density (with associated increases in organic matter) increases water-holding capacity of
the soil. There should be a similar change with time in the graph of organic matter vs.
soil water content. Samples with greater soil water content have greater potential for
accumulation of organic matter due to decreases in rates of decomposition associated
with saturated soils.

 The change in these relationships is driven by natural processes and should occur
provided the site is capable of supporting vegetation and other biota. These relationships
integrate site hydrology and productivity and provide information on historical site
conditions, while methods of assessing wetlands by current vegetation, particularly
herbaceous vegetation, take into account only current conditions.

 Figure 7.31 used data from all soil subsamples from this study to represent the
relationships discussed previously. Using the same data, Figure 7.32 was constructed to
illustrate the 95% confidence intervals around the best-fit line. These graphs represent a
target for these relationships that has been reached and even exceeded by some sites,
while others have failed. Four methods could be used to assess the development of
wetland soils based on these relationships.

 All soil samples within a given site must fall above the shaded areas.

 The residuals associated with the exponential regression, upon which the
 curve is based, and the soil samples from a wetland could be summed. Soil
 samples falling in the shaded areas would have positive residuals, meaning
 they have exceeded the standard, and samples falling elsewhere would have
 negative residuals. A residual score greater than or equal to zero would be
 considered successful.

 Compare the regressions of soil relationships from individual sites with the
 standard. Regression relationships that are not significantly different from the
 standard would be considered successful.

 All subsamples for an individual constructed wetland must fall within the 95%
 confidence intervals.

 Figures 7.33, 7.34, 7.35, 7.36, and 7.37 show results of these comparisons for
each of five wetland sites. Figure 7.33 depicts a young site that lies on the lower range of
soil water content and soil organic matter, while bulk density is still high. This site also
falls above the mean of community wetland status (Figure 7.7). Over one half of the
samples are above the mean for constructed forested wetlands in Figure 7.33a and 7.33b
and above the mean in Figure 7.33c. In addition, there is little differentiation in bulk
density or organic matter along the soil water content gradient. This information
combined suggests that it is too early to determine if this will develop into and be
sustained as a forested wetland.


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