Photovoltaic deployment on closed landfills: microclimate regulation, vegetation response, and implications for cover...

Closed landfills are increasingly being considered as potential sites for photovoltaic (PV) development; however, the impacts of PV infrastructure on landfill cover integrity and ecological restoration remain insufficiently understood. This study presents a one-year field investigation conducted at a landfill with integrated PV arrays. Continuous monitoring of soil temperature and moisture, coupled with seasonal vegetation surveys, was employed to evaluate microclimatic changes and the associated ecological responses induced by PV arrays. The results showed that PV arrays caused a significant cooling effect on shallow soils, with seasonal mean temperatures up to 2.3 °C lower than those in non-PV area. Soil moisture exhibited pronounced spatial heterogeneity beneath the panels. At 10  cm depth, the mean annual soil moisture in the front, middle, and back sections beneath the panels was 0.55, 1.23, and 1.04 times that of the non-PV area, respectively, revealing a distinct moisture deficit in the front section. Ecologically, during the main growing season (April to September), plant height beneath the PV panels was 27-58 % lower than that in the control area. Notably, species richness and community heterogeneity increased significantly beneath the panels, with a shift toward shallow-rooted, shade-tolerant species. These ecological changes may support landfill-cover management by promoting lower-growing, shallow-rooted vegetation, but localized drying beneath the panels requires long-term attention. This study provides new insights into the influence of PV infrastructure on landfill covers and offers practical recommendations for the sustainable reuse of closed landfill sites.