Soil enzyme activities as potential indicators of soluble organic nitrogen pools in forest ecosystems of Northeast China

Table 3 The activities of soil enzymes per unit soil mass in adjacent natural secondary forest (SF) stands and larch plantation (LP) stands

Sampling time	Soil depth (cm)	Forest type	N-acetyl-β-glucosaminidase (μmol g⁻¹ soil h⁻¹)	Urease (μmol g⁻¹ soil h⁻¹)	l-asparaginase (μmol g⁻¹ soil h⁻¹)	Protease (μmol g⁻¹ soil h⁻¹)	N-acetyl-β-glucosaminidase (μmol g⁻¹ soil C h⁻¹)	Urease (μmol g⁻¹ soil C h⁻¹)	l-asparaginase (μmol g⁻¹ soil C h⁻¹)	Protease (μmol g⁻¹ soil C h⁻¹)
Jun 2010	0–5	SF	2.5 ± 0.1*	8.8 ± 2.2*	3.9 ± 0.4*	1.8 ± 0.2*	37.9 ± 2.1	133.2 ± 33.5	58.8 ± 5.2	27.6 ± 2.6*
	0–5	LP	1.9 ± 0.1	4.7 ± 0.6	2.5 ± 0.2	0.9 ± 0.2	44.5 ± 2.5*	107.7 ± 16.2	57.1 ± 2.2	21.4 ± 3.4
	5–15	SF	0.9 ± 0.1*	4.6 ± 1.9	2.0 ± 0.5*	0.9 ± 0.2*	25.9 ± 0.7	124.2 ± 44.3	54.8 ± 5.4	23.7 ± 4.3
	5–15	LP	0.8 ± 0.1	2.5 ± 1.0	1.2 ± 0.1	0.4 ± 0.1	39.0 ± 3.2*	123.4 ± 38.0	56.0 ± 4.6	22.1 ± 5.2
Oct 2010	0–5	SF	3.2 ± 0.3*	17.6 ± 3.5*	4.0 ± 0.5*	2.1 ± 0.2*	48.9 ± 3.9	269.3 ± 59.3*	60.7 ± 7.5	32.7 ± 4.8
	0–5	LP	2.5 ± 0.2	8.5 ± 1.3	2.4 ± 0.3	1.2 ± 0.2	55.6 ± 2.7*	194.7 ± 21.3	54.7 ± 3.9	27.4 ± 3.3
	5–15	SF	0.8 ± 0.1	6.1 ± 2.7	1.5 ± 0.5	0.6 ± 0.2	21.2 ± 1.4	160.5 ± 45.3	41.0 ± 10.1	16.9 ± 2.9
	5–15	LP	0.7 ± 0.1	3.8 ± 1.4	0.8 ± 0.2	0.4 ± 0.0	34.2 ± 2.7*	178.7 ± 45.0	37.3 ± 3.8	19.1 ± 3.5

Values shown in tables are means ± standard errors (n = 4)
*P < 0.05 levels, indicate significant differences between the secondary forest and larch plantation of the corresponding depth

ISSN: 1297-966X