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Table 2 The δ15N values (‰) and N concentration (%) of trees and soils as affected by N addition, precipitation reduction and their combination (mean ± S.E)

From: Variations in the natural 13C and 15N abundance of plants and soils under long-term N addition and precipitation reduction: interpretation of C and N dynamics

   Control N addition Precipitation reduction Combined effects
15N (‰) Foliage −0.98 ± 0.03 − 0.43 ± 0.05 − 0.80 ± 0.01 0.73 ± 0.03
Litterfall −1.82 ± 0.07 −0.56 ± 0.02 −1.45 ± 0.04 − 0.10 ± 0.02
Fine roots (< 2 mm) − 0.46 ± 0.04 − 1.43 ± 0.04 − 0.32 ± 0.10 0.09 ± 0.05
Coarse roots (> 2 mm) − 0.76 ± 0.03 −1.72 ± 0.02 −1.09 ± 0.10 − 0.19 ± 0.09
Soil layer (0–10 cm) − 0.11 ± 0.02 1.79 ± 0.13 0.86 ± 0.01 1.23 ± 0.20
Soil layer (10–20 cm) 3.37 ± 0.10 2.32 ± 0.16 3.35 ± 0.11 3.62 ± 0.22
Soil layer (20–30 cm) 6.64 ± 0.09 6.14 ± 0.40 6.44 ± 0.11 6.46 ± 0.08
N (%) Foliage 2.55 ± 0.01 2.45 ± 0.07 2.32 ± 0.02 2.35 ± 0.07
Litterfall 1.11 ± 0.01 1.38 ± 0.03 1.01 ± 0.04 1.06 ± 0.02
Fine roots (< 2 mm) 1.50 ± 0.01 1.35 ± 0.00 1.47 ± 0.01 1.46 ± 0.07
Coarse roots (> 2 mm) 0.77 ± 0.00 0.61 ± 0.03 0.85 ± 0.08 0.79 ± 0.06
Soil layer (0–10 cm) 1.71 ± 0.06 1.37 ± 0.01 1.71 ± 0.08 1.71 ± 0.02
Soil layer (10–20 cm) 1.03 ± 0.07 1.19 ± 0.02 1.01 ± 0.05 1.18 ± 0.10
Soil layer (20–30 cm) 0.18 ± 0.01 0.16 ± 0.01 0.29 ± 0.01 0.25 ± 0.08