Table 1 Effects of N addition levels and methods on NH₄⁺-N concentrations in soil planted with four tree species during the experimental period

AM

Jun. 2012

8.0 ± 1.2ab

9.9 ± 1.8a

5.6 ± 1.3bc

4.9 ± 0.3c

4.4 ± 0.6c

4.1 ± 1.0c

Dec. 2012

11.4 ± 0.8a

6.9 ± 0.8bc

5.7 ± 1.0bc

8.0 ± 0.3b

4.6 ± 0.9 cd

4.3 ± 1.3d

Apr. 2013

25.6 ± 3.6a

14.8 ± 2.9bc

12.5 ± 1.0c

22.8 ± 4.3ab

14.6 ± 1.6c

14.0 ± 3.1c

Jul. 2013

25.6 ± 4.4a

7.3 ± 0.5b

6.4 ± 1.2b

19.6 ± 4.7a

10.2 ± 1.5b

5.0 ± 0.1b

Nov. 2013

37.9 ± 0.8a

23.0 ± 0.7bc

16.9 ± 4.0 cd

25.8 ± 6.1b

10.6 ± 1.0d

10.8 ± 2.0d

OP

Jun. 2012

4.3 ± 0.5

5.8 ± 2.2

6.4 ± 0.4

5.2 ± 0.3

5.3 ± 0.5

4.1 ± 0.6

Dec. 2012

9.2 ± 2.4a

5.8 ± 0.4bc

7.3 ± 1.9ab

8.5 ± 1.6a

3.6 ± 0.7bc

3.2 ± 0.8c

Apr. 2013

26.1 ± 3.7

17.5 ± 2.2

15.2 ± 1.3

27.1 ± 8.0

17.0 ± 3.5

18.3 ± 4.4

Jul. 2013

19.7 ± 3.5a

8.7 ± 3.3ab

6.4 ± 1.9b

17.1 ± 7.4ab

10.9 ± 1.9ab

7.7 ± 3.9b

Nov. 2013

26.9 ± 2.9a

19.6 ± 1.5a

9.9 ± 1.3bc

18.4 ± 6.0ab

10.3 ± 2.9bc

8.4 ± 1.6c

SS

Jun. 2012

7.1 ± 0.5a

4.7 ± 1.4b

4.6 ± 0.8b

5.4 ± 1.0ab

5.3 ± 0.8ab

4.6 ± 0.3b

Dec. 2012

10.0 ± 2.4a

4.2 ± 1.5b

4.0 ± 0.5b

6.3 ± 0.7ab

3.7 ± 0.6b

4.8 ± 1.3b

Apr. 2013

30.1 ± 0.4a

16.4 ± 1.9 cd

9.5 ± 1.4d

26.7 ± 2.2ab

19.6 ± 2.5bc

17.9 ± 4.9c

Jul. 2013

21.4 ± 1.8ab

6.2 ± 1.7c

4.0 ± 0.8c

26.1 ± 8.7a

12.0 ± 5.7bc

9.4 ± 1.7bc

Nov. 2013

30.1 ± 2.2a

16.0 ± 1.3bc

11.5 ± 1.4c

22.4 ± 4.3ab

13.6 ± 1.9bc

9.4 ± 1.5c

PM

Jun. 2012

6.4 ± 0.6

5.5 ± 0.9

4.7 ± 0.3

6.8 ± 0.4

6.8 ± 0.5

5.7 ± 1.6

Dec. 2012

8.4 ± 3.6ab

4.1 ± 1.1b

4.0 ± 0.1b

11.9 ± 3.4a

5.2 ± 0.6b

5.4 ± 1.2b

Apr. 2013

19.5 ± 6.7ab

15.3 ± 0.1b

19.5 ± 3.8ab

32.2 ± 1.8a

18.7 ± 4.3b

13.4 ± 4.0b

Jul. 2013

27.3 ± 2.7a

14.2 ± 5.0b

7.1 ± 0.5b

25.9 ± 1.5a

6.9 ± 2.2b

5.7 ± 2.7b

Nov. 2013

32.5 ± 4.9a

12.1 ± 1.8bc

7.9 ± 1.5c

28.4 ± 8.9a

20.7 ± 2.0ab

10.7 ± 1.9bc