DISCUSSION


 In this report, measurements of selected biotic and abiotic parameters were
 conducted on constructed forested wetlands to answer the question, "Do development of
 constructed forested wetland ecosystems result in measurable successional trajectories?"

 Field measurements documenting the results of self-organization of
 constructed wetlands suggest that the developing ecosystems represented by
 the chronosequence of research sites are quite different in several respects, but
 that time alone is not responsible for the differences.
 Successional trajectories with time for only a few individual parameters are
 apparent, but the successional trajectory of an ecosystem may not be
 discernible from trajectories of individual components.
 Successional trajectories may be far more complex than a simple parameter
 trajectory and may only be observable as changes in emerging properties
 resulting from interactions among ecosystem components.


 CHRONOSEQUENCE OF CONSTRUCTED FORESTED WETLANDS


 Canopy Tree Species

 The self-organization of many aspects of the canopy tree component of
constructed forested wetlands on phosphate mined lands is initially more dependent on
human intervention than natural processes. Species richness is more a factor of the
number of species planted during the construction process than of recruitment of species
from natural areas. When comparing species richness of constructed forested wetlands
with that of natural wetlands, the number of dominant species are similar. Sharitz and
Mitsch (1993) provide a list of dominant species for a variety of bottomland hardwood
swamps in the Southeast. Species richness ranged from one dominant species in cypress
swamps to three dominant species in several other forest types. When including not only
dominant tree species but also major associates, only three research sites match the
species richness of natural systems (10-12 species). Davis and others (1991) report
species richness in cypress domes, bayheads and hardwood swamps of Florida as 7.2, 6.8
and 13.5, respectively. Species richness in constructed forested wetlands ranged from 2
to 12 species.

 Davis and others (1991) provides the frequency of occurrence of dominant
species in Florida wetlands. Frequency of occurrence in their study was considered as
the number of transects on which a species occurred divided by the total number of
transects. Figure 7.23a shows the frequency of occurrence of canopy tree species in three
types of natural forested wetlands in Florida. Table 7.14 provides the species codes for
Figure 7.23. The six dominant species found in constructed forested wetlands were
selected for comparison, and their frequencies in natural Florida wetlands are depicted in


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