TABLE 1.

DNA yields and copy numbers of the 16S rRNA and the narG, nirK, nirS, and nosZ genes from soils of different successional ages^a

Sampling mo	Successional age (yr)	DNA yield (μg g−1 of soil)	No. of gene copies (ng−1 of DNA)
			16S rRNA	narG	nirK	nirS	nosZ
August	25	7.92 A	5.1 × 105 A	2.3 × 104 A	1.1 × 103 A	2.9 × 103 A	1.8 × 103 A
	40	8.04 A	8.9 × 105 A	2.1 × 104 A	1.4 × 103 A	2.9 × 103 A	4.7 × 103 A
	44	22.41 A	7.5 × 105 A	6.4 × 103 B	9.1 × 102 A	4.1 × 103 A	2.0 × 103 A
	72	24.89 A	6.6 × 105 A	3.3 × 103 B	1.3 × 103 A	2.5 × 102 A	4.8 × 103 A
	129	64.54 B	6.3 × 105 A	2.1 × 103 B	9.5 × 102 A	5.7 × 102 A	4.7 × 103 A
September	25	7.81 A	5.5 × 105 A	2.6 × 104 A	1.2 × 103 A	6.4 × 103 A	1.7 × 103 AB
	40	9.15 A	6.9 × 105 A	2.1 × 104 B	1.1 × 103 A	2.7 × 103 B	5.5 × 103 D
	44	18.15 A	5.4 × 105 A	7.3 × 103 C	7.4 × 102 B	2.4 × 103 B	1.2 × 103 A
	72	22.24 A	5.7 × 105 A	7.2 × 103 C	1.2 × 103 A	1.4 × 103 B	3.7 × 103 C
	129	45.27 B	4.9 × 105 A	2.9 × 103 C	7.6 × 102 B	1.8 × 103 B	3.2 × 103 BC

^aSuffix letters (A to D) indicate significant differences between successional stages.