altered locations. Distinguishable effects attributable to line 

 installation that exceed or contribute significantly to road- 

 associated effects are considered negligible. Thus, when such lines 

 follow existing road easements, the alterations are considered to be 

 of minor consequence to the ecosystem. 



However, when overhead electrical lines or buried utility and flow- 

 lines require overland routes, the magnitude of attribute altera- 

 tions increases. Vegetation is cleared as needed within the ease- 

 ment. Cutting requirements are regulated by the community type, 

 being least demanding in grasslands and most rigorous in woodlands. 

 Overhead lines require removal of woody components that interfere 

 with installation and operation. Overhead line easements are 

 typically 6 m (20 ft) wide, which alters about 0.6 ha per km (2.4 acres 

 per mi) of easement. Buried utility and flowlines require further, 

 often complete, vegetation removal along the alignment for placement 

 and temporary spoil storage. 



♦ 



Easement dimensions are approximately equivalent to overhead line 

 easements. An immediate loss of wildlife food and cover results. 

 Such small food and cover losses, however, are relatively minor for 

 most mammalian and avian species due to the restricted areal extent 

 of the line as compared to adjacent undisturbed areas. Partial 

 compensation is provided by pioneering herbaceous annuals and peren- 

 nials and shrubs that invade and temporarily dominate newly exposed 

 soils following removal of community dominants and abandonment of 

 the site. Long narrow corridors of more diversified flora are 

 created, increasing local habitat diversity and "edge effect" (Cody, 

 1975). Subsequent effects on local consumer populations, however, 

 are probably not noticeable due to the relatively small quantitative 

 increase in diversity. Energy linkages to the various consumer 

 levels are not followed any further. Vegetation removal and soil 

 alterations temporarily interrupt nutrient and detrital cycles at 

 the specific site, but these alterations are considered to be of 

 minor ecosystem consequence because of the limited areal extent. 



Within the working easement, changes in soil structure occur as 

 installation equipment variously compacts or loosens the soil. 

 Compaction results from vehicular traffic of all types. Soil loosen- 

 ing occurs by digging, piling, and refilling activities. Proportion- 

 ately more area is probably compacted than loosened, particularly 

 with respect to overhead lines. Decreased soil structure reduces 

 water infiltration rates, locally increasing surface-water runoff. 

 This runoff, however, is quickly moderated by surrounding vegetative 

 cover and porous soil structure since the areal extent of the right- 

 of-way is usually small. Flat topography (slope) also discourages 

 intensification of erosional forces. Other pathways - regulated by 

 (1) soil structure, such as water-holding capacity, water percola- 

 tion rates, groundwater recharge, and soil moisture evaporation, and 

 by (2) vegetative cover, which controls certain soil structure 

 aspects and evapotranspiration losses to the atmosphere - are 



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