Table 7. Significant correlations among the biomass, contents and yields of Cu, Fe, Mn and Zn.

		Content (mg/kg)				Biomass (g/m2)	Yield (mg/m2)
		Cu	Fe	Mn	Zn		Cu	Fe	Mn	Zn
Content (mg/kg)	Cu	1	ns	ns	0.626**	−0.347*	0.420**	ns	ns	ns
	Fe		1	0.871**	0.452**	ns	ns	0.682**	0.539**	0.482**
	Mn			1	0.440**	0.307*	ns	0.658**	0.623**	0.513**
	Zn				1	ns	0.418**	ns	ns	0.537**
Biomass (g/m2)						1	0.654**	0.860**	0.922**	0.827**
Yield (mg/m2)	Cu						1	0.605**	0.637**	0.772**
	Fe							1	0.965**	0.868**
	Mn								1	0.881**
	Zn									1

Note:

The data of all stand ages and cuts were used for analyzing the correlations. “ns” was represented insignificance (P > 0.05). The asterisk (*) and double asterisks (**) represent significant correlations at P < 0.05 and P < 0.01, respectively.