Insect pollinators provide critical ecosystem services across the planet. A 2011 study in the journal Oikos estimated that between 75 and 95 percent of the planet’s flowering plant species, including many of our food crops, depend on animal pollinators for reproduction. However, insect pollinators have been declining across the globe over the course of the past few decades. The monarch butterfly, which the U.S. Fish & Wildlife Service in 2024 proposed to list as “threatened,” exemplifies this problem. Monarchs declined in North America from an estimated 388 million individuals in 1996 to an estimated 21 million individuals in 2024. Scientists have not identified a single cause in the pollinator declines, but they believe habitat loss, increases in extreme weather events, smoke, pollution, and widespread pesticide use all play a role.
In the eastern United States, many pollinators prefer to forage in early successional habitats, which often have a higher percentage of flowering plant species than mature forests. These regenerating habitats have been disappearing in much of the Northeast and Midwest during the past 50 years due to widespread land use changes and development. To combat the loss of these habitats, those concerned about the fate of native pollinators have been exploring novel ways to provide suitable pollinator habitat, from planting wildflowers along highway medians to converting lawns to wildflower meadows, to adding native wildflower gardens to urban areas. In an article published in the March 2025 issue of Northeastern Naturalist, a group of researchers from West Virginia University investigated whether natural gas pipeline corridors could help support pollinator populations.
Increased natural gas production in the Appalachian region during the past decade has resulted in the creation of natural gas pipeline corridors. These corridors are composed of underground pipes that transport natural gas and the above-ground rights-of-way (ROW). Regular mowing (every 2 to 3 years) along the ROW minimizes woody plant growth, thereby maintaining herbaceous plant cover.
To examine whether these areas might provide suitable pollinator habitat, the authors conducted pollinator and habitat surveys in natural gas ROW in northern Pennsylvania. Researchers randomly selected 80 study plots along ROW. About half of these had been “reclaimed” (seeded) with a traditional “contractor” seed mix primarily comprising annual ryegrass (Lolium multiflorum) and tall fescue (Festuca arundinacea), both native to Europe but widely used in North America as ground cover. The other half were reclaimed using one of 16 pollinator-friendly seed mixes composed heavily or entirely of native grasses and wildflowers.
Researchers surveyed each plot along a 100-meter transect four times between May and August in 2020, and visually identified pollinators to the lowest taxonomic level possible. The authors focused on butterfly species richness and density as well as bee density. They also recorded vegetation and abiotic characteristics of each study plot. For vegetation data, they measured maximum vegetation height, percentage of ground covered by vegetation, and percentage of flowering plants within three 1-meter-square plots along each transect. For abiotic parameters at each plot, they obtained ROW width, total forest opening width, and ROW age. Researchers examined these parameters in a suite of models to identify whether any of these features were associated with pollinator richness or density.
The authors found that the percentage of actively flowering plants was the most important variable for predicting butterfly species richness and density and bee density in the natural gas pipeline ROW. Based on these results, the authors confirmed that natural gas pipeline ROW can provide important habitat and resources for pollinators, but only when managed in a pollinator-friendly manner. The authors proposed that ROW reclamation work use multispecies seed mixes composed of native flowering plants with asynchronous flowering cycles to provide nectar resources over the course of the entire growing season. They also suggest that any mowing done to maintain herbaceous cover and to inhibit woody growth occur following the first frost in autumn.