Responses of Soil Arthropod Communities to Varying Shading Levels in Agriphotovoltaic Systems

AgriPhotovoltaic (APV) systems integrate solar energy production with agriculture and offer a potential solution to land-use conflicts between food and energy demands. While their effects on crop yield and environmental parameters are increasingly documented, impacts on soil biodiversity-particularly soil arthropods-remain poorly understood. Soil arthropods are key drivers of ecosystem functioning and are highly sensitive to microclimatic and edaphic changes. This study was conducted in a dual-axis APV system in northern Italy and compared two shading configurations: standard (13% shading) and expanded panels (41%). Treatments included wheat and tomato grown under each shading regime, crops under full sun, and an unshaded grass-covered control. Wheat was assessed under all treatments, whereas tomato was evaluated under standard panels and full sun only. Soil samples were collected across crop development stages and analyzed for pH, organic matter (soil organic matter [SOM]), CO₂ emissions, and arthropod communities. Biological quality (QBS-ar), CO₂ emissions, and arthropod diversity were driven more by crop type and season than by shading. Control plots consistently supported higher QBS-ar and Collembola diversity. Panel effects were context-dependent: Expanded panels increased soil moisture and modified pH in wheat, while standard panels mitigated early-season stress by maintaining higher soil temperature and SOM. In tomato, shading effects were limited, although increased soil moisture under panels during late growth favored moisture-sensitive taxa such as Collembola. These findings indicate that elevated APV systems modulate soil conditions without disrupting core soil biodiversity patterns, while highlighting the role of semi-natural grasslands as biodiversity reservoirs within APV landscapes.