Table 1 Ranges of the ‘adequate to optimal’ (A/O) nutritional class for tree foliar concentrations (mg g−1) of nitrogen (N), potassium (K) and magnesium (Mg) as compiled by Stefan et al. (1997), ratios of N/Mg and N/K according to Mellert and Göttlein (2012); species-specific critical limits of the molar ratio of base cations to total aluminium (Bc/Al) and of the inorganic N concentration in the mineral top soil solution (Nmin, mg L−1) regarding nutrient imbalances, and the critical limit for the mineral N concentration in the soil solution below the rooting zone (Nmin) regarding nitrogen saturation
From: Exceedance of critical loads and of critical limits impacts tree nutrition across Europe
Species groupa | Foliage | Soil solution | ||||||
|---|---|---|---|---|---|---|---|---|
mineral topsoil | deepest lysimeters | |||||||
N a | K a | Mg a | N/Mgb | N/Kb | Bc/Al c | Nmin d | Nmin d | |
Spruce | 12–17 | 3.5–9 | 0.6–1.5 | 10.7–21 | 1.7–3.3 | 1.2 | 0.2 | 1 |
Pine | 12–17 | 3.5–10 | 0.6–1.5 | 10.8–22.9 | 2–4 | 1.2 | 0.2 | 1 |
Silver fir | 12–17 | 3.5–9 | 0.6–1.5 | 10.7–22.9* | 1.7–4* | 1.2 | 0.2 | 1 |
Douglas fir | 12–17 | 3.5–10 | 0.6–1.5 | 10.7–22.9* | 1.7–4* | 0.3 | 0.2 | 1 |
Other conifers | 12–17 | 3.5–10 | 0.6–1.5 | 10.7–22.9* | 1.7–4* | 1.2 | 0.2 | 1 |
Beech | 18–25 | 5–10 | 1–1.5 | 8.2–21.8 | 1.9–3.8 | 0.6 | 0.4 | 1 |
Birch | 18–25 | 5–10 | 1–1.5 | 8.1–21.8* | 1.7–3.8* | 0.8 | 0.4 | 1 |
Oak | 15–25 | 5–10 | 1–2.5 | 8.1–21.8 | 1.7–3.7 | 0.6 | 0.4 | 1 |
Other broadleaves | 15–25 | 5–10 | 1–2.5 | 8.1–21.8* | 1.7–3.8* | 0.6 | 0.4 | 1 |