fires, or absence thereof, exert an influence as great as that of climate and 

 soil in determining the persistent vegetation type. Cessation of periodic 

 prairie fires has been a primary cause for the recent transition of coastal 

 grasslands to brushlands and maritime woodlands. Development of extensive gas 

 and oil fields and other types of coastal land use contributes to the potential 

 elimination of periodic fire from large land tracts. Woody vegetation is 

 encouraged to expand into herbaceous grasslands that formerly were perpetuated 

 indefinitely by recurrent fires. Transition can sometimes occur quite rapidly. 

 As plant assemblages change, faunal populations also readjust. Two classic 

 examples of coastal upland wildlife populations that have responded to such 

 shifts are the white-tailed deer, a brushland associate that has increased in 

 abundance as its preferred habitat (brush-grass complex) has expanded, and the 

 Attwater's prairie chicken, formerly abundant, but now rare due to loss of 

 grassland habitats. The more expansive a developed field becomes, the more 

 important fire is in the assessment of the long-term effects of this land use 

 on coastal uplands. 



Development of oil and gas fields with all associated facilities may not 

 only suppress system regulatory processes, but may also cause ecosystem-wide 

 changes via a large volume of small but accumulative site-restricted abiotic 

 and biotic alterations. Each roadway, well-pad site, pipeline corridor, line 

 installation, treatment/storage complex, and pumping station removes support- 

 ing habitat within the immediate site as well as modifies, and perhaps degrades, 

 nearby habitats for sensitive species. Unrestrained growth and development of 

 an oil field maximizes habitat fragmentation, which can radically alter biotic 

 diversity, dispersion, and abundance. Not only is wildlife habitat removed 

 directly through facility placement and site alterations, but the intrusion of 

 man, his activities, and facilities into previously undisturbed wildlands 

 alter additional habitat areas and trigger behavioral changes by sensitive 

 faunal species. Widely scattered single facilities may cause only minor 

 changes in regular movements, but as development and disturbances increase, 

 intolerant wildlife species abandon areas, even though other aspects of support- 

 ing habitat remain adequate. Dislocated individuals may relocate to other 

 suitable, unoccupied habitats, if available. Such incremental increases are 

 individually small, but the cumulative effects inherent to development of a 

 major field can be significant. 



Regulations can effectively mitigate many potential adverse effects of 

 gas and oil exploration and development by (1) minimizing the amount of land 

 committed to gas and oil activities; (2) maximizing the efficient utilization 

 of lands that must be committed to unavoidable alterations; and (3) restricting 

 oil-related activities to refuge sites of low biological quality or those 

 capable of rapid recovery with implementation of rehabilitation techniques. 



MARSH ECOSYSTEMS 



As is the case with upland ecosystems, petroleum exploration and extrac- 

 tion operations produce two obvious levels of ecological effects in marsh 



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