8172

• UCREFRP Catalog Number: 8172
• Author: Jacobi, G. Z., J. E. Sublette, S. J. Herrmann, D. E. Cowley and M. D. Hatch.
• Title: Final Report
• USFW Year: 1998.
• USFW - Doc Type: Investigations of an Index of Biotic Integrity in New Mexico.
• Copyright Material: NO

The reason for the importance of several of
the factors is more apparent when
three-dimensional plots of site scores on the
rotated factors are considered (Figures 2, 3,
4, and 5). Figures .2 and 3 reveal clearly
that three sites are outliers with respect to
the other sites in the upper Rio Grande
drainage. Two sites on the lower Jemez
River were downstream from Soda Dam, an
artesian. hot- -mineral spring,-.-both of-these
Jemez River sites had unusually high values
for potassium and sodium and they were
outliers on Factor 2. The Chama River
above Espanola was an outlier for Factor 3,
which contrasted land use designation with
total phosphorus and total suspended solids.
The Chama River above Espanola had
unusually high values for total phosphorus
and total suspended solids and it had the
lowest possible score for land use
designation.
Site scores for Factors 2, 3, and 5 are
plotted in Figure 4. An additional outlier
site, the Rio. Grande at Buckman Well
(Buckman Crossing, Appendix 1), was
identified for Factor 5. Recall that Factor 5
contrasted substrate composition with
Kjeldahl nitrogen and watershed area. The
Rio Grande at Buckman Well had the
highest value of all sites for watershed area,
the second highest value for Kjeldahl
nitrogen, and the lowest possible score for
substrate composition.
Site scores for Factors 2, 3, and 6 are
plotted in Figure 5. Two additional outliers
are identified for Factor 6, a contrast of
ammonia with nitrate/nitrite. The Chamita
River had high ammonia content and low
nitrate/nitrite, whereas, Casias Creek had
high nitrate/nitrite and low ammonia.
was successful at (1) producing factors that
eliminated colinearity among the original
variables and (2) identifying six outlier, or
anomalous, sites in the upper Rio Grande
drainage.
The site scores on each of the six
varimax-rotated environmental factors were
subjected to cluster analysis. The cluster
-tree for the -31- sites- in -the upper Rio Grande
drainage is shown in Figure 1. The analysis
identified two ecoregions and one group of
three outlier sites (one-half of the six outlier
sites identified in ordination plots).
Aquatic Ecoregion 1 (cluster 1 in Figure 1,
see also Figure 6) includes middle to high
elevation sites with a mean of 8504 feet and
a range of 7400 feet to 10520 feet. Two of
the high elevation sites in the upper Rio
Grande drainage did not cluster with the
other high elevation sites, i.e., Casias Creek
and the Clamita River. Both of these sites
were identified as outliers with respect to
Factor 6, a contrast of ammonia with
nitrate/nitrite. Aquatic Ecoregion 2
(clusters 2a, 2b, and 2c in Figure 1, Figure
6) encompassed low to middle elevation
sites with a mean of 6740 feet and a range
of 5410 feet to 9550 feet. Ignoring the two
high elevation outlier sites noted aboves, the
mean elevation for sites in Ecoregion 2 is
6474 feet with a range of 5410 feet to 7500
feet. Thus, Aquatic Ecoregion 1 and
Aquatic Ecoregion 2 have a boundary
somewhere around 7400 feet. The
boundary between ecoregions is very near
the boundary between ecoregions in the
upper Rio Granule drainage that were
proposed by Omernik (1986, 1987) (Figure
7).
Within Aquatic Ecoregion 2, three clusters
Thus, ordination, in the absence of data of sites were obtained (clusters 2a, 2b, and
transformation or elimination of variables
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