December 2012 Number 1 - Utah Native Plant Society

Calochortiana December 2012 Number 1
in the town of Shiprock near plant locations range from
a high/low in January (coldest month) of 44.4 o F/17 o F to
a high/low in July (hottest month) of 95 o F/58 o F (Ladyman
2004). The federal listing of Mesa Verde cactus
provides detailed information on habitat, soil and climatic
requirements of the plant, providing great detail to
compare to model data.
Mesa Verde Cactus has 208 species location points.
Models were developed using 146 for model training
and 62 for model test validation points. The full, pruned
and topo models were used to analyze suitable habitat
for Mesa Verde cactus. The AUC score of the full
model, incorporating all of the environmental variables,
was 0.9977. The AUC score of the pruned model, developed
from jackknife analysis, was 0.997. The pruned
model showed geology as the highest predictive vari-
able. In comparison, the topo model AUC score was
0.831. The accuracy of the three niche models measured
by AUC scores, demonstrated that all three models performed
better than random (AUC 0.5). The full and
pruned models were nearly identical in AUC scores
(0.9977, 0.997). The topo model was out performed by
both the full and pruned models.
Variable isolation during jackknife analysis indicated
geology, minimum temperature of coldest month, mean
temperature of coldest quarter and temperature seasonality
were the most predictive variables, with an AUC of
0.9 or above (Table 3). Variable inclusion during jackknife
analysis did not show any significant results; the
AUC scores only changed 0.001 between models. The
least predictive variable was slope aspect.
Table 3: Mesa Verde Cactus model AUC scores.
Sclerocactus mesae-verdae Jackknife Variable Exclusion Jackknife Variable Isolation
#Training samples 146 AUC without Geology 0.997 AUC with only Slope Aspect 0.5824
Iterations 500 AUC without BIO 4 0.9974 AUC with only BIO 2 0.6194
Training AUC 0.9977 AUC without BIO 1 0.9975 AUC with only Slope Angle 0.7073
#Test samples 62 AUC without BIO 10 0.9975 AUC with only BIO 12 0.7626
Test AUC 0.9977 AUC without BIO 11 0.9975 AUC with only BIO 19 0.7773
AUC Standard Deviation 0.0005 AUC without BIO 13 0.9975 AUC with only BIO 17 0.7802
AUC without BIO 16 0.9975 AUC with only BIO 14 0.7907
AUC without BIO 17 0.9975 AUC with only BIO 5 0.8222
AUC without BIO 18 0.9975 AUC with only BIO 18 0.834
AUC without BIO 19 0.9975 AUC with only BIO 13 0.8354
AUC without BIO 8 0.9975 AUC with only BIO 16 0.8423
AUC without BIO 9 0.9975 AUC with only BIO 7 0.8472
AUC without BIO 12 0.9976 AUC with only BIO 3 0.8556
AUC without BIO 14 0.9976 AUC with only BIO 10 0.8608
AUC without BIO 15 0.9976 AUC with only BIO 1 0.8774
AUC without BIO 2 0.9976 AUC with only BIO 9 0.8813
AUC without BIO 3 0.9976 AUC with only BIO 8 0.8919
AUC without BIO 5 0.9976 AUC with only BIO 15 0.8961
AUC without BIO 6 0.9976 AUC with only BIO 4 0.9141
AUC without BIO 7 0.9976 AUC with only BIO 11 0.9169
AUC without Slope Angle 0.9976 AUC with only BIO 6 0.9655
AUC without Slope Aspect 0.9976 AUC with only Geology 0.9888
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