Environmental Heterogeneity Imposed by Photovoltaic Array Alters Grassland Soil Microbial Communities

Abstract

The rapid expansion of photovoltaic (PV) energy production has generated concern over its potential ecosystem impacts. PV arrays induce unique microenvironmental conditions by altering resource availability and substantially impacting aboveground processes. However, the belowground consequences of PV development are understudied, limiting our understanding of overall ecosystem impacts. Here, we paired soil physiochemical, molecular, and functional analyses with aboveground measures to assess plant–soil–microbial responses to distinct microsites beneath a single-axis tracking PV system in a semi-arid C₃ grassland. We hypothesized that each PV microsite would harbor a unique suite of soil physiochemical properties and microbiomes. We found only subtle differences in soil organic matter and pH, corresponding with aboveground productivity patterns, but other physiochemical properties remained unchanged. However, soil microbial community structure and function differed markedly across PV microsites and from a reference grassland plot. Within the array, microbial decomposition rates were highest where plant productivity and organic matter were greatest, but surprisingly lowest where soil moisture remained elevated throughout the growing season. Overall, these findings suggest that PV arrays create disparate patterns of soil microbial community structure and function, which may feedback to influence overall ecosystem functionality. Coarse measures of soil physiochemical properties, such as total carbon, may overlook key impacts of PV development.