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Table 1 Soil available carbon, nitrogen, and phosphorus, soil cations, as well as fine root biomass under different treatments

From: Different responses of soil respiration and its components to nitrogen and phosphorus addition in a subtropical secondary forest

 

Year

CK

N

P

NP

Available C&N&P

 DOC (mg·kg− 1)

2014

299.2 ± 8.3 a

281.6 ± 6.1 a

310.4 ± 19.1 a

314.1 ± 28.3 a

2015

294.8 ± 2.8 b

288.9 ± 5.5 b

316.0 ± 3.1 a

324.3 ± 5.3 a

 MBC (mg·kg− 1)

2014

571.7 ± 3.8 a

557.1 ± 3.5a

589.3 ± 2.9 a

588.2 ± 19.6 a

2015

563.4 ± 15 ab

545 ± 10.3 b

593.2 ± 4.8 a

587.0 ± 1.7 a

 NH4+ (mg·kg− 1)

2014

8.1 ± 0.2 b

10.9 ± 0.6 a

6.8 ± 0.1 b

7.4 ± 0.5 b

2015

7.7 ± 0.1 a

8.7 ± 0.6 a

6.7 ± 0.1 b

8.1 ± 0.03 a

 NO3− (mg·kg− 1)

2014

38.4 ± 0.9 b

42.4 ± 1.1 a

35.0 ± 0.3 c

37.1 ± 0.9 bc

2015

40.6 ± 0.1 b

48.1 ± 2.3 a

36.9 ± 0.3 b

41.6 ± 0.7 b

 AP (mg·kg− 1)

2014

27.5 ± 8.4 b

24.8 ± 4.3 b

149.3 ± 11.9 a

150.6 ± 21.4 a

2015

29.3 ± 3.6 b

22.3 ± 4.1 b

139.4 ± 12.8 a

131.9 ± 9.8 a

Soil cations

 Soil pH

2014

4.7 ± 0.04 a

4.5 ± 0.07 a

4.6 ± 0.03 a

4.5 ± 0.1 a

2015

4.6 ± 0.08 a

4.2 ± 0.04 b

4.4 ± 0.1 b

4.3 ± 0.01 b

 Al3+ (mmol·kg− 1)

2014

38.0 ± 1.0 c

50.2 ± 1.0 a

42.4 ± 0.8 b

44.8 ± 0.9 b

2015

38.4 ± 3.2 c

60.4 ± 0.4 a

48.7 ± 0.8 b

61.0 ± 1.4 a

 Ca2+ (mmol·kg− 1)

2014

33.6 ± 3.1 a

25.1 ± 1.8 b

28.8 ± 0.3 ab

25.0 ± 0.7 b

2015

30.3 ± 2.9 a

20.1 ± 0.5 c

26.0 ± 0.2 ab

22.6 ± 0.5 bc

 Mg2+ (mmol·kg− 1)

2014

4.7 ± 0.4 a

4.3 ± 0.2 a

4.2 ± 0.4 a

4.2 ± 0.1 a

2015

4.2 ± 1.0 a

3.5 ± 0.6 a

3.7 ± 0.1 a

3.3 ± 0.1 a

 Na2+ (mmol·kg− 1)

2014

1.5 ± 0.2 a

1.4 ± 0.04 a

1.3 ± 0.3 a

1.3 ± 0.2 a

2015

1.2 ± 0.2 a

1.3 ± 0.4 a

1.2 ± 0.1 a

1.2 ± 0.1 a

Plant

 Fine root biomass (g·m− 2)

2014

172.2 ± 1.3 a

147.4 ± 4.0 c

161.9 ± 0.7 b

152.2 ± 1.5 c

2015

178.9 ± 1.9 a

142.6 ± 1.7 d

159.7 ± 1.4 b

148.6 ± 1.2 c

  1. Notes: Values are means with SE. The different lowercase letters in the same row indicate significant differences among the four treatments at P < 0.05 level. CK, control; N, nitrogen addition; P, phosphorus addition; NP, nitrogen and phosphorus addition