Table 3.

Slopes of the linear regression between the grounding resistance and the vertical distance to the C2/P2 electrode (experiment 2), the vertical distance between the P1 electrode and the water level (experiment 3 ‘gradual rising’), and the vertical distance to the root cut plane (experiment 3 ‘root severing’), respectively

	Experiment 2 ‘bark conductance’	Experiment 3 ‘gradual rising’	Experiment 3 ‘root severing’
Scots pine	24.1±4.1	22.9±2.8	0.25±0.11
Norway spruce	19.5±2.8	16.5±0.9	0.09±0.02
Pedunculate oak	17.1±1.8	14.1±0.8	0.05±0.01

Regressions were in the form y=ax+b where a and b are constants, y is the grounding resistance, and x is the respective distance. Data are given as slope estimates [MΩ cm⁻¹] ±confidence interval.