Integrating native grassland restoration into solar energy development: Microclimatic effects of solar panels on plant diversity and seeded native grass establishment in the Canadian Aspen Parkland

The rapid expansion of solar energy infrastructure raises concerns about its ecological compatibility with native grassland restoration in northern ecosystems. This study examined how solar panels induced microclimatic variation affected vegetation productivity, diversity, and establishment of seven species of seeded native grass two years after seeding on formerly abandoned cropland in the Canadian Aspen Parkland. Vegetation and microclimate were monitored along twelve 6-m transects established in dry and wet sites caused by water pooling. Each transect spanned three microsites defined by distance from the solar panel supporting poles: shaded under-panel, partial-light at the edge of the solar panel, and sunny between adjacent rows of solar panels. Soil temperature, moisture, and light intensity were measured biweekly during the 2024 growing season, and vegetation biomass, diversity, cover, and composition were quantified at peak biomass in July. Solar panels created strong microclimatic gradients: light intensity was 11.6× higher, soil temperature 3.2 °C warmer, and soil moisture 12% lower in sunny microsites compared to those under the solar panel. Additionally, wet sites had 68% greater total biomass and 95% greater grass biomass than dry sites. Vegetation diversity more than doubled in sunny microsites. Seeded native grass and noxious weed cover were higher in sunny microsites, while introduced perennial grasses ( Bromus inermis , Poa pratensis ) persisted across all microsites. Seeded species responses varied: Festuca hallii and Nassella viridula established best under shaded conditions, whereas Hesperostipa comata , Pascopyrum smithii , and Koeleria macrantha performed best in sunny microsites. Microclimatic heterogeneity generated by solar infrastructure structured fine-scale vegetation patterns. Incorporating both drought- and shade-tolerant native grasses into seed mixes may improve restoration outcomes in solar developments across northern grasslands.