[Soil microelements under different vegetation restoration patterns in yellow soil slope region of mid-subtropics]

With the Nüerzhai watershed in Wuling Mountain as a case, this paper studied the contents and availabilities of soil microelements and their relationships with soil organic matter and pH value in yellow soil slope region of mid-subtropics under seven typical vegetation restoration patterns, i. e., Pinus massoniana natural forest (I), Cunninghamia lanceolata plantation (II), Eucommia ulmoides plantation (III), Vernicia fordii plantation (IV), Machilus pingii secondary forest (V), Phyllostachys edulis - C. lanceolata mixed forest (VI), and wasteland-shrub community (VII). It was found that in 0-20 cm soil layer, the contents of B and Mn, Mo and Cu, Zn, and Fe reached the peaks under VII, IV, III and VI; while in 20-40 cm soil layer, III, IV, Vand VII had the highest contents of Cu, Zn, B, and Fe and Mn, Mo, respectively. In both two soil layers under VI, the contents of B, Mo, Cu and Mn were the lowest. Mn had the biggest single element available index, while Cu had the smallest one. The biggest and smallest total available index of soil microelements was 12.28 for VII and 2.95 for VI, respectively. There existed the regularities of Mn > Zn > Fe > Mo > B > Cu for single microelement available index and VII > V > III > IV > I > II > VI for comprehensive microelement available index under different vegetation patterns. A good linear relationship was observed between soil organic matter and B and Zn availabilities, and the relationship of soil organic matter with available Mn could be described by a quadratic equation. Soil pH was highly positively correlated with soil Cu and Zn contents, correlated with soil Mo and Mn contents, slightly correlated with soil B content, and slightly negatively correlated with soil Fe content.