soil erosion, enhances soil moisture, soil aeration, and fertil- 

 ity. The site is prepared for later plant changes. 



3.3 Brush-grass complex 



The brush-grass complex is also a relatively easy and rapid 

 cover type to reestablish. Replacement with mixtures of native 

 forbs, shrubs, and grass species may compensate some of the 

 upland consumer species adversely affected by woodland losses. 



Disturbance factors should be recognized as an important consid- 

 eration because they extend the project impacts beyond the 

 boundaries of the immediate site. 



4. Key attribute alterations 



Restoration of soil structure is the pivotal aspect of site rehabili- 

 tation which controls other regulatory parameters that determine the 

 suitability of the edaphic environment for plant growth. Soil 

 structure regulates the infiltration of soil air and soil moisture, 

 surface-water runoff, water permeability, and water-holding 

 capacity. Second-order effects include regulation of soil erosion, 

 nutrient availability, and soil salinity. Several management tech- 

 niques are available which accelerate site recovery and allow selec- 

 tion of specific plant assemblages for reestablishment. 



Salt Marsh 



Seismic preexploration. 



1. Activity sequence 



Surveyors enter the marsh by marsh buggy or foot, stake the lines, 

 and mark the areas where shot holes and geophones will be placed. 

 Vegetation may be cleared along a path 3 to 4 m (10 to 15 ft) wide 

 if the plants are tall and/or dense. A drilling buggy and one or 

 two support buggies enter next; holes are drilled, charges and 

 recording equipment are placed, and shots are fired. Geophones are 

 retrieved and placed for the next series of shots. After completion 

 of an entire shot line, the holes are plugged and the crew exits. 



2. Primary ecological alterations 



2.1 Creation of ruts or depressions in the land surface 



175 



