Constraints on Soil Arthropod Recovery in a Ground-Mounted Photovoltaic Park

Abstract

Solar energy is considered one of the important tools for mitigating global warming, however, the installation of photovoltaic parks has also raised concerns about potential soil degradation. This study investigates how soil arthropod communities and soil organic carbon respond during the early stage of vegetation reestablishment following the conversion of a lowland forest plantation into a ground-mounted photovoltaic (GMPV) park Beneath 12 spatially discrete solar panels, vegetation cover was monitored monthly, and soil arthropods were sampled using pitfall traps for one year. Four additional pitfalls were installed in a nearby forest plantation as reference. Soil samples were collected in 2022 (during construction), and again in 2024 and 2025 (1 and 2 years post-operation), to assess changes in soil organic carbon (SOC) and total nitrogen concentrations. As vegetation cover steadily increased beneath the PV panels, the abundance of soil arthropods surpassed that observed in the adjacent forest plantation, with taxon richness reaching a comparable level although community composition remained significantly different from that of the forest. While increased vegetation cover facilitated the re-establishment of soil arthropods under the solar panels, it did not promote nutrient recovery, as the fern-dominated vegetation provided limited organic input to the soil. Future management of vegetation and maintenance of soil quality will be important for reconciling renewable energy development with the conservation of soil biodiversity.

Keywords: land-use change, renewable energy, vegetation cover, soil arthropods, soil organic carbon, soil quality

Methodology and Implementation Steps

This study was conducted at a ground-mounted photovoltaic park in Fenglin Township, Hualien County, Taiwan, with a nearby plantation used as a control group. Soil samples were collected at depths of 0–5, 5–15, and 15–30 cm during the construction phase (2022) and the operational phase (2024–2025). A total of 16 plots (12 in the photovoltaic park and 4 in the plantation) were established and monitored monthly from November 2023 to October 2024. In the photovoltaic park, grass was not mowed except when it touched the panels, in which case it was cut to a height of approximately one meter. Vegetation cover was recorded monthly using vertical photographs, and plants were identified to the species level based on photos and specimens. Soil arthropods were collected using pitfall traps deployed for 48 hours each time. Soil samples were dried at 40°C and sieved, with approximately 10 g dried at 105°C to determine bulk density, and another 2 g ground to less than 0.1 mm to analyze total organic carbon and total nitrogen using a TOC analyzer. Arthropods were classified into suborders for Collembola and Acariformes, orders for Insecta, Araneae, and Pseudoscorpiones, and classes for Chilopoda, Diplopoda, and Isopoda. Statistical analyses included Kruskal-Wallis tests to compare differences across years, land-use types, and sampling months (with Dunn's test for post-hoc comparisons), and Wilcoxon rank-sum tests for comparisons between land-use types at specific soil depths. Additionally, general linear regression was used to evaluate the relationship between vegetation cover and arthropod abundance and richness, while non-metric multidimensional scaling (NMDS) and permutational multivariate analysis of variance (PERMANOVA) were used to evaluate significant differences in community composition. All statistical analyses were performed using R software (version 4.2.3).

Innovation and Cross-Disciplinary Collaboration

Ground-mounted photovoltaic systems are rapidly expanding worldwide under the goal of 2050 net-zero emissions. However, their construction and operation may alter the original vegetation and soil ecosystems, thereby impacting soil biodiversity. While some studies have begun to focus on the ecological impacts of ground-mounted photovoltaic parks, relevant research in subtropical regions remains relatively insufficient. Through field work and monitoring, this study analyzes the relationship between vegetation recovery beneath solar panels and soil ecosystems, aiming to fill the current knowledge gap in subtropical regions.

Expected Results and Contributions

This study suggests that in the future planning and management of ground-mounted solar park, if maintaining soil quality is considered, construction-induced soil compaction can be reduced, or management measures during the operation and maintenance phase can be adjusted. Such as lowering mowing frequency and retaining surface litter, to increase organic matter accumulation and improve the soil environment. This also promotes the recovery of soil arthropod communities and soil ecosystem functions. While current global research is mostly concentrated in temperate or arid regions, this study provides experience from high-temperature and humid subtropical regions, offering reference data for understanding how ground-mounted photovoltaic park affects soil ecosystems under climatic conditions like Taiwan's, and providing a scientific basis for the ecological planning and sustainable management of future photovoltaic facilities.