Table 2: Pearson correlation coefficients (r) of environmental variables with site index and overfitted regression significance levels ( ) for a site index model with all independent environmental variables by species for stands sampled in the Southern Appalachian Mountains of North Carolina, USA.

EnvironmentalPearson correlation (r)Variable significance ( )
Red oakYellow-poplar

A-horizon thickness 0.820.89
Solum thickness 0.780.1
Elevation 0.160.85
Aspect 0.930.61
Gradient 0.50.1
Landform index 0.020.01
Model significance 0.050.05

a Pearson correlation coefficient was not significant at
bPearson correlation coefficient was significant at .