Pollinators play a crucial role in ecosystems. They are instrumental in the reproduction of 80 to 95 percent of plant species in natural habitats and three-quarters of our major food crops. A diverse group of species fulfills this essential work, including bats, bees, birds, flies, wasps, moths, butterflies, and beetles. Unfortunately, many of these populations are in rapid decline. Habitat loss, degradation, and fragmentation are major threats to these important critters.
A team of researchers at the Argonne National Laboratory investigated if pollinator-friendly solar farms can mitigate threats to pollinators while generating clean energy, and their research was published in a study in Environmental Science & Technology. They examined 2,800 planned and existing utility-scale solar energy facilities across the continental United States. Their findings are encouraging, especially in the Midwest and East Coast regions.
The Benefit to Farmers
Argonne researchers, Leroy Walston and Heidi Hartmann, attempted to quantify the monetary benefits of increased crop yields associated with increasing pollinator habitat at utility-scale solar farms on soybeans, almonds, and cranberries. These crops rely on insect pollinators for crop yields. If all existing and planned utility-scale solar facilities near these crops included pollinator habitat and boosted yields by a mere one percent, crop values could increase by $1.75 million for soybeans, $4 million for almonds, and $233,000 for cranberries.
Many solar farms have gravel or turfgrass around the panels. However, native plants, including native prairie grass or wildflowers, would improve pollinator habitat in many regions. The population of wild bees declined in 23 percent of the continental U.S. from 2008 to 2013, according to a 2015 study published in Proceedings of the National Academy of Sciences. Yet these insects are important to many crops. Ironically, this population decrease is largely associated with the conversion of natural habitat to row crops, which are often dependent on pollinator populations.
In addition to benefitting nearby farmers, native landscapes could reduce solar farm maintenance costs over time and help prevent erosion. Native wildflowers are often drought resistant, reducing solar farm landscaping maintenance over time.
Native Plants versus Turfgrass
“The long-term cost over the life of the facility to maintain pollinator habitat is half or even less than the cost to establish and maintain turfgrass,” says Hartman in an interview with Earth911. “I’ve seen a variety of costs, and it varies job by job because of the mowing costs. In the first four years, pollinator habitat is more expensive because the wildflower seeds are more expensive than the turfgrass seeds. Once established, native wildflowers need much less maintenance and they only need one mowing a year. They are also much more resistant to drought and soil erosion. Even 20 years down the road, the soil underneath will be in good condition to return it to valuable cropland.”
Native plants adapt well to soil and climate conditions in their area and are ideally suited to provide nectar, pollen, and seeds for native insects, butterflies, and wildlife. They help provide shelter to wildlife and promote biodiversity. The deep root systems of many wildflowers reduce water runoff and help prevent soil erosion. In addition, reduced mowing requirements reduce carbon emissions and help promote air quality. Turfgrass, by contrast, typically requires fertilizer and is a monoculture.
The Value of Natives to Solar Farms
The ecosystem benefits of native plants may be helpful in getting support for solar farms, especially in agricultural communities. “Some solar developers are looking at where ecosystems are really friendly to establishing native plantings and wildflowers,” says Hartmann. “The solar facility will have better ecosystem services if they establish pollinator habitat. Developers are finding that there is a lot of interest in this within the local communities. Many solar facilities are going into former agricultural land, and this is a great way to gain acceptance for these projects.”
Establishing pollinator habitat will not have a negative impact on solar energy output, according to Hartmann. Because solar panel efficiency drops when the panels get too hot, native plantings under the panels may actually be beneficial. The plants could help cool panels compared to commonly used gravel, which can absorb heat. Ultimately, establishing pollinator habitat depends on solar developers, but policies and public support can help encourage progress in this area.
As population growth requires greater food cultivation, the importance of pollinators will only increase. Creating more habitat for these remarkable creatures is essential for healthy ecosystems and crop production alike.
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