establishment of diverse vegetation including tree species (Titus 1990). Huenneke and
Sharitz (1986) found that tree seedlings in natural and disturbed swamps were more
likely to occur in areas of stabile substrate where they were able to escape inundation.
Seedlings were much less dense in areas of unconsolidated soils with complete
inundation during the growing season. Kozlowski (1984) showed that tree species are
much more sensitive to environmental variations (such as water level fluctuations) as
seedlings than they are as adults. Water most likely becomes a limiting factor in
bottomland tree survivorship only on sites continuously flooded for long periods of time
during the growing season (Hosner 1960). Lowry (1994) found that in swamps with
flooding during more than 35% of the growing season, woody plants are restricted to
mounds (hummocks). These studies have shown that varying hydrology and unique soil
conditions created by microtopographic variations are valuable within a forested wetland.


SITE INFORMATION

 The initial goal of this project was to incorporate microtopography, in the form of
hummocks, into one or more constructed wetlands and to study the change in the
hummocks over time, soils, vegetation, and hydrology to assess the effects on the
wetland. Two reclamation projects were found and hummocks incorporated into their
design. A final mature site, with constructed hummocks, served as a comparison to the
immature sites. Figure 5.1 shows the location of the sites.

 Agrifos L.L.C. and Janine Callahan, the reclamation coordinator for Agrifos,
incorporated microtopography into the design of a current reclamation project. Eighteen
hummocks were constructed; nine hummocks approximately 4m x 2m x 0.6m (length,
width, and height) and nine hummocks approximately 4m x 2m x 0.9m. Hummocks
were placed in-groups of three, with each group having one hummock constructed from
each soil type. Soil materials used were sand tailings, mine overburden, and organic
compost made from recycled yard waste in Sarasota. One pop ash (Fraxinus caroliniana)
and one sweet bay (Magnolia virginiana) were planted on each hummock. No other
vegetation was planted on the hummocks. Monitoring began after the site construction
was completed in late March 1999 to establish baseline data for each hummock. Further
monitoring took place bi-monthly. The site plan for the Agrifos wetland, including the
hummock location and the hummock layout as constructed in the wetland, is shown in
Figure 5.2.

 Cargill Fertilizer, Inc. and reclamation coordinator Rosemarie Garcia also
incorporated hummocks into a constructed wetland. Twelve hummocks were built in the
wetland, half using mine overburden and half using harvested muck. Hummocks are
approximately 6m x 6m x 0.9m. Sand tailings were not used in this project. Construction
was completed in September 1999. One green ash (Fraxinus caroliniana), one sweet bay
(Persia borbonia), and one bald cypress (Taxodium distichum) were planted on each
hummock. No other vegetation was planted on the hummocks. Monitoring began in
September 1999 and took place bi-monthly. The site plan for the Cargill Phase 7
reclamation is shown in Figure 5.3 along with the hummock placement and layout.