Geographic Patterns and Stand Variables Influencing Growth and Vigor of Populus tremuloides in the Sierra Nevada (USA)

Table 5

Generalized linear mixed model of aspen crown ratio (CR) for 𝑛=707 aspen trees in 9 stands around Lake Tahoe Basin. −2 Log Likelihood = 879.0. Dependent variable = Sin⁻¹(CR^0.5). 𝐸_Std.: Estimate for standardized coefficients of fixed effects.

Effect	Parameter	Estimate	s.e.	df	𝑡	pr>𝑡	𝐸Std.
Fixed	Intercept	1.11220	0.0398	8	27.92	<0.0001	0.8
	Ln Dbh	−0.05220	0.0098	695	−5.31	<0.0001	−0.8
	SDI^0.5	−0.00500	0.0009	695	−5.39	<0.0001	−1.1
	SDI^0.5  × Pct. conifer BA^a	−0.00146	0.0005	695	−3.16	0.0017	−0.6
Random	Site (𝑛=9)	0.00452	0.0025
	Residual	0.01546	0.0008

^aPercent conifer BA (arcsine transformed) = Sin⁻¹((0.01 * percent conifer BA)^0.5).