The Influences of Canopy Species and Topographic Variables on Understory Species Diversity and Composition in Coniferous Forests

Table 3

Results of the CCA showed correlation coefficients between environmental variables and the CCA axes, species-environment correlation, cumulative variance relationship with the four axes, and variance inflation factor of each environmental variable (VIF).

Variables	Axis 1	Axis 2	Axis 3	Axis 4	VIF
Elevation	−0.775***	−0.302	−0.149	0.089	2.52
Aspect	−0.474*	0.611***	−0.110	0.087	1.83
Slope position	0.318	0.378*	−0.132	−0.273	1.79
Slope	−0.464*	−0.089	−0.132	−0.311	1.65
SOIL	−0.159	−0.588**	−0.069	0.304	1.72
Canopy cover	0.574**	−0.079	−0.006	0.066	2.49
Basal area	0.467*	−0.066	−0.346	−0.050	1.97
Tree density	0.607***	−0.083	0.303	−0.238	3.25
Species-environment correlations	0.907	0.908	0.840	0.713
Cumulative percentage variance
Of species data	13.9	25.1	32.1	35.9
Of species-environment relation	32.3	58.3	74.5	83.3

^∗𝑃<0.05; ^∗∗𝑃<0.01; ^∗∗∗𝑃<0.001.