Predicting the outcome of competition along a nitrogen gradient – a case study with Erodium cicutarium and Geranium pusillum

Figures & data

Figure 1.  The relationship between nitrogen applied to the plants grown in the greenhouse and the mean individual plant biomass at density 200 plants m⁻², 400 plants m⁻² and 1000 plants m⁻². (a) G. pusillum grown in mix with E. cicutarium; (b) G. pusillum grown in monoculture; (c) E. cicutarium grown in mix with G. pusillum; and (d) E. cicutarium grown in monoculture. Variation is shown as standard error.

Table I Analysis of variance on the mean biomass of each treatment in the greenhouse.

	DF	Type III SS	Mean Square	F values	Pr>F
Species	1	0,4395	0,4395	35,01	<0,0001
Nitrogen	3	0,1974	0,3991	31,80	<0,0001
Culture-type	1	0,0899	0,0899	7,16	0,0115
Density	2	2,2898	1,1449	91,21	<0,0001
Species×Culture-type	1	0,2553	0,2553	20,34	<0,0001
Nitrogen×Density	6	0,3535	0,0589	4,69	0,0015

Figure 2.  The relationship between nitrogen applied to the plants and the probability that c _E >c _G .

Figure 3.  The probability of different outcomes of the competition between E. cicutarium and G. pusillum along the nitrogen gradient at ecological equilibrium. (a) Probability of germination and establishment: E. cicutarium=0.1 and G. pusillum=0.1; (b) Probability of germination and establishment: E. cicutarium=0.05 and G. pusillum=0.1.