2.4 IntroductTon of toxic chemicals into the site's soils 



2.5 Displacement of sensitive wildlife species from adjacent areas 

 due to drilling operations and 24-hour-a-day human activities 



Attribute alterations 



Wellsite preparation removes all biotic components within the 

 project boundaries through cutting and clearing, grading, filling, 

 and excavation activities. Similar effects are produced in all 

 three community types. A direct loss of one to two ha (three to 

 five acres) of sustaining habitat results for primary and second- 

 ary consumers. 



Food and cover elimination is particularly significant for small 

 mammals, breeding songbirds, and soil invertebrates since propor- 

 tionally larger portions of their resource bases are altered. 

 Secondary consumers are affected indirectly by the removal or reduc- 

 tion of herbivorous prey organisms as well as loss of cover. 

 Nesting, foraging, escape, and resting areas are altered or destroyed. 

 Avian and mammalian species vary widely in their tolerance to habi- 

 tat disturbance. Some species tolerate little alteration, while 

 others (some of the sparrows, for example) can adopt to very 

 disturbed situations. In each case, species response is a function 

 of time elapsed and the creation or destruction of the required 

 niche. Impact magnitude is a function of the species' resource base 

 and dependence upon removed vegetation. 



A typical wellsite location alters approximately 1.2 ha (3 acres) of 

 existing habitat. Removal of plant cover encourages surface-water 

 runoff from barren, newly exposed sediments onto adjacent upland 

 systems. The resultant effects, as partially regulated by slope and 

 elevation, are usually restricted in areal extent. Interruption of 

 detrital and nutrient cycles, with subsequent nutrient reserve 

 depletion through runoff and leaching may inhibit rapid plant recov- 

 ery following site abandonment and restoration attempts. 



Soil structure within the road easement is decreased by compaction 

 due to vehicular activity. Water infiltration rates are reduced by 

 losses of soil porosity, thereby decreasing soil moisture and water 

 percolation through the soil. Surface-water runoff is intensified 

 by compacted nonporous soils, lack of vegetative cover, and 

 increased berm slopes and elevation. Sediment transport is typi- 

 cally yery localized in the coastal upland sites because of little 

 topographic relief or slope and more porous soils enclosing the 

 activity site. Large-scale upland effects at the ecosystem level 

 are of minor consequence. Sediment and nutrient transport into 

 adjacent wetlands or streams, however, is of greater concern, as 



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