Effects of Single-Axis and Fixed-Tilt Photovoltaic Array Construction on the Soil Seed Bank Characteristics in Semi-Arid Grasslands

With the rapid global development of photovoltaic power generation, research on its impact on land and ecosystems has become increasingly significant. However, its impact on soil seed bank characteristics has yet to be better assessed. In this study, monitoring plots were established in a semi-arid grassland undergoing solar energy development. This setup allowed us, for the first time, to investigate how soil seed bank characteristics respond to the construction of two typical photovoltaic array systems: single-axis and fixed-tilt systems. This study demonstrated that in both single-axis and fixed-tilt systems, the establishment of photovoltaic arrays resulted in a significant increase in soil seed density, with seed counts rising by approximately 47.5% compared with control sites without arrays. The aggregation effect of soil seed density under the photovoltaic array primarily occurred in the 0-10 cm soil layer. The soil seed density under the single-axis arrays was higher than that under the fixed-tilt arrays. The construction of photovoltaic arrays resets local soil and directly changes the micro-environment-including reductions in solar radiation, decreases in average temperature by 0.1 degrees C, and wind speed decreases by 1.5 m/s-which negatively affected the richness and diversity of the soil seed bank, resulting in a 21.1% decrease in species richness and a 10.1% reduction in seed diversity. Furthermore, this study highlights that seed germination in semi-arid grasslands is under pressure due to environmental changes associated with photovoltaic construction areas. Specifically, soil moisture and organic matter were the key factors affecting the vegetation restoration potential of the entire construction area. We recommend selecting the single-axis system of photovoltaic components. This selection is crucial, which considers both energy production efficiency and supports the facilitation of future vegetation ecosystem succession. Altogether, this study provides information for future land-use planning in photovoltaic construction areas and sustainable development of photovoltaic power generation.