Modelling the variation in wood density of New Zealand-grown Douglas-fir

New Zealand Journal of Forestry Science

Table 3 Correlations and partial correlations between breast height outerwood density and various site and environmental variables

Variable		North Island (n = 182)		South Island (n = 130)
Variable		r^a	r_age ^b	r^a	r_age ^b	r_age,MAT ^c
Stand age (years)		0.37**	-	0.53**	-	-
Latitude (deg.)		−0.14	−0.09	0.19*	0.29**	0.11
Longitude (deg.)		0.13	0.05	0.28**	0.38**	0.19*
Elevation (m)		−0.22**	−0.22*	−0.47**	−0.51**	−0.06
Mean annual rainfall (mm)		−0.13	−0.03	−0.20*	−0.26**	0.07
Mean temperature (°C)	Annual	0.19**	0.21**	0.57**	0.72**	-
	Spring	0.12	0.14	0.56**	0.68**	−0.04
	Summer	0.14	0.16*	0.44**	0.57**	−0.24**
	Autumn	0.14	0.19*	0.57**	0.59**	0.05
	Winter	0.12	0.18*	0.58**	0.72**	0.22**
Mean maximum daily temperature (°C)	Annual	0.16*	0.13	0.49**	0.64**	0.04
	Spring	0.15*	0.15	0.51**	0.66**	0.09
	Summer	0.12	0.10	0.30**	0.44**	−0.11
	Autumn	0.14	0.13	0.47**	0.59**	0.02
	Winter	0.16*	0.16*	0.60**	0.74**	0.30**
Mean minimum daily temperature (°C)	Annual	0.07	0.20**	0.51**	0.61**	−0.01
	Spring	0.01	0.14	0.51**	0.61**	−0.05
	Summer	0.12	0.20**	0.48**	0.59**	−0.19
	Autumn	0.00	0.13	0.47**	0.58**	−0.03
	Winter	−0.01	0.15	0.41**	0.52**	0.04
Soil C:N ratio^d		-	-	0.60^**	0.55^**	0.70^**

^aPearson correlation between outerwood density and the given variable
^bPartial correlation between outerwood density and the given variable adjusted for age
^cPartial correlation between outerwood density and the given variable adjusted for age and MAT
^dSoil C:N ratio was available for 18 South Island stands
Significance levels are indicated by *(p < 0.05) and **(p < 0.01)