Light heterogeneity shapes contrasting ecological responses to photovoltaic arrays in Tibetan alpine grasslands.

Alpine grassland ecosystems are highly sensitive to climatic fluctuations and anthropogenic disturbances. The construction and operation of photovoltaic (PV) power stations may alter environmental conditions, yet the relationships among PV-induced microenvironmental changes, vegetation responses, and soil processes remain poorly understood. In this study, we investigated two PV power stations located in alpine meadow and alpine steppe settings, integrating microenvironmental monitoring, vegetation surveys, soil measurements, correlation analyses, and partial least squares path modeling to characterize the relationships among environmental factors, vegetation characteristics, and soil properties under PV arrays. The results showed that PV arrays reduced total solar radiation, photosynthetically active radiation, and soil temperature at both power stations, whereas volumetric water content exhibited site-specific responses. At the alpine meadow station, PV arrays decreased belowground biomass and were associated with higher soil carbon, nitrogen, and phosphorus contents, but aboveground vegetation remained unchanged. At the alpine steppe station, PV arrays decreased both aboveground and belowground biomass while increasing community height and plant diversity, accompanied by shifts in dominant species composition, but most soil nutrients showed limited responses. Integrated analyses showed that PV-induced radiation reductions linked microenvironmental changes to vegetation productivity responses across both sites. However, changes in soil moisture and nutrient availability were not consistently translated into improved vegetation performance. Overall, ecological responses under PV arrays were jointly driven by changes in radiation, thermal conditions, moisture availability, and belowground processes, but the observed response patterns contrasted between the two study sites. These findings provide scientific support for ecological assessment and management of PV development in alpine regions.