56 



possible that an error was made in combining the hydrologic data from 

 the two gauges. It seems ironic that the only zone correctly predicted 

 at this site was Zone 4. Table 13 also shows the percentage probability 

 of each of the 55 sites occurring in a zone. 



Figure 11 shows the mean site FTI plotted against the observed and 

 predicted hydrologic zones. As expected, mean FTI numbers were greater 

 than the observed hydrologic zones at the low end (Zone 2) and less than 

 the zones at the upper end (Zone 6) of the hydrologic gradiant due to 

 the lack of outlying zones (e.g., Zones 1 and 7) to pull these averages 

 toward either extreme. Therefore, using DFA classification decision 

 points shows that average site FTI numbers as high as 3.45 would still 

 be in Zone 2, and average site FTI numbers as low as 5.33 would still be 

 in Zone 6. The lower end of the predicted Zone 4 (4.16) compares favor- 

 ably with the observed (4.0). Zone 5 predicted and observed zone values 

 are the same (5.0). 



Regional Variation in Species FTI Numbers 



Because the 17 sites in this study occur over a broad geographic 

 area, the possibility of regional differences in species FTI numbers was 

 a concern. To test for possible differences, the sites were grouped 

 into three regions: Gulf Coast (sites 1, 2, 10, 11, 12), Mississippi 

 Valley (sites 3 through 9), and Atlantic Coast (sites 13 through 17). 



A two-factor analysis of variance (ANOVA) was used to test for 

 differences in importance values between regions and clusters for trees. 

 There was no significant interaction between region and cluster trees 

 (F = 0.71, p = 0.68); therefore, importance values of species within a 

 cluster do not differ among regions. There was a significant difference 



