Soil structure within the road easement is decreased by compaction 

 due to vehicles. Water infiltration rates are reduced by losses of 

 soil porosity, thereby decreasing soil moisture and water percola- 

 tion through the soil. Surface-water runoff, intensified by com- 

 pacted nonporous soils, lack of vegetative cover, and increased road 

 shoulder slopes and roadbed elevation, increases the erosional 

 transport of sediments and nutrients into adjacent areas. Transport 

 is typically very 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 

 sediment introduction may cause significant system changes. Analy- 

 sis, therefore, requires treatment through the appropriate aquatic 

 ecosystem. Other soil structure aspects such as soil aeration, 

 groundwater recharge, water-holding capacity, evaporation, and soil 

 moisture are not considered further because either (1) contributions 

 (or the lack thereof) to the ecosystem from these sources is insigni- 

 ficant in comparison to contributions from other sources, or (2) the 

 parameters are inappropriate for further consideration since revege- 

 tation of the roadway is precluded by its use. 



Road construction may disrupt the existing surface hydrology by 

 blocking or filling stream channels or natural depressions. Peren- 

 nial streams are either bridged or temporarily diverted while 

 conduit is positioned. Intermittent or shallow drainages, however, 

 may be totally blocked by the roadbed, creating impoundments of 

 varying size and duration on the upstream side. Such increased 

 surface water causes a new soil macropore-water/soil-air equilibrium 

 to develop that produces more macropore water and less micropore air 

 upstream and the reverse conditions immediately downstream. Subse- 

 quent major vegetational changes depend on the degree and duration 

 of soil saturation and the areal extent involved. If drainage 

 alterations are such that long-term increases in soil water result, 

 then plant successional trends will shift more toward mesic communi- 

 ties of grasses and grass-like vegetation ( Scirpus , Juncus , Cyperus , 

 Eleocharis ), as macropore water concentrations increase. Con- 

 versely, filling of low wet areas increases the local substrate 

 depth, which decreases the soil macropore water (increases the soil 

 air) and encourages invasion by more xeric plant assemblages. 



3.1 Woodlands 



Among coastal upland community types, the most extensive con- 

 sequences result from the loss of acorn-producing oaks, espe- 

 cially the mature live oak, which has a recovery time of 50 to 

 70 yr. This species, in all its various life stages, is an 

 important regulator by virtue of its consistent food- and 

 cover-producing capacities. The following consumer groups are 

 dependent at some point on the live oak for food or cover: 

 hoofed mammals, small mammals, granivorous songbirds and game- 



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