Number Page 



Davis 



1 - Progressive development of ROW denudation and erosion problems 



in the Oak-Pine Zone, Long Island, N.Y., due to uncontrolled vehicular 

 access: 



(la). Before right-of-way 212 



( 1 b). At completion of right-of-way 212 



(Ic). Post right-of-way land degradation 213 



Cairns 



1 - Modes of action of perturbants on ecosystems 222 



2 - Relation of perturbation type with modes of action 223 



3 - Diagram to illustrate the meaning of several policy options for 



management of natural ecosystems 226 



4 - Disturbances in general ecosystems create vegetational setbacks and 



complete recovery is slow, whereas disturbances in perturbation- 

 dependent ecosystems usually stimulate pulses of growth which 

 rapidly decline unless disturbed again 229 



5 - Location of the sampling stations on the South Fork and the main 



stem of the Shenandoah River, Warren County, Virginia 230 



6 - Sampling stations on the South River, Virginia for the 1978 



biojogical survey 23 1 



7 - Comparison of macroinvertebrate community diversity (9) for the 



1970 and 1978 South River surveys 233 



8 - Comparison of the number of macroinvertebrate taxa collected 



for the 1970 and 1978 South River Surveys 235 



9 - Macroinvertebrate density comparison for the 1970 and 1978 South 



River Survevs 235 



IX 



