Table 1 Plotwise aggregated response and predictor variables selected for the PLS regression models

F ₂₅

Mean percentage of trees of the selected species with defoliation > 25 %

All models

0–43.3 %

0–72.0 %

0–32.7 %

 Null model

 Tree density

Trees per hectare

All models

 Latitude

All models

38°25′–55°57′ N

45°45′–67°59′ N

46°17′–66°21′ N

 Longitude

All models

0°39′ W–16°10′ E

1°48′ E–29°19′ E

7°42′ E–29°20′ E

 Altitude

All models

25–1525 m a.s.l.

25–1775 m a.s.l.

25–475 m a.s.l.

 Pr

Annual precipitation amount (mm)

All models

641–2038 mm year⁻¹

543–2845 mm year⁻¹

577–1551 mm year⁻¹

 SummerPr

Percentage of precipitation during the growing season

All models

32.7–69.9 %

45.6–82.2 %

48.7–80.7 %

 BADoAP

Mean reported BADoAP on foliage of trees of the selected species

Reference + BADoAP

0–2.0

0–2.7

0–0.7

Reference + BADoAP + N_thrdep

 Soil

 Soil_pH

pH (CaCl₂) of the mineral top soil, pH unit

Reference + soil

3.10–6.95

2.91–4.68

2.93–4.33

 BCE

Exchangeable Base Cations in mineral top soil

Reference + soil

0.57–51.2 cmol⁺ kg⁻¹

0.24–7.78 cmol⁺ kg⁻¹

0.17–2.29 cmol⁺ kg⁻¹

 C/N

C/N ratio of mineral top soil

Reference + soil

12.9–22.1

14.5–29.8

2.8–53.8

 Tree foliar nutrition

 N/P

N ratio to P, Ca, Mg, K concentrations in foliage (current year for evergreen species)

Reference + foliar

16.2–30.1

6.0–21.8

8.4–15.2

 N/Ca

Reference + foliar

1.8–8.1

2.1–11.6

2.9–8.3

 N/Mg

Reference + foliar

11.2–38.7

7.7–25.1

11.0–30.4

 N/K

Reference + foliar

2.6–4.9

1.6–30.4

1.5–4.1

 N deposition

 N_thrdep

Throughfall N deposition

Reference + NN_thrdep

Reference + BADoAP + NN_thr dep

10.4–24.8 kg ha⁻¹ year⁻¹

1.5–32.3 kg ha⁻¹ year⁻¹

2.1–26.7 kg ha⁻¹ year⁻¹