Abstract: Aims Grassland ecosystems store large amounts of organic carbon. In recent years, the construction of large-scale photovoltaic (PV) power plants in grassland distribution areas has dramatically altered the microclimate, vegetation and soil characteristics of the parks, thereby affecting the ecosystem carbon cycle. However, there is a lack of systematic research on the effects of PV development on vegetation and soil storage. Methods In order to investigate its impact on the carbon stock of desertified grassland ecosystems, this study adopts the method of substituting space for time to analyze the changing rules of the aboveground biomass carbon density of vegetation, total soil carbon, organic carbon, inorganic carbon and readily oxidizable organic carbon stock and other indexes in the Tala Beach Photovoltaic Power Station in Republican County with different years of construction. Important findings The results showed that: (1) the average storage of total soil carbon in the study area under the PV panels, between the panels, and outside the station were 118.83 t·hm-2, 119.08 t·hm-2, and 108.15 t·hm-2, respectively; the organic carbon was 61.97 t·hm-2, 61.29 t·hm-2, and 58.14 t·hm-2, respectively; the readily oxidizable organic carbon was 23.95 t·hm-2, 25.21 t·hm-2, 19.18 t·hm-2; and the biomass carbon density on the plant floor was 47.58 g·m-2, 43.69 g·m-2, 26.03 g-m-2g·m-2, respectively; in addition to the organic carbon and oxidizable organic carbon storage under the boards, the under- and inter-boards were significantly larger than those outside the station. (2) The aboveground biomass carbon density of the vegetation increased at a rate of 6.91 ·m-2·a-1 and 10.01 ·m-2·a-1 in the sub-slab and inter-slab, respectively, with the increase in the number of years of construction of the power station. There was a significant positive correlation between soil organic carbon and easily oxidized organic carbon stocks and the number of years of PV construction. (3) Above-ground biomass carbon density of vegetation was mainly affected by PV construction and vegetation cover, and easily oxidized organic carbon stock was also most affected by PV. In conclusion, although the effects of PV construction on soil organic carbon and total carbon were not statistically significant in the short term, it significantly increased the aboveground biomass carbon density and oxidizable organic carbon stock of vegetation. In the future, with the extension of PV construction years, the soil in the region will continue to function as a carbon sink. Therefore, large-scale photovoltaic development has a positive effect on enhancing the carbon sequestration capacity of alpine desertified grassland in China and realizing the goal of carbon neutrality.

Key words: Photovoltaic ecological effects, Soil carbon sequestration, Desertified grasslands, Grassland carbon stocks, Carbon sinks