The plant-available nutrients calcium, magnesium, potassium, phosphorus, and
iron, show possible threshold ranges based on the presence of vines. Table 6.13 provides
a summary of the mean values of plant available nutrients at each site according to
whether herbaceous or woody vines were or were not rooted. The following figures
reflect only areas where vines occur, as zero value for rooted vines and vine biomass
were excluded.

 Figure 6.36 shows that herbaceous vines grew throughout a broad range of soil
calcium concentrations from 100-8,500 g calcium/m3, yet woody rooted vines had a
narrower range, growing predominantly in areas with 7,500-8,500 g calcium/m3. Figure
6.37 shows that vines grew in soil magnesium ranges from 10-800 g magnesium/m3, yet
there was a concentration of rooted vines within the 10-300 g magnesium/m3 range.
Woody vines occurred in soils with lower magnesium concentrations, ranging from 10-
150 g magnesium/m3. Figure 6.38 illustrates the distribution of vines throughout the 5-70
g potassium/m3 range of soil concentrations. Few rooted vines occurred at potassium
concentrations below 10 g potassium/m3, with the greatest concentration of vines in the
range of 10-35 g potassium/m3.

 Figure 6.39 shows that the greatest concentration of vines occurred in the 0-1,000
g phosphorus/m3 range, with a few outliers in areas greater than 1,000 g phosphorus/m3.
Figure 6.40 displays the uniform distribution of rooted vines and vine biomass
throughout the entire 10-100 g iron/m3 range of soil iron concentrations. Only 6-year-old
Nichols Mine recorded vines at soil iron concentrations greater than 75 g iron/m3.

 Ammonium-nitrogen concentrations (NH4-N) ranged between 0-8 g NH4-N/m3
with woody vines occurring at this elevated soil ammonium-nitrogen level. Figure 6.41
shows that soil ammonium-nitrogen levels may have little bearing on vine presence.
Figure 6.42 displays similar results for soil nitrate-nitrogen concentrations (g N03-N/m3).
A majority of the rooted vines and dry weight vine biomass were located within the 0-4 g
NO3-N/m3 range, with various soil nitrate-nitrogen levels in quadrats without vine, with
rooted herbaceous vines, and with rooted woody vines.

 Table 6.14 provides the Spearman coefficients correlating soil parameters and
whether no vines, herbaceous vines, or woody vines were rooted. A positive 1.000 value
such as between g NO3-N/m3, g Ca/m3, and g Mg/m3 means that a perfect positive
correlation exists, and values of zero suggest that no correlation exists (Eddison 2000).
Rooted vines and soil moisture have a -0.377 correlation (P = 0.013), and rooted vines
have positive correlations with the available soil nutrients. The nutrients NH4-N (rS =
0.412, P = 0.006) and Fe (rS = 0.108, P = 0.489) appear to correlate the greatest with
rooted vines, with the remaining plant-available nutrients Ca, Mg, K, P, and N03-N
having Spearman correlation coefficients < 0.065.


SIMULATION MODELING

 To test the hypothesis concerning the role and management of vines in
constructed forested wetlands, a systems diagram and simulation model were developed.


6-84