Table 1 Investigated parameters that may influence \( {\text{N}}{{\text{O}}_3}{^{ - }_{\text{seepage}}} \) with measurement depth/layer and time/period
Parameter group | Parameter | Unit | Layera | Time/period of measurment | Number of variables |
|---|---|---|---|---|---|
Nitrat in sepage water | NO −3 | mg l−1 | 4 | April–October | |
N input via throughfall | Input of NH +4 , NO −3 and total inorganic N | mg m−2 | −1 | July–October | 3 |
Average volume weighted concentration of NH +4 , NO −3 and total inorganic N | mg l−1 | −1 | July–October | 3 | |
Water input and substrate availability in the organic layer | Input of water | l m−2 | −1 | July–October | 3 |
Dry weight organic layer | g dw m−2 | 0 | October | 1 | |
Depth of organic layer | cm | 0 | October | 1 | |
N-turnover parameters in the organic layer | Net N mineralization, net nitrification, gross nitrifikation | mg N day−1 kg−1 dw | 0 | July–August | 3 |
Pools of NH +4 and NO3 | mg N kg−1 dw | 0 | 2 | ||
N-uptake parameters | Tree root biomass (<2, 2–5, >5 mm) | g m−2 | 0–4 | October | 15 |
Vegetation cover of mosses, oxalis, other vascular plants | % coverage | −1 | July | 3 | |
Chemical soil parameters | pH in H2O and KCl |
| 0–4 | October | 10 |
N and C content | % | 0–4 | October | 10 | |
C/N | Ratio | 0–4 | October | 5 | |
Physical soil parameters | Bulk density | g cm−3 | 1–4 | October | 4 |
Pore volume of macro- (>50 μm), meso- (50–10 μm) and fine pores (<10 μm) and whole pore volume | vol.% | 1–4 | October | 16 | |
Grain size distribution | % sand, % silt, % clay | 1–4 | October | 12 | |
Stand parameters | Distance to next trees | cm | −1 | July | 1 |
Breast hight diameter of the next trees | cm | −1 | July | 1 | |
Basal area of trees within a radius 4 m | cm2 | −1 | July | 1 | |
Number of trees in a radius of 4 m | n | −1 | July | 1 | |
Sum of variables | 93 |