Appendix S2

Table S1. Information on fitted models with Akaike’s information criterion (AIC), Schwarz’s Bayesian information criterion (BIC) and adjusted R-squared (R-sq.(adj)) selections.

MODEL 1(Geomorphology)

Initial model

AX1 ~ s(Altit) + s(Asp) + Slope + Bare_rock

Start: AX1 ~ s(Altit) + s(Asp) + Slope + Bare_rock

AIC = 222.5288 BIC =243.6839 R-sq.(adj.) = 0.767

Trial 1: AX1 ~ s(Altit) + s(Asp) + Slope

AIC =252.2147 BIC = 270.7255 R-sq.(adj) = 0.691

Trial 2: AX1 ~ s(Altit) + s(Asp) + Bare_rock

AIC = 221.6461 BIC = 240.1569 R-sq.(adj) = 0.766

Trial 3: AX1 ~ s(Altit) + Slope + Bare_rock

AIC = 230.4935 BIC = 246.4173R-sq.(adj) = 0.737

Trial 4: AX1 ~ s(Asp) + Slope + Bare_rock

AIC = 328.647 BIC = 344.5134 R-sq.(adj) = 0.342

Trial 5: AX1 ~ s(Altit) + Bare_rock

AIC = 230.8813 BIC = 244.151 R-sq.(adj) = 0.734

Trial 6: AX1 ~ s(Altit) + s(Asp)

AIC = 250.4469 BIC = 266.3132 R-sq.(adj) = 0.694

Trial 7: AX1 ~ s(Altit) + Slope

AIC = 269.2379 BIC = 282.5077R-sq.(adj) = 0.625

Trial 8: AX1 ~ s(Asp) + Bare_rock

AIC = 330.1308 BIC = 343.3528 R-sq.(adj) = 0.323

Final model

AX1 ~ s(Altit) + s(Asp) + Bare_rock

MODEL 2 (Ecology)

Initial model

AX1 ~ Temp + s(Cont) + s(SoilR) + s(Nutr)

Start: AX1 ~ Temp + s(Cont) + s(SoilR) + s(Nutr)

AIC = 61.97611 BIC = 85.86176 R-sq.(adj) = 0.952

Trial 1: AX1 ~ Temp + s(Cont) + s(SoilR)

AIC = 109.2134 BIC = 127.7911 R-sq.(adj) = 0.919

Trial 2: AX1 ~ Temp + s(Cont) + s(Nutr)

AIC = 63.28767 BIC = 81.86539 R-sq.(adj) = 0.95

Trial 3: AX1 ~ Temp + s(SoilR) + s(Nutr)

AIC = 73.27642 BIC = 91.85414 R-sq.(adj) = 0.942

Trial 4: AX1 ~ s(Cont) + s(SoilR) + s(Nutr)

AIC = 174.3609 BIC = 195.5926 R-sq.(adj) = 0.875

Trial 5: AX1 ~ Temp + s(Nutr)

AIC = 74.06907 BIC =87.33887R-sq.(adj) = 0.94

Trial 6: AX1 ~ Temp + s(Cont)

AIC = 105.728 BIC = 118.9978R-sq.(adj) = 0.952

Final model

AX1 ~ Temp + s(Cont) + s(SoilR) + s(Nutr)

MODEL 3 (Structure)

Initial model:

s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero

Start: s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero

AIC = 264.2022 BIC = 298.7036 R-sq.(adj) = 0.691

Trial 1: AX1 ~ s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan,

AIC = 290.5867 BIC = 322.4343 R-sq.(adj) = 0.572

Trial 2: AX1 ~ s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Thero

AIC = 264.508 BIC = 296.3556 R-sq.(adj) = 0.687

Trial 3: AX1 ~ s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + Phan + Thero

AIC = 261.8702 BIC = 291.0638 R-sq.(adj) = 0.689

Trial 4: AX1 ~ s(NoSpe) + s(Tree_layer) + s(Moss_layer) + s(N_Phan) + Phan + Thero

AIC = 268.3878 BIC = 300.2353 R-sq.(adj) = 0.688

Trial 5: AX1 ~ s(NoSpe) + s(Tree_layer) + Cham + s(N_Phan) + Phan + Thero

AIC = 261.4812 BIC = 290.6748 R-sq.(adj) = 0.688

Trial 6: AX1 ~ s(NoSpe) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero

AIC = 286.9804 BIC =316.174R-sq.(adj) = 0.606

Trial 7: AX1 ~ s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero

AIC = 300.9426 BIC = 330.1362 R-sq.(adj) = 0.549

Trial 8: AX1 ~ s(NoSpe) + s(Tree_layer) + Cham + Phan + Thero

AIC = 259.5577 BIC = 283.4433 R-sq.(adj) = 0.685

Trial 9: AX1 ~ s(NoSpe) + s(Tree_layer) + Cham + s(N_Phan) + Phan,

AIC = 289.936 BIC = 316.4756 R-sq.(adj) = 0.562

Trial 10: AX1 ~ s(NoSpe) + s(Tree_layer) + s(N_Phan) + Phan + Thero

AIC = 267.1875 BIC = 293.7271 R-sq.(adj) = 0.665

Trial 11. AX1 ~ s(NoSpe) + s(Tree_layer) + Phan + Thero

AIC = 264.4183 BIC = 285.65 R-sq.(adj) = 0.665

Final model

AX1 ~ s(NoSpe) + s(Tree_layer) + Cham + Phan + Thero

MODEL 4 (Soil)

Initial model

AX1 ~ pH + s(Org_mat, k=6) + CN + Clay + Mg_per + s(K_per, k=6) + s(Na_per, k=6

Start: AX1 ~ pH + s(Org_mat, k=6) + CN + Clay + Mg_per + s(K_per, k=6) + s(Na_per, k=6)

