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

Ecological Processes

Table 6 Effects of aggregate sizes (> 2, 2–1, 1–0.25, and < 0.25 mm) and stand ages (0, 9, 17, and 26 years old) on the soil microbial biomass carbon in a chronosequence of Chinese fir plantations

Stand age (years)	Soil microbial biomass carbon (mg 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, df = 9
	> 2 mm	2–1 mm	1–0.25 mm	< 0.25 mm	F	P	F	P	F	P
0	96.66 ± 5.49 b	126.48 ± 4.18 b	141.51 ± 3.25 b	160.22 ± 2.73 b	80.063	< 0.0001	92.674	< 0.0001	0.829	0.594
9	105.84 ± 4.06 b	125.61 ± 2.46 b	151.63 ± 5.57 b	162.73 ± 8.04 b
17	150.49 ± 5.95 a	181.46 ± 2.39 a	192.61 ± 7.16 a	202.76 ± 6.19 a
26	102.44 ± 8.07 b	116.28 ± 5.60 b	138.50 ± 4.03 b	147.24 ± 3.60 b
Mean	113.86 ± 7.32 C	137.46 ± 7.93 B	156.56 ± 6.87 AB	168.24 ± 6.70 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