5. OVERVIEW OF IMPACTS ON ECOSYSTEM FUNCTION 



COASTAL UPLANDS 



Gas and oil extraction and development on the coastal uplands produce two 

 levels of ecological effects. First-order alterations affect specific site 

 characteristics. Although petroleum exploration and extraction processes may 

 radically change the immediate area, ecosystem energy linkages and material 

 storages remain essentially unchanged, permitting the system to continue to 

 function as before. Isolated site alterations usually remove or radically 

 change plant and animal assemblages as well as deplete or supplement local 

 abiotic storages such that existing flow equilibria are disrupted. Compensat- 

 ing system readjustments are activated and reestablish the system's equilib- 

 rium. 



Adjustments may include the export of surplus energy and materials or the 

 increased retention of mobile elements. The moderating nature of the surround- 

 ing unmodified terrestrial environment quickly absorbs such energy or material 

 pulses, thus preventing few, if any, changes large enough to affect the entire 

 ecosystem. Small-scale fluctuations within the ecosystem continually occur as 

 normal events and, unless artificially supressed, they automatically activate 

 compensatory biotic processes which begin channeling energy and materials 

 toward redevelopment of the initial or best-adapted plant assemblage. Consumer 

 response varies as a function of the species' habitat requirements, serai 

 stages replaced or introduced, areal extent and duration of the change, and 

 the nature of the activity. 



Second-order alterations are capable of producing fundamental ecosystem 

 changes in terms of energy and material transport and biotic composition. 

 Such large-scale changes result from (1) intensification or interruption of 

 elemental ecological processes responsible for regulating ecosystem dynamics 

 oyer extensive areas or (2) the accumulative/synergistic effects of numerous 

 sniall-scale, but high-density, alterations. Major area-wide ecosystem altera- 

 tions are typically characterized by extensive shifts in plant-community 

 interspersion, abundance, and distribution. Associated faunal responses are 

 predictable and are often characterized by major changes in species composition, 

 age structure, and population levels as vegetative components increase or 

 decrease. 



Among ecological factors affecting fundamental processes of the coastal 

 upland ecosystem, fire holds a position of major importance. Present-day 



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