DISCUSSION


GENERAL

 Analysis of the results yields only partial answers to the questions of which soil
type and hummock size are best and the value of hummocks in a wetland. The first thing
one must realize is that this study was designed to provide an overall picture of the
dynamics of hummocks, not provide specific information on why any one characteristic
behaves in a certain way. Those are questions to be answered by continued study. The
second thing one must realize when looking at these results is that they are for only one
growing season (only two months in the Cargill case). A long-term study would be
needed to get a clearer picture about what is really happening in the wetlands.

 Conditions within a newly established ecosystem can vary greatly over a few
years. Weather varies slightly from year to year, some years being drier than others. A
dry year such as 1999 can have a dramatic effect on a wetland, especially a new wetland.
The Agrifos wetland, which was not manually flooded, depended solely on rainfall for its
water. Below average rainfall kept the wetland relatively dry. The dry conditions were
not conducive to establishment of wetland plants in the infant wetland. The Cargill
wetland did not experience the same dry conditions, as water was pumped into the
wetland. In an older site like the Iluka Resources wetland, periods of drought might not
have as big of an effect on the overall organization of the wetland. Ecosystems self-
organize over time until they adjust to the conditions characteristic of the region (Odum
and others 1997). The newly constructed wetlands are still beginning that process.

 Though the wetlands are young and further study would be invaluable, that is not
to say nothing can be learned from this study. On the contrary, there is much valuable
information to be gleaned from the results of this study. Much can be said about both the
colonization of hummocks by vegetation and the ability of different soils to hold their
shape during early growth of the wetland. The ability of soils to hold moisture and
provide habitat for a wide variety of plants can also be seen. Data on overall tree growth
are limited because of the slow growth of trees, but survivorship during the early growth
stage can be tracked.


AGRIFOS

 Three types of soil were used to construct hummocks in the Agrifos wetland. As
shown in Figure 5.6, the organic material used deteriorated the most during the first
growing season. Hummocks constructed from sand tailings held their shape the best. This
result is somewhat surprising due to the fact that sand tends to be more susceptible to
erosion than the other two soils (Thomas and others 1985) and the fact that sand
hummocks had the least percent cover of vegetation (Table 5.1). With little vegetation
growing, there was no root structure to hold the soil together. The organic hummocks had
a much higher percent cover of vegetation and thus likely much more root structure to


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