Effects of Landform on Site Index for Two Mesophytic Tree Species in the Appalachian Mountains of North Carolina, USA

Table 2

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

Environmental	Pearson correlation (r)		Variable significance (𝑃>|𝑡|)
variable	Redoak	Yellow-poplar	Red oak	Yellow-poplar
A-horizon thickness	−0.06^a	0.23^a	0.82	0.89
Solum thickness	0.02^a	−0.08^a	0.78	0.1
Elevation	−0.50^b	−0.58^b	0.16	0.85
Aspect	−0.07^a	0.03^a	0.93	0.61
Gradient	0.10^a	−0.14^a	0.5	0.1
Landform index	0.75^b	0.73^b	0.02	0.01
Model significance	−	−	0.05	0.05

^a Pearson correlation coefficient was not significant at𝑃<.05.
^bPearson correlation coefficient was significant at 𝑃<.05.