Changes in soil C-N-P stoichiometry after 20 years of typical artificial vegetation restoration in semiarid continental climate zones

Vegetation restoration is one of the principal strategies for ecosystem recovery in degraded land of fragile regions, which is an important driving factor for soil fertility and elemental circulation. While the relationship between revegetation and soil C-N-P stoichiometry remains unclear. To evaluate the relationships between vegetation restoration and soil C-N-P stoichiometry, the distribution of soil C, N, and P within 0-30 cm soil depth under five typical artificial restored vegetation types on the Loess Plateau was analyzed and the influencing factors were evaluated. The results showed that soil C, N, and P contents were relatively lower at the study site than the mean values for topsoil in China. Compared with other vegetation types (Populus simonii Carr., Pinus tabuliformis Carr., and Caragana korshinskii Kom.), Medicago Sativa L. and Stipa bungeana Trin. helped improve soil fertility better; the soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents within the 0-30 cm soil layer respectively maximized under Stipa bungeana Trin. (3.30 g kg(-1)), Medicago Sativa L. (0.34 g kg(-1)), and Medicago Sativa L. (0.41 g kg(-1)). The values of soil C/N, C/P, and N/P for the five vegetation types were 9.50-11.85, 15.36-21.47, and 1.29-1.90, respectively. The contents of SOC and TN under the five vegetation types were significantly (P < 0.001) affected by soil depth and vegetation type (P < 0.001) and decreased with increasing soil depth. However, the TP content was significantly (P < 0.001) affected by vegetation type and not by soil depth. Considering the better adaptability of native species, native herb vegetation types should be considered first for ecological restoration in semiarid continental climate zones.