Photovoltaic arrays repartition soil carbon pools and carbon-cycling functional potential across microhabitats in arid ecosystems

Context Large-scale photovoltaic (PV) development in arid and semi-arid regions provides clean energy, yet its effects on soil carbon (C) pools and C-cycling functional potential remain insufficiently resolved at within-array (microhabitat) scales. Aims To test whether PV-induced microhabitat heterogeneity restructures soil C pools and C-cycling functional potential, and to identify the key environmental factors underlying these patterns. Methods Soils (0–10 cm) were sampled from four PV microhabitats – front-of-panel (FP), under-panel (UP), rear-of-panel (RP), and inter-row (IP) – and adjacent controls (CK) across eight PV parks. Soil organic C (SOC), total organic C (TOC), and dissolved organic C (DOC) were measured, and C pool indices were calculated. The C-cycling functional potential was quantified using the Quantitative Microbial Element Cycling high-throughput quantitative PCR platform, with gene-marker abundance spanning C degradation, C fixation, and methane cycling. Pearson correlations and redundancy analysis were used to relate marker patterns to microclimate, soil physicochemical properties, and vegetation attributes. Key results The PV arrays generated pronounced microhabitat-scale divergence in soil C pools: SOC and TOC were higher in FP and RP than in CK, markedly lower in IP (P < 0.05), and not significantly different between UP and CK. The C pool management index showed the same spatial structure, while the C dissolved fraction (DOC:SOC) was highest in IP (P < 0.05). Gene-marker abundance was consistently structured by microhabitat, with generally higher abundance in FP and lower abundance in IP; RP and UP showed distinct marker profiles (P < 0.05). Across markers, higher abundance was associated with greater SOC/TOC and vegetation attributes, and with lower soil bulk density and pH (P < 0.05). Conclusions The PV installations repartition soil C pools and microbial functional potential into microhabitat-specific accumulation and depletion zones. Implications Microhabitat-targeted management – enhancing panel-edge plant-derived inputs, alleviating inter-row compaction, and addressing alkaline constraints – can improve soil C outcomes in arid PV landscapes.