One Year of Grassland Vegetation Dynamics in Two Sheep-Grazed Agrivoltaic Systems

In agrivoltaic systems with solar fixed panels, the provision of ecosystem services by agricultural productions could be compromised due to very large changes in plant microclimate. But we still do not know properly the changes in grasslands ecosystem services. On two sheep-grazed sites located in lowland (Braize, Br) and upland (Marmanhac, Ma) grasslands of central France, we studied for one year the direct effects of various shading conditions induced by solar fixed panels on abiotic variables (light, water and soil temperature) and on vegetation (daily growth height, forage quantity and quality, number of species). Under exclosure of grazing, three treatments per site were set up, control (without solar-panel influence), inter-rows (variable influence) and panel (full influence). The results showed that light was reduced by 93% on average over the year in the shade of the panels with a cooler soil temperature of 2.6°C on Ma and 3.4°C on Br compared to the control. However, the soil moisture response varied between sites, depending on the different seasonal rainfall events and on soil texture. This resulted in 2.6 (Ma) to 3.2 (Br) times faster daily height growth and better forage quality. However, annual biomass production and species number showed no difference between the control and the panel. Only the inter-row treatment, which receives variable shading conditions throughout the day and seasons, shows variable biomass responses across sites. Experimental work will continue for several years in order to parameterise models to simulate the ecosystem services of agrivoltaic parks over the long term.