Figure 3: Detailed example of species response.

GLM results for Campanula rotundifolia (common name: harebell). Shown above are the marginal probabilities of occurrence individually by term from the best model for N deposition (a), N x pH (b), N x S (c), S deposition (d), S x pH (e), soil pH (f), precipitation (g), and temperature (h). All terms P<0.01 (Table S4). Black lines in main effect plots are average response and red lines are 95^th CI. For interaction terms (b, c, e) the effect of the modifying term is shown as separate quartile lines (Q1-Q4). The best model is shown below the species name. Also shown is a photo of the species (i), a range map from the USDA (j, ⁵⁹), and a plot map from this study (k). C. rotundafolia is a northern latitude wildflower that grows in drier, low nutrient soils.⁶⁰ This species had a hump shaped relationship with N (average CL = 7.9 kg N ha⁻¹ yr⁻¹; 10^th-90^th CL = 5.9–10.6 kg N ha⁻¹ yr⁻¹), and a negative relationship with S. Interactions were statistically significant with little effect on marginal relationships, except for the N x S interaction, where the eutrophication effect was stronger (i.e., higher peak and lower N CL) if S deposition was low. The 10^th-90^th interval reported here is similar to that reported for C. rotundafolia in Ireland ²² and lower than that found in acid grasslands across Europe ²¹. See Figure S1 for results for all 198 species.