CONCLUSIONS


 While no definitive conclusions about either the value of hummocks or the best
 material from which to construct them can be drawn from this project, a few
 recommendations can be made based on the features the hummocks are lacking. The
 composted organic material used in the Agrifos wetland showed 2% more change in
 cross sectional area than the overburden hummocks and 4% more than the sand
 hummocks. The composted organic material did not provide for tree survivorship as only
 17% of the pop ash and 33% of the sweet bay survived the first growing season. Sand
 tailings appear to be a reasonable choice because it has high diversity, 100% ash and 83%
 bay tree survivorship, and only 2% change in cross sectional area. Two functional flaws
 exist with sand tailings: it holds little pore water and has only 23% understory cover.
 Overburden had no fatal flaws and performed well in both the Cargill and Agrifos
 wetlands. The overburden hummocks had 100% tree survivorship in the Agrifos wetland,
 over 30% understory vegetation cover, high species diversity, and only 2% (Cargill) and
 4% (Agrifos) change in cross sectional area during the first growing season. The organic
 hummocks in the Cargill wetland also performed to a high standard and may prove to be
 the most desirable by long term study. Muck does have one drawback when compared to
 overburden in that it must be hauled into the site for construction. Overburden is already
 on site and thus costs less than muck. Those cost differences must be weighed against the
 performance of the hummock types. Continued data collection over multiple growing
 seasons would provide more definite information on the performance of these materials,
 especially tree survivorship and growth and long term stability of the hummocks. The
 data collected during this study show a definite advantage in using hummocks in order to
 increase species diversity, especially in situations where the wetlands will be flooded for
 the majority of the growing season. Further study will show if the superior tree growth
 seen in the Iluka wetland applies to more than cypress trees. Survivorship will also be
 better understood after the trees in the Cargill and Agrifos wetlands are monitored over
 multiple growing seasons. Based on this study and those of Sloan (1998) and Bukata
 (1999), hummocks do appear to be beneficial to the overall structure and health of a
wetland and should be included in new construction.


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