Table 1.

Statistics of warming and herbivory effects on leaf damage index.

	F	P
Soil OM content	0.3	0.563
Vascular plant cover	0.0	0.970
Lichen cover	2.8	0.096
Moss cover	0.8	0.362
Warming (W)	3.1	0.079
Herbivory reduction (H)	42.7	<0.001
Betula species (S)	5.6	0.023
W × H	3.5	0.062
W × S	0.8	0.471
H × S	0.5	0.662
W × H × S	3.5	0.016

The data collected in 2017 was log-transformed and analyzed using linear mixed models and Type I ANOVA (with two-sided significance tests). OM content and the areal cover of vascular plants, mosses, and lichens were treated as covariates and added to models to remove plot-to-plot variation that might otherwise confound the treatment effects. Field replicate block and birch genotype (nested within species) were included in the models as random effects, but are not reported. N = 234 experimental birch plantlet. F and P indicate F-statistics and P-values respectively; P < 0.05 are in bold.