Development Effects on Wetlands

        Before development can even begin in an area, there needs to be some way of getting there .  The answer to this problem is the establishment of roads.  Roads can have just as dramatic an effect on wetlands as development itself.  Water runoff can increase the amount of sediment that drains into the wetland, and during winter months road salt can also be washed into the wetland.  Roads can also effect the flow of rivers and streams into the wetland along with the drainage.  A study done on a suburban highway in Massachusetts has shown that roads can effect streams an wetlands within 100 m of the road.  Nine wetlands within 100 m all showed evidence of wetland drainage, indicating that they were smaller now then they were before road construction (Forman and Deblinger 2000).  Foreman and Deblinger (2000) also hypothesized that if measurements on sediment load, fish populations and streamflow regime were taken similar results in road effects would also be seen.                             

        Even after development has been established in an area, it can still have continued effects on the succession of wetlands.  Every ecosystem goes through periods of succession and re-development, always changing its overall composition.  It is still debated if ecosystems can hit a climax composition, but most believe that inter-ecosystem disturbance do not allow for a climax composition.  Empirical data has been gathered to illustrate the critical role of establishment and germination strategies in affecting wetland plant community structure (Shipley et al. 1989).  This lead Ellison and Bedford (1995) to run a model on the effect of disturbance on wetland plant community.  They found that responses to disturbance depended most heavily on seed germination and dispersal, which would directly effect wetland succession models established by van der Valk (1981).  Ellison and Bedford's model are in agreement with a seven year study done on observed changes of vegetation structure near a coal-fired power plant in Portage, Wisconsin.  If development restricts the ability of a wetland to change its composition and go through natural succession, then the wetland is susceptible to further change.  

       Other studies have shown that development around wetlands, such as road construction and forest transformation into agricultural area, has a negative realtionship to species diversity and richness.  Often times new regualtions focuss narrowly on preventing further wetland loss, and do not also consider adjacent lands that have been shown to have large effects on wetland functions (Burbridge 1994).  Roads may effect regional biodiversity by impeading local migration between populations, modifying wetland hyrology and siltation patterns, increase the amount of edge in habitat patches, increased mortality from roadkills, facilitating in the invasion of exotic species, and increasing human access to wildlife habitat (Findlay and Houlahan 1997).  Conversion of forested land into agriculture also aids in the forementioned effects and also contibutes to wetland eutrophication.  Multiple regression analysis done by Findlay and Houlahan (1997) shows that there is a positive relationship between wetland area and speices richness, meaning the larger the wetland the more species found there.  They also found a positive relationship between reptile and mammal richness and proportion of forest cover within 2 km.  These results provide evidence that road construction and forest removal can have significant negative results on wetland biodiversity.