Spatial heterogeneity of soil pH and nutrients in Miyaluo Subalpine dark coniferous forest of western Sichuan, southwestern China

  Objective  The spatial heterogeneity of soil pH and nutrients in Miyaluo subalpine dark coniferous forest of western Sichuan, southwestern China was studied, and the study results can provide scientific basis for further understanding soil quality and regional ecological restoration in the subalpine forest of western Sichuan, southwestern China.

  Method  The experimental site was in 9.6 ha (400 m × 240 m) Miyaluo subalpine dark coniferous forest dynamic plot of western Sichuan. By combining field sampling, laboratory measurement, classical statistics and geostatistical analysis, we analyzed the spatial heterogeneity of 0−10 cm surface soil pH and nutrients, including soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), ammonium nitrogen (AN), nitrate nitrogen (NN) and available phosphorus (AP), in the subalpine dark coniferous forest.

  Result  (1) The mean pH of the soil was 4.85. The mean contents of SOC, TN, TP and TK were 50.05, 3.40, 0.53 and 24.97 g/kg, respectively and the mean contents of AN, NN and AP were 11.44, 2.24 and 8.12 mg/kg, respectively; (2) pH was lower in the western portion. SOC, TN, TP and AN were generally abundant in the eastern portion of the dynamic plot. TK was abundant in a north-south strip pattern, and the distribution pattern of AN and NN was patchy; (3) the coefficient of variation (CV) of all soil properties ranged from 11% to 86%, the CV of soil pH was 11%, and that of NN and AP both was 86%. The nugget-sill ratio of soil properties ranged from 0.11 to 0.50, and NN and AP showed a strong spatial autocorrelation, whereas other soil properties showed a moderate spatial autocorrelation; (4) except for pH and TN, pH and TK, SOC and AN, TN and AP, TP and TK, TP and NN, TP and AP, the partial correlation coefficient between the other 21 pairs of soil properties reached a significant level (P < 0.05) or extremely significant level (P < 0.01).

  Conclusion  The soil in Miyaluo subalpine dark coniferous forest of western Sichuan is acidic and the nutrient content in the soil is relatively high. The spatial distribution of soil properties shows obvious spatial autocorrelation. The soil properties are generally interrelated with each other. SOC is the most representative of the 8 comprehensive variations of soil properties studied in this paper.