Researchers at Penn State have discovered in a recent study that Marcellus Shale fracking activity can aid in the spread of invasive, non-native plant species.
The findings, published in July in the Journal of Environmental Management, are a result of research that began in 2012 and focused on 127 natural gas well pads on state forest land in the north-central part of the state.
Lead researcher Kathryn Barlow, a doctoral candidate in Penn State’s department of plant sciences, said the team found that 61 percent of the wells studied have at least one invasive, non-native plant species growing around the edges of the well pads or along the sides of the access roads.
Of the wells that are being colonized by invasive plants, 19 percent have more than one non-native plant, such as Japanese stiltgrass, reed canary grass and crown vetch, according to the study.
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“We suspected that with any disturbance to a forest and human activity, there’s going to be spread of invasive plants, so it’s not surprising that we found them,” Barlow said. “But we felt that it would be important to quantify and better understand the colonization so far.”
As the research progressed, the team began discussions with the Department of Conservation and Natural Resources on a potential collaboration effort to advance the efforts of both parties to understand non-native plant behavior.
“These conversations led ultimately to a monitoring protocol that was adopted by both the bureau of forestry and Penn State,” Kelly Sitch, an ecologist at the state Department of Conservation and Natural Resources, said in an email.
The protocol helps DCNR’s gas monitoring teams to track invasive plants on the 180 well pads, 28 freshwater impoundments, 17 compressor stations and 34 infrastructure pads located on state forest land, Sitch said.
In addition to tracking the plants using the survey protocol, Penn State analyzed the role fracking vehicle traffic plays in spreading the seeds.
Fracking or hydraulic fracturing is the process of drilling into the earth and injecting fluid at high pressure into rock, fracturing the formation and releasing natural gas. To reach the desired well depth, about 1,200 one-way truck trips are required to deliver the fluid needed for the process, Barlow said.
The Penn State team measured how far the invasive plant seeds can blow based on the wind speed created by a passing vehicle. The team also discovered that the seeds can stick to the undercarriage of the vehicles, which Barlow said accelerated the spreading rate of the plant colonies.
While the study focused on fracking well pads and access roads, Sitch said the gas activity is not the lone propagation source of the invasive plants in the state forests.
“Any activity that results in the opening of the forest canopy or soil disturbance increases the likelihood of colonization by invasive plants,” Sitch said. “Certainly, as a result of the disturbance caused by Marcellus Shale-related construction, Penn State’s study has shown that invasive plants are spreading across many well pads.”
Invasive plants can grow and spread across sites quickly and displace native vegetation, Sitch said. In those areas, plant diversity is often reduced to one or two species. The ecosystem services provided by the once diverse collection of plants is lost, which creates a ripple effect for all other species in the forest habitat, he said.
Over the past decade, Barlow said the threat that fracking poses to an area’s water system has been well-covered, but as more research about the unintended consequences of natural gas extraction is published, a full understanding of the process is possible.
“It’s of course important to understand the impact on our water, but there’s been less emphasis on plant communities with this development,” Barlow said. “If plants are the foundation for what creates a habitat, I think the full story needs to be told.”