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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