Environmental Engineering Reference
In-Depth Information
Fig. 5.15 Cluster dendrogram of 39 wetlands based upon
Sphagnum
community dissimilarity.
Four groups have been constructed based upon interpretability
Exercise 4. Interpreting Multivariate Data
The following figures are output from a multivariate data analysis of 25
Sphagnum
species found in 39 different wetlands. Wetlands were clustered into groups based
upon their species dissimilarity using hierarchical cluster analysis (Fig.
5.15
)
and were ordinated within
Sphagnum
species abundance space using non-metric
multidimensional scaling (Fig.
5.16
).
1. Draw a line on the cluster dendrogram where the group cut-off occurs. What
percent of information is remaining at this point?
2. If you were to divide the black circle group into four sub-groups, which wetlands
would be included in each group?
3. Which wetland group is the least tightly clustered in this ordination diagram?
4. The red/gray lines are correlations of axes with environmental data collected
in each wetland. Which wetland group contains the oldest wetlands? Which
wetland group contains wetlands with the highest average groundwater specific
conductivity?
5. Which group of wetlands is closest to the centroid for
S. inundatum
on the
ordination diagram?
6. What species (three letter abbreviation) is most negatively correlated with
Axis 3? Which species is most positively correlated with Axis 3?
7. Which wetland sites (numbers) most likely have the most
S. flavicomans
?