AIC = 290.6903 BIC =321.9523R-sq.(adj) = 0.577

Trial 1: AX1 ~ pH + s(Org_mat,k=6) + CN + Clay + Mg_per + s(K_per,k=6)

AIC = 292.7291 BIC = 318.7808R-sq.(adj) = 0.537

Trial 2: AX1 ~ pH + s(Org_mat,k=6) + CN + Clay + Mg_per + s(Na_per,k=6)

AIC = 327.3799 BIC = 353.4316R-sq.(adj) = 0.338

Trial 3: AX1 ~ pH + s(Org_mat,k=6) + CN + Clay + s(K_per,k=6) + s(Na_per,k=6

AIC = 295.4405 BIC = 324.0974 R-sq.(adj) = 0.551

Trial 4: AX1 ~ pH + s(Org_mat,k=6) + CN + Mg_per + s(K_per,k=6) + s(Na_per,k=6),

AIC = 296.0534 BIC = 325.1417R-sq.(adj) = 0.578

Trial 5: AX1 ~ pH + s(Org_mat,k=6) + Clay + Mg_per + s(K_per,k=6) + s(Na_per,k=6)

AIC = 293.6693 BIC = 322.3262R-sq.(adj) = 0.559

Trial 6: AX1 ~ pH + Clay + Mg_per + s(K_per,k=6) + s(Na_per,k=6)

AIC = 290.42 BIC =313.8665R-sq.(adj) = 0.546

Trial 7: AX1 ~ s(Org_mat,k=6) + Clay + Mg_per + s(K_per,k=6) + s(Na_per,k=6)

AIC = 306.4057 BIC = 332.4574R-sq.(adj) = 0.509

Trial 8: AX1 ~ pH + Clay + Mg_per + s(Na_per,k=6)

AIC BIC logLik

AIC = 323.2855 BIC = 341.5217R-sq.(adj) = 0.309

Final model

AX1 ~ pH + Clay + Mg_per + s(K_per,k=6) + s(Na_per,k=6)

MODEL 5 (Chorotypes)

Initial model

AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(AMP) + s(BALK)

Start: AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(AMP) + s(BALK)

AIC = 209.052 BIC = 248.8614R-sq.(adj) = 0.841

Trial 1: AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(AMP)

AIC = 292.7291 BIC = 318.7808R-sq.(adj) = 0.537

Trial 2: AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(BALK)

AIC = 327.3799 BIC = 353.4316R-sq.(adj) = 0.338

Trial 3: AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + s(AMP) + s(BALK)

AIC = 244.801 BIC =281.9565R-sq.(adj) = 0.762

Trial 4: AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + BORE + s(AMP) + s(BALK

AIC = 255.1143 BIC = 289.6158R-sq.(adj) = 0.732

Trial 5: AX1 ~ s(SM) + ME.MO + EURIAS + s(ORO.S.EU) + BORE + s(AMP) + s(BALK)

AIC = 212.5401 BIC = 247.0416R-sq.(adj) = 0.807

Trial 6: AX1 ~ s(SM) + ME.MO + s(ATLANT) + s(ORO.S.EU) + BORE

AIC = 341.1431 BIC = 367.6827 R-sq.(adj) = 0.371

Trial 7: AX1 ~ s(SM) + EURIAS + s(ATLANT) + s(AMP) + s(BALK)

AIC = 301.7732 BIC = 330.9667R-sq.(adj) = 0.554

Trial 8: AX1 ~ EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(AMP) + s(BALK)

AIC = 212.8405 BIC = 244.688R-sq.(adj) = 0.819

Trial 9: AX1 ~ ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(BALK)

AIC = 216.4521 BIC = 245.6456R-sq.(adj) = 0.821

Trial 10: AX1 ~ ME.MO + EURIAS + s(ORO.S.EU) + BORE + s(AMP) + s(BALK)

AIC = 217.5895 BIC = 246.783R-sq.(adj) = 0.793

Trial 11: AX1 ~ ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(AMP)

AIC = 247.722 BIC = 276.9155R-sq.(adj) = 0.744

Final model:

AX1 ~ s(SM) + ME.MO + EURIAS + s(ATLANT) + s(ORO.S.EU) + BORE + s(AMP) + s(BALK)

MODEL 6 (All variables)

Initial model:

AX1 ~ s(Altit) + s(Asp) + Slope + Bare_rock + Temp + s(Cont) + s(SoilR) + s(Nutr) + s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero + pH + s(Org_mat,k=6) + CN + Mg_per + s(K_per,k=6) + s(Na_per,k=6) + s(SM) + MEMO + EURIAS + s(ORO.S.EU) + BORE

Start: AX1 ~ s(Altit) + s(Asp) + Slope + Bare_rock + Temp + s(Cont) + s(SoilR) + s(Nutr) + s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero + pH + s(Org_mat,k=6) + CN + Mg_per + s(K_per,k=6) + s(Na_per,k=6) + s(SM) + MEMO + EURIAS + s(ORO.S.EU) + BORE

AIC = 62.2874BIC = 173.3518R-sq.(adj) = 0.967

Final model:AX1 ~ s(Altit) + Bare_rock + Temp + s(Cont) + s(SoilR) + s(Nutr) + s(NoSpe) + s(Tree_layer) + s(Moss_layer) + Cham + s(N_Phan) + Phan + Thero + s(Org_mat,k=6) + CN + s(SM) + MEMO + EURIAS + s(ORO.S.EU)

AIC = 58.74807BIC = 143.3686R-sq.(adj) = 0.967