Figure 2 Effects of shading and snail biomass on shoot number and internode length of P. crispus . shoot number (A) and internode length (B) . S0 indicates full light, S1 indicates low light intensity under shading. Lines are fitted by gam functions in package ggplot2, and a solid line indicates p < 0.05, and a dashed line indicates p > 0.05. Dot symbol indicates nutrient loading, and triangles indicate no additional nutrients were added. P values in the panel indicate a significant effect of shading on the mean of the response variable.