Vegetation Restoration Increases Soil Carbon Storage in Land Disturbed by a Photovoltaic Power Station in Semi-Arid Regions of Northern China

Abstract

The photovoltaic industry is developing rapidly because of its renewable energy and other advantages. However, the installation of this infrastructure may affect soil, vegetation, and carbon dynamics, making it is necessary to carry out vegetation restoration work at a plant’s location in the later stages of its construction. For this reason, three types of artificial vegetation were selected (Pinus sylvestris var. mongolica, Astragalus membra-naceus var. mongholicus and Medicago sativa) as research objects in an ecological photovoltaic power plant in Northern China, to study the changes in soil organic carbon storage (SOCS), carbon:nitrogen ratios (C:N) and C:phosphorus ratios (C:P) at different soil depths and for different vegetation types. Natural vegetation plots undisturbed by the construction of the power plant were used as a control. Seven years after revegetation, we found that the storage and content of soil organic carbon in all three artificial vegetation plots were notably lower compared to the control. Nevertheless, the soil’s organic carbon content for Medicago sativa plots increased was significantly higher by 1.2 g·kg−1 compared to Pinus sylvestris var. mongolica and A. membranaceus var. mongholicus plots, while organic carbon storage increased significantly by 3.55 t·ha and 7.15 t·ha. SOCS, C:N, and C:P concentrations in the 0–20 cm soil layer exhibited a significantly higher value in comparison to those of the 20–40 cm soil layer. As the soil depth increased, all the concentrations declined gradually. Vegetation type and soil depth, as well as their interaction, had a significant impact on soil carbon storage, C:N, and C:P. The study area was restricted by the availability of P. In general, vegetation restoration is a beneficial ecological practice for soil restoration at photovoltaic power stations. It is believed that planting alfalfa can accelerate the improvement of soil carbon with an extension of vegetation recovery time. In order to restore the balance of nutrients for plants, it is necessary to avoid human interference at the later stage, and to supplement phosphorus as soon as possible to minimize phosphorus limitation at the later stage of vegetation growth, which is of great importance to increasing the likelihood of success in reclaiming disturbed land.