2.4 Creation of pathway for increased rate of flow of runoff 



2.5 Creation of pathway for increased inundation (saltwater or fresh- 

 water) 



3. Attribute alterations 



The movement of work crews and marsh vehicles tramples and crushes 

 vegetation in a zone wider than that cleared for shot placement. 

 Vegetation may be completely uprooted and destroyed in some cases; and 

 extent and degree of destruction are dependent on the hydrological 

 conditions of the area. Because meadow and emergent vegetation types are 

 located on higher elevations, they are more susceptible to such destruc- 

 tion; submergent and floating vegetation types are less likely to be 

 completely removed from production. Any loss results in an immediate 

 decrease in food and cover for the consumers in the area. In cases where 

 the existing vegetation is a pest species, destruction may be considered 

 beneficial for several reasons: (1) it reduces the reproductive poten- 

 tial of the pest species, (2) it opens dense stands of vegetation and 

 increases the "edge effect," and (3) it might allow the zone to be in- 

 vaded by more desirable species. The total area affected is usually 

 small in comparison to the remaining area of undistrubed marsh, and the 

 effects of transpiration, evaporation, sediment trapping, fire, available 

 nutrients, and peat accumulation are insignificant. 



The depth and number or ruts created by marsh vehicles are dependent upon 

 the total number of trips and the degree to which vehicles retrace ex- 

 isting tracks. In areas that are submerged continuously (or nearly so), 

 the depressions are less likely to significantly alter water movement 

 patterns. In such regions, confinement of marsh vehicle traffic to a 

 narrow corridor may be wise. However, in areas of higher elevation, deep 

 ruts resulting from retraced trails will form depressions for the move- 

 ment of water and, if deep enough, may result in standing bodies of water 

 during wet seasons. The orientation and depth of the depressions deter- 

 mine whether they (1) remain for long periods of time and (2) alter the 

 water regime of a given area of land by increasing or decreasing the 

 frequency of submergence/ emergence, average depth, and duration of 

 submergence. Areas dominated by maiden cane may be replaced by stands of 

 rushes, sedges, canes, or other emergent species when the frequency 

 and/or duration of submergence inceases. The converse may occur when 

 frequency and/or duration of submergence decreases. Although the total 

 area affected is site specific, it is usually small when compared to the 

 total area of undisturbed marsh. Because both of these vegetation types 

 support the same consumers, no significant changes in fauna would be 

 expected. 



The depressions allow a faster runoff of surface and standing water in 

 localized areas. The long-term effects on suspended sediments and 

 nutrients are slight. If vehicle tracks occur in areas of the marsh 

 where isolated ponds exist, intramarsh circulation could be affected. 



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