Sowing grasses and wildflowers among solar panels can bring big increases in bees and aid crop pollination in nearby fields, a four-year study in the US suggests.
The expansion of solar energy is sometimes seen as a threat to the environment because of the large amounts of land required, but solar developments can be designed to restore habitat and bring biodiversity gains.
at Argonne National Laboratory in Illinois and his colleagues monitored the impact on insects after two solar farms in Minnesota were planted with native vegetation.
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The solar farms were built in 2017 on land that was previously used to grow rows of crops. The entirety of both sites were sown with specially designed seed mixes in 2017, and smaller, experimental plots were sown again a year later.
From annual surveys of the experimental plots in the summer, Walston鈥檚 team found that the number of beneficial insects tripled and their diversity increased by 13 per cent from 2018 to 2022. There was a particularly big impact on native bees, with their numbers increasing 20-fold over the study period.
The researchers also counted insects visiting flowers in adjacent soybean fields, finding a comparable level of visits as there were in fields next to grasslands enrolled in a restoration programme. This suggests attracting pollinators to the solar sites has a spillover effect on nearby farmland.
Several programmes have been established in US states to encourage the creation of wildlife habitat on solar farms. One of the most notable is in Massachusetts, which features a graded and financial incentives for developers.
鈥淲hile we prefer solar energy projects avoid ecologically sensitive areas altogether, solar-pollinator habitat can be a means to mitigate some ecological impacts associated with the conversion of lands to solar energy,鈥� says Walston.
鈥淚n some cases, where solar facilities have been properly sited on disturbed or marginal lands, habitat-friendly solar may provide a net benefit to biodiversity.鈥�
The study included recommendations on best practice for growing pollinator-friendly plants, highlighting the importance of soil preparation, mowing regimes and the height of solar panels.
鈥淭here is a great deal we don鈥檛 know yet about how best to establish and maintain native vegetation at solar arrays in ways that benefit pollinators, as well as other wildlife,鈥� says at the University of Massachusetts Amherst. 鈥淭his study provides a great example of how we can begin to fill in those data gaps.鈥�
Environmental Research Letters
