Effects of solar panels and management on soil mesofauna, respiration and plant traits in solar parks of two southern French regions

Solar parks require large areas to produce sufficient electricity, affecting plants and soil through changes in microclimatic conditions, in particular light reduction. Solar parks need to be managed by grazing or mowing to avoid overgrowth of solar panels. Both microclimate changes and management may affect pant communities, soil fauna and biological activity, and thus potentially change local ecosystem functioning. This study analysed plant functional traits (morphology, chlorophyll), soil physicochemical characteristics (nutrients, density, moisture, temperature), mesofauna communities (mites and springtails), and soil respiration by comparing three treatments (under solar panels, between panel rows and in continuously unshaded areas (outside) within twenty solar parks located in two southern French regions of different climate. We found that soil respiration and mesofauna abundance were 62 % and 38 % lower, respectively, under panels compared to areas outside solar panels. The community-weighted mean of chlorophyll content, lateral spread, leaf length, leaf height, and specific leaf area increased significantly under the panels with differences depending on management and region. With differences depending on management and region panel effects on soil respiration were independent of management and region in our path analysis, soil mesofauna abundance was particularly reduced under panels of mown solar parks. It is crucial to understand how solar park management interacts with the effects of solar panels on plant and soil biodiversity in order to develop strategies that reduce ecological impact while maintaining ecosystem functions. • Solar panels negatively affected soil physico-chemical and biological parameters and the vegetation. • Solar panels affected the soil trophic network through soil and vegetation. • Solar panel effects on the soil trophic network depended on management. • Appropriate management may mitigate negative panel effects, in particular on plant functional traits.