Table 1 Assignment of N availability levels according to VDI Guideline 3959 Part 1 [41] and the C/N ratios in the topsoil for the nutrient cycle types of the reference states for forest ecosystems according to Jenssen et al. [23]
Parameter | Category | ||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
N-availability “appraisal” | Very low “dystrophic” | Low “oligotrophic” | Medium “mesotrophic” | High “eutrophic” | Very high “very eutrophic” | ||||||||||||||||||||
Ellenberg–N score | < 3.4 | 3.4–4.3 | 4.4–5.3 | 5.4–6.1 | > 6.1 | ||||||||||||||||||||
Humus form | Raw humus, meager | Raw humus, meager | Raw humus | Moder-raw humus/raw humus-moder | Moder | Brown- mull | Mull | Calcareous mull | |||||||||||||||||
Nutrient cycle type | A1 | A2 | B1 | B2/C1 | C2 | D1 | E1 | E2 | |||||||||||||||||
C/N | > 33 | 33 | 32 | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | < 11 |