Competitiveness of the Exotic Silphium perfoliatum against the Native Urtica dioica: A Field Experiment

Table 4

Relative neighbor effect (RNE) based on the living aboveground dry biomass.

Central species	Year of growth	n	Surrounding species	Biomass
S. perfoliatum	1	9	S. perfoliatum	0.74
		8	U. dioica	0.90
	2	9	S. perfoliatum	0.86
		8	U. dioica	0.91
	1-2	18	S. perfoliatum	0.84
		16	U. dioica	0.91

RNE is calculated as equation (1). The higher the RNE is, the higher is the competitive effect. Bold type indicates that the parameter in the given treatment is significantly lower than the control; indicates that the parameter in the given treatment is significantly lower than in the treatment with the other surrounding species (Tukey’s post hoc test on LM with log-transformed living aboveground dry biomass).