Variations in the natural 13C and 15N abundance of plants and soils under long-term N addition and precipitation reduction: interpretation of C and N dynamics

Forest Ecosystems

Table 4 Pearson correlation coefficients between δ¹⁵N, N, δ¹³C and C in trees foliage, fine roots and surface soil layer (0–10 cm)

	Foliage ¹⁵N⁺	Foliage N^&	Foliage ¹³C	Foliage C^#	Fine root ¹⁵N	Fine root N	Fine root ¹³C^#	Fine root C^#	Soil layer ¹⁵N^#	Soil layer N⁺	Soil layer ¹³C
Foliage ¹⁵N⁺	1
Foliage N^&	0.175
Foliage ¹³C	−0.382*	0.381*
Foliage C^#	0.268	−0.779**	−0.613**
Fine root ¹⁵N	−0.229	−0.404*	−0.623**	0.661**
Fine root N	−0.290	−0.745**	−0.430*	0.603	0.337
Fine root ¹³C^#	0.180	−0.077	0.512**	−0.159	− 0.481*	−0.034
Fine root C^#	−0.066	0.108	−0.157	0.106	0.233	−0.399*	−0.390*
Soil layer ¹⁵N^#	−0.554**	0.061	0.143	−0.276	−0.356	0.170	0.069	−0.163
Soil layer N⁺	0.418*	0.242	0.233	−0.082	0.154	−0.452**	− 0.056	0.241	− 0.502**
Soil layer ¹³C	0.275	−0.331	−0.117	0.097	−0.307	0.327	0.062	−0.274	0.438**	−0.678**
Soil layer C⁺	0.496**	0.091	0.078	0.003	0.188	−0.374*	− 0.054	0.187	− 0.720**	< 0.830**	− 0.001

To approximate normality, the response variables are Ln-transferred. # Log; + Square; & Exponent. * The level of significance of correlations is p < 0.05. ** The level of significance of correlations is p < 0.01