The effects of photovoltaic panels coverage area on artificial grassland restoration in alpine region

Background In alpine regions, large-scale photovoltaic(PV) panels construction has exacerbated the contradiction between ecological vulnerability and energy development while promoting clean energy development. The region's climate is cold and ecologically sensitive, and the laying of PV panels may change the local microenvironment. The effectiveness of vegetation restoration under PV panels is the key to balancing ecological protection and energy development, which directly affects the carbon sequestration capacity of the land, the maintenance of biodiversity and the sustainable development of the region. Currently, the impact mechanism of different PV coverage area on artificial grasses is not clear, including how changes in light, water, temperature and other environmental factors affect the growth of grasses, and systematic research is urgently needed to solve the developmental dilemma. Methods This study focuses on the effects of PV panels mulching on vegetation restoration in alpine regions, and build a long-term monitoring system by setting up graded PV panels mulching treatments of single, double and triple panels. The research team systematically collected soil temperature and humidity data from different treatment areas, and measured the above-ground/underground biomass of artificially planted grasses, plant nitrogen, phosphorus and potassium nutrient contents, analyzed the basic nutrient indexes such as total soil nitrogen, phosphorus and potassium, as well as the parameters of soil microbial biomass of carbon, nitrogen and phosphorus, and revealed the relationship between the indexes through Pearson correlation analysis. Results The results showed that. 1) PV panels have significant seasonal regulation of soil temperature and moisture, and triple PV panels provided the best insulation and moisture retention, as well as the most stable soil temperature and moisture. 2) Total plant biomass increased significantly with the increase in area covered by PV panels, and the total biomass of the double and triple PV panels increased by 48.21% and 45.53%, respectively, compared to single PV panels treatment. 3) Compared with single PV panels treatment, double and triple PV panels significantly increased soil total carbon, total nitrogen, and total phosphorus content, while there was no significant difference in the carbon, nitrogen, and phosphorus content of soil microbial biomass between treatments. Both below-ground biomass and total biomass were significantly positively correlated with soil total carbon, total nitrogen and total phosphorus contents. Conclusions PV panels mulching can reshape the material cycle and energy flow pattern of soil-plant system by regulating microenvironmental factors such as soil temperature and humidity, light intensity and so on. In this study, the response mechanisms of vegetation growth and soil ecology were revealed based on experiments of PV panels treatments with different shading areas. The results of this study provide a quantitative basis for optimizing the layout of PV facilities and determining reasonable shading thresholds, laying a theoretical foundation for the construction of a “photovoltaic + ecological” synergistic development model in alpine regions, and promoting the realization of a dynamic balance between clean energy development and ecological protection.