reduced, locally increasing surface-water runoff. This runoff, 

 however, is quickly moderated by surrounding vegetative cover and 

 porous soil structure. Flat topography (slope) also discourages an 

 intensification of erosional forces. Other effects are 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 evapotranspi ration losses to the atmosphere. These 

 pathways are certainly altered at the specific activity site but are 

 of little consequence when compared to other contributing ecosystem 

 sources. 



3.1 Woodlands 



Alteration of food and cover resources persists for long 

 periods because of the long community regeneration time (50 to 

 70 yr). Seismic lanes create long grass corridors, increasing 

 both local habitat diversity and edge effect. A long-term 

 change results in community structure, biomass, and plant 

 species composition within the lane. Effects on consumer 

 populations are probably minor due to the restricted size of 

 the seismic corridor. 



3.2 Grasslands 



Habitat changes caused by seismic activity in grasslands are 

 \ery restricted in areal extent and of short duration (less 

 than two yr). The open nature of this community type neces- 

 sitates minimal clearing. Grassland recovery rates are rela- 

 tively rapid (within two yr). 



3.3 Brush-grass complex 



Grass and/or brush removal increases the amount of shrub/grass 

 interface (edge) by decreasing the shrub component and in- 

 creasing early successional herbaceous grasses and forbs. The 

 dominating influences of established plants on available soil 

 moisture and light are removed. The amount of increased edge 

 contributed by this activity is probably of minor consequence 

 in increasing diversity within such a heterogenous community. 



Displacement factors should be considered for all phases of 

 activities. Disturbances associated with seismic testing 

 vehicular traffic, human presence, and blasting noises - cause 

 temporary displacement of sensitive wildlife species from 

 otherwise favorable nearby habitats. Such factors cannot be 

 traced through the ecosystem diagrams. The implications and 



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