Effects of simulated acid rain on soil respiration and its component in a mixed coniferous-broadleaved forest of the three gorges reservoir area in Southwest China

Forest Ecosystems

Table 3 Variation in soil organic C, total N, C:N ratio, hydrolysable N, available P, and total P. Data are the mean ± standard error

Treatment	Soil organic C (mg∙g⁻¹)	Total N (mg∙g⁻¹)	C:N ratio	Hydrolysable N (mg∙g⁻¹)	Available P (mg∙kg⁻¹)	Total P (mg∙g⁻¹)
UTCK	18.17 ± 3.19a	1.46 ± 0.24a	12.41 ± 0.32a	0.21 ± 0.01a	1.62 ± 0.77a	0.41 ± 0.03a
UT4.0	21.91 ± 1.77b	1.54 ± 0.16a	14.23 ± 0.24b	0.18 ± 0.02b	1.5 ± 0.54a	0.22 ± 0.04b
UT3.25	25.99 ± 3.61c	1.65 ± 0.22a	15.77 ± 0.49c	0.15 ± 0.02c	1.34 ± 0.59a	0.23 ± 0.02b
UT2.5	25.61 ± 3.04d	1.64 ± 0.18a	17.81 ± 0.45d	0.15 ± 0.01c	1.41 ± 0.80a	0.36 ± 0.03c
TCK	19.76 ± 2.18a	1.49 ± 0.17a	13.26 ± 0.47a	0.22 ± 0.01a	1.66 ± 0.71a	0.39 ± 0.03a
T4.0	20.84 ± 2.58a	1.59 ± 0.21a	13.11 ± 0.28a	0.24 ± 0.01a	1.83 ± 0.70a	0.21 ± 0.02b
T3.25	29.11 ± 1.53b	1.59 ± 0.07a	18.33 ± 0.36b	0.14 ± 0.01b	1.59 ± 0.84a	0.20 ± 0.04b
T2.5	29.12 ± 3.04b	1.50 ± 0.15a	19.44 ± 0.44b	0.19 ± 0.02c	2.02 ± 0.51a	0.34 ± 0.04c

Values followed by different letters are significantly different between treatments (P < 0.05). UTCK, UT4.0, UT3.25, and UT2.5 indicate control, pH 4.0, pH 3.25, and pH 2.5 simulated acid rain in the untrenched plots, respectively; TCK, T4.0, T3.25, and T2.5 indicate the control, pH 4.0, pH 3.25, and pH 2.5 simulated acid rain in the trenched plots, respectively