased aluminum mobility and associated toxicity, 



7. reduced availability of phosporus to plants, 



8. increased mobility of some organic soil components. 



Effects on the soil affect hydrology. For instance, acid precipitation 

 increases aluminum mobility and the aluminum transferred to the lacustrine 

 system has been shown to be toxic to lake fishes (Cronan and Schofield 1979). 

 In coastal areas, sea spray contributes significantly to the chemistry of 

 precipitation (Likens et al. 1979). Consequently, precipitation in coastal 

 areas affected by sea spray may be characterized as dilute sea water, since 

 the atmosphere there contains many of the ions abundant in sea water, the ions 

 Na+ and Mg+, the anion C1-, and to a lesser extent the cations Ca++, K+ , and 

 the anion SO4 (Likens et al. 1979). These ions tend to neutralize atmospheric 

 acids. Boyce and Butcher (1976), in studying the effect of a local source on 

 the composition of precipitation in south-central Maine, found a sharp 

 gradient of decreasing sodium concentration with increasing distance from the 

 ocean. Inland, high concentrations of sodium were associated with constant 

 east and northeasterly winds, which carry marine air into the region. The pH 

 levels in rain during periods in which these winds prevailed was 5.8, compared 

 with levels of 4.0 and 5.0 when the precipitation was not influenced by marine 

 air. 



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