Table 3.

Results of preliminary MANOVA tests for the main effects of tree age, site, year and canopy position and their interactions on SNC severity index, foliage retention, and foliage nitrogen (TN) in study areas in western Oregon.

	SNC Severity Index (5 sites²)			Foliage retention (7 sites³)			Foliage TN (7 sites³)
	F-value	p-value		F-value	p-value		F-value	p-value
(Intercept)	295.9	< 0.001	***	4197.1	< 0.001	***	3705.1	< 0.001	***
Tree age	172.6	< 0.001	***	5.1	0.033	*	0.0	0.865
Site	28.9	< 0.001	***	21.4	< 0.001	***	7.1	0.001	**
Tree age × Site	6.7	0.002	**	2	0.098	.	0.4	0.794
Year	12.1	0.003	**	0.1	0.740		74.0	< 0.001	***
Tree age × Year	17.1	0.001	***	0	0.886		2.2	0.156
Site × Year	10.9	< 0.001	***	0.6	0.740		3.6	0.024	*
Tree age × Site × Year	7.7	0.001	***	2.5	0.046	*	0.3	0.857
Canopy	7.1	0.006	**	18.9	< 0.001	***	17.8	<0.001	***
Tree age × Canopy	1.5	0.260		3.4	0.050¹	*	3.5	0.053	.
Site × Canopy	3.5	0.004	**	2	0.050¹	*	0.9	0.516
Tree age × Site × Canopy	2.1	0.057	.	1.4	0.180		1.3	0.287
Year × Canopy	2.8	0.086	.	1.5	0.248		2.6	0.100
Tree age × Year × Canopy	2.8	0.086	.	2.0	0.153		0.2	0.785
Site × Year × Canopy	0.4	0.923		0.7	0.736		0.2	0.992
Tree age × Site × Year × Canopy	0.3	0.944		1.5	0.159		0.8	0.636

The tree age x canopy and site x canopy interaction terms were not statistically significant (p-value = 0.19 and 0.50, respectively) when the foliage retention data for Soapgrass Mountain and Toad Creek were excluded from the MANOVA, indicating that canopy differences at the five lower elevation sites were similar but different than at the higher elevation sites.

Including sites Cascade Head, Woods Creek, and Klickitat Mountain, Moose Mountain, and Falls Creek. Soapgrass Mountain and Toad Creek were excluded because almost all SNC values from those sites were zeros.

Including sites Cascade Head, Woods Creek, and Klickitat Mountain, Moose Mountain, Falls Creek, Soapgrass Mountain, and Toad Creek.