A recently published study has shown how solar farms planted with native grasses and wildflowers have caused insect populations to flourish.
The research, conducted over a five-year period at two sites in southern Minnesota, USA, examined how vegetation established and how insect communities responded to the newly restored habitat.
Global insect biodiversity has been in decline due to habitat loss, pesticides and climate change. However, the restoration of insect habitat paired with smart land-use changes toward renewable energy developments could help reverse observed declines.
Monarch caterpillar on Common Milkweed leaf at a solar farm in Minnesota, US (Lee Walston / Argonne National Labratory).
Eco-friendly solar farms
Solar energy is widely regarded as one of the most effectives means of decarbonisation. In the US alone, approximately 400,000 ha of land will be needed for large-scale solar development by 2050 in order to meet climate-change goals. Disturbed or degraded land, such as that used for agriculture, is the most commonly sourced land for solar-farm installations.
Solar farms offer the opportunity for the land to be used for other means alongside the generation of energy. Agrivoltaics is the combination of solar-energy production with agricultural and vegetation-management practices. One type of agrivoltaics focuses on the establishment of habitat for insect pollinators and other wildlife that can provide important ecosystem services, such as pollination.
While pairing solar-energy facilities on previously disturbed lands with habitat enhancement sounds like a win-win strategy to address energy and biodiversity challenges, there had been very little field data available to document the feasibility and the ecological benefits of this novel land-use approach.
The two studied solar sites were planted with native grasses and flowering plants in early 2018. Between August 2018 through August 2022, the researchers conducted 358 observational surveys for flowering vegetation and insect communities. They evaluated changes in plant and insect abundance and diversity with each visit.
Monarch has declined significantly in North America (Alexander Viduetsky).
Increase in biodiversity
By the end of the field campaign, the team had observed increases for all habitat and biodiversity metrics. There was an increase in native plant species diversity and flower abundance. In addition, the team observed increases in the abundance and diversity of native insect pollinators and agriculturally beneficial insects, which included honeybees, native bees, wasps, hornets, hoverflies, other flies, moths, butterflies and beetles.
Flowers and flowering plant species increased as well. Total insect abundance tripled, while native bees showed a 20-fold increase in numbers. The most numerous insect groups observed were beetles, flies and moths.
In an added benefit, the researchers found that pollinators from the solar sites also visited soybean flowers in adjacent crop fields, providing additional pollination services.
"This research highlights the relatively rapid insect community responses to habitat restoration at solar energy sites," said Lee Walston, an Argonne landscape ecologist and environmental scientist who was lead author of the study. "It demonstrates, if properly sited, habitat-friendly solar energy can be a feasible way to safeguard insect populations and can improve the pollination services in adjacent agricultural fields."
The research findings suggest two important implications of habitat-friendly solar energy. One is that these sites can play an important role in conserving biodiversity. Large amounts of ground-mounted solar is expected to be developed in the future, but if properly sited, habitat-friendly solar can offset the losses of natural areas to provide biodiversity benefits.
Second, habitat-friendly solar sites can help mitigate land-use conflicts associated with the conversion of farmland for solar energy production. As approximately 80% of future ground-mounted solar development could occur on agricultural lands, the proper siting of habitat-friendly solar energy on marginal farmland can not only preserve prime farmland, but it could make prime farmland more productive through the pollination services provided by habitat-friendly solar energy.
Reference
Walston, L J, Hartmann, H M, Fox, L, Macknick, J, McCall, J, Janski, J, and Jenkins, L. 2023. If you build it, will they come? Insect community responses to habitat establishment at solar energy facilities in Minnesota, USA. Environmental Research Letters. DOI: 10.1088/1748-9326/ad0f72
