Distribution of organic carbon fractions in soil aggregates in Chinese fir plantations with different stand ages

Ecological Processes

Table 3 Effects of aggregate sizes (> 2 mm, 2–1, 1–0.25, and < 0.25 mm) and stand ages (0, 9, 17, and 26 years old) on the soil organic carbon concentration in a chronosequence of Chinese fir plantations

Stand age (years)	Soil organic carbon concentration (g·kg⁻¹)				Effects
	> 2 mm	2–1 mm	1–0.25 mm	< 0.25 mm	Aggregate size (A), df = 3		Stand age (S), df = 3		A × S, d.f.df = 9
	> 2 mm	2–1 mm	1–0.25 mm	< 0.25 mm	F	P	F	P	F	P
0	6.80 ± 0.70 b	8.84 ± 0.45 c	10.58 ± 0.72 c	13.50 ± 0.89 c	78.217	< 0.0001	192.986	< 0.0001	6.450	< 0.0001
9	8.29 ± 0.60 b	15.86 ± 1.41 b	18.39 ± 0.77 b	22.30 ± 1.01 b
17	16.13 ± 1.12 a	23.21 ± 1.62 a	27.85 ± 1.46 a	31.30 ± 1.34 a
26	8.82 ± 0.95 b	10.84 ± 0.67 c	12.12 ± 1.12 c	12.83 ± 0.30 c
Mean	10.01 ± 1.15 B	14.69 ± 1.72 AB	17.23 ± 2.10 A	20.16 ± 2.38 A

Data represent the average of 3 replicates ± standard errors. Different lowercase letters indicate significant differences among the different stand ages. Different capital letters indicate significant differences among the different aggregate sizes